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General Forums => Aircraft and Vehicles => Topic started by: Shuckins on June 28, 2007, 08:01:23 AM

Title: Corsair Turning Ability in AH
Post by: Shuckins on June 28, 2007, 08:01:23 AM

Is there a discrepancy between the Corsair's turning ability in AH as opposed to real life? Reading some of the posts in this forum I hear a fair number of sticks talking about the Corsair getting down and dirty, turning on a dime, outmaneuvering Spits, hanging pretty well with Zeros, and the like.

This contradicts much of what I've read about the subject over the years. Some of you who have much more info on the subject than I can offer some incite into the reality of this issue.

The best source I have for this is Francis Dean's tome
America's Hundred Thousand. In it he cites a comparison of the turning ability of top American fighters in the turning game, as they were rated by actual World War II fighter pilots at one of the fighter conferences held during the war.

Dean's data is for clean aircraft configuration, gear and flaps retracted, and no external stores. The assumption is made in each case that engine power available is sufficient to keep the plane in level flight, not sinking, during the turn. In such a case the minimum turn radius occurs when the wing develops the maximum possible lift coefficient without stalling. The radius depends on the wing loading and maximum wing lift coefficient.

The information available was for stall speeds in three g turns. In any of the aircraft, if the control system was suitable, wing flaps could be more or less quickly dropped to a maneuver position to give increased wing lift coefficient and thus provide tighter turns, but these cases are not reflected in Dean's data. For ranking purposes the quickest turning aircraft, the FM-2 Wildcat, was given an arbitrary value of 100%, and the rest are ranked relative to it.

The other U.S. fighters tested yielding the following turning performance:

P-63A at 8780 lbs gross weight: 124%.

P-61B-1 at 27,000 lbs gross weight: 133%

F6F-5 at 12,500 lbs gross weight: 137%

P-51D-15 at 9500 lbs gross weight: 179%

P-38L at at 17,488 lbs gross weight: 205%

P-47D-30 at 14,300 lbs gross weight: 206%

F4U-1D at 11,803 lbs gross weight: 212%

The results for the Corsair, Dean states, seems to be due to a relatively low maximum lift coefficient, because wing loading was not overly high. The spoiler placed on the right wing of the Corsair to eliminate an unsymmetric stall problem is suspected of dropping the overall lift coefficient considerably, in fact an NACA test report notes this was indeed the case.

As to the matter of flaps, would they really make that much of a difference in the case of the Corsair. With a turning ability rated at 212% of that of the Wildcat, it had a lot of ground to make up to catch the top-turning fighters in this comparison.

Also, given the Corsairs nasty stall characteristics in real life, which were not-fully resolved even by the end of the war, a close, hard-turning knife-fight was not where a pilot wanted to be in a Corsair....even WITH flaps deployed.

Widewing, et. al, what information do you have on this?

Regards, Shuckins

Title: Corsair Turning Ability in AH
Post by: hitech on June 28, 2007, 10:26:22 AM

You are just measuring stall speeds, it makes no difference if you are at 3 g or 1 g, the ranks I.E. order of the planes will be the same.

Stall speed is only 1 component of turn performance.

HiTech

Title: Corsair Turning Ability in AH
Post by: mtnman on July 02, 2007, 01:36:05 PM

All things being equal, the AH F4U's won't out-turn spits, zero's, hurris, etc. Put the F4U against any of these on the deck, at the same fairly low airspeed, and the F4U is dead. It's heavy, doesn't accelerate very well, and stalls nastily when you try to make it do things it doesn't want to do.

From everything I've read (including my "Pilot's Manual for the F4U Corsair") the F4U's handle about like I would expect. They stall at the correct speed, etc. From watching the corsairs at the EAA airshow every year, and watching video footage, I would say that the AH corsair feels like what I would expect it to, based on what I've seen. Obviously I've not seen them get real down and dirty though.

My radio-control F4U would kick the crud out of the AH F4U's though. This I would also expect with the thicker airfoil, lighter wing loading, and higher power/weight ratio of the RC version.

That being said, there really isn't an airplane in AH that causes problems for a decent F4U stick. It comes down to the pilots. Can I out-turn those uber-turners? Yes. But only if I can convince them to stay fast, and then I can only do it for a turn or two. Getting them fast is no problem. I act like I'm going to run away, so they chase me, then I get dirty to get behind them for a quick shot. If I kill them, they perceive it as the F4U out-turning the spit, or zero or whatever, and label it as a flight model error.

In actuality it was an error on the part of the spit, zero, or hurri pilot.

If I don't get my quick kill, I have two options. One- I continue to turn with the spit, zero, or hurri. Unless the other stick is a newbie, I'm gonna die. Two- I realize that my advantage is gone or will be very quickly, so I exit to try again. This is also easy. I simply set up my maneuver so I can dive out one direction (south, say), while the spit is going up the other direction (north, say). He has to reverse, which allows me time to get speed and some seperation (1-1.5K).

Now we repeat- he thinks I'm running (I'm not, I'm looking at him as an easy kill). This makes him try really hard to catch me. His quicker acceleration will help, and if not I drop throttle a bit to appear more tasty. I really only want about 250-300 mph anyway. So as he closes, I slow down, get the overshoot, and kill him. Briefly as he goes by I will be able to turn tighter than him, because I'm slower. Not because the F4U out-turns the spit though, but because the spit is too fast again. Again, as he slows down, if I haven't killed him yet, he will eventually out-turn me, in which case I exit again. I'll get it right eventually. I have all day, it's not like a spit, zero, or hurri can run away from me, hehe.

So hopefully you can see that they way things are percieved by the AH pilots is not necessarily the way things really are. F4U's out-turning the classic turn-fighters can be viewed as an uber-flap plane, or as a skewed flight model favoring the American planes, or a myriad of other things.

You'd be further ahead to realize that it is the TECHNIQUE used to out-turn the other plane that matters. Not a "messed up flight model". Those that realize this will be able to APPEAR to do wondrous, often impossible manuevers. Those that don't will be left in the hanger, or here on the boards whining about uber planes.

MtnMan

Title: Corsair Turning Ability in AH
Post by: Oleg on July 02, 2007, 02:32:43 PM

Of course, you cannt outturn spit5, any zero or hurr in corsair at slow speed (unless their pilots really suck). But corsair can handle very well against spit8/9/16 and most of other planes at any speed.

Title: Corsair Turning Ability in AH
Post by: Sketch on July 02, 2007, 03:29:23 PM

Quote

Originally posted by mtnman
My radio-control F4U would kick the crud out of the AH F4U's though. This I would also expect with the thicker airfoil, lighter wing loading, and higher power/weight ratio of the RC version.

What's the perk value on that? And does it have a 20mm setup? :D

Title: Corsair Turning Ability in AH
Post by: Furball on July 02, 2007, 03:33:27 PM

I wonder why the F4U has no bad handling qualities at all. It wasn't known as the Ensign Eliminator because it chewed up flags (yes, granted the view didn't help things). It just kinda floats around like it is on a magic carpet and goes wherever you want it to without any effort.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 02, 2007, 04:36:10 PM

The F4U's low speed stall is a lot nastier than a lot of people seem to think. I've been flying the Corsair almost exclusively for going on two years and there's times where she still gets out from under me at low airspeeds when I try to push her just a bit too hard.

The guys that manage to keep her floating like that know just how hard to push her, or have the control to be able to regularly recover in that first split-second of departure, before it turns into a full spin.

Title: Corsair Turning Ability in AH
Post by: Trikky on July 02, 2007, 07:21:45 PM

I've seen more Spits enter flat spins than F4U's.

Whenever I've flown em, which is rare, biggest problem I have is dropping too much flap and having the nose elevate a couple of hundred degrees past my target.

Think its got something to do with the G key.

Title: Corsair Turning Ability in AH
Post by: CAP1 on July 02, 2007, 08:50:39 PM

Quote

Originally posted by mtnman
.

My radio-control F4U would kick the crud out of the AH F4U's though. This I would also expect with the thicker airfoil, lighter wing loading, and higher power/weight ratio of the RC version.

MtnMan

this is off topic, but i HAVE to ask..........what kind is it? is it a kit, or an arf? what size engine? i fly a P51 with a saito 1.5 4 stroke,, and also a hangar nine T34, with an os .50 in it......i do havean electric corsair.....by alpha models...it has an axi outrunner motor, and for how small it is it hauls arse!!......handles unbelievably well too........

have fun dude!

<>

Title: Corsair Turning Ability in AH
Post by: BaDkaRmA158Th on July 02, 2007, 09:09:50 PM

The REAL problem is the fact the lower the flaps are,the more STABLE it becomes.

This should not be, granted the f4u's tourque is still then same, the airflow under its wings less, thus harder to keep from a spin.

Right now,you drop flaps to full and the dman thing is more like a jet.

For a plane with horrible tourque, with flaps..it doesnt exsist.

A major error if every their was one.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 02, 2007, 09:26:08 PM

"this is off topic, but i HAVE to ask..........what kind is it? is it a kit, or an arf? what size engine? i fly a P51 with a saito 1.5 4 stroke,, and also a hangar nine T34, with an os .50 in it......i do havean electric corsair.....by alpha models...it has an axi outrunner motor, and for how small it is it hauls arse!!......handles unbelievably well too........

have fun dude!"

I've never flown an ARF, beyond teaching someone else how to fly theirs with a buddy-cord. All my planes ve been kits or scratch-built. My first 15-20 planes were scratch-built from plans or 3-views that I drew up to fit my engines. I couldn't afford kits back then, but was an artist so found it easy to draw up what I wanted. I learned lots that way too.

My current F4U is a Top Flite kit, with a .75 SuperTigre. I'm actually in the process of rebuilding it after an "incident" while landing. I fly behind my house (live on a farm), and the road is narrow, with several obstacle's. I bought another kit and am rebuilding it now. Before that, I flew a "short-kit" corsair (brand??) and a scratch-built Ultimate Bipe. Along with a bunch of others.
My first P51 caused me some problems too. An incident involving about $10,000 damage to a doctor's office condominium in Missoula, Montana while I was in college. Damage to the secretary's office (double-paned gas filled window on the third floor, computers, fax machines, printers, etc, etc...) was pretty severe. I ended up working on the owners (one of the Doc's) llama ranch for credit to repay it. Kinda funny, but it also kinda sucked.

I'm also scratch-building a Pitts Super Stinker now, and am flying a .40 Cherokee.

"I wonder why the F4U has no bad handling qualities at all. It wasn't known as the Ensign Eliminator because it chewed up flags (yes, granted the view didn't help things). It just kinda floats around like it is on a magic carpet and goes wherever you want it to without any effort."

Sounds like it ranks up there with all the other planes in AH when you describe it that way.

MtnMan

Title: Corsair Turning Ability in AH
Post by: mtnman on July 02, 2007, 10:11:15 PM

The nickname of "Ensign Eliminator" was earned mainly due to issues with landing, and in particular landing with full flaps and not enough power by inexperienced pilots. I think it would be an error to judge a flight model based on a nickname. If we did, the issue that would arise next would be whether it should be modeled as the "Ensign Eliminator", or as the "Sweetheart of Okinawa". I'm guessing the model wouldn't be the same for both nicknames.

The landing issues reported by most literature seem to exist in the AH version. Has anyone heard of a new corsair pilot NOT complaining about the ground loops on landing?

I've heard that torque is not modeled as harshly as it could be, on ANY of the AH planes. Maybe true? I have no idea. I've heard one supposed actual pilot with F4U-4 experience says the AH -4 is undermodeled. I don't know. I'd let him speak for himself if he so chooses.

Maybe the pilot manual for the F4U has the answers.

It says under "Stalls" (pg 44 of my manual)- "The stalling characteristics of the airplane are not abnormal, and warning of the approach of the stall exists in tail buffeting, the abnormal nose-up attitude, and increasing left wing heaviness with power on." Sounds like what I see in AH.

It says under "Spins" (pg 45)- Recovery from the incipient stage of a spin following a stall is rapid on normal use of the controls, and, if prompt action is taken, no trouble need be experienced, as the stalling characteristics of the airplane are not particularly abnormal." Hmmm, that sounds real familiar too.

Seems doubtful the manual would downplay potentially dangerous characteristics. That could lead to bad things.

Or this article on the F4U handling characteristics-

All variants of the Corsair are known for a tendency to fall off on the left wing in power-on stalls, rolling over onto the side or back and losing as much as several hundred feet of altitude before control can be fully regained. When there is sufficient altitude, the pilot is easily able to regain control, but at low altitudes this can prove fatal, leading to the moniker, "Ensign Eliminator" during early Navy tests of the plane.[citation needed]
Ground handling was a challenge for inexperienced pilots, due to the combination of a castoring tailwheel (that is, it freely swivels unless locked) and the length of the fuselage and cowling ahead of the cockpit (which inspired the nickname "Hose Nose"). The Corsair must be taxiied as a series of S-turns, with the pilot using the brakes to turn the plane first one direction then the other, in order to see past the nose. Crosswinds or sloppy use of the throttle or brakes rapidly leads to embarrassment for the pilot, as the plane veers off the taxiway or (in extreme cases) spins around in a low-speed groundloop and finally stops pointing the wrong direction. When the plane is taxiied a long distance, brake fade —the tendency for hot brakes to become unreliable— can also cause these problems. Pilots may wait a few moments before beginning the takeoff roll in order to let the brakes cool, so that they will have even steering during the first part of the roll before the rudder becomes effective.[citation needed]
The early models of the F4U had a major problem in landing, as the oleo struts in the landing gear would compress, then bounce the plane upward, riding the ground-effect cushion between the wing and the ground, which was increased when the tail was low in a three-point landing. A bad bounce could leave the pilot with tons of airplane, now out of ground effect, falling out of the sky without enough airspeed to keep the left wingtip from dropping toward the ground. The main gear would hit the ground hard enough to begin the cycle again, finally ending either in a series of smaller bounces or in a crash. Until the problem was solved (in a test program which took months), F4U pilots learned to land at high speed and keep the tail high until airspeed and lift bled off enough to keep the plane on the ground when the tail came down.[citation needed]
An added danger was that the shape of the inverted gull wing on the Corsair blanks out the elevators and rudder when the tail is down on the ground. This problem was relieved somewhat by lengthening the tail gear struts to lift the tail a few inches, where there was cleaner airflow.[citation needed]
Due to the long nose, pilots landing on aircraft carriers were unable to see the Landing Signal Officer (LSO)—or the rest of the aircraft carrier, for that matter—during the final, critical moments of final approach. American pilots developed a technique of applying right rudder and left aileron, crabbing the plane toward the flight deck, keeping the LSO in sight by keeping the nose pointed at an angle. British Commonwealth pilots simply modified their approach pattern into a long, shallow turn to the left, again to keep the nose pointed to the right until the signal to land had been given. (Plenty of footage shows USN and USMC pilots landing while making a left turn. The goal was to see the LSO. Pilots did not land unless the LSO gave the "OK and Cut". It is reasonable to think that a combination of left turn and crabbing were used while coming aboard.[citation needed] Interviews with US Corsair pilots support this as well.[citation needed]

One POSSIBLE problem I do see with the AH modeling (sorry Hitech, not tryin' to pick a fight with you...) is that my manual says the power on stall is 66 knots with 50 degrees of flaps. The power they show is 23" Hg, 2400 RPM. I can't get mine that slow, and I appear to be using more power. Maybe the AH stall is too soon?

BadKarma- Why else have flaps, if not to be more stable at slow speeds. It seems crazy that flaps on planes would be so popular if they led to instability at slow speed. Especially since slow speed and low alt are basic ingredients to landing. Please explain more. How is the corsair jet-like? In acceleration maybe?

Honestly sounds like some are getting spanked by the F4U's, and just need to learn how to deal with them. Maybe your current strategy is less than perfect.

MtnMan

Title: Corsair Turning Ability in AH
Post by: Saxman on July 02, 2007, 10:15:10 PM

Karma --

You ever tried to roll right full power, full flaps at speeds under 100-150mph?

Or...

Have you ever been at reduced power for a landing, full flaps, gear extended, properly trimmed, then all the sudden had to goose the throttle?

If not, try it sometime.

The F4U strongly dislikes turning to the right under low-speed, full-flap conditions. Right roll is very sluggish in this situation when power is on full, and the aircraft has a HEAVY tendency to try and snap roll left and flip over on her back. I HATE being in a low-speed fight where the target makes me go right.

Similarly, she strongly resists executing a snap roll to the right. The roll is slower, very loose, and she'll naturally recover within a revolution after releasing the stick and rudder. On the contrary, in a left snap roll the rate of roll is extremely high and the path of the roll very tight. She'll stay in it indefinitely, until you either recover or hit the ground.

Sudden direction changes under low speed conditions, (especially trying to change from left turn to right turn) even under full flaps, can be VERY unstable. It takes a firm but careful hand to keep her from slipping out of control.

If the aircraft is full flaps down and trimmed for 0 roll and straight flight while power is either reduced or at full idle, suddenly firewalling the throttle will cause the F4U to pull HARD to the left. She won't necessarily snap roll or spin, but it WILL take almost immediate corrective action (such as combat trim) to 0 out the roll and yaw.

Title: Corsair Turning Ability in AH
Post by: SteveBailey on July 03, 2007, 12:50:43 AM

Quote
Originally posted by mtnman

That being said, there really isn't an airplane in AH that causes problems for a decent F4U stick. It comes down to the pilots. Can I out-turn those uber-turners? Yes. But only if I can convince them to stay fast, and then I can only do it for a turn or two. Getting them fast is no problem. I act like I'm going to run away, so they chase me, then I get dirty to get behind them for a quick shot. If I kill them, they perceive it as the F4U out-turning the spit, or zero or whatever, and label it as a flight model error.

In actuality it was an error on the part of the spit, zero, or hurri pilot.

If I don't get my quick kill, I have two options. One- I continue to turn with the spit, zero, or hurri. Unless the other stick is a newbie, I'm gonna die. Two- I realize that my advantage is gone or will be very quickly, so I exit to try again. This is also easy. I simply set up my maneuver so I can dive out one direction (south, say), while the spit is going up the other direction (north, say). He has to reverse, which allows me time to get speed and some seperation (1-1.5K).

Now we repeat- he thinks I'm running (I'm not, I'm looking at him as an easy kill). This makes him try really hard to catch me. His quicker acceleration will help, and if not I drop throttle a bit to appear more tasty. I really only want about 250-300 mph anyway. So as he closes, I slow down, get the overshoot, and kill him. Briefly as he goes by I will be able to turn tighter than him, because I'm slower. Not because the F4U out-turns the spit though, but because the spit is too fast again. Again, as he slows down, if I haven't killed him yet, he will eventually out-turn me, in which case I exit again. I'll get it right eventually. I have all day, it's not like a spit, zero, or hurri can run away from me, hehe.

MtnMan

Do this in a mustang and you are a lucky, dweeb, runner, gamer, coward, cherry picker, altmonkey, scorepotato, gangbanger, spray-and-prayer, no-skill, noob, tard, opportunistic, hack, squeaker, cheater, exploiter,(mustangs can't do that so I must be cheating/exploiting). At least that's what I've been called. All this from flying around no higher than 8k looking for the biggest darbar. :aok

Title: Corsair Turning Ability in AH
Post by: Knegel on July 03, 2007, 02:16:28 AM

Hi,

the F4U itself turn in a credible way as long as no flaps get used, but the flaps make a stall fighter out of it, which is able to outturn the Spit14 and the F4U´s can employ the flaps at a very high speed, what give it a big extra advantage over most other planes.

The flaps are a major problem in AH in general, they all work like big fowler flaps, while normal flaps in general decrease the turnratio and glide path but not the radius in a sustained turn, if they are extracted more than 10 degree.

The flaps in AH seems to work over the complete length of the wing, while real flaps most only comver 50-70% of the wing, so if the flaps get used, only 50-70% of the wing get the extra lift, while the rest of the wing dont provide much lift anymore, cause at speeds where the "flap-airfoil" provide better lift, the "normal " airfoil stall or dont provide much lift at all(depending to the AoA). As result the lift of the the complete wing with extened flaps dont get higher, it rather decrease, but the wing provide this smaler lift at smaler speeds, where the wing without flaps already would stall.

Normal flaps have the highest influence to the C/L max, if they are extended by around 6 degree, at this moment the wing without flaps(wingtips) still create good lift and the wing with lift also have a good gain, resulting in a rather high lift with rather smal amount of drag, thats why this is called combat setting. With a higher angle the flaps mainly produce drag, used to influence the glidepath, while the lift remain rather constant(possible lift increasement due to the flaps get event out by the decreasing lift of the wingtips).

Imho the tunr relations without flaps fit rather good and the turn performence with 1 step flaps is also still credible, but then it get out of hand.
This count for many planes, not only the F4U.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: mtnman on July 03, 2007, 04:08:06 AM

Pg 44- under "Manuever Flaps"

"The wing flaps have been designed for possible use in manuevering. The flaps may be used to increase lift and thereby decrease the radius of turns at low speeds. The flaps are also useful in increasing the drag of the airplane so that it may be quickly decelerated to the optimum speed for a short radius turn. In general, flap deflections of 20 degrees or less will be the most helpful in improving maneuverability. Therefore, a setting of 20 degrees has been established as the "maneuver flap" condition."

Are there any planes other than maybe the bombers in AH that CAN'T out-turn a Spit14?

Direct hit Steve! I didn't mean to imply that you would be popular if you managed to A- live, and B-kill the other guy, lol. Obviously, a pony can't kill a spit. Neither can a hog. Something must be screwy with the game, or flight model, or your computer is better than mine, or my connection is getting me killed, or you cheated, right! NO WAY can you beat my TnB plane!

You guys should try flying the corsair with full flaps deployed for the duration of your fight. See how long you can hold your E. If you're dropping them, and leaving them down, or assuming the other guy is, that may explain your confusion. Dropping them and leaving them down creates lots of drag, and kills your E. You get the most turn advantage at the lower settings. The higher settings may help briefly, but in the end the spit or whatever will eat you alive. Generally, I can kill him before that happens, especially if the spit is WEPing to try to get around me quicker.

Maybe Hitech should neuter planes that hurt peoples feelings. I can't believe those WW2 designers! How dare they design something that worked! Didn't they realize they practically lived in the stone age? How rude...

MtnMan

Title: Corsair Turning Ability in AH
Post by: Knegel on July 03, 2007, 01:27:31 PM

Hi,

i think you dont know the fakts, eh??

You should use this comparison page a bit more before you write your hero storys, that the pilot make the winner etc.

http://gonzoville.com/ahcharts/index.php

Turnradius no flaps:

F4U-1: 674ft
F4U-1D: 702ft
F4U-4: 691ft
SpitIX: 632ft
Spit14: 629ft
A6M5 : 423ft
F6F-5: 649ft
109G6: 648ft
P38J: 817ft
190A5: 787ft

Turnradius full flaps:

F4U-1: 425ft (37% smaler radius) :rofl
F4U-1D: 427ft (39% smaler radius) :rofl
F4U-4: 428ft (38% smaler radius) :rofl
SpitIx: 433ft (31,5% smaler radius)
Spit14: 509ft (29% smaler radius)
A6M5 : 342ft (29% smaler radius)
F6F-5: 465ft (28,5% smaler radius)
109G6: 481ft (26% smaler radius)
P38J: 598ft (27% smaler radius) This plane has folwer flaps.
190A5: 548ft (30,5% smaler radius) this is also strange

And dont forget, the Spit14 not only have a much better powerload than the early F4U´s and still a better one than the F4U-4.

The turnradius gain of the F4U´s is so much outstanding, thats what i call a joke. The F4U-flaps wasnt something special, the F4U wasnt designed to be a turnfighter at all and it dont got used as such.

Since the F4U-4 can employ the combat flaps at higher speeds than most other planes in fact it can outturn even the A6M5 at a wide range of speed.

Unfortunately we cant see the turn rate with full flaps in that comparison, but the F4U´s are also rather good while that. With full flaps they hoover around like a helicoper.

Actually all planes behave strange with full flaps, but the F4U´s are most outstanding. Most planes had enough torque to make stallspeed flights with full power and full flaps impossible, while our planes turn nice tight, good controllable, they also make nice tight loops while that. VERY strange that is, and most strange is the F4U airframe in AH.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Saxman on July 03, 2007, 01:59:07 PM

Check the pilot's manual scans F4UDOA posted sometime back. The amount of lift generated by the F4U's flaps is quite remarkable (based on comparisons in stall speed at full and no flaps). In fact, at only one or two notches, the F4U's flaps reduce the aircraft's stall speed by the same percentage as the P-51's do at FULL flaps (again, this is taken from pilot's manuals).

Then consider these stall speeds are conservative, at best, for safety purposes, and are conditions that would be likely exceeded by pilots in combat (such as, as mentioned in other threads, the "speed limt" at which the main gear could be deployed as airbrakes).

Title: Corsair Turning Ability in AH
Post by: Red Tail 444 on July 03, 2007, 02:07:41 PM

The instant turn rate is excellent in the corsair, and ovet 300 knots, she turns very well.

She's not designed to turn with zekes, and wasn't designed to shoot down allied aircraft, either. that being said, the only aircraft I don;t have supreme confidence fighting is the spit 5 and F4F, and the hurricane 4 cannon model.

I fly the F4u exclusively, and while still only an average stick at best, know enough secrets to outmanuver many planes with a smaller turn radius.

Like all rides, it's about flying close to the edge, and like anotherposter said, regardles of doing everything right, if you push too close to the edge, you'll get into a very bad situation.

I had a 109k4 by the gonads in my F4U-4 during an extended 1-1, and snap rolled it into an orchard. never saw it coming, and couldn't get out of it. I don;t know if it's overmodeled or not, but I can assure you that it's probably the least forgiving ride in the game.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 03, 2007, 03:37:00 PM

Quote
Originally posted by Saxman
Check the pilot's manual scans F4UDOA posted sometime back. The amount of lift generated by the F4U's flaps is quite remarkable (based on comparisons in stall speed at full and no flaps). In fact, at only one or two notches, the F4U's flaps reduce the aircraft's stall speed by the same percentage as the P-51's do at FULL flaps (again, this is taken from pilot's manuals).

Also the P51 flaps on two notches reduce the stallspeed to almost the same like the P51 with full flaps!!
Thats what i did explain before, full flaps dont bring a lift gain, but a drag gain.

Quote
Originally posted by Saxman
Then consider these stall speeds are conservative, at best, for safety purposes, and are conditions that would be likely exceeded by pilots in combat (such as, as mentioned in other threads, the "speed limt" at which the main gear could be deployed as airbrakes).

If the the stallspeeds are conservative, they are conservative for all planes, so there is nothing to gain.
Actually the stall speeds in a horizontal flight are rather credible, but the full power behaviour at stall speed and the behaviour while turning fully banked at stallspeed with full flaps is very strange.
Since the stallspeed of the F4U isnt below that of other planes in this group i realy doubt the tunrperformence with full flaps.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: bozon on July 03, 2007, 04:22:09 PM

F4u truly remarkable quality in AH is its stability at stall speeds, not its potential turn ability.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 03, 2007, 05:14:32 PM

Hope F4UDOA doesn't mind me borrowing his scan, but:

(http://mywebpages.comcast.net/markw4/F4Ustall.jpg)

Check the chart down in the bottom-right.

F4U stall speed clean and power on is 84kts. Power on full flaps reduces the F4U's stall speed to 66kts. If all flaps generated was an increase in drag the stall speed would be the same REGARDLESS.

As a better comparison, take a look at the power off settings which range from clean to full flaps:

Clean - 87kts
20 - 79kts
30 - 77
50 - 75

The biggest increase in lift is between clean and 20 degrees (which fits within the behavior stated by mtnman. The F4U receives its greatest boost from one or two notches of flaps). However the lift generated STILL continues to increase as the flaps continue to deploy. So these flaps do NOT just generate extra drag beyond the second notch.

bozon: I disagree. I've found it takes a more experienced stick to keep the F4U stable at stall speeds than other aircraft and someone new to the game won't have that control, which is why you can pretty quickly tell an experienced Hog driver from a newbie. She can, does, and WILL depart without warning, and as I said I've been flying the thing almost exclusively in here for a year and a half, and she still gets away from me time to time.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 03, 2007, 06:17:51 PM

Knegel, I'm familiar with the comparison page you mention. I don't wish to just use one source for my information when making an educated judgement.

If you think the plane makes the winner, and not the pilot, that would be an easy fix. Lets just set up a system where the correct plane will always win based on plane type, rather than pilot. So we could say that when a spit sees an F4U, it will automatically win, because it just should. We could even throw in an "odds" factor- when the spit sees the F4U, the pilots of each plane could see some dice spin in the corner, and have their fate decided that way. That takes the pilot out of the equation.

Maybe another option would be to make all the planes fly identically, but with different skins so we could tell which ones were zekes and which were B24's. That way it's all fair.

The charts you mention are based on planes flying with a set amount of flaps, over a set, flat course. If not, they would be meaningless. If one plane is turning flat and the others aren't, there would be no sense in comparing them.

Get in a fight, drop your flaps, and turn flat. See how long you last. Your more successful F4U pilots are not doing things that way. Maybe that's cheating?

Those comparison's aren't taking one heck of a lot of variables into play. They're useful as a basic starting point, but that's about it. What if one plane is faster? Managing throttle? Using the verticle? What if one pilot is a better shot, and makes a quick kill where if he'd missed he would have eventually lost? Heaven forbid one pilot is actually better, or smarter, or faster thinking, or just plain luckier than the other!

Flat out, NOBODY is fighting in the MA under the conditions those test's were conducted. If you (or anyone else) is using those charts in an effort to predict the outcome of a fight, I'd recommend a serious reconsideration.

So far, I've seen your opinion, and a list of comparisons conducted showing how things currently are. I've seen literature from the manual, and from other internet sources describing what I feel I see in the game. Can you produce anything that shows that what we see in the game is flawed as you say? Or do we take your word for it? Is it just plain unfair that one plane would benefit from flaps more than another? What does a corsair "really" do under the circumstances questioned? What does a spit, hurri, 109, or anything else do?

Honestly- I want to fly the most realistic version of the planes possible. If you can show the F4U should be changed, then damn-it I want it changed. I'll fly it no matter how it behaves in the game, because I like it. If you are saying it should be changed "just because", well, I can't side with you there.

MtnMan

Title: Corsair Turning Ability in AH
Post by: Gooss on July 03, 2007, 10:06:10 PM

Great. Just what we need, more Hog dweebs.

Shush.

Let 'em fly cannon planes.

HONK!
Gooss

P.S. How do you do the nasty little thing that gets on their six?

Title: Corsair Turning Ability in AH
Post by: Knegel on July 04, 2007, 01:06:38 AM

Quote
Originally posted by mtnman

Honestly- I want to fly the most realistic version of the planes possible. If you can show the F4U should be changed, then damn-it I want it changed. I'll fly it no matter how it behaves in the game, because I like it. If you are saying it should be changed "just because", well, I can't side with you there.

MtnMan

Hi,

if you dont want to agree to what i say, ok, but you shouldnt ask me to teach you. There are heaps of free informations regarding manouvering with flaps and flight physics in general in the net, go out and take a look.

http://selair.selkirk.bc.ca/aerodynamics1/Lift/Min_Radius.html

Here you can get an idea what flaps in general do, they simply lower the stall speed, but not the max lift that much.

You say the flaps provide more lift, but thats not true, they mainly lower the speed where a rather similar amount of lift is available. Further more the drag increase much with full flaps, resulting in a worse thrust/drag relation, so in less effective thrust, what is needed to stay fast with a high bankangle.
Further more, full power fligths at stall speed are not good possible due to the extreme torque effects of a so powerfull engine, which cant get overcome due to bad working alerons at this speed.
As result the turn radius must rather increase than decrease, when flying with full flaps.

There are comparisons, made by US WWII pilots, nowhere you cant read about a extraordinary turn performence of the F4U, actually it got rated as the most bad turning US fighter. If the flaps would have been a so big advantage, someone would have written about it, like we know it from the P38 and its fowlerflaps, which increase the wingarea and are a real bringer regarding the turnperformence.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: mtnman on July 04, 2007, 04:17:37 AM

The claims "I" made about the flaps causing more lift were quotes from the manual. Who wrote those?

I agree with you by the way. Full flaps are a huge drag. That's why the more successful F4U pilots are not putting them all the way down and leaving them there for a long time. If things get to that point, the F4U is wallowing and an easy target. At least the ones I've flown are.

I get the most benefit with 10-20 degrees, as the manual says I should.

I'll drop more in an effort to stay out of the trees, but it comes with a large drag "fee", so if things are that bad I'm in trouble already.

I don't want you to teach me anything. I've read everything I can find about the F4U and flying in general, and have done that over 25 years. I have never read anything that describes the F4U flying the way you say it should. Problems, yes, but as I've quoted to you already. And then Saxman showed you the same thing.

Agree to disagree? Sure.

Show Hitech that they have it wrong. I see no reason they wouldn't want to correct it. Or that anyone else wouldn't want it corrected.

MtnMan

Title: Flap deployment speed?
Post by: EagleDNY on July 04, 2007, 09:48:10 AM

Interesting that the scan of that manual has a warning about deploying flaps over 200 knots. I wonder if that is just for the F4U-1 - it seems like the AH2 F4U jocks can pop the flaps out at much higher speeds than that.

I tend to only fly the F4Us on our squad nights, but I do note the weird "anti-gravity drive" effect that seems to kick on when you pop the flaps, and I don't see that on anything else I fly. I have to wonder if Knegel isn't right about the flight model calculating flaps as covering the entire wing as opposed to the actual area.

I know it's a subjective observation, but the F4Us just seem weird that way to me.

EagleDNY
$.02

Title: anti-gravity dive?
Post by: Patches1 on July 04, 2007, 01:28:19 PM

What is an anti-gravity dive when loaded with 2x1ks and 8 rox, and about 50% fuel over target?

Just curious....

Title: BTW...
Post by: Patches1 on July 04, 2007, 01:31:01 PM

I don't use flaps or dive brakes when dropping ords....I do plan ahead a bit, though....

Title: Corsair Turning Ability in AH
Post by: WOOD1 on July 04, 2007, 01:57:02 PM

You F4U pilots probably already know this but there is a neat F4U training film at http://www.zenoswarbirdvideos.com/F4U.html It runs about 22 minutes, it's in color with sound and available for real media or win media player.

AKwoodee

Title: Corsair Turning Ability in AH
Post by: Gooss on July 04, 2007, 02:23:06 PM

I use Artlaw's method to drop ord. From about 10-12k, I select ord and roll in on a hangar. My angle of attack is about 45 degrees. I keep full power until the wings start to creak about 450 kts. Chop throttle (yes, it is possible to make a hog compress). Put my gunsight directly on the hangar. Release bombs, switch to rockets, release, pull level, full throttle with wep, lift skirt, and extend making girlie noises. Hopefully an LA7 will follow me out.

I release ord at about 500 kts and that takes the quesswork out of using the gunsight. At 500 kts, bombs and rockets fly real straight.

Hogs hold speed well. Pulling level gently can get me out of trouble usually. For some reason, LA7s seem to be most likely to pursue. By the time they start to close, we're usually in a 1 v 1.

Hmm, sounds like so much fun, I should go back to doing it more often.

HONK!
Gooss

Title: Corsair Turning Ability in AH
Post by: ForrestS on July 04, 2007, 03:09:08 PM

Quote
Originally posted by hitech
You are just measuring stall speeds, it makes no difference if you are at 3 g or 1 g, the ranks I.E. order of the planes will be the same.

Stall speed is only 1 component of turn performance.

HiTech

Whoa they do read the forums.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 04, 2007, 06:36:48 PM

EagleDNY- "Interesting that the scan of that manual has a warning about deploying flaps over 200 knots."

I questioned that too when I noticed that awhile back. I went through the manual in an attempt to correlate the manual to the F4U in AH.

The info pertaining to the planes in AH provided by Hitech is in MPH, not Knots (available through their Home Page). It is my understanding that the gauges in AH are in mph, rather than kts.

The figure I have to convert MPH to Knots is that 1kt = 1.16mph.

So 200kts would equal 232mph. According to Hitech the flaps will deploy on the F4U at 230mph.

You would have to convert all the other manual speeds the same way to compare to game speeds. So the power-on stall speed of 66 knots converts over to 76.56mph, etc...

MtnMan

Title: Corsair Turning Ability in AH
Post by: mtnman on July 04, 2007, 08:50:45 PM

Anybody happen to have a scan of the F4U manual, pg 40 (bottom right) and pg 41 (top left) that they could post?

Those pages describe trimming for torque, and also using full flaps for take-off when the shortest ground distance is necessary. Those pages would apply here, because it would seem that a shorter take-off would require the flaps to provide more lift at higer deflection, rather than just higher drag.

Obviously, more lift comes at a price of higher drag, resulting in a lower climb rate.

I can/will post scans of those pages, but can't right now as I'm headed out of town until Sunday night.

I'd appreciate it if someone (Widewing maybe? or Saxman?) could post them earlier than that...

MtnMan

Title: Corsair Turning Ability in AH
Post by: Saxman on July 04, 2007, 09:41:06 PM

I'm the wrong person to ask for scans. I just grabbed the one I posted from an older discussion on this issue. :D

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 04, 2007, 09:48:54 PM

I am trying so hard to stay out of this conversation it is giving me a headache.

A few things

Knegal- I know you read that the F4U was a poor turning aircraft in AHT but Mr.Dean used incorrect Cl max numbers in his calculation. If you use NACA documented Clmax numbers you will find that his turn index looks quite different. Also many head to head turn test have been performed and documented and I assure you other than the FM-2, F6F and a select few other that the F4U was one of the best turning American fighters with or without flaps. I can provide original documents to prove this and I can point you to the origin of Mr.Dean's Cl max numbers is "The 1944 Joint Fighter Conferance" also published by Mr.Dean under Shiffer Publishing and tell you that they were measured in IAS not CAS and that makes a huge differance. The F4U was also one of the best instantanious turn performers also well documented.

Another item is the torque roll on the F4U. Many high powered aircraft had torque issues at low speed and high power and the F4U was no different. However what seems to be lost in the stall problem suffered by the F4U was not the result of torque alone it was more the by product of an Assymetrical wing root stall that was most prominent with full flaps deployed not the Gyroscopic effect of the propellor. This problem did NOT exist without power applied so in a power off stall or glide it should fly very evenly at the stall. However in a full power waveoff is when the problem really reared its head again because of the wings stalling unevenly not the rudder or rudder trim.

Also a note about the F4U Flaps. they deployed very quickly and were actually supposed to be used in combat. Many other aircraft did not have flaps that could be used at high speed, deployed and retracted manually 1 notch at a time or that provided as much lift. The P-51D's flaps barely accounted for more than 6MPH in stall without power less than 1/2 of the F4U flaps in the same condition.

Could an F4U out turn a Spit IX? Probably not but last time I checked in AH it could not either. It should out turn P-51's, P-47's, P-38's (Which I feel the flaps may be undermodeled) and F6F's in certain loads and flap settings.

The F4U did have a very low stall speed with flaps which gives it a very small turning circle. In all of the flight test I have every seen I have never seen any record of someone doing a WEP max performance turn with full flaps so this is where AH may be a bit "Gamey" despite following the letter of the physics law.

FYI, Dean's calculation for the Clmax of the F4U is correct, it is the other aircraft that are off. Try NACA report 829 on the NACA reports server.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 05, 2007, 02:56:08 AM

Quote
Originally posted by mtnman
The claims "I" made about the flaps causing more lift were quotes from the manual. Who wrote those?

MtnMan

Hi,

more lift dont mean more lift over the full speed range, only more lift at slower speeds.

If you read in the link i posted before, you will find some hints to the influence of the bankangle to the list load and stall speed.

A little less thrust due to a higher drag already minimize the max possible bank angle while a sutained turn and this alone is a reason why planes with flaps dont turn as tight as someone would expect by comparing the stall speed(with vs without flaps).

F4UDOA,

we talk about a sustained turn here, i also believe that the F4U had a good initial turn, as long as there was speed to give up, otherwise i trust the other comparisons.
The FW190 also is a bad sustained turner, but while a highspeed turn it could turn with a Spitfire.
The AH F4U also turn very well without flaps as long as its fast.

I only question turn radius gain by using full flaps in a sustained turn, not only in the F4U, but this plane have BY FAR the highest advantage, while the P38 with the fowler flaps should have it(though, the P38 manouver flaps wasnt fowler flaps).

There was also other planes that could use the flaps in smal steps at higher speeds(109 for example), but they cant employ them above 190mph, what is a huge disadvantage.

For a very short runways it might be usefull to use full flaps for take off, while the liftgain full full flaps is rather smal, but a level flight is something absolut different than a banked flight, where the pilot need to fight side slip and yaw and where we need more power(more torque) to maintain altitude.

The planes are designed to manouver without flaps or with only a bit flaps at speeds good above stall speed. At slow speeds the alerons are not very effective anymore, while the plane like to yaw and swing, with other words, it get unstable, specialy if a huge torque effect work and the plane is banked.

http://www.canyonflying.com/canyonturns.html

This is also a very interesting article, from people who need to turn tight.

This is one of the more important parts:
"Another risk factor of steep turns is that bank angles beyond 30° rapidly increase the load factor and stall speed. For example, the load factor in a 30° bank is only 1.15 G with a 7.5% increase in stall speed. However, a 60° bank imparts a 2G load factor and a 41% increase in stall speed".

But our AH F4U-4 turn with less than 100mph, with full flaps and around 60 degree banking, absolutly alone, without the need to pull the elevator, only with a very smooth correction with the alerons.

Thats magic!

In a decelerated turn flaps will minimize the radius, but once at stall speed not many WWII flaps was able to reach that, simply cause the max lift at a given bank angle while a sustained turn dont increase much, but mainly shift to a slower speed. The little gain in max lift(if at all), at given bank angle while a sustained turn, get evened out by a much higher drag and much worse handling characteristics.
Only planes with endless power without torque (jets) would be able to take benefit by using ful flaps to decrease the turnradius that much in a sustained turn, but then most flaps couldnt stand the forces.

Would be interesting to see some CL diagrams of real WWII planes with split flaps and without flaps in comparison.

Interesting is, the AH F4U-4 turnrate remain almost the same with full flaps and without .

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Knegel on July 05, 2007, 03:59:42 AM

btw, there is a big discrepance inside the FM itself.

The AH F4U-4(100% fuel) + WEP:

With full flaps it turn with roundabout 110mph in 20sec/360°, thats a radius of 512ft.
The climb with this setting at 110mph is roundabout 1900ft/min.

Without flaps it turn with roundabout 180mph in 19sec/360°, thats roundabout 756ft

The climb with this setting is above 4000ft/min.

Now the question:
How can the lift while turning provide a MUCH smaler radius, while the plane in same condition provide just enough lift for less tahn the half climb ratio??

So regarding the climb ratio AH follow my assumtion, that the drag gets so high, that the climb get MUCH worse, so the increased lift get overtuned by far by the drag, but while turning its absolut different.

Thats why i think the flaps in AH work more like balloons, cause their full lift work also upward, no matter if the plane is banked or not, or the planes miss gravity related sideward(downward) movement, if they are banked.

With less upward lift, or more gravity related downward force due to a banked plane, the bank angle of the plane would need to get reduced to keep a level flight and this would reduce the turn rate and increase the radius.

Otherwise the planes would need to climb with full flaps same good like without flaps, but at a slower speed.

Dont get me wrong, i absolutly dont know exact how it should be in reality, but this discrepancy simply cant fit and the "balloon effect" imho is obvious.

Greetings,

Knegel

Title: Floating...Ballon Effect?
Post by: Patches1 on July 05, 2007, 06:54:59 AM

I really don't understand your description, Knegl. I've been "flying" the F4Us for about 3 years and I am regularly killed by many aircraft in the MA.

There is nothing about the F4U that is unusual except that pilots who tamed it claimed that it was a very "nimble" aircraft, albeit an unforgiving aircraft.

Perhaps energy management and SA are more an issue than flaps?

Title: Corsair Turning Ability in AH
Post by: EagleDNY on July 05, 2007, 10:00:54 AM

Quote
Originally posted by mtnman

I
The info pertaining to the planes in AH provided by Hitech is in MPH, not Knots (available through their Home Page). It is my understanding that the gauges in AH are in mph, rather than kts.

The figure I have to convert MPH to Knots is that 1kt = 1.16mph.

So 200kts would equal 232mph. According to Hitech the flaps will deploy on the F4U at 230mph.

MtnMan

Didn't know that about the AH gauges. Learn something new every day ;)

EagleDNY

Title: Re: Floating...Ballon Effect?
Post by: Knegel on July 05, 2007, 10:26:28 AM

Hi,

Quote
Originally posted by Patches1
I really don't understand your description, Knegl. I've been "flying" the F4Us for about 3 years and I am regularly killed by many aircraft in the MA.

At what point is my description not clear to you??

Quote
Originally posted by Patches1
There is nothing about the F4U that is unusual except that pilots who tamed it claimed that it was a very "nimble" aircraft, albeit an unforgiving aircraft.

If you would take a look to the turn circle comparison with and without full flaps, you should agree that the F4U flaps work in a outstanding way.

Nevertheless, i wrote before, the "baloon effect" happen to all Ah planes, while the F4U´s gain most by it(yesterday i found that also the P47´s turn like mad with full flaps).

btw, if you get killed or not isnt realy a argument for anything. If you think the F4U´s are unforgiven, you should try a FW190´s, Bf109´s, P51, Spit14 or 110 while a stall fight with full flaps.
Actually there are not many planes that are less forgiving and higher performing with full flaps than the F4U´s.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Simaril on July 05, 2007, 10:50:46 AM

<----Definitely not an engineer or performance stats guy!

But I find myself wondering -- isn't there a rather large gap between flight test, level turn radius information, and combat conditions in AH?

It seems to me that in AH combat conditions, a given plane's climb ability is very important in the turn fight. The big, heavy, slow climbing hog can be at a big disadvantage against a better climbing opponent, who can maintain nose up better and progressively gain energy at the same speed. (Isnt climb ability a function of power/weight?) So it seems to me that a bird with a larger turn circle (ie La7, full flaps = 453ft vs F4U-1 425) ) can easily compensate by spiral climbing into smaller circles, and then use the potential energy to win the fight. So AH experience may not be a modelling issue at all...

If nothing else, the sluggish acceleration performance makes it harder for the hog to change tactics.

Title: Corsair Turning Ability in AH
Post by: Patches1 on July 05, 2007, 12:17:02 PM

"Ballooning" and "floating" aren't clear to me

Title: Corsair Turning Ability in AH
Post by: Patches1 on July 05, 2007, 12:17:48 PM

yes...I've "flown" the other aircraft as well

Title: Corsair Turning Ability in AH
Post by: Patches1 on July 05, 2007, 12:21:57 PM

I only mentioned being killed because I've died many times deploying flaps at the wrong time, and, at the wrong speed.

Title: Corsair Turning Ability in AH
Post by: dedalos on July 05, 2007, 12:47:12 PM

Quote
Originally posted by Furball
I wonder why the F4U has no bad handling qualities at all. It wasn't known as the Ensign Eliminator because it chewed up flags (yes, granted the view didn't help things). It just kinda floats around like it is on a magic carpet and goes wherever you want it to without any effort.

And if you drop the gear, it floats and climes even better lol.

There was a pach that cam out a while back, around the time of the new look of the planes I think, that took the already perfect flight models of the F4Us and 109s and made them, well, perfect again. That was the time of a lot of the 109 turning ability and flap usage complaining. Never seen a complain since then :rofl
In anycase, F4Us and 109s fly a lot more like Spits now

Title: Corsair Turning Ability in AH
Post by: Patches1 on July 05, 2007, 01:11:20 PM

In an F4U...if I have to drop my gear.....I screwed up!

I'd better have a good shot...or else I'm dead.

Title: Corsair Turning Ability in AH
Post by: Brooke on July 06, 2007, 05:27:16 AM

I think the F4U and its flaps probably work correctly, but it might be that other aircraft (the P-38 for example) are not as close. Here is an analysis:

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/stallSpeedMath.html

Title: Corsair Turning Ability in AH
Post by: Knegel on July 06, 2007, 11:08:12 AM

Hi,

as far as i can see this is for levelflight, not for fully banked flights.

As i wrote many times before, the stall speeds are ok in a level flight, while there is a strange discrepancy as soon as the plane is banked.

I would be happy, if someone could explain why the AH F4U lose more than 50% climb performence cause full extended flaps, while the turn rate remain the same.

Afaik in a suatained turn, the turn rate should also decrease(radius remain almost the same) while flying with full falps, simply cause the high drag of the flaps bind to much thrust energy to keep a high banked flight(what is needed to turn tight). At least thats the reason why the plane lose so much climb performence and i dont see a reason why it shouldnt be the same while turning.

And once again, this isnt a F4U specific problem!!

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Brooke on July 06, 2007, 01:37:35 PM

Quote
Originally posted by Knegel
Hi,

as far as i can see this is for levelflight, not for fully banked flights.

The two are very closely related. I'll post the math of it when I can.

Title: Corsair Turning Ability in AH
Post by: Krusty on July 06, 2007, 02:28:33 PM

Full flaps should not increase climb much, because they are increasing drag as well. When climbing you're fighting gravity more than when you are turning level.

How did you test climb rate with flaps? Did you just auto climb with flaps out? That is set to (example) 150mph for clean climb. If you drop flaps, the nose pitches down to make up for the drag. In effect, you are reducing climb rate because the auto-trim is trying to keep the proper speed.

You need to set the speed to a lower value, then engage flaps during climb. The problem is the minimum speed allowed for that command is 100mph.

By how many MPH do the flaps reduce stall speed in clean level flight? You will probably need to reduce the auto climb speed by the same amount. You may find that the climb rate does not drop as much.

I used to play around with climbing on flaps. I would engage auto climb, then let the speed equalize, then toggle auto trim off and angle trim on quickly. Then I would pop a notch of flaps. Climb rate increased, but as the aircraft got higher you would constantly have to increase speed (decrease angle of trim) because the air is getting thinner. Then after a while you would slow down because the flaps caused drag. I did this all back when the Ki84 first came out, so it has changed a little since then. However, there was a short term rise in Rate of Climb using flaps in a climb.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 06, 2007, 11:47:49 PM

Hi Krusty,

it dont matter if the plane have to fight gravity more while a climb or not, cause we have the climb and turn without flaps to compare.

It need a while until the plane reach a steady climb position with full flaps.

With autoclimb this is rather impossible, cause the plane tend to swing up and down, untill it stall(the autotrim react to slow). I did adjust the trim to keep a steady climb at 110mph.

As i wrote before, the result was 1900ft/min with WEP (F4U-4 100% fuel).

So the climb is by far not better, its much worse, while the turn is better and thats what i dont understand.

That the climb is so much worse i would explain with the much higher drag, which eat the thrust, needed to climb, but same i would expect while turning.

Hi Brooke,

i agree, the two are very closely related, thats why iam so suprised about the discrepancy between climb lost and turn gain.

Would be nice, if someone could make some calculations regarding the climbrate and turnrate with full flaps.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on July 07, 2007, 12:35:30 AM

Quote
Originally posted by Knegel
I would be happy, if someone could explain why the AH F4U lose more than 50% climb performence cause full extended flaps, while the turn rate remain the same.

Very simple. The drag associated with flaps is not linear but varies with Cl.

(http://www.badz.pwp.blueyonder.co.uk/images/Flaps.jpg)
Source: Badboy (from Perkins & Hague)
http://www.badz.pwp.blueyonder.co.uk/images/Flaps.jpg

When you're in auto-climb in AH Cl is lower because the aircraft is at best-rate-of-climb airspeed and supporting lift for 1-g. Note points A & B on the chart. For this flap at a lower Cl you have more drag due to the flap vs. not while at the same Cl.

However, in a turn Cl is greater and supporting lift greater than 1-g. Note the points C & D on the chart. At greater Cl you have equal drag with flaps vs. not. Also for the same drag you have greater Cl with flaps vs. not in this situation.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 07, 2007, 01:58:49 AM

Hi,

i did climb at 110mph and did turn at 110mph, as i wrote above, i didnt use Autoclimb.

The points C + D are at stall spead without flaps and it might be that the F4U-4 at stall speed climb even less than 1900ft/min, but this dont explain the discrepancy between a the turn/climb result without flaps at 180mph and the turn/climb result with full flaps at 110mph.

I cant understand why the climb with 110mph and full flaps is so much worse than the climb at 180mph without flaps, while the turn rate remain the same.

Edit:
With full flaps my climb test AND turn test is made at roundabout point "D" in your graphic.

Without flaps the climb test AND turn test is made at roundabout point "A".

And in AH it looks like the much higher CD at "D" cause more then 50% climb lost, despite the much higher CL, but while turing this dont seems to happen.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: hitech on July 07, 2007, 09:11:36 AM

Knegel: You do realize lift has absolutely nothing to do with climb performance correct?

Title: Corsair Turning Ability in AH
Post by: dtango on July 07, 2007, 09:53:47 AM

Knegel:

I'm not sure where you're point of misunderstanding is. The chart above shows you that at higher Cl's there's a part of the envelope that the drag between having flaps vs. not is the same. So essentially it's the same power required. The key is at for the same amount of drag you get a higher Cl with flaps.

Why is this important for better turn performance? Just look at the turn radius and rate equations:

Radius = 2 * (W/S) / g*rho*Cl

Rate = g*rho*V*Cl / 2*(W/S)

Greater Cl, greater turn performance.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 07, 2007, 03:50:09 PM

Quote
Originally posted by hitech
Knegel: You do realize lift has absolutely nothing to do with climb performance correct?

So we can erase the wings while turning and of course its a myth that the clipped wing Spitfire, despite its a bit more light, have a much worse climb?

Title: Corsair Turning Ability in AH
Post by: Knegel on July 07, 2007, 04:12:07 PM

Quote
Originally posted by dtango
Knegel:

I'm not sure where you're point of misunderstanding is. The chart above shows you that at higher Cl's there's a part of the envelope that the drag between having flaps vs. not is the same. So essentially it's the same power required. The key is at for the same amount of drag you get a higher Cl with flaps.

Why is this important for better turn performance? Just look at the turn radius and rate equations:

Radius = 2 * (W/S) / g*rho*Cl

Rate = g*rho*V*Cl / 2*(W/S)

Greater Cl, greater turn performance.

Tango, XO
412th FS Braunco Mustangs

Hi,

(http://www.raf-roy.com/share/knegel/Screenes/1-109-1.jpg)

This diagram show the influence of the 109E flaps to the Ca, as you can see the Ca get increased much with full flaps and this should influence the smalest possible radius while a sustained turn.
We have a higher CL, which will decrease the decelerated turn(i wrote this before), but the also much increased Ca work against this while a sustained turn.

Your formula is for a constant turn(with altitude lost or with very much power), but i talk about a sustained turn.

If the plane have enough power to fly with the max CL, the turnradius would decrease, but then it also should have the power to climb with the max CL at same speed(like turning speed, thats good above stall speed) and then the climb also should increase.

To have a MUCH smaler turn radius but a MUCH worse climb ratio is what i cant understand.

Btw, i found a F2A article, where the testers wrote that from a speed above 115mph the smalest turn radius can get archived without flaps.
Also in a hight of 27000ft, while a horizontal (sustaied) turn, the smalest radius get archived without flaps, simply cause the plane did miss power to reach the max CL(the drag due to the flaps was to high).
Unfortunately they dont write about a sustained turn in 13000ft(the other test altitude), but they write that they did need to give up altitude to archive the smalest possible radius while flying with flaps, while they could do a max CL turn without flaps without to give up atlitude.

You can find the test on this page:

http://mitglied.lycos.de/luftwaffe1/index2.html

So the question remain, why do we have a so big performence lost while climbing, but not while turning?

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: gripen on July 07, 2007, 07:27:46 PM

Well, the material posted by Knegel actually supports dtango's argument. The problem here is that pointing that out will probably take several pages and hundreds (or thousands) lines of text.

Title: Corsair Turning Ability in AH
Post by: Brooke on July 08, 2007, 12:46:22 AM

Quote
Originally posted by Knegel
Hi Brooke,

i agree, the two are very closely related, thats why iam so suprised about the discrepancy between climb lost and turn gain.

Would be nice, if someone could make some calculations regarding the climbrate and turnrate with full flaps.

Greetings,

Knegel

In my previous post, I meant that stall speed and turning performance are closely related. Stall speed (or turning performance) and climb rate are not closely related.

I'll post some math when I can.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 08, 2007, 02:02:04 AM

Quote
Originally posted by dtango
Knegel:

The chart above shows you that at higher Cl's there's a part of the envelope that the drag between having flaps vs. not is the same. So essentially it's the same power required.
The key is at for the same amount of drag you get a higher Cl with flaps.

Tango, XO
412th FS Braunco Mustangs

And exactly here you have a misunderstanding, cause you "say the drag between having flaps vs. not is the same", but to compare you use the drag of the stall speed without flaps, but at turning speed without flaps the drag is much smaler(point "A" in your graphic).

----------------------------------------------
Edit: Now i mixed up the points!
While a turn without flaps the plane turn at point "D", but while a turn with flaps the plane also turn on its stall speed, therefor the Ca is higher than at point "D".
----------------------------------------------------

And just to make it clear: I understand that the min turn radius is smaler with flaps, i wrote this plenty of times now, as long as the plane have enough thrust to fly with max CL.

But is this so in a sustained turn??

The F2A test show that this is not the case(for this plane) in 27000ft, while its not clear if this is still the case in 13000ft, where the power load is better.

And while climbing the higher CD of course can be handycap, but since the plane fly much more slow(less zero drag) and cause the flaps provide more lift the discrepancy between the climbratio with/without flaps and turnratio with/without flaps seems to be to big to me.

I will test if the AH planes behave like the F2A with reduced power, this will show, if the flaps work ok.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Knegel on July 08, 2007, 03:00:21 AM

suprise suprise, even with much reduced power the sustained turnratio remain the same with/without full flaps.

This stands in a big contrast to what at least the F2A test show.

Title: Corsair Turning Ability in AH
Post by: dtango on July 08, 2007, 03:06:01 AM

Quote
Originally posted by Knegel
Your formula is for a constant turn(with altitude lost or with very much power), but i talk about a sustained turn.

Nope :), the turn performance equations posted are for any kind of level turn, sustained included.

Quote
Originally posted by Knegel
...I cant understand why the climb with 110mph and full flaps is so much worse than the climb at 180mph without flaps, while the turn rate remain the same..
...To have a MUCH smaler turn radius but a MUCH worse climb ratio is what i cant understand...
...So the question remain, why do we have a so big performence lost while climbing, but not while turning?

It's pretty straightforward. I tried communicating this with the diagram. Let's try it this way using your 110mph & 180mph example. What's happening is:

In a steady climb (constant velocity):
==========================
110mph full flaps (1-G) drag > 180mph no flaps (1-G) drag.

The power required at 110mph full flaps 1-G is GREATER than that of the power required at 180mph no flaps 1-G therefore you climb better without flaps.

In a sustained turn (no airspeed or alt gain/loss):
===================================
110mph full flaps (x-Gload) drag = 180mph no flaps (y-Gload) drag.

The power required at 110mph full flaps x-G's is EQUAL to that of the power required at 180mph no flaps y-G's therefore sustained turn rate is about the same (while at 110mph turn radius is better).

[EDIT: this is an inaccurate statement. Drag may not be the same, but power required is the same]

The chart I posted shows this charateristic in the drag polars between flaps and no flaps with changing Cl. Why is the drag polar different at 1-g but the same at a higher g-load?[/i] Because at higher lift coefficients the drag polar ceases to be parabolic. The reason is lift-dependent drag due to angle of attack is strongly affected by viscous separation. (Some folks call this variation delta-CDp, or increase in profile drag with increasing aoa.)

The end result, in a sustained turn you have the same amount of power available from your engine, and the same amount of power required due to drag between 110mph full flaps and 180mph no flaps at some gload/lift coefficient.

Let's be clear here. This relationship is dynamic. Here's another chart Badboy has posted in the past to illustrate this concept:

(http://www.badz.pwp.blueyonder.co.uk/images/AHP-38flaps.jpg)

Note how this plays out in sustained turn performance between flaps and no flaps.

Hope this helps!

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: dtango on July 08, 2007, 03:27:26 AM

Quote
And exactly here you have a misunderstanding, cause you "say the drag between having flaps vs. not is the same", but to compare you use the drag of the stall speed without flaps, but at turning speed without flaps the drag is much smaler(point "A" in your graphic).

----------------------------------------------
Edit: Now i mixed up the points!
While a turn without flaps the plane turn at point "D", but while a turn with flaps the plane also turn on its stall speed, therefor the Ca is higher than at point "D".
----------------------------------------------------

LOL ;). Sorry, knegel you'll have to restate what you're trying to say here because you totally lost me with this statement.

I thought I was clear about what I said: Drag at points A & B are different. Drag at points C & D are the same. I think this is what you're referring to?

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 08, 2007, 03:33:42 AM

Hi,

whats about the much more big CL while climbing(actually i understand that the climb must be worse with full flaps)??

And whats about the real tested F2A, why do it not behave like that??

And why do you think the drag while a sustained turn with and without flaps is the same??

(http://www.raf-roy.com/share/knegel/Screenes/Flaps.jpg)

And your graphic isnt universal, it could be a graphic for fowler flaps, which show the CL/Cd relation in a to good light for the "with flaps" setting.

At least the F2A test make me believe this.

The F2A has a increased turn radius while a sustained turn in 27000ft, even with the "good" 22° flap setting, with full flaps the disadvantage was more big.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on July 08, 2007, 03:54:35 AM

Quote
And why do you think the drag while a sustained turn with and without flaps is the same??

Ah, I made an error in my statement. Power required is the same. Drag isn't the same. So...

in a sustained turn in your example:
=========================
D*V (110mph full flaps) = D*V (180mph no flaps)

++++++
The graphic is of a split flap (for which airfoil I don't know) and not a fowler. It's from the famous Perkins & Hague aero textbook. However I have plenty of other drag polars for various other types of flaps that show the similar relationship.

++++++
You can fly a sustained turn at Clmax at a certain part of the envelope. On Badboy's EM chart the region you can do this in is along the lift limit portion of the curve, from the bottom and up to where the Ps=0 line intersects it. Here's another plot that has things labeled if you're unfamiliar with the EM charts.

(http://www.badz.pwp.blueyonder.co.uk/images/Corner.jpg)

I really must get to bed now! :)

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: gripen on July 08, 2007, 04:42:39 AM

Quote
Originally posted by dtango

The graphic is of a split flap (for which airfoil I don't know) and not a fowler. It's from the famous Perkins & Hague aero textbook. However I have plenty of other drag polars for various other types of flaps that show the similar relationship.
[/B]

There is Figure 5. in the F2A-3 turning performance report showing pretty much the same phenomena.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 08, 2007, 05:27:41 AM

Hi,

the results of the F2A turn tests make me believe its rather like this:

(http://www.raf-roy.com/share/knegel/Screenes/Flaps_01.jpg)

And in this case the turn ratio should decrease in a sustained turn, while the radius can be smaler, but dont have to(depending to the available thrust).

At least for the F2A this is the case and i dont know why it shouldnt be the same regarding the F4U and the other planes, which had a rather similar flap system.
Fowler flaps may vary here, cause they increase the wingarea, so they dont create the more lift only by using a higher AoA.

btw, maybe we have a different understanding of a "sustained turn"? For me thats a turn in level flight, without altitude and speed lost or gain.

Maybe there are more turn performence tests around, similar to the F2A??

Sleep well! :)

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Knegel on July 08, 2007, 06:16:38 AM

Hi,

some more testresults to proof my assumption right:

AH F4U-4, 100% fuel, WEP, climb from sea level upward.

Climb at 100mph without flaps: 2800ft/min (thats very close to stall speed, stall horn is always enabled)

Climb at 100mph with full flaps: 1900ft/min

100mph should be roundabout at point "C" + "D" in your graphic.

If your assumtion would be right, the CD would be the same there, while full flaps would provide more lift, therefor the climbratio would increase with full flaps. (same thrust, same drag but more lift = better climb).

But, as we see, while a slow speed climb the AH F4U-4 (probably other planes do it similar in AH) have much worse climb rate with full flaps, this would fit much better to my red line in your graphic, i posted above.

So if this is the case also the turn ratio with full flaps must decrease in a sustained turn, but this dont happen in AH and there i see a rather big discrepancy to what it should be or at least to the climb results.

We cant have one without the other.

If the drag is the same, the climb must be the same as well(rather better due to the more lift).

If the drag with full flaps is so high to decrease the climbratio by 30%, also the turn ratio must decrease and the radius cant be that much better, cause the less available effective thrust dont allow a that high bank angle anymore(wihtout alt lost, cause we still need to overcome the -1G to keep a level flight).

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Saxman on July 08, 2007, 09:37:51 AM

I've gotten completely lost in this argument, but hasn't it ALREADY BEEN STATED that rate of climb does NOT relate/equate to turning capability and is instead a completely different animal?

Title: Corsair Turning Ability in AH
Post by: dtango on July 08, 2007, 11:08:12 AM

Knegel:

In your 100mph example two key points to make:
CD is not the same at the same velocity, 100mph in your case with and without flaps. As others have stated lift has nothing to do with climb. The reason is that drag at 1-g is not the same as drag at n-g's in a sustained turn.

When you're in a steady climb you're at 1-g. When you're in a sustained turn your g-load is > 1g.

I'm off to church right now so I'll post the math to demonstrate this when I get back in the afternoon.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 08, 2007, 12:51:30 PM

Hi,

lift has nothing to do with climb?? So we can retake the wings while climbing?? I would say this only work if the thrust is big enough to provite
a vertical climb. .
A climb is exact the same like a constant 1G turn without gravity, the gravity only hinder the plane to make a turn, if the gravity would stop, the climbing plane would perform a nice turn. If a higher CL decrease the turnrate while a 1G turn, it also must increase the climb ratio.

In my 100mph example the F4U fly at stall speed, therefor it is very close to its max CD, while the same plane with full flaps fly a bit above its stall speed, therefor both must be rather close to "C" and "D" in your graphic(stall speed with full flaps is around 75mph).

If it would be like you say, the F4U with full flaps would have at least at one speed a higher lift AND a smaler drag than the same plane without flaps, but max AoA. But you can try what you want, the F4U dont will performe a better sustained climb than 1900ft/min with full flaps, therefor the AH F4U NEVER have a smaler CD with full flaps, than the same plane without flaps at max AoA.

The F2A test also confirm my thoughts. The plane can turn more tight in 13000ft, but not without altitude lost, so with more thrust. If you look to the testdatas, you will see that the radius while a sustained turn with full flaps decrease by just 20%, while the turn rate increase.
F2A, at 13000ft, 900HP:
Radius no flaps: 825ft , 114mph, 9°/sec
Radius 22° flaps: 730ft, 90mph, 7,2°/sec, 13% radius gain, 20% turnrate lost.
Radius 54° flaps: 660ft, 85mph, 6,4°/sec, 20% radius gain, 30% turn rate lost.

If i compare this with the AH F4U-4 results, the AH F4U, but also the other planes must have magic flaps, cause they dont realy decrease the turn rate, while they decrease the radis by almost 40%.

Even with much reduced power the F4U-4 keep the same turn rate with/without full flaps.

I remeber a time when the AH flaps of most planes did work like the F2A flaps in the test, at that time many did complain the incredible f4U flaps, now all have this behaviour, although its not as extreme, at least its a bit more even.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Brooke on July 08, 2007, 09:23:47 PM

OK, I said I'd post math and here it is -- The Math of Turning:

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningMath.html

I have also added Appendices to talk about how stall speed and climbing performance relate to turning performance. As I summarized before, stall speed has a lot to do with turning performance -- the math shows why. As Hitech has summarized before, stall speed and lift by itself has little to do with climb rate -- again, the math shows why. It will also show that dropping flaps is going to decrease your maximum steady-state climb rate and why.

This is a lot of (tedious) math. If by some miracle someone actually goes through the math of it, if you find errors, please let me know.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 08, 2007, 10:06:57 PM

Well, I just got back from Chicago. Going through all these posts I can safley (very safely) say I don't have anything worthwhile to add. You guys have taken this discussion well above my level, hehe.

I enjoyed reading the math explanations, etc, and feel I'm getting the basics...

Brooke- Hats off to you for that math and a write-up I can follow!

MtnMan

Title: Corsair Turning Ability in AH
Post by: dtango on July 08, 2007, 11:20:00 PM

Great post Brooke. Thanks for taking the effort to putting together the write up.

Mtnman – I just got back from Chicago myself ;)! Was there for the 4th and just returned Saturday evening.

+++++++
Knegel where do I start ;)? Let’s try making a single statement at a time here to get on the same page.

Why isn’t a sustained turn and a steady climb the same thing? Because a turn means there is a net force creating acceleration normal (90 degrees) to the flight path. In a steady climb (climb at constant velocity) however, there is 0 normal acceleration to the flight path because the net force normal to the flight path is zero.

What does this mean? Let’s say the airplane is wings level with the horizon. If there was no gravity (like your example you gave) and you had a 1g lift force, then you would end up with a vertical turn, NOT a steady climb at constant velocity. A turn means you’re going around in basically a circular path either oriented vertically or horizontally. If you had a sustained turn in the vertical you would end up in a loop, not a steady climb.

On the other hand a steady climb means you’re going up an inclined straight path. The flight path is straight because there is no normal acceleration to the flight path to cause it to curve.

Circular vs. straight. Normal acceleration > 0 vs. normal acceleration = 0. Turn vs. climb. Not the same thing.

Let’s start here. We have to agree on this topic before we discuss anything else. This is fundamental to the discussion. Do you agree with the above concept?

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 09, 2007, 12:26:28 AM

Thanks brooke for this nice article,

i found this in your article, when reading about sustained turns:

"However, note that max turn rate is lower than for flaps up"

".......dropping full flaps tends to slightly decrease maximum turn rate"

Nothing more and nothing less is my point!!

Also the F2A turn tests confirm this and the turnratio lost with full flaps is 30% in that case, while the radius just get reduced by 20%.

You conclusion, that a plane turn more tight with flaps, dont work always in a sustained turn, or only count if we dont consider the engine thrust.

As the F2A test show, in high alt, where the plane have much less power, the plane have the most tight turn without flaps and also the best turn ratio. Simply cause the drag eat the thrust, while the lift is needed to overcome the -1g, so the plane only can reach a rather smal bank angle with full flaps, resulting in a worse turn radius.

dtango,

although a plane while a steady climb dont perform a turn, the same forces, which would perform a turn right away, only by banking the plane, work. If i trim a plane into a steady climb, and if you then bank the plane, the plane will turn(and lose altitude).
With other words, the plane itself produce the same forces while turning and climbing, they only seems to work different. Actually we could say, climbing is special kind of turning. btw, the speed to archive the best turn ratio is very similar to the best climb speed.
If i increase the lift of a plane, without to increase the drag, the plane will have a better climb performence and better turn.

If i increase the drag, the climb ratio will decrease, but also the turn ratioin a sustained turn(like brooks article confirm) and since the turn ratio decrease(the plane is forced to fly with a smaler bank angle) the radius increase, despite the lift is the same.

While flying with full flaps, we increase the lift, but also the drag, so in a sustained turn and climb the ratios get decreased, how much the radius get influenced while a sustained turn depends to the available thrust.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on July 09, 2007, 12:34:22 AM

Quote
With other words, the plane itself produce the same forces while turning and climbing, they only seems to work different. Actually we could say, climbing is special kind of turning.

Nope, I disagree :). Until we agree on this concept then all the other discussion is for not I'm afraid because the physics of flight and all the derived equations around turns and climbs come from the concept that a turn and a steady climb are not the same.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 09, 2007, 01:35:06 AM

Hi,

they are not exactly the same, but the forces produced by the plane are the same.
A steady climb is the same like a 1G turn, if no gravity would exist.

Its only more sencefull to describe the climb with the drag and trust, cause the needed lift to overcome 1G is always the same in a steady climb, but the lift influence the climb angle, so the lift isnt unimportant.

The climb and turn ratio get influenced by the ability to produce more lift over the smaler needed AoA to produce the same lift, so over the induced drag.
The climb angle and turn radius get influenced by the max lift and effective thrust(thrust force minus drag froce).

Thats why the behaviour of the AH planes cant be realistic.

They cant lose climb ratio like mad with full flaps, but the same turn ratio remain.
In the 100mph example the plane without flaps fly in its most bad condition regarding its induced drag(max AoA) and no matter with what speed the "full flaps plane" fly, it always lose at least 30% of the climb ratio.

The high lost in climb ratio, cause using full flaps, indicate a much increased drag, as result the turn rate, at same speed must decrease as well, but it dont.

The F2A test confirm this, same like Brookes calculation.

If you can explain why the F2A test show a so much different picture to the AH planes, it could help. Even the A6m2 and Ya9T, which are two of the few planes that realy lose turn ratio and dont gain that much regarding the radius, are by far better than the F2A in the test.

In BW, in IL-2, in EAW, in the MS flight simulator and CFSII the flaps similar results like the tested F2A flaps, so you can go on to try to explain why the AH flaps work ok, or you can start to try to find out if something is wrong.

Who did say this??
A scientist tend to find what he want to find.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on July 09, 2007, 08:04:45 AM

Quote
A steady climb is the same like a 1G turn, if no gravity would exist.

Nope it is not :). If no gravity existed, a continuous 1G lift force would result in steady loop NOT a steady climb. This is the salient point that the rest of the discussion hinges on.

If I get a chance later, I'll post some free-body diagrams and equations to demonstrate.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: dtango on July 09, 2007, 12:57:40 PM

Here are some diagrams. Equations to come later.

Based on Newton’s laws, if a force constantly acts perpendicular to the path of a moving object, the object will move in a circular path at constant speed. The following diagram graphically depicts this. This is fundamental physics.

(http://brauncomustangs.org/images/centripetal.jpg)

Guess what? Lift is a force perpendicular to the path of a moving airplane. If you remove gravity as you suggest and you have a 1G lift force, the 1G lift force constantly acts perpendicular to the airplane. The next diagram depicts the results.

(http://brauncomustangs.org/images/loop2.jpg)

Look familiar? By Newton’s laws the perpendicular lift force to the motion of the airplane causes the airplane to move in a circular path, not a steady inclined climb.

Add gravity and therefore weight back into the equation. If L > W then you still get a curved (actually an egg-shaped) path not a steady inclined climb in a straight path.

In a steady climb there is no net force acting perpendicular to the motion of the airplane because Lift and the component of Weight opposing it cancel each other out. That’s why a steady climb isn’t a 1G turn.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: mtnman on July 09, 2007, 01:35:38 PM

Knegel, you seem to be using the terms "turn radius" and "turn ratio" interchangably.

Radius measures the SIZE of the circle- Ratio measures the TIME needed to complete a 360 degree circle. Those two circles will not be the same size if the best results are wanted.

A plane turning its best RADIUS circle will probably be turning its smallest radius circle by flying at or near minimum controllable airspeed. Any excess speed would make the RADIUS larger, counter-productive to measuring for smallest RADIUS.

A plane flying for best turn RATIO is trying for the highest degrees per second around a circle. This plane would do best (I believe) by flying at "corner velocity". In the F4U, I understand this to be about 250 mph, which is well above minimum controllable airspeed. Any slower than corner velocity would take longer than needed to complete the circle. Any greater speed should increase the distance traveled...

A plane trying for best turn RATIO would NOT want flaps, but would want to be very near the speed where flaps would help. A plane trying for best RADIUS would want to be slow, and would want / need flaps to have the extra lift provided to stay aloft for this slow, tight turn.

A plane flying slow enough for a small radius turn would find excessive bank to be detrimental, so would not want/need a whole lot of aileron. SOME bank is needed of course, but too much aileron would probably cause problems with adverse yaw effect. Rudder would seem to be more important, which the plane in question has lots of. Rudder in this situation would supply the needed bank to complete the turn.

Brookes statement-

"However, note that max turn rate is lower than for flaps up"
".......dropping full flaps tends to slightly decrease maximum turn rate"

-would be seen to hold water- turn RATE may suffer from flaps, but RADIUS would suffer from LACK of flaps. Drag induced by flaps during a timed competition would be bad, but would be acceptable if the competition was NOT based on TIME.

Two planes flying identical RADIUS turns (the charts you posted at the beginning of this discussion measured radius, not rate) would not have the same turn RATE if one was flying faster than the other.

If your lift/drag/thrust/climb/turn at 1G argument where true, what happens if the plane is flying level at 1G?

You seem to argue that lift fights drag, and that lift also fights gravity. I think the basic idea is that lift fights gravity, and thrust fights drag. Drag does not necessarily hinder lift. It could be argued that drag PROVIDES lift, or IS lift- at least until it gets excessive.

"A steady climb is the same like a 1G turn, if no gravity would exist."

If gravity didn't exist we would be having this discussion, for a whole LOT of reasons.

The plane climbing at 1G is using excess THRUST to CLIMB, not lift. The plane in a 1G turn is using excess thrust to provide SPEED translated to LIFT to keep it aloft for the turn. The energy is not used the same way.

MtnMan

Title: Corsair Turning Ability in AH
Post by: Knegel on July 09, 2007, 02:16:30 PM

Quote
Originally posted by dtango
Nope it is not :). If no gravity existed, a continuous 1G lift force would result in steady loop NOT a steady climb. This is the salient point that the rest of the discussion hinges on.

Tango, XO
412th FS Braunco Mustangs

Thats exactly what i say, cause a loop in a room without gravity is nothing more than a turn, of course a turn without bank(no need to bank without gravity), but the plane turn and this show that the forces are exact the same, while in the case of a steady climb the gravity hinder the plane to turn.

A plane with more lift but same drag, weight and thrust will have less drag at the end, cause a smaler AoA is needed to produce lift to overcome 1G, as result, the lift need to get reduced(otherwise the plane would start to loop) and so the induced drag get reduced and the climbratio increase.
If the AoA dont get adjusted, the plane with more lift start to loop, then it will decrease the speed, so the lift reduce, but also the zero drag, at the end the plane will have a more steep climb and only a bit better climb than the one with less lift (Edit: Its rather the ability to produce lift (lift factor CL) than the lift itself where iam talking about).

Of course we can also simply say the plane climb better cause it have a smaler drag, and this of course is enough for calculations regarding every steady climb at best climb speed, but we shouldnt forget why the plane have less drag. The reason is the better CL.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Knegel on July 09, 2007, 03:33:03 PM

Hi,

Quote
Originally posted by mtnman
Knegel, you seem to be using the terms "turn radius" and "turn ratio" interchangably.
MtnMan

I dont use it interchangeable, i only try to point out that the relation between turnratio and turn radius of most AH planes with/without flaps is unrealistic.

Quote
Originally posted by mtnman
A plane trying for best turn RATIO would NOT want flaps, but would want to be very near the speed where flaps would help.

As the turn radius AND turn rate tests made by me and posted by me in this theatre show, the AH F4U dont lose turn ratio with full flaps, thats what i criticize.

Quote
Originally posted by mtnman

A plane trying for best RADIUS would want to be slow, and would want / need flaps to have the extra lift provided to stay aloft for this slow, tight turn.

In the F2A (Brewster Buffalow) test of a real plane(i posted the link to this test here), you can see that it depends to the powerload and air density, if the radius with flaps is smaler.

Quote
Originally posted by mtnman
A plane flying slow enough for a small radius turn would find excessive bank to be detrimental, so would not want/need a whole lot of aileron. SOME bank is needed of course, but too much aileron would probably cause problems with adverse yaw effect. Rudder would seem to be more important, which the plane in question has lots of. Rudder in this situation would supply the needed bank to complete the turn.

The possible bank angle depends to the effective thrust, and the radius depends in big degree to the bank angle. Thats why the F2A in low alt with full flaps perform a 20% smaler radius than without flaps(better thrust cause more power and more air density), while the radius in high alt increase while flying with flaps. Otherwise i agree and thats some more arguments why a turn at very slow speed isnt that good.
In all cases the turn ratio of the tested and calculated F2A while a sustained turn decrease.

Quote
Originally posted by mtnman

......................... (the charts you posted at the beginning of this discussion measured radius, not rate) .................

I did offer turn rate and turn radius results later in this theatre.

Quote
Originally posted by mtnman
You seem to argue that lift fights drag, and that lift also fights gravity.

I just saw that its rather the lift factor where iam talking about and the lift factor is responsible for the induced drag.

Quote
Originally posted by mtnman

I think the basic idea is that lift fights gravity, and thrust fights drag. Drag does not necessarily hinder lift. It could be argued that drag PROVIDES lift, or IS lift- at least until it gets excessive.

The idea is that the ability to produce lift influence the drag, afterward the thrust fights the drag.

Quote
Originally posted by mtnman

The plane climbing at 1G is using excess THRUST to CLIMB, not lift. The plane in a 1G turn is using excess thrust to provide SPEED translated to LIFT to keep it aloft for the turn. The energy is not used the same way.

MtnMan

btw, while climbing with a very high AoA, the wing need to produce less lift than 1G, cause the propeller already point upward.
While climbing with full flaps at rather high speed the wing often need to produce more than 1G lift, cause the nose tend to point downward while a steady climb.

But anyway, this all is absolutly not important to value the AH turn performence with/without flaps, while a sustained turn.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Badboy on July 09, 2007, 05:11:04 PM

Quote
Originally posted by Brooke
If by some miracle someone actually goes through the math of it, if you find errors, please let me know.

One big one and a couple of little ones... check your mail.

Badboy

Title: Corsair Turning Ability in AH
Post by: Knegel on July 09, 2007, 11:46:07 PM

Quote
Originally posted by Knegel

btw, while climbing with a very high AoA, the wing need to produce less lift than 1G, cause the propeller already point upward.
While climbing with full flaps at rather high speed the wing often need to produce more than 1G lift, cause the nose tend to point downward while a steady climb.

But anyway, this all is absolutly not important to value the AH turn performence with/without flaps, while a sustained turn.

Greetings,

Knegel

I just see that this is also a reason why a plane with flaps cant have a that good turn ratio and radius. With flaps the max AoA get reduced and the angle between the wing and the fuselage change. As result planes with flaps tend to have a "nose down" behaviour while a steady flight(this is wanted to provide a better sight while landing).
While a turn with flaps this mean: The nose dont point as far inward as without flaps, the thrustline is worse for turn and climb, so we have less thrust into turning/climbing direction and we need more lift to overcome this.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: gripen on July 10, 2007, 12:58:52 AM

Brooke,
Badboy might have allready noted this out but it seems that you assume the value of the e constant with and without flaps. In practice the flaps also change the value of the e and you can see this by looking the figure 5. in the F2A data (the value of the K gives the slope of the Cl^2/Cd line).That is also the point in dtango's argumentation.

Otherwise I found your notation difficult to read because the most of formulas are inside the text, a better idea would be separating all the formulas from the text.

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 10, 2007, 07:53:19 AM

Gents,

A while ago someone was using a very basic calcualtion for circumferance based on flight speed. I cannot find it and I was wondering if someone could repost it if possible.

Knegal,

You are reffering to turn rate, turn radius and turn ratio. What are you using to determine turn ratio? Are you using Dean's formula for this? What is your definition of "Turn Ratio". Also how are you measuring turn rate?

Thanks

Title: Corsair Turning Ability in AH
Post by: Krusty on July 10, 2007, 08:58:14 AM

F4uDOA, do you mean this:

Make compete revolutions several times to make sure your speed is the same, and time how long it takes to make one complete turn on the compass. Then take the speed you have.

Then you have the time it took to make a full circle, and you have the MPH, so do the math to figure out how far you went in that time (say, 20 seconds at 150mph) that gives you circumference. Then divide by pi to get turn radius (or is it diameter?).

That what you were thinking of?

Title: Corsair Turning Ability in AH
Post by: Knegel on July 10, 2007, 10:23:55 AM

Quote
Originally posted by F4UDOA
Gents,

Knegal,

You are reffering to turn rate, turn radius and turn ratio. What are you using to determine turn ratio? Are you using Dean's formula for this? What is your definition of "Turn Ratio". Also how are you measuring turn rate?

Thanks

Hi,

i just got aware that there may be a different between turn ratio and turn rate(actually iam dont know if there is a different, cause i always thought thats two words for the same, so much to my english knowledge :) ), this both i did use interchangable, measured in °/sec or sec/360° .
So i meant always turn rate, sorry for the mess.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 10, 2007, 12:17:36 PM

Krusty,

Thanks a bunch, I find myself out sourcing parts of my brain everyday. Pretty soon I will just sit in a chair all day with a name tag and drule.

Knegal,

No problem, you are doing fine, I just wasn't sure if you were using Dean's formula for turning or turn rates. I was getting confused:rolleyes:

Title: Corsair Turning Ability in AH
Post by: Knegel on July 14, 2007, 08:49:26 AM

Just will bring this up again, maybe someone is out there who is able to explain if and why the Ah flaps dont work ok, or at least why the F2A test results with/without flaps differ so much from the AH results(with/without flaps).

If noone is able to do it, this is maybe something for the bug forum.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: ForrestS on July 14, 2007, 12:14:58 PM

I just wanna say that this airplane is AWSOME!!!

I was playing in the H2H arena and NoobFire introduced me to it. I usally fly the Mustang and the Lightning. But the F4U-4 is NICE. It goes really fast and turns nice. And it can land on Carriers.

(http://www.compass.dircon.co.uk/corsair_68.jpg)

Title: Corsair Turning Ability in AH
Post by: SteveBailey on July 14, 2007, 12:24:27 PM

Quote
Originally posted by dtango
Here are some diagrams. Equations to come later.

Based on Newton’s laws, if a force constantly acts perpendicular to the path of a moving object, the object will move in a circular path at constant speed. The following diagram graphically depicts this. This is fundamental physics.

(http://brauncomustangs.org/images/centripetal.jpg)

Guess what? Lift is a force perpendicular to the path of a moving airplane. If you remove gravity as you suggest and you have a 1G lift force, the 1G lift force constantly acts perpendicular to the airplane. The next diagram depicts the results.

(http://brauncomustangs.org/images/loop2.jpg)

Tango, XO
412th FS Braunco Mustangs

This would be pretty but does not account for the forward thrust of the aircraft. A plane flying in "no gravity" would not loop as lift is only one force working here.

Title: Corsair Turning Ability in AH
Post by: dtango on July 14, 2007, 03:51:16 PM

Steve:

I'm assuming (a) T=D, and (b) there is a forward velocity v as pointed out on the diagrams.

If there wasn't any forward velocity then the plane would go straight up.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: dtango on July 14, 2007, 03:58:32 PM

Knegel:

I don't know what else to tell you. To prove that the AH FM is incorrect you have to prove that it is violating:

Ps = (T - D) * V / W

You haven't done that yet. It's much more complicated than it looks. The catch is how this relationship varies in 1g flight vs. >1g flight.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 14, 2007, 04:47:34 PM

I know I'm going to sound rather stupid, but I'd like to point out that the F4U only seems to turn extremely well (initially as i might add) or as Knegle has said 'out of hand' because of the combat trim.

The CT causes a large upward trimming motion while the flaps come out and while the plane slows down. When your flaps are all the way down and your trim is all the way up, the F4U doesn't feel as much as the uber turner it once was at 180 - 250 mph. Besides, in many of the other flight sims out there, the Corsair seems very tail heavy even at speeds of 170 mph, so trimming up would simply make it turn tight during the actual execution of the trim. Add flaps to that and you got one nice turner.

Just my pair of Lincoln heads.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 14, 2007, 05:04:54 PM

Really, trim doesn't do much to affect the F4U's turning ability. It doesn't actually make it turn any tighter. All combat trim is design to do is keep your attitude level (minimize drift/yaw, roll and pitch away from level flight).

Kicking in combat trim gives the illusion of improved turn/pitch performance, because if your plane is out of trim (let's say, so that your nose is trimmed down) and you turn on combat trim, all the sudden your nose pops up because CT automatically corrects, not because it's making you turn tighter.

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 14, 2007, 06:19:00 PM

Knegel/Hosenose,

Does this help at all? The F4U-1/4 can pull 2G's (instantanious) at 110Knots (126MPH) at 12,000LBS no power/no flaps. The CAS/IAS chart for the F4U shows no error at that speed so that is a real number. When power is applied the stall number comes way down as airflow increases over the wing from the prop. In postwar test of the F4U it could reach 3G's with no flaps at just over 100Knots IAS. These are examples of turning without flaps.

With flaps the drag from the flaps can be used to slow the airplane from higher speeds however the thrust/drag curve starts to change at lower speeds the parasite drag from the flaps becomes less of a force and the lift is more powerful especially when combined with the airflow created from the 2,000HP up front. Evident of this is the ability to take off with a 4,000LBS payload. If the drag was more powerfull than the lift the airplane could not takeoff in such a loading condition.

IMHO what should happen is what does happen: as you add flaps and turn you slow from 170MPH down to 110MPH when you no longer deccelerate and you seem to accelerate through the turn because your lift and thrust far exceed the drag and G force being applied at low speed.

So basically the flaps add drag at low speed but not enough to overcome 2,000HP and the lift of the wing and flaps which is also considerable.

(http://mywebpages.comcast.net/markw4/F4UG.jpg)

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 14, 2007, 10:00:05 PM

Quote
Originally posted by Saxman
Really, trim doesn't do much to affect the F4U's turning ability. It doesn't actually make it turn any tighter. All combat trim is design to do is keep your attitude level (minimize drift/yaw, roll and pitch away from level flight).

Kicking in combat trim gives the illusion of improved turn/pitch performance, because if your plane is out of trim (let's say, so that your nose is trimmed down) and you turn on combat trim, all the sudden your nose pops up because CT automatically corrects, not because it's making you turn tighter.

Well, theoretically, the upwards trimming motion seems to increase the elevators' upward pitch. If you look closely, the elevators move upwards as you trim up even though your stick is already fully up. So just theoretically, the up trim should do something while it's in the process of moving up.

In real life, we have actual tabs, which unlike in IL-2 and AH:II are smaller control surfaces that actually move upwards instead of having the actual elevators 'going up' even further (I'm sure you know, but I'm just saying to reinforce my point). This thus 'curves' the elevators even more producing an even tighter turn. I'm still young and I have a lot to learn, however so correct me if I'm wrong :D

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 14, 2007, 10:20:30 PM

That's wrong. The trim tabs in reality actually move opposite of the direction they move the elevator. Thus they theoretically work against the elevator in terms of maximum deflection, rather than adding to it (though the amount is so tiny that it doesn't really matter). In short, you would actually get more elevator deflection by trimming full down and fighting the trim by pulling the stick all the way back (assuming you had enough strength, which is doubtful).

I say that everyone who has not personally used trim tabs on a real airplane should refrain from attempting to describe them, because those people invariably get it terribly wrong.

(http://users.adelphia.net/~j.r.engdahl/josh/Trim.gif)

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 14, 2007, 10:28:55 PM

Quote
Originally posted by Brooke
I think the F4U and its flaps probably work correctly, but it might be that other aircraft (the P-38 for example) are not as close. Here is an analysis:

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/stallSpeedMath.html

Could you explain further? I assume that you mean that the P-38 should possibly have more lift, either turning better or having a lower stall speed. As this is something I've long suspected, I'm very interested in hearing what you have to say about it.

Title: Corsair Turning Ability in AH
Post by: Krusty on July 14, 2007, 10:32:30 PM

In AH we don't have trim tabs, we have pressure on the stick in the cockpit.

Hosenose, it doesn't work that way. Hitech has explained that trim is only within the bounds of max deflection. If a stick's max deflection is N degrees, then max deflection with max trim is still N. Trim only helps in cases when not using max deflection, in this game. It makes stick forces lighter, not greater.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 14, 2007, 10:47:26 PM

Aces High II's trim is as realistic as a simulator can get it. Unfortunately, commercial simulators cannot replicate real trim unless everyone has precise joystick which mechanically match the physical gaming stick angle to that of the virtual stick's. It would also thus have to be able to withstand any pressure that a user could put on it, meaning about two hundred pounds.

All real trim does is move the position at which the stick will return to if you let go of it. It doesn't increase or decrease maximum elevator deflection at any time. It only decreases the amount of strength required to reach that deflection.

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 15, 2007, 11:21:35 PM

Quote
Originally posted by Benny Moore
Aces High II's trim is as realistic as a simulator can get it. Unfortunately, commercial simulators cannot replicate real trim unless everyone has precise joystick which mechanically match the physical gaming stick angle to that of the virtual stick's. It would also thus have to be able to withstand any pressure that a user could put on it, meaning about two hundred pounds.

All real trim does is move the position at which the stick will return to if you let go of it. It doesn't increase or decrease maximum elevator deflection at any time. It only decreases the amount of strength required to reach that deflection.

Oh I see. thanks for posting that out guys ... well. I've got a lot to learn. So in real life, the 'negative trim' could actually help you turn better, but not in AHII, correct due to Krusty's explanation of N being maximum deflection in-game.

Well, let's sit back, grab some popcorn and continue watching these guys argue. I can't help but to wonder what conclusion we'll have.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 15, 2007, 11:22:56 PM

Quote
Originally posted by dtango
Knegel:

I don't know what else to tell you. To prove that the AH FM is incorrect you have to prove that it is violating:

Tango, XO
412th FS Braunco Mustangs

Hi,

tell me why the F2A test show a so much different result.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 15, 2007, 11:25:34 PM

Quote
Originally posted by mtnman
Anybody happen to have a scan of the F4U manual, pg 40 (bottom right) and pg 41 (top left) that they could post?

Those pages describe trimming for torque, and also using full flaps for take-off when the shortest ground distance is necessary. Those pages would apply here, because it would seem that a shorter take-off would require the flaps to provide more lift at higer deflection, rather than just higher drag.

Obviously, more lift comes at a price of higher drag, resulting in a lower climb rate.

I can/will post scans of those pages, but can't right now as I'm headed out of town until Sunday night.

I'd appreciate it if someone (Widewing maybe? or Saxman?) could post them earlier than that...

MtnMan

If it's still needed, I can scan the post the pages.
After I figure out how to ... please don't say I have to download software.

:eek:

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 15, 2007, 11:35:21 PM

Quote
Originally posted by HoseNose
Oh I see. thanks for posting that out guys ... well. I've got a lot to learn. So in real life, the 'negative trim' could actually help you turn better, but not in AHII, correct due to Krusty's explanation of N being maximum deflection in-game.

Not quite. In real life, "negative" trim could perhaps theoretically help you turn better (at least at speeds low enough that you could overcome it enough to pull the stick back all the way, which would be very low), but only by perhaps 1%. It would not be anything approaching worthwhile for the tremendous amount of strain it would put on your arms (since you would be fighting the trim, trying to pull full positive elevator while trimmed fully negative). The whole point of trim is to relieve pressure. If the aircraft designers wanted you to have more elevator deflection, they would move the gimbal limits, instead of watching you kill yourself trying to use your trim tab as a secondary elevator.

Trim in reality does not ever affect the maximum elevator deflection, only makes that deflection require less strength to reach. In other words, the limit to elevator deflection is the gimbal limit. Trim will never change that. The only thing that trim does is allow you to reach that gimbal limit; at high speeds, the forces required to reach the elevator's gimbal limit might exceed a pilot's strength. And that is what trim is for.

The Aces High II trim, like real trim, does not allow you to change your elevator's gimbal limit. Like real trim, it merely lessens the forces on the stick. Where the unavoidable unrealism comes in is here; it lessens the forces on the virtual stick. It can't lessen the forces on the physical gaming joystick, because there are none. You see, your gaming joystick isn't directly controlling the virtual stick. You rather control pilot input. 100% deflection on your real joystick doesn't mean 100% deflection on your virtual stick, it simply means that your virtual pilot is exerting 100% of his strength. At high virtual speeds, your virtual pilot won't be able to reach his airplane's virtual gimbal limit even when he is exerting 100% strength.

Confused yet?

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 15, 2007, 11:44:21 PM

Lol I catch on quick. I understand exactly what you mean now. Anywho, here are the Corsair manual pic links. It was the only way I knew how to upload the files.

Page 40 - F4U manual (http://www.imagehangar.com/view.php?pic=large/94917100_1184560645.jpg)

Page 41 - F4U manual (http://www.imagehangar.com/view.php?pic=large/06073100_1184560981.jpg)

Title: Corsair Turning Ability in AH
Post by: Knegel on July 15, 2007, 11:45:16 PM

Quote
Originally posted by F4UDOA
Knegel/Hosenose,

Does this help at all? The F4U-1/4 can pull 2G's (instantanious) at 110Knots (126MPH) at 12,000LBS no power/no flaps. The CAS/IAS chart for the F4U shows no error at that speed so that is a real number. When power is applied the stall number comes way down as airflow increases over the wing from the prop. In postwar test of the F4U it could reach 3G's with no flaps at just over 100Knots IAS. These are examples of turning without flaps.

With flaps the drag from the flaps can be used to slow the airplane from higher speeds however the thrust/drag curve starts to change at lower speeds the parasite drag from the flaps becomes less of a force and the lift is more powerful especially when combined with the airflow created from the 2,000HP up front. Evident of this is the ability to take off with a 4,000LBS payload. If the drag was more powerfull than the lift the airplane could not takeoff in such a loading condition.

IMHO what should happen is what does happen: as you add flaps and turn you slow from 170MPH down to 110MPH when you no longer deccelerate and you seem to accelerate through the turn because your lift and thrust far exceed the drag and G force being applied at low speed.

So basically the flaps add drag at low speed but not enough to overcome 2,000HP and the lift of the wing and flaps which is also considerable.

Hi,

noone say that the flaps cause so much drag that the thrust cant overcome their drag.

I only say that a plane, while a sustained turn with full flaps, should have a slower trun rate than without flaps.

The F2A test confirm this and a few planes in AH act like this, although they still dont lose turn rate in the extreme way like the F2A(with full flaps 30%).

I think this is the proof that the flaps dont work right:

The F4U with 100mph climb without flaps 2800ft/min(on WEP). This is at stall speed, so with max AOA, the worst case without flaps, more drag the plane cant produce at this speed, without flaps.

Now also 100mph, but with full flaps, the climb reduce to 1900ft/min.

Since both have produce the same lift in a strait climb, its clear that full flaps cause much more drag and/or the more low thrustline of the full flap condition hinder the plane to climb better(the result is the same). With max AoA(around 80mph with full flaps) the discrepancy will be even bigger.

Now the question, how can a plane, with so much drag still can produce a higher turn rate.

At least the F2A test confirm my assumption.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 15, 2007, 11:55:51 PM

Correct me Benny and others since I know I'm wrong, but the climb rate of an aircraft has a lot more to do with power loading and to a smaller extent, prop blade efficiency, correct? If so, it seems quite dicey to base drag and turning comparisons on climb performance.

Also, on the top left of page 41 of the Corsair manual I've posted a bit above, it says something about the tail not being able to stay on the ground with full flaps and a MAP of 44" HG (whatever that means). It is also advised that a full 50 degree deflection is necessary only for very short T/O. I'm therefore assuming that the lift co-efficient really IS high and that the drag encountered isn't enough to stop the plane from lifting off from a much shorter distance than with just 0 - 20 degrees deflection meaning that the Hog's flaps seem to be performing quite accurately as the drag they induce does not overcome the lift Cl given off even at full deflection.

If you guys need more manual pages I'm happy to serve.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 16, 2007, 12:37:52 AM

MAP of 44" (manifold pressure of forty-four inches) is something like three quarters throttle for the F4U.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 16, 2007, 11:28:39 AM

Quote
Originally posted by HoseNose
If so, it seems quite dicey to base drag and turning comparisons on climb performance.

We talk about sustained turning and the related turn rate here. A sustained turn is a manouver with a constant G-force, same like a constant climb. For a sustained turn the drag to power relations(exess thrust) is one of the most important values, same like while climbing.
Planes with low power(F2A in high alt for example) cant turn with full flaps and max AoA without to lose altitude. As result the turn rate is slower and also the radius increase, no matter what flap position get used(as more flaps as less good the turn get). Closer to sea level the F4U and also the F2A dont suffer this problem, thats why the radius decrease while using flaps, but the turn rate of the F2A still decrease as well.

I took the climb as example, simply cause a climb at max aoa cause the same drag like a turn at max AoA. As the results show, the AH F4U-4 without flaps have less drag without flaps, even under the most bad condition.

Quote
Originally posted by HoseNose
Also, on the top left of page 41 of the Corsair manual I've posted a bit above, it says something about the tail not being able to stay on the ground with full flaps and a MAP of 44" HG (whatever that means). It is also advised that a full 50 degree deflection is necessary only for very short T/O. I'm therefore assuming that the lift co-efficient really IS high and that the drag encountered isn't enough to stop the plane from lifting off from a much shorter distance than with just 0 - 20 degrees deflection meaning that the Hog's flaps seem to be performing quite accurately as the drag they induce does not overcome the lift Cl given off even at full deflection.

The F4U can take off more early cause it have a slower stall speed with full flaps and of course the power is high enough to take off. Withoutflaps, the F4U cant get to the max AoA without to touch the tail wheel down, this increase the runway even more.
The AH F4U-4 still climb with around 1250ft/min with full flaps and 70mph, thats enough to take off from a short CV.

Btw, so the AH F4U-4 with max AoA and full flaps climb 1250ft/min @ 70mph, while the same plane, also with max AoA, without flaps reach 2800ft/min @110mph.

Since both planes climb with the same lift and same thrust, the drag of the full flap condition must be MUCH higher than that of the no flap condition.
At least while a climb this is so.

But while turning, also both conditions with max AoA, the full flap F4U-4 not only turn 39% more tight, it also keep the same turn rate. :rolleyes:

I dont need much math or a super understanding of the physical law to see that there is a mistake, but maybe also the earth is the center of the universe and of couse its flat.

If someone can bring some math to prove me wrong, or other good arguments, ok, but for now the math, which got offered, did rather confirm what i say(although it seems there are mistakes included) or it wasnt related to a sustained turn.

The F2A test proof that my general understanding of how flaps influence the flight are absolut right, although we also could assume that the F2A had the most bad flap system of all WWII planes.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 16, 2007, 12:42:20 PM

Well turn rate is defined by degrees per second right? Simply, the F4U started turning at a physically slower speed with the flaps down (i.e. mph) due to drag but because it was now turning at more degrees with the flaps, it was able to keep the same turn rate.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 16, 2007, 07:29:46 PM

Adding drag doesn't increase the turn rate, it merely decreases the turn radius. It actually hurts the turn rate. Dropping flaps, at least in most aircraft of the time period, should make the airplane turn tighter but fewer degrees per second. Fowler flaps (which of all the fighters in the game, only the P-38 and Ki-84 should have) might be an exception.

And that is the problem being debated. Knegel and I take the stance that the game is wrong because in reality, with the possible exception of Fowler flaps, dropping flaps should be worsen turn rate and improve turn radius. In Aces High II, dropping flaps seems to improve both (at least at certain flap settings). It's like the drag model isn't working quite right. I've not tested it myself, I am rather using the numbers at Netaces.

Title: Corsair Turning Ability in AH
Post by: TequilaChaser on July 16, 2007, 09:03:47 PM

Quote
Originally posted by mtnman
A plane flying for best turn RATIO is trying for the highest degrees per second around a circle. This plane would do best (I believe) by flying at "corner velocity". In the F4U, I understand this to be about 250 mph, which is well above minimum controllable airspeed. Any slower than corner velocity would take longer than needed to complete the circle. Any greater speed should increase the distance traveled...

Sorry, mtnman, I got mindslapped trying to cipher your description

Corner Velocity / Corner Speed gives the best instantaneous turn rate / turn radius for given aircraft type

sustained turn rate is at a bested sustained speed where the aircraft acheives its best sustained ( continous) turn radius without giving up alt/degrees/speed

Instantaneous Turn vs. Sustained Turn Descritptions from Aces High Trainer's Website (http://trainers.hitechcreations.com/instturn/instturn.htm)

is funny seeing people argue over the same things for 6+ years..........

Title: Corsair Turning Ability in AH
Post by: SgtPappy on July 16, 2007, 09:21:58 PM

i think hose means that the corsair is turning tighter and though the drag is slowing it down, the fact that it's turning tighter allows for the same turn rate. Turning tighter, but slowing down... He's not saying the drag helps. But I think this would only be possible with 10 degrees. Anymore, the turn rate should drop dramatically in a full circle.

haha. i remember starting a thread just like this one a while back.
i guess WideWing got tired of owning us and is currently watching us with a bag of popcorn in his hands.. laughing.. just. laughing.

Please WW! I summon thee!

Title: Corsair Turning Ability in AH
Post by: mtnman on July 16, 2007, 10:07:11 PM

TC- Thank you for pointing me to that link. I understand the instantaneous turn advantage and use it regularly. How do I find the best speed for sustained turns? At different flap settings?

Benny- "I say that everyone who has not personally used trim tabs on a real airplane should refrain from attempting to describe them, because those people invariably get it terribly wrong."

I've seen/heard actual pilots who were confused by this believe it or not. Apparantly, using an item or tool doesn't guarantee an understanding of it. If people only stuck with things they already had experience with nobody would have ever invented the wheel. Thankfully some are willing to stick their necks out and risk failure or correction once in a while. Heck- I've got lots of hand-on experience with my wife, but painfully little understanding of how she actually works...

I also think people should realize that more deflection wouldn't necessarily be a good thing in regards to control surface movement. I'd hope the designers would set the travel limits at the "best" limit. Think how many air crashes would result if pilots could manipulate the elevator for more deflection. Think how poorly 90 or 100 degrees up elevator would work, hehe. The wing will stall when it will, whether the elevator is deflected zero degrees or 45.

HoseNose- Thanks for posting those pages. I was willing but dreading it. I'm on 28K dial-up, so loading / downloading anything on the web bites bad!

MtnMan

Title: Corsair Turning Ability in AH
Post by: Vulcan on July 17, 2007, 12:03:36 AM

Quote
Originally posted by Benny Moore
Trim in reality does not ever affect the maximum elevator deflection, only makes that deflection require less strength to reach. In other words, the limit to elevator deflection is the gimbal limit. Trim will never change that. The only thing that trim does is allow you to reach that gimbal limit; at high speeds, the forces required to reach the elevator's gimbal limit might exceed a pilot's strength. And that is what trim is for.

So how about the 109s elevator trim then :)

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 17, 2007, 12:08:20 AM

Quote
Originally posted by Benny Moore
Interstingly, the German fighters in World War Two worked completely differently than American ones and modern aircraft. In German aircraft, trimming actually moved the stabilizer or something like that. So in that case, trimming actually did move the elevator's physical limit. But that's an exception.

Sorry, I had posted this in the wrong thread.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 17, 2007, 12:24:47 AM

Quote
Originally posted by HoseNose
Well turn rate is defined by degrees per second right? Simply, the F4U started turning at a physically slower speed with the flaps down (i.e. mph) due to drag but because it was now turning at more degrees with the flaps, it was able to keep the same turn rate.

The problem is, that a planes the planes in AH show much more drag while climbing with may AoA and full flaps than without. Not a little bit, much more drag!!
While a sustained turn we also fly with max AoA as long as the thrust is high enough to provide this, without to lose altitude(as more AoA as more drag).
Since also while a sustained turn we need to overcome the 1G gravitiy force, we cant fly with 90° banked.
As more thrust we have, as faster we can fly, as more lift get produced as more we can/need to bank the plane to keep a level flight, as more of our lift we can use to turn tight.
If now a plane show so much more drag(around 40% more drag) while a max AoA climb, how the hell it shal bank enough to provide a 40% more tight turn, without to lose turn ratio??

And even more interesting:
With 3000rpm, the F4U-4(100% fuel) realy act like the F2A. Without flaps its able to perform a smooth turn at around 120mph and 40sec/360°, while with full flaps the plane almost cant bank without to lose altitude.

With 4000rpm more, its still like the F2A do it, the turn rate without flaps is much faster, but with 5000rpm and specialy WEP the full flap dont show this? Why not??

The F2A test show that flaps at higher speeds dont increase the trun rate, neighter the turn radius, simply cause the lift decrease at a certain speed(the resulting ugly airfoil of extended flaps is probably the reason), maybe this is missing in AH. But even without, i see a mistake in the current flap setup.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 17, 2007, 10:00:43 AM

Um I believe the F4U-4's max revs is 2700 rpm. Where'd 5000 come from? :p

Title: Corsair Turning Ability in AH
Post by: Knegel on July 17, 2007, 12:34:49 PM

Quote
Originally posted by HoseNose
Um I believe the F4U-4's max revs is 2700 rpm. Where'd 5000 come from? :p

Oh my god, no arguments left that you need to pic on obvious typos??

mfp, not rpm of course.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 17, 2007, 01:35:04 PM

What picking? 5000rpm is WAY more than just a typo.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 18, 2007, 02:09:48 AM

LOL not 5000 is the typo, rpm is the typo, it should have been mfp(main fold presure) and for all who ever did look to the AH F4U gauges this is pretty obvious.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 18, 2007, 04:38:40 AM

I've looked at the AH F4U gauges more than most I would guess, and it was far from obvious to me. I had no idea where you came up with those numbers.

I still think the 5000 thing is off a bit. My F4U gauges say 30, 40, 50, as do the ones in my manual. Are yours different?

Not that this typo thing really means anything...

MtnMan

Title: Corsair Turning Ability in AH
Post by: Knegel on July 18, 2007, 07:10:42 AM

Obvious is that rpm dont have that much to do with the power setting of the engine in AH(it remain constant), while the mfp change, when i change the throttle position.

But anyway, this all seems to be more like in IL-2 now, where the people wanna believe they have the most realistic FM.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 18, 2007, 07:27:54 AM

5000" MAP would probably cause the engine to implode, lol!

In the game F4U has a maximum of ~57" MAP with WEP engaged. Pretty sure this got as high as 60" in the field.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 18, 2007, 02:53:45 PM

QUOTE]But anyway, this all seems to be more like in IL-2 now, where the people wanna believe they have the most realistic FM.[/QUOTE]

Isn't this natural? Who ever wants to believe they have the worst of something? Especially if what they do have seems to work.

In the few years I've been here, Hitech has seemed willing to fix issues with their game if enough evidence shows a discrepency. You don't need to convince us, just them.

That said, with the amount of time this thread has been active it doesn't seem to me that your evidence has swayed that many people's opinions. That doesn't mean you're wrong. But with your arguments compared to all the others, I'm not convinced either.

A- If something IS wrong with the flight model, I'd prefer it would be changed- as I'm sure the majority who play this game would.

B- I don't feel you've shown that YET, as it seems most of the others reading this thread feel based on their response, or lack of.

C- If what you say is correct, it seems it would affect all the planes in the set accordingly, which seems like the planes would all turn worse, but still compare similarly to the way they do now? Zero's and Hurri's would still out-turn F4U's, but all would turn "less tight"?

I don't know, maybe your evidence isn't convincing, or maybe the way you've presented it?

MtnMan

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 18, 2007, 07:22:22 PM

Oooo. Mtnman brings up a good point. And no, Knegle I'm not picking on you.. don't be so girly lol. we're all good friends here just talking about the stuff we think is awesome - aircraft of WWII (more specifically AHII).

Title: Corsair Turning Ability in AH
Post by: Krusty on July 18, 2007, 08:19:14 PM

Okay, He's trying to show that something's wrong.

We know SOMETHING is wrong. Perhaps its what he says, perhaps it's something unrelated.

All I know is that SOMETHING is wrong with current F4u flight modeling.

Quote
Originally posted by Widewing
Then again, I have some issues with the flight modeling. The F6F-5 is at least 20 mph too slow at its best altitude (should be neck and neck with the F4U-1D at 20k). There is a serious dynamic instability in the roll axis at high angles of attack. On the contrary, the F4U, which should be notably less stable than the Hellcat, is rock steady under those conditions and a paragon of genteel handling. Our F4Us display none of the vices known in the RW. The F6F-5 has vices that didn't exist in the RW. If they ever fix the F6F, it'll move up in the standings. It should also be able to carry the centerline tank AND 2 bombs, or 3 bombs (as should the F4U-1D).

Quote
Originally posted by Bodhi
Excellent post Widewing... although I can not choose the 1A over the 1d... just like the 1d more, probably stupid in that, but it's the U-bird I learned first... As for the F6F and F4u handling characteristics, I agree whole heartedly. The F6F is described by everyone I know who has flown it (both veterans and current pilots) as being better named a ***** cat when it's flight characteristics are considered. The contrary is the F4u's flight model, and every one I know that has major time in tem is do not get low and slow and try to maneuver. The stall below 200 kts and 6k AGL is unrecoverable as the wing drops and a spin results which is unrecoverable given the altitude. Given altitide the F4u is still a monster in the spin, and the few pilots I know that have intentionally spun the Corsair say they will never try it again. The U-bird is a beast in all sense of the word. It is very poorly protrayed here with regards to stall characteristics, that and it's very lightened load, especially cosidering the -1d's and the -4's. The '4's were carrying field modified pylons that could and did carry two 1k bombs each.

Passage to note:

"every one I know that has major time in tem is do not get low and slow and try to maneuver. The stall below 200 kts and 6k AGL is unrecoverable as the wing drops and a spin results which is unrecoverable given the altitude. Given altitide the F4u is still a monster in the spin, and the few pilots I know that have intentionally spun the Corsair say they will never try it again."

In this game the F4u is as docile as a spitfire. I have almost NEVER spun out, EVER, at any speed fast or slow. I can go from 350mph to 150 in the blink of an eye and then pull 3G+ turns without any negative handling.

That alone proves the flight model is wrong.

Now, I don't think Knegel's got it right. The argument he makes isn't very good. I think it's just the code in the F4u that's messed up, is all. They need to make the plane fly like a spit14 and it would be more realistic.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 18, 2007, 10:06:00 PM

Quote
Originally posted by Krusty
I think it's just the code in the F4u that's messed up, is all. They need to make the plane fly like a spit14 and it would be more realistic.

That's not how it works. Hitech's model isn't some scripted thing like IL-2 where the developers artificially hand-write behavior into each aircraft ("Hmm, this book says that the P-40 should have a nasty spin, so I'll type in 'if AoA > 18 then exec "nasty spin"'"). Hitech's model uses lift, drag, weight, and thrust vectors, lots of them, and they are calculated at all times.

Making the F4U fly like the Spitfire Mark XIV would entail giving the F4U some of the Spitfire's lift and drag values. That would be exceedingly unrealistic, since Hitech uses real values. If there's a problem, it's probably that some of the data points are wrong. Either that, or the model itself isn't as complex in a certain area as it needs to be (for example, flaps). I suspect the latter. Still, it's by far the closest any flight model has come so far.

Quote
Originally posted by Bohdi
The stall below 200 kts and 6k AGL is unrecoverable as the wing drops and a spin results which is unrecoverable given the altitude.

While I agree that the F4U's stall in the game probably isn't nearly as severe as it should be, I must object to this statement. It is quite possible to recover from at least some types of stall in a real Corsair without a major altitude loss. You can see an example of this in the U.S.A.A.F. training video. Of course, it's a power-off slow stall, not a power-on accelerated stall. And he does not let the spin develop in the first place, but recovers immediately after the stall. But it all depends on how far you let the stall develop; that's true of nearly any airplane. I'm sure that even the docile Cessna could be placed into an unrecoverable spin, if you try hard enough.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 19, 2007, 12:27:08 AM

Quote
But it all depends on how far you let the stall develop...

THIS is the important statement. I've said this before, but the F4U in the game can be a HANDFUL for an unwary inexperienced pilot to try and fly slow in the weeds. I think part of the reason why she seems more forgiving is because a lot of the guys saying it are ALSO veterans who've already gone through the teething process of learning how to handle departure situations in the game.

The F4U, if flown with too rough a hand on the stick, WILL depart without warning. While I do agree the characteristics may be somewhat more docile than they should, I believe at least a part of this is an illusion because players in this game have the bonus lives to learn how to detect and recover before there's a problem, or just how far she can be pushed before she gets out from under them.

I've entered spins at high altitude and needed a good 5000-6000ft to recover again. The same would most certainly be a fatal crash in the typical MA furball. I don't think it's so much the aircraft isn't departing when it should, but that guys here, through the type of practice, trial and error that the HISTORICAL pilots didn't benefit from, have learned how to correct and recover almost before the problem starts.

Guaranteed, if you take a total newbie (as in no prior flight simulation experience whatsoever) to Aces High with in-game flight hours roughly equivalent to the average flight time of a rookie WWII fighter pilot just arrived at the front for his first check flight and stick him in the Corsair, then have him try and pull the sort of maneuvers the vets here with hundreds, if not THOUSANDS of game hours in the Hog can execute, he'll very quickly screw himself right into the ground.

Who was it a couple months ago who posted video of a REAL F4U pulling the EXACT same sort of gravity-defying maneuvers people are calling "BS!" on in this thread?

Title: Corsair Turning Ability in AH
Post by: mtnman on July 19, 2007, 06:27:01 AM

Hmmm, Saxman, could that be the video that was through You-Tube? Maybe someone with a better internet connection could do a search...

I'm on 28K dial-up, and don't think I'll have the required time to do it myself. I'd be interested in the link if anyone finds it again.

I wonder how much the Combat Trim is responsible for the reduced severity of the spins? I know in my early days I was known to spin the F4U into the ground from as high as 12k, but I was REALLY BAD back then, hehe.

MtnMan

Title: Corsair Turning Ability in AH
Post by: Saxman on July 19, 2007, 07:19:06 AM

I can't remember. I suppose I could always do a forum search, but there's been about a hundred of these "F4U Turn Performance is BS!!!!" threads since then.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 19, 2007, 09:18:54 AM

I'd love to see it, if only because it's footage of a real Corsair doing aerobatics.

Title: Corsair Turning Ability in AH
Post by: Krusty on July 19, 2007, 09:33:48 AM

Benny, HTC doesn't just plug in values. They have greater control than that. They can make the stall as gentle as a P38's or as rough as a 190's. They have control over a LOT of things.

Including, for example, the CoG on the Mossie. That's hard-coded in, and they'd have to redo it from scratch to fix the CoG bug currently seen with the mosquito.

So they can and have done plane-specific coding.

If you ask me, it's fine if they hard-code each plane. It's more work for them, but as long as the end results are correct....

Currently, the end results are not correct.

I don't agree with saxman, though. We don't have it easier because we're all veterans. Even veterans wouldn't stall a corsair on purpose. In this game I've almost never spun out in a corsair. It's hard to make it. I'm quite ham-fisted on the stick, and the most I can seem to do is snap-roll it by pulling back really hard on the stick. We have it easier because it is easier.

I can tell when it's experience kicking in vs the plane simply doing what it does. Landing a corsair or a Ta152 = experience. Stalls in corsairs = the planes. The difference? One requires thought, even if ever so brief.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 19, 2007, 09:55:20 AM

Quote
Originally posted by Krusty
Benny, HTC doesn't just plug in values. They have greater control than that. They can make the stall as gentle as a P38's or as rough as a 190's. They have control over a LOT of things.

Yes, but this is not done by scripting, as "stall gentleness = 35.7, buffetting = 22.2, wing drop = 51.9" but rather by editing the lift, drag, thrust, and weight vectors. Since there are so many of them, if they give each one the correct value (assuming that they have an accurate source for all of them), the end result is quite realistic. The flaps are where I think the problem is. I think that the calculation used for how much drag and how much lift they add is quite a bit off.

Title: Corsair Turning Ability in AH
Post by: SIK1 on July 19, 2007, 09:55:26 AM

O.k. where do I get the corsair that out turns spits, 'cause the ones I'm flyin' sure don't.

Actually I agree with Benny, and Saxman on how far you let the stall develop. I have learned that if you kick right rudder, as soon as the hog starts to depart you can usually save it before you get one rotation of a spin. Note I did say usually. If you get more than one rotation you better have some altitude.

Saxman I don't think I have seen the video you are talking about, is it an airshow video, or is it a USN training video, if it's the latter you might try Zenos.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 19, 2007, 10:03:33 AM

Sik1, if you drop flaps in the F4U-4, it will indeed out-turn most Spitfires in Aces High II. Look it up. Dokgonzo's page says it turns tighter, flaps down, than all Spitfires except for the Marks I and V. My experiences in it agree with that. And yet people wonder why I have the F4U-4 disabled in my server.

Title: Corsair Turning Ability in AH
Post by: Krusty on July 19, 2007, 10:04:59 AM

Quote
Originally posted by Benny Moore
Yes, but this is not done by scripting, as "stall gentleness = 35.7, buffetting = 22.2, wing drop = 51.9" but rather by editing the lift, drag, thrust, and weight vectors. Since there are so many of them, if they give each one the correct value (assuming that they have an accurate source for all of them), the end result is quite realistic. The flaps are where I think the problem is. I think that the calculation used for how much drag and how much lift they add is quite a bit off.

Benny we've seen screenshots of some of their tools, so we know they do model flight over various parts of the wings, and can control that.

However, that does not account for everything. That's not the ONLY thing they do. There are many aspects that may not be linked to that in any way, so you can't say "Oh they just tweak this and it's done" -- because you're not 'on the inside' so to speak :)

P.S. Sik, DokGonzo link in my sig

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 19, 2007, 10:09:09 AM

If they artificially script aircraft behavior, I'll eat my hat. Hitech?

Title: Corsair Turning Ability in AH
Post by: Krusty on July 19, 2007, 10:17:57 AM

I wouldn't call it "artificial" -- it's all game code, it's 100% artificial. They have certain elements that react different ways. There's no way to know what/how they get the end results unless they tell us.

And we all know how open and informative they are on their internal coding, right? :D

Title: Corsair Turning Ability in AH
Post by: SIK1 on July 19, 2007, 10:46:03 AM

For some reason I have issues with DokGonzo's websight. The info doesn't show up and I have tried it from several differant computers.

I hardly ever fly the -4 hog so I am not very familiar with what it will and will not do.

Title: Corsair Turning Ability in AH
Post by: Krusty on July 19, 2007, 10:53:55 AM

Hrm... I never have problems.

Anyways, this is what it says:

Plane: no flaps / full flaps
F4U-4: 691 / 428
Spit IX: 632 / 433
Spit VII: 568 / 448
Spit XVI: 567 / 450
F4U-1: 674 / 425

I'm not sure if the F4U-1 is a -1 or a -1A. It doesn't have a -1A on that site.

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 19, 2007, 10:54:02 AM

I'm very smelly still and I've tried outturning spits, but I'll just stick to my scissors with 20 degrees and gear if necessary. Blows less energy and your always ready to run away if need be.

Title: Corsair Turning Ability in AH
Post by: SgtPappy on July 19, 2007, 10:57:10 AM

It,s an F4U-1, Krusty. The A-Hog hasn't been updated in there. Those are all the old values of the old Corsairs.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 19, 2007, 12:07:19 PM

I've never been able to get that page to load correctly either. It takes 10-15 minutes for the few items to load that will, and the others just "x" out.

When it says-

Plane: no flaps / full flaps
F4U-4: 691 / 428
Spit IX: 632 / 433
Spit VII: 568 / 448
Spit XVI: 567 / 450
F4U-1: 674 / 425

Does it happen to give the speed and/or time required to complete the circle? If the spit is actually flying any faster than the corsair through that circle, then the corsair isn't actually out-turning it.

My experience in the Lufberry's with spits is that I can't keep up with them and they crawl around behind me.

Also, from what I remember of the spit flaps, you're comparing apples to watermelons. Spits have the split flaps right? The ones that are either up or down, with no variation of degrees? How much deflection do they give? Aren't they of less chord? Weren't spit flaps advertised for slowing down to land, rather than to aid in manuevering? (Far from a spit afficianado here)

MtnMan

Title: Corsair Turning Ability in AH
Post by: Krusty on July 19, 2007, 12:34:25 PM

It just says "turn radius."

Spit flaps don't work very well, as you noted, but in all fairness I included them.

It doesn't matter, though, because F4U flaps are by FAR the most effective flaps in the game (for no particular reason), second would probably be P-38, and behind both of those the other US planes. I believe Karaya/Masherbaum did some comparison once across the board based on stall speeds.

Title: Corsair Turning Ability in AH
Post by: SIK1 on July 19, 2007, 02:47:49 PM

Quote
Originally posted by mtnman
I've never been able to get that page to load correctly either. It takes 10-15 minutes for the few items to load that will, and the others just "x" out.

Maybe the site just doesn't like hog drivers.:O :noid

Title: Corsair Turning Ability in AH
Post by: Knegel on July 19, 2007, 06:09:16 PM

Hi,

if i got it wrong, can somone please explain why the F2A test and calculations are so far away from what we have in game??

Even similar planes regarding the powerload+wingload dont show a similar turn rate reduction like the F2A. Look to the F4F, HurriIa, SpitIa, 109E4 or the 110C. They simply dont lose turn rate like the F2A, but the turn radius reduction is much higher.

Are the F2A flaps the most worse of all WWII fighters and are the calculations offered before so much wrong, or is the modeling of the flaps in AH wrong??

Again, this wasnt always so, actually for most planes this is rather new(the 109´s and 190´s for example), so the makers once must have had a other understanding than now.

Benny, the makers can insert different datas for each plane, the problem is to find datas. Where do we get the lift and drag datas of the F4U-4 from?? Where do we get the lift and drag datas of the full flap condition from??

The airfoil datas dont help that much, cause the wing planform (wing shape), the form of the fuselage and wing tips and other influences, like cannons, not covered undercarriages, dust, etc make a calculation of this values hopeless. We always will result in a "greyzone of realism", where we have a bandwith of credible possibilitys(even the real planes of the same type never had the same values and so behaviour).

Thats why i dont wanna discuss, if the F4U turn to good or not, imho its inside the "greyzone of realism", although its imho more on the optimistic side, but how all flaps in AH work probably is badly wrong.

We have the F2A turn calculations and tests, if someone can proof them wrong, or if someone have similar turntests of other planes with "normal" flaps, which show similar results like the AH planes, iam willing to believe all is ok.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Knegel on July 19, 2007, 07:07:53 PM

Just another reason why a plane with full flaps dont take that much advantage out of the higher lift:

The plane with full flaps conditions will turn with a much smaler speed than the one without flaps and although the max CL is a bit higher, the resulting lift is smaler, cause the different speeds. Since both planes need to waste the same lift to overcome the same -1G to keep a level turn, the slower flying plane need to waste more % of its lift to stay in a level flight. With other words, as slower the plane fly, as less it can bank. (if i remeber right, speed influence the lift in square).

So although the full flap condition result in a better max CL, the "excess lift" stand in a less good relation.

Further more the full flap condition while a sustained turn and climb result in a not to smal "nose down" position. So the thrust line have a much worse direction(in relation to the no flap thrust line).

Further more, without flaps the planes have a higher max AoA of around 2°, this provide a even better thrust line(the thrustline point more toward the center of the turn and more upward while climbing).

Further more the planes have a basic trim setup for higher speeds, so while flying at very slow speed more trim or rudder variation is needed(more drag, more yaw/shift moments, less lift).

While a full banked flight at slower speeds, the upward lift by the fuselage is much smaler, as result the plane have even less max lift and cant be banked that much again.

Isnt it like this?
At the same turn rate the g-forces are the same, this is comperable with a steady climb. Both planes must create the same lift and same ammount of drag and so same ammount of exess thrust.
So if a plane in AH turn sustained at different speeds with max AoA with same G-force, they should also climb with max AoA same good (same excess thrust).

So my question remain:
Why the F4U-4 lose around 30% climb ratio (max AoA), while a very similar turn ratio(5% difference) at max AoA indicate a very similar g-force and so lift and drag and so excess thrust?

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 19, 2007, 09:45:14 PM

Krusty,

Where did this quote come from?

Quote
every one I know that has major time in tem is do not get low and slow and try to maneuver. The stall below 200 kts and 6k AGL is unrecoverable as the wing drops and a spin results which is unrecoverable given the altitude. Given altitide the F4u is still a monster in the spin, and the few pilots I know that have intentionally spun the Corsair say they will never try it again."

I have read countless accounts of F4U handling and I have never read that. In fact the P-51D has far worse high speed stalls than the F4U.

In the 1989 Flight test performed by the SoETP (Socioty of Experamental Test Pilots) they documented the stalls of the P-47D , F6F-5, P-51D and FG-1D.

The 3G accelerated Stall results power on (METO Power) are as follows with high loss listed (All speeds IAS) No flaps.

P-47D
Stall Warn=126Knots
Stall Speed = 109Knots
High loss= 100FT

P-51D
Stall Warn=122Knots
Stall Speed= 122Knots <== No Warning at all
Hight Loss= 500FT

F6F-5
Stall Warn=100Knots
Stall Speed= 95Knots
Hight Loss= 150FT

FG-1D
Stall Warn=103Knots
Stall Speed= 100Knots
Hight Loss= 150FT<=Same as the F6F

A couple of other notes about the test,

1. The F6F was 400lBS lighter than the F4U when tested and it should be 200LBS heavier. So you can imagine the results would be different with the extra weight.
2. The F6F IAS/CAS problem was apparent during this test so it's air speed was more than likely higher than indicated.

I will try to scan the rest of the report so you can see it. In the final conclusion the pilots make note of the "Gentle Stall" of the F4U and call it the "Weapon of Choice" for air to air combat among those tested.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 19, 2007, 11:08:50 PM

From what I understand, the Mustang's departure behavior was absolutely wicked, especially where there was gas in the fuselage tank. The P-51 just had the benefit of not trying to land on a carrier deck.

Title: Corsair Turning Ability in AH
Post by: dtango on July 20, 2007, 12:53:42 AM

Quote
Isnt it like this?
At the same turn rate the g-forces are the same, this is comperable with a steady climb. Both planes must create the same lift and same ammount of drag and so same ammount of exess thrust.

Knegel:

(1) same turn rate does not mean the same g-forces.

(2) one of the fundamental issues is that a steady climb is not the same as a sustained turn. More specifically the variables that effect power required are non-linear so you can't equate power-required in a steady climb to power-required in a sustained turn.

(3) the NACA F2A-3 report demonstrates the above.

No time to post anything else on this topic at the moment :).

Let me be clear. I'm not suggesting there isn't anything wrong with the AH flap model.

However you can't make the conclusion that the AH flap model is wrong based on the assessment thus far because the physics in the argument is inaccurate.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Brooke on July 20, 2007, 01:22:16 AM

I have redone the calculations of turn rate and turn radius based on a much-more appropriate modeling of thrust vs. velocity (as suggested by Badboy).

The results are here. Again, if anyone sees any problems with the math, please let me know:

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningMath.html

Title: Corsair Turning Ability in AH
Post by: Brooke on July 20, 2007, 03:03:06 AM

I added a little more detail to the P-51D and F4U-1 models (calculating C_L_max for each based on stall speeds listed in the pilots' manuals).

The models still show turn rate for F4U-1 with full flaps slightly less than without flaps, but it is a very close thing. The F4U-1 truly has an amazing wing, with excellent C_L_max, expecially amazing flaps, with even more excellent C_L_max (at least compared to a plane like the P-51D). All it takes to get turn rate with full flaps to be about the same as turn rate without flaps is a little better e or C_D_min (or both) with flaps than what I'm assuming.

Title: Corsair Turning Ability in AH
Post by: dtango on July 20, 2007, 08:07:55 AM

Quote
Originally posted by Brooke
All it takes to get turn rate with full flaps to be about the same as turn rate without flaps is a little better e or C_D_min (or both) with flaps than what I'm assuming.

Yep, that's the secret :). At higher angles of attack the drag polar ceases to be parabolic because lift dependent drag is strongly influenced by viscous separation. Gripen and I pointed this out earlier. What that means is e is no longer constant at higher aoa's but varies with aoa. For the type of flaps in question (non-fowlers) Clmax occurs at a lower aoa with flaps down vs. with flaps up. So if e varies with aoa then "voila!", e is better (higher) with flaps down vs. with flaps up.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Krusty on July 20, 2007, 08:57:27 AM

F4UDOA: The quote is directly from Bodhi, who works on corsairs for a living and probably talks to their pilots frequently. You can ask him specifically for more detail, I was merely quoting something he said not too long ago in another thread.

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 20, 2007, 09:55:08 AM

Brooke,

I was looking at your math most of which frankly sailed over my head but I did notice one thing. Your Clmax numbers seem high on both the P-51D and F4U-1.

I recalculated the Clmax number (power off) for the F4U in clean and landing condition and came up with this.

(391*11,300) / (97MPH^2 * 314) Clean no power
4418300 / 2954426
1.49Clmax

(391*11,300) / (86MPH^2 * 314) Landing condition no power
4418300 / 2322344
1.9 This is the listed Clmax in the Vought documentation as well.

Question:

If two aircraft fly circles around the same center point but one flys a greater radius than the other they may both be flying at the same rate even if one is flying much slower than the other. IE the aircraft flying closer to the Axis may be flying at 120MPH and the one flying further away from the axis can be flying at 160MPH and they can both have the same turn rate.

I believe this explains why Knegal doesn't understand why the flaps do not cause the F4U-1 to lose turn rate despite flying much slower however I cannot prove this mathmatically. Do you agree?

Thanks

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 20, 2007, 10:18:06 AM

Krusty,

I did not know that about Bodhi, I will have to ask him.

One thing that I find in reading about modern Corsair pilots/owners that is common is the ease of flying the F4U. From the SETP to Jeff Ethell and multiple other articals etc it is a common theme. Even the 1944 JFC echoes the same findings in stability and control.

The general theme with the F4U is stay within the flight envelope and you are safe. When exceeding it the stalls can be dramatic but are recoverable. This is common to most warbirds except the F6F. The P-51 stall behaivior far exceeds the F4U but it was land based so it did not have the same criteria for success.

The findings of the SEPT test were that the F4U was for the experianced pilot and the F6F was almost like flying a trainer and was better for less experianced pilots (Ensigns). The F4U did give ample stall warning and had higher G-Limits than the F6F without entering buffet in max performance turning.

The Strength of AH (IMHO) is that it reley's on fact not annecdote. I think many in this community expect the F4U to spin and crash everytime you pull the stick. This airframe stayed in service for 30 years without change, I don't think it was quite that lethal.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 20, 2007, 10:59:56 AM

IIRC the biggest problem with the Corsair's departure wasn't just the port wing drop during the stall at low speeds in of itself, but inexperienced pilots over reacting and trying to power on too hard to compensate. That much torque that suddenly contributed to a significant number of the fatal spins at low altitude.

You can see this to lesser degrees in AH (yes, I DO think it's milder than it should be). Put the F4U in landing configuration at reduced power near stall speed, trimmed for level flight or slow descent. As the plane stalls and the left wing dips jump right to power on full. The F4U makes a noticeable attempt to roll left.

Title: Corsair Turning Ability in AH
Post by: dtango on July 20, 2007, 12:33:51 PM

Quote
Originally posted by F4UDOA
If two aircraft fly circles around the same center point but one flys a greater radius than the other they may both be flying at the same rate even if one is flying much slower than the other. IE the aircraft flying closer to the Axis may be flying at 120MPH and the one flying further away from the axis can be flying at 160MPH and they can both have the same turn rate.

I believe this explains why Knegal doesn't understand why the flaps do not cause the F4U-1 to lose turn rate despite flying much slower however I cannot prove this mathmatically. Do you agree?

F4UDOA: Yes that is correct.

turn-rate = gravity * sqrt ( gload^2 - 1) / V

For instance two planes at different airspeeds and turning at different g's:

mph g rate
170 2.90 20.1
110 2.02 20.1

Different airspeeds, different g-load's, but same turn rate.

Actually I think the main source of Knegel's issue is that he's misapplying

Ps = (T - D) * V / W

between a steady climb and a sustained turn.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Charge on July 20, 2007, 05:03:02 PM

"I think many in this community expect the F4U to spin and crash everytime you pull the stick."

Yes I'm sure Knegel was trying to point that out... :rolleyes:

"Actually I think the main source of Knegel's issue is that he's misapplying
Ps = (T - D) * V / W
between a steady climb and a sustained turn."

And you claim that a loop and a sustained turn are the same?

Do you assume the speed to decay to the extent that the acceleration upward against the G gradient stays at 1 G? Do you assume that when the plane goes down the G gradient once again stays the same OR that the average between the rise and fall stay the same? If so, then why cannot WW2 fighters fly constant loops without losing altitude even if they can fly constant turn at some G without losing altitude?

-C+

Title: Corsair Turning Ability in AH
Post by: dtango on July 20, 2007, 05:53:40 PM

It is if you remove gravity as Knegel was suggesting. You should read before you reply :).

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Brooke on July 20, 2007, 10:23:13 PM

Quote
Originally posted by F4UDOA
Brooke,

I was looking at your math most of which frankly sailed over my head but I did notice one thing. Your Clmax numbers seem high on both the P-51D and F4U-1.

I recalculated the Clmax number (power off) for the F4U in clean and landing condition and came up with this.

(391*11,300) / (97MPH^2 * 314) Clean no power
4418300 / 2954426
1.49Clmax

(391*11,300) / (86MPH^2 * 314) Landing condition no power
4418300 / 2322344
1.9 This is the listed Clmax in the Vought documentation as well.

Question:

If two aircraft fly circles around the same center point but one flys a greater radius than the other they may both be flying at the same rate even if one is flying much slower than the other. IE the aircraft flying closer to the Axis may be flying at 120MPH and the one flying further away from the axis can be flying at 160MPH and they can both have the same turn rate.

I believe this explains why Knegal doesn't understand why the flaps do not cause the F4U-1 to lose turn rate despite flying much slower however I cannot prove this mathmatically. Do you agree?

Thanks

I was using stall speed for the F4U with power on. I think that is more accurate, as power is on during stallfight turns. For C_L_max with power off, though, here is how it would turn out (with v_stall = 97 mph calibrated airspeed, clean, power off). 97 mph = 97 * 1.467 ft/sec = 142 ft/sec, W = 11300 lbs, rho = 0.0748 lbs/ft^3 / 32 ft/s^2, S = 314 ft^2:

C_L_max = 11300 / (0.5 * 0.0748/32 * 142^2 * 314) = 1.53

So, that is a bit less than the C_L_max you get when v_stall (with power on) = 94 mph.

With flaps down, power off (86 mph = 126 ft/sec):

C_L_max = 11300 / (0.5 * 0.0748/32 * 126^2 * 314) = 1.94

For the question, yep, a plane with a smaller turning radius could have a smaller turning rate than a plane with a larger turning radius. This is often what happens with full flaps. The plane without flaps has a larger turning radius but also a larger turn rate.

Knegel, I think, believes that the fact that the F4U has a higher turn rate with full flaps (unlike most planes) points to a problem in its flight model in Aces High. I talk about that in the document. It's unusual, but I'm not sure it's a problem. It depends on what things like e and C_D_min are for F4U's with full flaps.

Title: Corsair Turning Ability in AH
Post by: dtango on July 21, 2007, 03:28:55 AM

OK Knegel, I set aside some time to put the following together to explain in more detail. I hope you appreciate it!! :P

The Physics:
Specific Excess Power (Ps) governs an aircraft's performance in a steady climb and a sustained turn.

(http://brauncomustangs.org/images/ps-eq.jpg)

(Don't let this elegant form of this equation trick you though! It looks simple but it's not and also not easy to calculate requiring knowledge of quite a few different curves and polars for a specific aircraft.)

So if a steady climb and a sustained turn are a function of the specific excess power of an airplane, why can't we extrapolate the performance of a steady climb to that of a sustained turn?

Let's breakdown just the power-required portion (Drag * Velocity) of the equation to demonstrate the reason why:

(http://brauncomustangs.org/images/pr-eq.jpg)

So when we breakdown power required, we see that it is a combination of the PARASITE power required and the INDUCED power required of the airplane. Assuming weight is constant, induced power required is a function of g-load, velocity, altitude, and oswald/span efficiency (e).

Excess power then depends on load-factor (squared), airspeed, altitude, and e. Ignoring altitude, the values of these variables are not the same between a steady climb vs. a sustained turn. The variables are also non-linear. Power required (overall) varies with cube of velocity and the square of load factor. Also e is no longer constant at higher angles of attack and varies non-linearly with increasing angle of attack.

The result is that the conditions for specific excess power for a steady climb are different from that of a sustained turn so you can't extrapolate steady climb performance to sustained turn performance.

Demonstration of Variation in Specific Excess Power - Steady Climbs vs. Turns
Let's create a basic model of the F4U to illustrate the physics above.

For our basic F4U model let's use the following static parameters to compare a Corsair with and without flaps:

(http://brauncomustangs.org/images/specs1.jpg)

For propeller efficiency we'll use a generalized prop efficiency based on the following curve:

(http://brauncomustangs.org/images/prop-e.jpg)

For key aerodynamic coefficients different between an F4U with and without flaps let's use the following values to compare the F4U’s:

(http://brauncomustangs.org/images/specs2.jpg)

CD0 come from a NACA wind tunnel F4U1-A test for flaps and no flaps. CL is calculated based on the 1g stall speeds listed. A couple of assumptions in my model: 1) it doesn’t factor in the effect of propwash on drag, and 2) constant e because I don’t have a good drag polar for the F4U to estimate the variation at higher aoa from.

Sparing everyone the gory math, using these parameters let’s see the results for specific excess power (Ps) for a steady climb vs. a sustained turn.

STEADY RATE OF CLIMB:

(http://brauncomustangs.org/images/roc.jpg)

This is a comparison of the rates of climb at constant velocity for our F4U at 0 degrees and 50 degree flap settings. Rate of climb is specific excess power of the aircraft at 1g. Its obvious here that the excess power required due to flaps is much greater than that of the F4U without flaps deployed. The F4U with 50 degrees flaps deployed has a worse climb rate across the board compared to that of the F4U without flaps deployed.

Now let’s take a look at the Ps calculations for the F4U in a sustained turn, flaps and no flaps.

SUSTAINED TURN RATE AND Ps:
The following are the calculations comparing turn rates of the F4U with and without flaps as well as the associated specific excess power. The performance is based on turns made at Clmax at the various velocities.

(http://brauncomustangs.org/images/ps-tr.jpg)

The Ps curves represent the specific excess power of the F4U with flaps and no flaps in a turn at Clmax. Notice how differently they are shaped compared to the Ps curves for the same aircraft in a steady climb at 1g. This is because of the impact on specific excess power due to variation in g-load and velocity in a turn vs. a steady climb.

Note the Ps axis and Ps curves. There is a point where Ps=0 for a turn at Clmax. Turns at Clmax above this airspeed result in Ps values <0 which would result in loss of altitude or airspeed. Turns at Clmax below this velocity result in Ps values >0 which mean the aircraft would gain altitude or airspeed. Point 1 is where Ps=0 for the F4U with 50 degree flaps. Point 2 is where Ps=0 for the F4U with no flaps.

Ps=0 is a key part of the aircraft’s envelope. This is where power-available of the aircraft directly equals power-required of the aircraft in a turn. This is the point where the best sustained turn occurs for the aircraft.

Plotted along with Ps is the rate of turn associated for that aircraft turning at Clmax at a given velocity for that specific excess power. If we draw a vertical straight line at the velocity for Ps=0, where the line intersects the turn-rate curve is the best sustained turn-rate for that aircraft. For our basic F4U model these are point 3 (for 50 degree flaps) and point 4 (for 0 degree flaps).

Notice the best sustained turn rates for our basic F4U model. For 50 degree flaps vs. no flaps they are essentially the same for all intents and purposes at ~18.5 dps which translates to ~19 seconds to complete 360 degrees!

So there you have it! Steady climb performance with flaps down is worse than that with flaps up, yet the best sustained turn rates are the same! Why? Because specific excess power varies with 1)load factor, 2)velocity, 3)altitude, 4)e – and these are different in a steady climb vs. a sustained turn. (Note also that in my basic model that I even left e constant and the results still yielded what they did.)

NACA F2A-3 Turn Performance Report
What about the NACA F2A-3 report referenced? It demonstrates the physics principles above at work.

The report talks about two types of turns tested: 1) constant speed turns and 2) sustained level turns. These turns were tested at various flap settings.

Let’s look at figures 32 and 34. These are diagrams show performance of the F2A-3 at 13,000 ft with 0 degrees of flaps vs. 56 degrees of flaps. Below I’ve taken figure 34 (56 degrees of flaps) and overlaid the “angle of climb” curve from figure 32 (0 degrees of flaps) onto the diagram.

(http://brauncomustangs.org/images/climb-angle.jpg)

The angle of straight climb curves basically give us a way to gauge the excess thrust of the F2A-3 in 1g flight with flaps and without flaps.

Sin(theta) = (T – D) / W

(theta) = sin^-1 [ (T – D) / W ]

(Theta) is the angle of climb. Knowing this gives us a way to calculate steady rate of climb for that velocity.

rate of climb = V * sin (theta)

So based on this equation we can visually see that the steady rate of climb of the F2A-3 is better without flaps vs. the rate of climb with 56 degrees of flaps. Power required is greater with flaps vs. without flaps. This relationship holds true except just under 80mph.

So now let’s take a look at sustained turn performance of the F2A-3 with and without flaps and see how that compares. Figure 22 and 24 in the report show the sustained turn radius and turn rates of the F2A-3 at 13,000 ft. Below are just the turn-rate portions of the graphs.

(http://brauncomustangs.org/images/f2a-turn-rate-0f.jpg)

(http://brauncomustangs.org/images/f2a-turn-rate-56f.jpg)

Notice how similar the best sustained turn rates are for 0 degrees of flaps vs. 56 degrees of flaps ~25-27 seconds to complete 360 degrees of a sustained turn.

So here we have it again. The F2A’s rate of climb without flaps is better than the rate of climb with 56 degrees of flaps. Yet the best sustained turn rates are virtually the same with flaps at 56 degrees vs. no flaps.

Why? Because specific excess power varies with load-factor, velocity, altitude and e which are not the same in a 1g steady climb vs. a >1g sustained turn.

A key note about all this. My calculations above aren't intended to measure the accuracy of how closely HTC has modeled the F4U. The intention was to illustrate the factors that govern specific excess power.

Hope this helps!

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: dtango on July 21, 2007, 10:47:31 AM

A correction. I mistyped the CD0 value for 50 degree flaps I was using. I've updated the image. Here are the parameters.

(http://brauncomustangs.org/images/specs2.jpg)

Cheers!

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Brooke on July 22, 2007, 03:28:33 AM

Tango, thanks! Also, thanks to you, I found the NACA report the F2A. Which is the one for the F4U? Is it the one for the wind-tunnel test on the model with full-span flaps?

Title: Corsair Turning Ability in AH
Post by: Knegel on July 22, 2007, 07:47:21 AM

Hi dtango,

i appreciate your work for sure!

But i think your calculation forget some important factors.

Whats about this arguments??
-----------------------------------------------------------------------------
The plane with full flaps conditions will turn with a much smaler speed than the one without flaps and although the max CL is a bit higher, the resulting lift is smaler, cause the different speeds. Since both planes need to waste the same lift to overcome the same -1G to keep a level turn, the slower flying plane need to waste more % of its lift to stay in a level flight. With other words, as slower the plane fly, as less it can bank. (if i remeber right, speed influence the lift in square).

So although the full flap condition result in a better max CL, the "excess lift" stand in a less good relation.

Further more the full flap condition while a sustained turn and climb result in a not to smal "nose down" position. So the thrust line have a much worse direction(in relation to the no flap thrust line).

Further more, without flaps the planes have a higher max AoA of around 2°, this provide a even better thrust line(the thrustline point more toward the center of the turn and more upward while climbing).

Further more the planes have a basic trim setup for higher speeds, so while flying at very slow speed more trim or rudder variation is needed(more drag, more yaw/shift moments, less lift).
------------------------------------------------------------------------

Furthermore i think your turn/climb curves dont fit to each other(they show the same discrepancy i see in AH).

(http://www.raf-roy.com/share/knegel/Screenes/climb_turn_discrepancy.JPG)

Thats why i still think, if the plane climb much better at max AoA, it also should have a beter turnrate at max AoA, or the other way around, if the plane have a similar turn rate at max AoA, they also should have a similar climb rate.

If the turn would be like your diagram show, the climb should be like this:

(http://www.raf-roy.com/share/knegel/Screenes/roc_correction.JPG)

So at slower speeds, the plane with flaps should climb better than without flaps, but i think thats simply impossible with normal flaps with all the disadvantages the flaps offer(my Arguments in the beginning of this post).
Edit: After thinking about it, i think the plane with full flaps should realy climb better than the plane without flaps at stall speed(without flaps).

Hi F4UDOA,

i absolutly understand that the plane with the smaler radius dont need to fly that fast to reach the same turn ratio.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 22, 2007, 07:59:30 AM

The reason why an airplane should have a worse turn rate with flaps, even while enjoying a turn radius improvement, is that flaps are draggy and inefficient. They produce more drag than lift. Again, Fowler flaps are a possible exception to this, but even those probably are less efficient than a clean wing (though obviously much more efficient than conventional flaps).

Title: Corsair Turning Ability in AH
Post by: Knegel on July 22, 2007, 08:07:27 AM

I absolutly agree Benny!

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 22, 2007, 09:06:18 AM

Knegal,

That 100MPH stall speed is based on no power stalls, even the power on stall numbers in the manual are at 18"MAP idle power, when you add full power airflow increases over the wing you can fly well into the stall range.

The F4U-1 could takeoff at weights up until 17,000LBS only because of the lift caused by the full flaps. If the drag was more than the lift at low speed then the airplane could never take off.

Take a look at this climb curve for full flaps (Purple line). Right at the peak of the climb around 110MPH-120MPH the F4U is still accelerating. This means below 120MPH the drag from the flaps is negligable. Below that speed the aircraft still accelerates and above that speed the drag degrades the climb although it is still accelerating against gravity. In fact it still accerates up until almost 200MPH.

I have document from Vought that states exactly this. That the drag from the flaps and external ordinance has no bearing on climb, only the additional weight from ordinance. And infact it says not to retract flaps while climbing while heavily loaded because this will cause a stall. If the flaps were not provong more lift than drag then you should just retract them but this is not the case.

(http://brauncomustangs.org/images/roc.jpg)

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 22, 2007, 09:22:04 AM

I believe that turn rate should only be lower at particular speeds.

At some speeds the initial deployment of flaps and even when the flaps go all the way down, the aircraft will turn at more degrees per second (or turn rate) at slightly lower speeds. If the opposing aircraft (let's say they're both F4U-4's for example) is flying in the speed range without flaps, it will not turn at the same degrees per second. Once the opposing F4U-4 (no flaps) reaches a speed high enough, it will then turn at more degrees per second than the F4U-4 with full flaps.

If we could have a chart with 'degrees per second' on the y-axis and 'mph' on the x-axis for our in-game F4U-4 and perhaps 3 different lines (one indicating F4U at no flaps, one with F4U at maybe 20 degrees and one F4U at 50 degrees) that would help.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 22, 2007, 09:41:27 AM

As far as I'm concerned, the math shows that HTC has the F4U's turn performance more or less correct. Perhaps stall behavior is a tad more docile than it should be, but as F4UDOA pointed out (was it this thread, or another one, I've lost track) people around here seem to assume the Corsair should be ready to snap over the instant the stick deflects from neutral.

Knegel, you need to give us something more than the same argument and how you THINK it should be without any corresponding hard data to back in up (as far as I'm concerned the F2A report you keep quoting is insufficient because it doesn't say WHY it is like in dtango's calculations. It makes your alterations of his charts seem completely arbitrary. Also, applying a performance report from one aircraft to a COMPLETELY DIFFERENT one is significantly flawed).

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 22, 2007, 01:16:32 PM

I mistyped in my last post.

The document I have states no bearing on takeoff not climb. I shouldn't paraphrase without re-reading the doc but the same principle applies.

I will post the doc shortly.

Quote
I have document from Vought that states exactly this. That the drag from the flaps and external ordinance has no bearing on climb, only the additional weight from ordinance. And infact it says not to retract flaps while climbing while heavily loaded because this will cause a stall. If the flaps were not provong more lift than drag then you should just retract them but this is not the case.

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 22, 2007, 01:24:42 PM

Quote
The reason why an airplane should have a worse turn rate with flaps, even while enjoying a turn radius improvement, is that flaps are draggy and inefficient. They produce more drag than lift. Again, Fowler flaps are a possible exception to this, but even those probably are less efficient than a clean wing (though obviously much more efficient than conventional flaps).

Benny,

Decreasing your turn radius increases your turn rate as long as speed or G-Load remains constant. Even if you lower speed and G load you can maintain your turn rate even at much lower speeds. Dtango showed that earlier.

mph   g   rate
170   2.90   20.1
110   2.02   20.1

Significantly lower speed and G load but the turn rate is constant.

Title: Corsair Turning Ability in AH
Post by: Benny Moore on July 22, 2007, 01:51:36 PM

You're forgetting about the drag; in order to improve the turn radius and have the same turn rate, you'd need to add as much lift as drag.

Title: Corsair Turning Ability in AH
Post by: Brooke on July 22, 2007, 05:25:18 PM

OK, based on the references Tango found, I have updated my calculations for the F4U-1. See the Appendix: F4U-1 in this document:

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningMath.html

The calculations, with actual and wind-tunnel data, agree very closely with the F4U-1 in Aces High -- including that the F4U turns at a higher turn rate with full flaps.

Yes, the F4U in real life does seem to have magical flaps -- backed up by real data and real aerodynamic calculations.

Aces High once again got it right.

Title: Corsair Turning Ability in AH
Post by: gripen on July 22, 2007, 06:44:41 PM

Quote
Originally posted by Brooke

Yes, the F4U in real life does seem to have magical flaps -- backed up by real data and real aerodynamic calculations.

The F2A data (Figure 5) shows pretty similar increase in value of the e with flaps. Because the e can be presented as:

e = 1/(pi*AR*K)

And the F2A data gives values of K:

flaps 0deg K = 0,070 => e = 0,78
flaps 22deg K = 0,068 => e = 0,80
flaps 56deg K = 0,057 => e = 0,95

So the same phenomena is there but the output of the engine limits the turn performance more than in the case of the F4U and the flaps system is not particularly effective (there were much more effective setups giving similar drag characters as in the figure from Perkins&Hage posted by dtango in the page two of this thread).

Title: Corsair Turning Ability in AH
Post by: Brooke on July 22, 2007, 07:03:55 PM

Gripen, good point about e and other factors.

For the F4U, it is both the high e and the high C_L_max with full flaps that gives the effect of better turn rate with full flaps (and the T to allow chugging around at that high a drag, as you point out).

Title: Corsair Turning Ability in AH
Post by: gripen on July 22, 2007, 07:14:55 PM

Brooke, did you got my email on determining the e? The median system you use is not particularly accurate.

Title: Corsair Turning Ability in AH
Post by: Brooke on July 22, 2007, 07:26:03 PM

It's reasonably OK -- I looked at the fit manually. Best is probably least squares, but median gives correct value +/- about 0.01 or 0.02 or so.

Title: Corsair Turning Ability in AH
Post by: Brooke on July 22, 2007, 07:48:58 PM

I just did a quick plug-in of data for the P-38J. It seems that the P-38J should have higher turning rate than the F4U both with and without flaps (unless I made an error, of course) but a larger turning radius.

I was using, from America's Hundred Thousand:

A = 8.24
S = 327.5 ft^2
BHP = 1600 HP
N = 3000/2.1 = 1429 RPM
D = 11.5 ft
W = 15,500 lbs

From P-38J pilot's manual at W = 15,000 lbs, clean, v_stall = 94 mph ias = 110 mph CAS. With full flaps, v_stall = 69 mph IAS = 84 mph CAS. So, C_L_max at 15,500 lbs = 1.5 flaps up and 2.58 with full flaps.

I assumed e = 0.8 for clean and e = 0.9 with full flaps. I assumed C_D_min = 0.02 clean and 0.09 with full flaps.

Doing all this in the spreadsheet (a link to which is in the my document), I have to correct for T = 2 * (thrust per engine), and I get:

max turn rate with flaps = 22.75 deg/sec, radius = 525 ft
max turn rate flaps up = 20 deg/sec, radius = 875 ft

The spreadsheet I'm using is here:

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningPerformance-v3.xls

Note that for P-38's, you have to manually modify the T column (add a multiplier of 2 in the formula).

Title: Corsair Turning Ability in AH
Post by: gripen on July 22, 2007, 08:23:36 PM

Quote
Originally posted by Brooke
It's reasonably OK -- I looked at the fit manually. Best is probably least squares, but median gives correct value +/- about 0.01 or 0.02 or so.

I got the e value about 0,76 (you got 0,81) for clean condition using least squares from the chart you quoted (it's pretty hard to read). The Cl^2/Cd chart also shows if the curve starts to bend from linear when nearing stall.

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 22, 2007, 08:57:23 PM

Quote
You're forgetting about the drag; in order to improve the turn radius and have the same turn rate, you'd need to add as much lift as drag.

Benny,

At low speed drag is not much of a factor only weight.

(http://mywebpages.comcast.net/markw4/F4Udrag.jpg)

Title: Corsair Turning Ability in AH
Post by: Brooke on July 23, 2007, 12:18:21 AM

Quote
Originally posted by gripen
I got the e value about 0,76 (you got 0,81) for clean condition using least squares from the chart you quoted (it's pretty hard to read). The Cl^2/Cd chart also shows if the curve starts to bend from linear when nearing stall.

I digitized the graph. Here is a table of data. I get 0.81 and 0.95 or so when I look for best fit of C_D_actual vs. C_D_formula (plotting one vs. the other) for various values of e.

Clean
C_L, C_D

-0.408945687   0.031011236
-0.234504792   0.022921348
-0.064536741   0.019325843
0.015974441   0.019325843
0.074121406   0.019325843
0.172523962   0.019325843
0.253035144   0.021123596
0.423003195   0.031011236
0.575079872   0.043595506
0.731629393   0.060674157
0.932907348   0.085842697
1.111821086   0.11011236
1.27284345   0.138876404
1.366773163   0.155955056
1.402555911   0.164044944

Full flaps
C_L, C_D

-0.230031949   0.101123596
-0.064536741   0.093932584
0.132268371   0.093033708
0.3514377   0.100224719
0.512460064   0.111910112
0.72715655   0.127191011
0.923961661   0.144269663
1.125239617   0.16494382
1.268370607   0.193707865
1.438338658   0.221573034
1.594888179   0.256629213
1.791693291   0.295280899
1.961661342   0.333033708
2.104792332   0.37258427

Title: Corsair Turning Ability in AH
Post by: Brooke on July 23, 2007, 12:21:46 AM

I also made a general-purpose spreadsheet (easy to use, I hope) so that folks can estimate the turning performance of any aircraft as long as you know things like prop diameter, HP, wing area, aspect ratio, weight, etc.

Here it is. It would be interested to see people plug in various other aircraft to see how they compare to performance Aces High.

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningPerformance-v4.xls

Title: Corsair Turning Ability in AH
Post by: gripen on July 23, 2007, 02:35:54 AM

Brooke,
You include nonlinear part of the Cl^2/Cd (below about Cl 0,15) to the calculation and also the part above Cl 1. The wind tunnel data in this case is a bit strange because above Cl 1 the e actually raise, normally it decrease due to separation (this indicates that there might be something wrong in the wind tunnel data corrections). If you look Perkins&Hage, you can see that they don't include nonlinear parts to the slope of the Cl^2/Cd curve and also NACA measured e in range between Cl 0,2-1.

If I use your values at that range (Cl 0,2-1), I got e values around 0,75-0,77 depending what I include to the calculation. Full positive Cl range (including nonlinear parts) gives e value 0,80.

Title: Corsair Turning Ability in AH
Post by: Brooke on July 23, 2007, 03:00:04 PM

For most flight modelling (modelling climbs, level flight, etc.), they want the model to fit best at lower C_L's, as that's where the plane is flying. For this modelling, we want C_D as a function of C_L that works when C_L is higher, as that's the performance regime the system is trying to model. For me, by eye, it looks like a truly great fit with e = 0.8 clean and e = 0.95 with full flaps.

Title: Corsair Turning Ability in AH
Post by: HoseNose on July 23, 2007, 07:47:00 PM

I just watched Borat... I'm in absolutely in no condition to even attempt to understand anything beyond common second grade knowledge.

My brain...she burns.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 23, 2007, 11:23:19 PM

Quote
Originally posted by gripen
The F2A data (Figure 5) shows pretty similar increase in value of the e with flaps. Because the e can be presented as:

e = 1/(pi*AR*K)

And the F2A data gives values of K:

flaps 0deg K = 0,070 => e = 0,78
flaps 22deg K = 0,068 => e = 0,80
flaps 56deg K = 0,057 => e = 0,95

So the same phenomena is there but the output of the engine limits the turn performance more than in the case of the F4U and the flaps system is not particularly effective (there were much more effective setups giving similar drag characters as in the figure from Perkins&Hage posted by dtango in the page two of this thread).

To lower the flaps increase the aspectratio, that will increase e, thats ok, but at same time the wingarea get reduced!! This will even out the + of e, it also result in a less effective thrustline and no all parts of the wing produce the max lift anymore(the parts without flaps never reach its max AoA).

You also ignore in all your calculations that despite the fact that the CL max is higher, the max lift is smaler at so much slower speed(110mph vs 180mph, best turnspeeds for the AH F4U-4), but at both conditions the planes need to overcome the 1G, as result the slower flying plane need to waste more of its lift to stay in a level flight, so it have a smaler "excess lift" than expected. With other words, the plane cant bank as tight, without to lose altitude.

This factors together make a sustained turn, same like the climb less effective with flaps.

Title: Corsair Turning Ability in AH
Post by: dtango on July 23, 2007, 11:23:54 PM

Knegel:

Gosh, where do I start?? :) I'll post a response when I get a chance to pull a few things together.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 23, 2007, 11:25:45 PM

Quote
Originally posted by HoseNose
I believe that turn rate should only be lower at particular speeds.

At some speeds the initial deployment of flaps and even when the flaps go all the way down, the aircraft will turn at more degrees per second (or turn rate) at slightly lower speeds. If the opposing aircraft (let's say they're both F4U-4's for example) is flying in the speed range without flaps, it will not turn at the same degrees per second. Once the opposing F4U-4 (no flaps) reaches a speed high enough, it will then turn at more degrees per second than the F4U-4 with full flaps.

If we could have a chart with 'degrees per second' on the y-axis and 'mph' on the x-axis for our in-game F4U-4 and perhaps 3 different lines (one indicating F4U at no flaps, one with F4U at maybe 20 degrees and one F4U at 50 degrees) that would help.

We still talk about a sustained turn here. For now noone argue aginst the positive influece of flaps while a decelerated turn(turn with energy lost).

Title: Corsair Turning Ability in AH
Post by: Knegel on July 23, 2007, 11:55:22 PM

Quote
Originally posted by F4UDOA
Knegal,

(http://brauncomustangs.org/images/roc.jpg)

As i wrote before, if this climb chart is ok, then the plane must be able to climb at even slower speeds and it must be able to turn at this speed, but in AH it cant. Thats my point.

The F2A test show that no matter if sustained or decelerated, the turn with flaps/no matter what flap position) result in a less good turnrate and radius above speeds of 110mph IAS. Lets say the F4U is more big and so the speed is a bit higher, but flaps simply dont provide more lift at highspeed, the speed where the airflow cant follow the airfoil is very low with flaps and the flaps start to work as leverage below the plane, as result mainly drag get produce and the nose down behaviour start to(at highspeed) occur.
While our AH flaps dont stop to produce more and more lift.

If i remeber right, british testers also fund that the 109 flaps dont brought an advantage regarding the turn radius.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: Brooke on July 24, 2007, 12:17:08 AM

Knegel, are you arguing that the F4U should not turn better with full flaps?

If so, I have the opposite belief. Unless there is an error in my model (and I am quite confident in it at this point) -- the F4U does turn better with full flaps.

If you want to try the model on the F2A, click on the spreadsheet link here. You can put in F2A prop diameter, HP, wing area, aspect ratio, etc. and see how it works out.

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningPerformance-v4.xls

Title: Corsair Turning Ability in AH
Post by: Knegel on July 24, 2007, 12:30:20 AM

Quote
Originally posted by dtango

(http://brauncomustangs.org/images/f2a-turn-rate-0f.jpg)

(http://brauncomustangs.org/images/f2a-turn-rate-56f.jpg)

Notice how similar the best sustained turn rates are for 0 degrees of flaps vs. 56 degrees of flaps ~25-27 seconds to complete 360 degrees of a sustained turn.

So here we have it again. The F2A’s rate of climb without flaps is better than the rate of climb with 56 degrees of flaps. Yet the best sustained turn rates are virtually the same with flaps at 56 degrees vs. no flaps.

Tango, XO
412th FS Braunco Mustangs

Hi,

i just saw this, you be right here, but in oposide to the F4U in AH, the turn rate decrease at least by 2 sec and with only a bit flaps its even worse and at highspeed the turn rate decrease even more in relation to the no flap condition.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: F4UDOA on July 24, 2007, 08:44:21 AM

Knegal,

Look at the flaps (of any aircraft) and lift provided in 1G or turning flight like this.

Do the flaps provide the aircraft more lift than drag at lower speeds and what is there purpose? In the F4U 50 degrees of flap reduces the 1g level speed stall by almost 20MPH with idle power applied. They reduce runway takeoff distance by 30% while allowing the aircraft to takeoff with 5,000lbs of ordinance.

These are all indications that the lift generated by these flaps far out weights the drag created by a good margin. The faster you go the greater the drag becomes and the less efficient the flaps are but at low speeds these flaps are extremely efficient.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 24, 2007, 01:07:02 PM

Hi,

your arguments only indicate that flaps lower the sall speed, noone argue this.

The take off run without flaps get even longer than expected, cause the plane dont reach the max AoA with all three wheels down, therefor it have to be much faster than stall speed and therefor the plane need a longer time to accelerate to the needed speed.

My argumentation is that a plane with full flaps have a more bad thrust line, the "excess lift" isnt as high as expected and specialy the drag is very high. All this points dont got recogniced while the simple lift/thrust calculations.
Another point is that a so powerfull plane, like the F4U-4, but also many other WWII planes, should have problems to make a full power turn with full flaps at all. Simply cause the torque is so extreme, while the alerons at 110mph dont work that good, but the planes in AH are most easy flyable while a full flaps stall turn.
Another point is, that the F2A with flaps, no matter what flaps position, show the best tun rate and radius without flaps at speeds above 113mph and this not only in a sustained turn, also while a turn with altitude lost.
While the AH flaps have a better radius and turn rate even at 300mph as result.
What i absolutly dont understand is that the early F4U-1D have a wider turn radius, but gain gain more by using full flaps, like the F4U-4, while the powerload of this planes is much more bad. So much more powerfull plane should be able to bank much more and so the "excess lift" should be higher(that would be my argument for the better turn wihtout flaps, despite the higher weight).
Anyway, the early F4U´s dont have a much better powerload than the F2A and a much worse than the F4U-4, but the radius gain by using full flaps is rather constant.

Iam still sure there is something badly wrong.

But i wanna thank you all for this discussion, i got a better picure of the whole.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on July 24, 2007, 01:16:46 PM

Knegel:

Don’t you find it odd that Brooke and I, independently doing calculations have arrived at similar conclusions? Something to think about ;). We aren’t making stuff up.

-------------------------------------
You asked a fundamental question in your response to my calculations. For the basic F4U model I presented …

Q: Why can the F4U perform a steady climb at 100mph @ 2600 fpm at CLmax while it can’t sustain a level turn at 100 mph?

A: Because the F4U is stall limited to perform a level turn at 100mph even though it still has excess power to perform a climb.

In a level turn total Lift must be greater than Weight.

To perform a level turn at 100mph the F4U must produce enough lift to satisfy this equation:

L = W/cos(bank angle)
L= n*W [eqn says: total lift must be greater than weight by “n” amount]

At 100mph wings level, the F4U is flying at Clmax and already producing the maximum amount of lift achievable for that velocity so that L=W.

At 100 mph if you wanted to perform a level turn (without losing altitude), L>W (or L=nW). To increase lift you would have to increase aoa which is not possible without stalling because you are already at Clmax.

In other words, the F4U is limited by stall and not by power for a level sustained turn in this part of the performance envelope.

Here is another diagram of our basic F4U model with no flaps to illustrate:

(http://brauncomustangs.org/upload/power-turn.jpg)

This is another view of the calculations for the other graphs I posted earlier. The top part of the graph are the Power Available and Power Required curves. The bottom part is the same turn-rate data we’ve seen already.

There are 3 power curves bolded:
1) Pa- Power available (engine_BHP*prop_eff/velocity)
2) Pr 1G- Power required for 1G level flight (drag@1g * velocity)
3) Pr Clmax- Power required for Clmax flight (drag@clmax * velocity)

100mph
===============
At 100mph we have excess power available, but the turn rate is 0. Why? Because we are limited by critical aoa (Clmax) for the turn even though excess power exists for a climb.

>100mph to 160mph
===============
Notice the Pa and Pr_Clmax curves. Above 100mph excess power exists for the F4U until the Pa and Pr_Clmax curves cross at ~160mph. This means that excess power exists while turning at Clmax in this envelope.

Because we are now traveling faster than 100mph, at Clmax the F4U now generates more total lift than weight to satisfy:

L = nW

Therefore it can perform a level turn. The maximum amount of lift and thus the level turn performance it can achieve is bound by this equation:

L = .5 * air_density * wing_area * V^2 * Cl

Within this envelope (100-160mph) critical aoa and airspeed are the primary limit for level turn performance, not power. In other words we are limited by the amount of lift we can produce and not power.

>160mph
===============
Above ~160mph, power required to turn at Clmax becomes greater than power available. (You can still turn at Clmax above 160mph. You would just lose airspeed or altitude which is no longer considered a sustained turn.) So above 160mph sustained turn performance is no longer limited by the amount of lift we can produce but the amount of power required to hold the turn.

---------------------------------
BTW, the ROC and turn rate charts are correct based on the aerodynamic coefficients and variables used. There is a minor error for the Ps curve on the turn rate chart which I will fix later when I get home. On the turn rate chart the Ps curves are actually (Pa-Pr). It’s supposed to be (Pa-Pr)/W. The point of Ps=0 doesn’t change. The shape of the curves change slightly.

I’ll try and answer some of your other questions later.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: SgtPappy on July 25, 2007, 12:00:57 AM

Hmm. Wish i understood everything. Then perhaps I could fly better heheh.

Title: Corsair Turning Ability in AH
Post by: Saxman on July 25, 2007, 12:39:06 AM

Heh. My head popped a couple pages ago.

All I know is the math both agrees with flight data on the F4U referenced by F4UDOA, (both Vought at the time, and current sources) and shows AH has the turn and flap performance more or less correct, while Knegel keeps arguing the point based on test data for an entirely DIFFERENT aircraft even though he's been shown that if he plugs in the necessary data particular to the F2A (prop diameter, engine power, weight, etc) the math works out to fit THAT as well.

Title: Corsair Turning Ability in AH
Post by: Knegel on July 25, 2007, 03:51:50 AM

Hi dtango,

thanks for your clarification, i got what you mean, regarding the turn/climb, but actually a "dirty" turn at 100mph is possible. I dont was aware of this and this turn is rather difficult to maintain, but its possible. Its a very unstable nose up turn. Its possible to get there, from the 100mph climb, by banking the plane.
While making a horizontal turn, its not possible to get into this 100mph turn, without to start a initial climbturn.

But i still think that the turn rate with full flaps should be worse than what we have now.

Imho thats caused by the rather bad CD/CL² relation, which at least the F2A show. Where the 10° flap variation should provide a more effective sustained turn.

(http://www.raf-roy.com/share/knegel/Screenes/CDCL_e.JPG)

I dont think that a plane with less effective CD/CL² relation can produce a much smaler radius, without to lose turn rate. And this is only the CD/CL² relation of the wing, the worse thrustline, the wose "excess llift", the greater thrust problems/the higher needed aleron variation etc at slower speed dont will help to offer a so much better turn radius with very similar turn rate, like we have it in Ah now.
Of course, as long as the calculations dont include the disadvanced thrust line and the relative smaler "excess lift" and the other rather problematic factors while slow flights, all looks more friendly.
Specialy for a plane with so much power the thrustline must be a significant influence to the climb and turn.

Some more thoughts to the excess thrust / turn discrepancy i see:

If the plane with full flaps and max AoA climb with 75mph with only 1700ft/min, while the plane with 100mph and also max AoA (close to) climb with 2700ft/min, this display that the drag(not the CD) is much higher with full flaps, despite the fact that the plane without flaps fly much faster, therefor the CD must be even worse.
But in your turn diagram, where also both planes turn with max AoA, one at 100mph, the other at 160mph, both planes offer the same excess thrust.

How is that possible??

btw, the full F4U-4 have its min turn speed at 110mph and 170mph, so accordingto your diagram, the faster plane should turn faster.
And where do you got that curves from?

And Brooke dont had the same conclusion, he wrote that the turnrate should increase with full flaps. That other sims and also AH some time ago do/did it in the way i say is also something to think about.

Anyway, i think only real tests can show how it realy was, smal different values in the calculation would show how i think it should be.

Are there more tests similar to the F2A around?? Unfortunately thats the only real good turn test i ever saw, specialy with flaps included.

Hi Saxman,

currently i dont saw any turn test for any F4U, the calculations dont include the changed thrustline, neighter the smaler relative "excess lift" cause the slower speed, while flying with full flaps.

Unfortunately the F2A test dont include a climb test with/without flaps, so we also cant get a good idea how the flaps influence the climb at different speeds, i even dont saw any sources to display the influence of the climb speed to the climb rate. So we even dont know if the F4U-4 without flaps had realy a climb ratio of around 2700ft/min at 100mph.

I still have my doubts regarding the way it is in AH now.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on July 25, 2007, 09:25:49 AM

Knegel:

(1) Brooke came to similar conclusions. You missed the post I assume.
Quote
Originally posted by Brooke
OK, based on the references Tango found, I have updated my calculations for the F4U-1. See the Appendix: F4U-1 in this document:

http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningMath.html

The calculations, with actual and wind-tunnel data, agree very closely with the F4U-1 in Aces High -- including that the F4U turns at a higher turn rate with full flaps.

Yes, the F4U in real life does seem to have magical flaps -- backed up by real data and real aerodynamic calculations.

Aces High once again got it right.

(2) You can't extrapolate excess power in a steady climb to vary the same way in a sustained turn. I already explained why and then went about demonstrating the principles with an example and from the F2A-3 document. I don't know why you've ignored this. You can't extrapolate steady climb performance to turn performance. Excess power depends on load-factor, airspeed, altitude, and e.

(http://brauncomustangs.org/images/pr-eq.jpg)

Excluding altitude these are not the same between a turn and a climb. This has been the main point that I've been actually trying to make.

(3) The F2A-3 tests show climb performance as well and pointed this out to demonstrate point #2. I discussed this in my detailed post for point #2. Go back and re-read it.

(4) All the L/D ratio stuff you bring up is included in assessing point #2.

(5) Thrust Line. Where do I begin?
a) It's fixed for the aircraft we deal with.
b) Thrust angle is small for the aircraft we deal with so usually ignored to simplify the calcs.
c) Induced thrust angle changes due to upwash from the wings and impact on lift is embedded in the Cl figures that come from flight/test data with power on. I calculated Cl based on the numbers you gave (~100mph 1g stall clean, ~75mph 1g stall full flaps) in order to demonstrate point #2 which assumes induced thrust angle changes factored in. If I use the the power on Cl figures from the F4U-1A test data then the best sustained turn rate is actually better with full flaps than without.

(6) My turn rate chart comes directly from the calculations to demonstrate #2. Nothing magical going on here. I didn't make it up.

(7) The faster plane has a higher G in a turn. This doesn't mean it turns any faster (turn rate) than the slower plane.

turn-rate = gravity * sqrt ( gload^2 - 1) / V

For instance two planes at different airspeeds and turning at different g's:

mph   g   rate
170   2.90   20.1
110   2.02   20.1

Faster plane, higher G. Slower plane, lower G. Turn rate is the same though.

--------------------------------------------------------------------------------
This thread has gone on 9 pages and we are just repeating ourselves. I hate to follow threads that go on ad nauseum :)! I'm nearing the point of being finished with this thread because I don't think anymore discussion is going to help anybody.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: SgtPappy on July 25, 2007, 10:42:25 AM

Crud. I have to take physics next year! Huzzah! i'm so totally dead.

Title: Corsair Turning Ability in AH
Post by: Crispy on July 25, 2007, 05:26:10 PM

Quote
Originally posted by Knegel
Hi,

.

There are comparisons, made by US WWII pilots, nowhere you cant read about a extraordinary turn performence of the F4U, actually it got rated as the most bad turning US fighter.
Greetings,

Knegel

Wow now your going overboard, the hog was considered a very manuverable plane.

Another thing, if the hog was so dang uber in AH you would see gobs of them...but you don't...why? it is hard to master...period. There is SOOOO much more to flight dynamics than simple turn radius. This whole thread is missing about 95% of what it takes to "out manuvering" another plane. Just simple angles...when you pull hard...the attidude you are at when you pull hard...lagging...geeese the list is endless. The mentality of the game is generaly people thinking how well they can flip flop a plane around...that is actually a very small part of the picture.

I can also tell you have not flown the hog much in AH...with full flaps it pitches around badly...nose bounce is terrible...you need a very delicate hand with many control inputs....even so... bang...your on your back.

You talk about internet sources well keep looking there are plenty actual comparisons of hog tests against many late war models of both sides and it pretty much did out turn any of them (later war planes) There are many ... MANY articles placing it as THEE best fighter plane of ww2. I am not so sure of that but it was very good.

I fly the hog 99% of the time and have for a decade and every time I get in any spit..La..niki...109 I feel like i got out of a pick up truck & into a sports car.

Think past turn radius, the fight is soooo much more than that.

cris

Title: Corsair Turning Ability in AH
Post by: mtnman on July 25, 2007, 07:06:32 PM

Another point worth considering-

Planes that are generally known as "turn-fighters" are known as such because of what they flew against, more than how they really turned.

Compare the F4U to the Zero. Which one fits the bill as the turn fighter? Which as the E fighter?

Compare the Spit to a 109. Turn fighter? E fighter?

Seldom would anyone not list the spit and the zero as the turn fighters- at least in a general sense, even though the spit is an awesome E-fighter.

What if the war was fought differently? What if zeros fought spits? Or 109's vs 190's. Now which one would be the turn fighter? Imagine- spit pilots being told to never turn with zero's! Fly the hog against a pony and I'm sure the hog would have been considered as a turn fighter. Pony pilots would have been warned- "DON'T turn against those agile corsairs!" It gets even worse if we fight hogs with hogs. Who's the turn fighter now?

The point is that what a plane was "known" for, may not apply in a game like AH. Not due to lack of realistic flight modeling, but because we don't fight in a "historic" sense.

If we did fight in a historic sense, we'd have a radically different game. No more "fair" 1v1's. ALL gangbanging, or at least an attempt at gangbanging at EVERY opportunity. Lancaster's in the daylight?? Get real! Occasionally only- the american bombers were much more common in daylight, BUT- only in large formations. Groups of only three bombers? Side balancing? Why enable your opponent to have a fair chance? Kill him quick and decisively. Go home to your family instead of letting him go home to his.

It seems Hitech has done a pretty good job of modelling a heck of a lot of different planes, and giving us an arena to play with them in an enjoyable atmosphere. (Maybe a bit TOO addicting, but I'm not complaining...)

It's actually kind of neat that after 9 pages of math and arguments we still can't argue effectively against Hitech's modeling...

MtnMan

Title: Corsair Turning Ability in AH
Post by: Ack-Ack on July 25, 2007, 08:02:11 PM

Quote
Originally posted by mtnman

What if the war was fought differently? What if zeros fought spits? Or 109's vs 190's. Now which one would be the turn fighter? Imagine- spit pilots being told to never turn with zero's!

MtnMan

Spitfires did fight Zeros and at first got trounced by the Zeros because they tried to turn with them. The Spitfire units had to adopt US tactics against the Zero and were instructed like US pilots, not to get into turn fights with the far more nimble Zero.

ack-ack

Title: Corsair Turning Ability in AH
Post by: mtnman on July 25, 2007, 08:20:26 PM

That's awesome Ack-Ack! I'd never heard that bit of info... I was just speculating.

MtnMan

Title: Corsair Turning Ability in AH
Post by: AKDogg on July 25, 2007, 09:54:44 PM

Quote
Originally posted by Crispy
Wow now your going overboard, the hog was considered a very manuverable plane.

Another thing, if the hog was so dang uber in AH you would see gobs of them...but you don't...why? it is hard to master...period. There is SOOOO much more to flight dynamics than simple turn radius. This whole thread is missing about 95% of what it takes to "out manuvering" another plane. Just simple angles...when you pull hard...the attidude you are at when you pull hard...lagging...geeese the list is endless. The mentality of the game is generaly people thinking how well they can flip flop a plane around...that is actually a very small part of the picture.

I can also tell you have not flown the hog much in AH...with full flaps it pitches around badly...nose bounce is terrible...you need a very delicate hand with many control inputs....even so... bang...your on your back.

You talk about internet sources well keep looking there are plenty actual comparisons of hog tests against many late war models of both sides and it pretty much did out turn any of them (later war planes) There are many ... MANY articles placing it as THEE best fighter plane of ww2. I am not so sure of that but it was very good.

I fly the hog 99% of the time and have for a decade and every time I get in any spit..La..niki...109 I feel like i got out of a pick up truck & into a sports car.

Think past turn radius, the fight is soooo much more than that.

cris

I agree here with Chrispy. There so much more to the hog then just flat turns. When I fly the hog, I not really turning the plane, I rolling into the turn. I use more rudder then ailerons to turn it. The Hog has a great tail slide, looping, and hammer head performance. Zoom climbs with the best of them. Got good airbrakes. The list goes on. IMO the hog has the most options then any other plane in AH during a fight. If u get a hog on the deck and he just does a flat turn with a spit. All the spit has to do is spiral climb slightly in the turn and the hog is dead. No ?'s asked. Now if the hog pilot is smart and sees this and can't get a shot on the spit, He better pull flaps back up and start to ease off the turn and then level and get speed up. Even in a chase by a spit on the deck, the hog can kill him with a very simple manev. I not gonna say what that manev is as it my secret. I sure mtnman, chrispy and saxman know what manev i talking about.

Title: Corsair Turning Ability in AH
Post by: Guppy35 on July 25, 2007, 10:14:45 PM

Quote
Originally posted by mtnman
That's awesome Ack-Ack! I'd never heard that bit of info... I was just speculating.

MtnMan

The Hurricane drivers that went out to Singapore and elsewhere expected no problem with the Zeros. Boy did they find out in a hurry.

The Spit drivers were definately boom and zoom vs the Zekes.

Title: Corsair Turning Ability in AH
Post by: mtnman on July 25, 2007, 10:57:52 PM

Quote
Even in a chase by a spit on the deck, the hog can kill him with a very simple manev. I not gonna say what that manev is as it my secret. I sure mtnman, chrispy and saxman know what manev i talking about.

:aok

MtnMan

BTW- You've all witnessed history! I actually figured out how to do quotes and smilies tonight! This is the first I've ever had it work right!

Some applause would be acceptable at this point...

Title: Corsair Turning Ability in AH
Post by: SgtPappy on July 25, 2007, 11:33:22 PM

Quote
Originally posted by mtnman
That's awesome Ack-Ack! I'd never heard that bit of info... I was just speculating.

MtnMan

Not only did they fight the Japanese and initially lose, they ran out of fuel over the ocean sometimes, on rare occasions. The Spitfire Mk.Vc's arrived in Australia in defense of Darwin early in '43 and fought many-a Zeke and Betty. They arrived with the sand-filtering Volkes air intake unit (designed to filter sand not the stuff of tropical climates) along with many MANY technical fallouts including oil line corrosion. Those of you who know how engines react to the smallest malfunction know that it can pull quite a few miles off the aircraft. The Volkes chin filter alone killed the Spitfire's ram-air performance, lessening its range, speed and climb rate. Add that to the tech. malfunctions and you got yourself one dead Spitty.

Eventually, the Spitfires used their better E fighting techniques (yeah I know, Spits aren't the greatest E fighters, but better so than the A6M) and BnZ'd the meatballs off those Zekes. In October 1943, the Aussies got their Spitfire Mk.VIII's. Boo-yah.

ANYWAY back to the topic. Crispy, when I get out of a Hog and into a Spitfire, La-7 and a Niki, it feels more like getting into a sports car .... right after getting out of a muscle car. That is a muscle car with dive breaks :aok

Try out-vertical scissoring a Zeke in a Spitfire and see what happens.

Title: Corsair Turning Ability in AH
Post by: dtango on July 30, 2007, 12:22:57 AM

There’s been a lot of discussion about the impact of flaps on turn performance. Specifically, how does the increased drag of flaps impact the rate of turn of an aircraft?

My previous responses to this question relied on a series of calculations to explain the physics at work in a sustained turn and the resulting turn rate performance. This explanation is harder to intuitively understand because of the stages of calculation needed. I’ve since found a more mathematically intuitive method to explain sustained turn rate performance.

The Problem
It’s widely stated that sustained turn performance is a function of an airplane’s specific excess power. As already discussed specific excess power is

(http://brauncomustangs.org/images/eq1-1.jpg)

Specific excess power is the sum of the energy usage in maneuvering the airplane. It gives us insight into the maneuvering loads an airplane can sustain bound by it’s energy gain or loss as a function of thrust and drag.

A difficulty, however, lies in how to translate specific excess power to turn performance. Turn performance is usually expressed as load factor, turn radius, and turn rate. Specific excess power does not give us direct visibility to these performance variables. They must be derived from key aerodynamic coefficients embedded in Eq. (1.1) in order to make them visible. For instance an aircraft’s rate of turn is

(http://brauncomustangs.org/images/eq1-2.jpg)

To arrive at a value for turn rate in Eq. (1.2) as a function of specific excess power from Eq (1.1) requires several stages of calculations. Therefore, it is non-intuitive to arrive at an aircraft’s turn performance through specific excess power.

Is there a more intuitive way of understanding the relationship between specific excess power and turn rate without having to go through a series of calculations to gain understanding? The answer is yes.

An aircraft in a sustained turn neither gains or loses altitude and airspeed while holding it’s turn. This means that the aerodynamic forces are in equilibrium while in a maneuver. In mathematical terms specific excess power equals zero (PS = 0). Bypassing the mathematical derivation, knowing this relationship leads to the following

(http://brauncomustangs.org/images/eq1-3.jpg)

where n is the load factor of the aircraft in a sustained turn as a function of the basic aerodynamic variables of lift, drag, thrust, and weight.

The Key Equation: Turn Rate as a Function of L/D, T/W, & Velocity
Substituting Eq. (1.3) for load factor in Eq. (1.2)

(http://brauncomustangs.org/images/eq1-4.jpg)

We now have an expression of an aircraft’s sustained turn rate in key aerodynamic ratios derived from specific excess power. Eq. (1.4) gives us a more intuitive way to understand how key aerodynamic factors affect an airplane’s sustained turn rate.

We can now intuitively evaluate the affect of deploying flaps on turn rate as a function of the flap’s lift and drag. From Eq. (1.4) we see that turn rate is a function of lift-to-drag ratio, thrust-to-weight ratio, and velocity. Rate of turn is maximized when lift-to-drag and thrust-to-weight are maximized while velocity is minimized.

We know that deploying flaps reduces an aircraft’s lift-to-drag ratio. Flaps increase the lift of aircraft but at a cost of increased drag as well. If L/D ratio reduces with flaps, then so should turn rate right? So what’s going on if turn rate remains the same or is actually better with flaps deployed?

The reason is we can’t forget about velocity in Eq. (1.4). Flaps also reduce the minimum maneuvering speed of an airplane too so while L/D decreases, so does velocity. Secondly for piston-propeller aircraft thrust varies with velocity as well increasing as velocity decreases.

The bottom line is sustained turn rate is a function of lift-to-drag ratio, thrust-to-weight ratio, and velocity which all need to be factored in because they all vary depending on the configuration and airspeed of the airplane.

Illustration Using the Equation
Let’s put some data to this to demonstrate the dependence of turn rate on the combined ratio of lift-to-drag and thrust-to-weight divided by velocity. For the below I used the same static variables and propeller efficiency curve from my previous calculations. The calculations represent sustained turns at maximum lift coefficient (Clmax), or the maximum lift-limit achievable by an aircraft.

Here’s a table with variation in Cl/Cd for comparison to evaluate Eq (1.4) above. At the point of best sustained turn rate (Ps=0) Cl/cd, V, T, and W were plugged into Eq (1.4). These are the results for turn rate.

Plane Config Clmax Cd0 Cd cl/cd V Ps=0 T W n rate (dps)
1 clean 1.6 0.02 0.2 8 160 3949 12400 2.55 18.4
2 flaps 2.8 0.1 0.6 4.3 100 5164 12400 1.79 18.7
3 flaps 2.2 0.1 0.4 5 120 4755 12400 1.92 17.1
4 flaps 2.8 0.18 0.7 3.8 97 5281 12400 1.64 17.2

Plane #1 and #2 were the same ones in my previous calculations (same results as before). Note that they are both approximately the same turn rate despite L/D ratio being lower for Plane #2. The reason is the thrust is greater while the velocity where thrust=drag is also lower. The net result is Plane #1 and #2 have approximately the same turn rate despite Plane #2 being "draggier" because of the flaps.

Plane #3 I hypothetically decreased Clmax. This results in a better lift-to-drag ratio (remember CD includes both the parasite and induced components of drag) compared to Plane #2, yet Plane #3 has a worse turn rate. The reason is the velocity where thrust=drag (Ps=0) has increased which also reduces the amount of thrust available. The combination of both the increase in airspeed for Ps=0 and reduction in thrust results in a lower turn rate.

Plane #4 I left Clmax the same but increased the profile drag from .1 to .18. This results in a lower velocity where thrust=drag (Ps=0) and higher thrust but in combination with the lower lift-to-drag ratio results in a lower turn rate compared to that of Plane #1 or Plane #2.

What happens if we changed the engine BHP available for Planes #1 and #2? It was assumed to be 2380 HP. Let’s reduce it to 2000 HP and see what the result is.

Plane Config Clmax Cd0 Cd cl/cd V Ps=0 T W n rate (dps)
1 clean 1.6 0.02 0.2 8 151 3520 12400 2.27 17
2 flaps 2.8 0.1 0.6 4.3 96 4625 12400 1.6 16.4

We see now that Plane #2 has a lower sustained turn rate compared to Plane #1. Changing the available horsepower changed the thrust and also the velocity where thrust=drag. The net result is a lower turn rate for Plane #2.

All these examples demonstrate that sustained turn rate is function of the combination of lift-to-drag, thrust-to-weight, and airspeed as expressed in Eq. (1.4).

A key learning is that we should be careful with making conclusions regarding airplane performance that rely on generalizations. Equation (1.4) demonstrates why conclusions such as increased drag of flaps reduces sustained turn performance or extrapolating steady climb performance to turn performance are inaccurate because they oversimplify what occurs in a sustained turn.

I hope this helps to illuminate the topic.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: Knegel on July 30, 2007, 01:19:05 AM

Hi,

i still think there is something badly wrong in that calculation.

Specialy the comparison between Plane #2 and #4 looks strange.
How shal a plane with same CLmax but more drag(less excess thrust) shal turn faster??
This would be like reducing power, this cant result into a faster sustained turn rate. With same CLmax it cant turn more tight and with more drag(less excess thrust) is must turn more slow.

With thrustline i mean the angle between flightpath and engine, while using full flaps this change much, not a bit, as faster the plane fly with flaps as more this phenomen get visible. This would count specialy for #3, where the thrustline must point far outside the flightpath. As result some parts of the thrust work against the lift and dont work into flight direction at same time. This minimise the excess thrust and increase the needed lift at same time.

The "excess lift" also dont seems to be included in your calculation. A slower plane produce less lift, as result the needed lift to keep a level flight(1G) weights more than in a faster plane.
As slower a plane fly as more problematic gets the gravity.
So a faster plane can bank more and have a higher "excess lift".

btw, what is "T" ?

Its difficult for me to follow all your explanations without a calrification of the values. Some vary from what we use in germany, some i simply never saw. Sorry for my ignorance.

Edit: Where in the F2A test we have the climb rate listed with flaps??

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on July 30, 2007, 10:26:34 AM

(1) Equation / calculation badly wrong?
-------------------------------------------------
I'm extremely confident in the equation (1.4). I've crossed checked the derivation against 3 separate aerodynamics texts. Feel free to check the math logic.

(http://brauncomustangs.org/images/eq1-4.jpg)

This equation gives sustained turn rate performance from the basic aerodynamic variables using the standard assumption of small thrust angle (alpha-t).

There is some rounding in the actual numbers I'm putting in but it doesn't change the outcome.

(2) Plane#2 vs. plane#4
--------------------------------
Plane #4 turns slower than Plane#2.

(3) Thrustline, thrust angle differences
-------------------------------------------------
Since you insist on including it here is the sustained turn rate equation with thrust angle factored in.

(http://brauncomustangs.org/upload/eq1-4b.jpg)

A little bit more messy but if you examine the key relationships between L/D, T/W and velocity are the same between Eq (1.4) and Eq (1.4b).

Alpha-t represents the thrust angle. For conventional aircraft it is usually between 2-7 degrees. (The Hellcat of course was odd in that it had a -2 degree thrust angle.)

Let's say you're right about the thrust angle issue (which I don't think is true at all in a turn as I explained earlier). But suppose you are right. Let's assume 7 degrees of thrust angle (very high for conventional aircraft). Let's assume that with full flaps as you say thrust angle is reduced by -7 degrees. Here's what we get for turn rate.

Plane Config Clmax Cd0 Cd cl/cd alpha-t V Ps=0 Thrust Weight n (g's) rate (dps)
1 clean 1.6 0.02 0.2 8 7 160 3949 12400 2.56 18.6
2 flaps 2.8 0.1 0.6 4.3 0 100 5164 12400 1.79 18.7
3 flaps 2.2 0.1 0.4 5 0 120 4755 12400 1.92 17.1
4 flaps 2.8 0.18 0.7 3.8 0 97 5281 12400 1.62 16.5

Alpha-t is the thrust angle. T=thrust. I've relabled the table so that you can see that.

Notice that the outcome really doesn't change at all.

(4) F2A Report:
--------------------
Regarding climb, fig 32, 33, & 34. Re-read my post that has it spelled out.

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: evenhaim on July 30, 2007, 10:41:35 AM

dam tango great stuff

Title: Corsair Turning Ability in AH
Post by: Knegel on July 31, 2007, 09:12:02 AM

Hi dtango,

thanks again for your clarification.
Regarding "2." , i had a "brain fart", of course #4 turns slower than #2, so all is ok.

With the thrust angle included the result looks much more friendly to me, what i still dont understand is, where in the sustained turn formula is the lift included to overcome the 1g, to keep a level flight?
While comparing planes that fly with same or similar speed this isnt that important, but while flying at so much different speeds(160mph vs 100mph), the needed lift to overcome the gravity should have a not to smal influence to the the bank angel and so to the "excess lift".

Although the full flap condition have a much better lift coefficient as result, the plane fly much more slow, as result the produced lift isnt in the same relation, while the needed lift to overcome the -1g (gravity) remain the same. As result the more slow flying plane suffer more by the -1g, than the faster plane.
This gets best visible when the planes fly with much reduced power. At one stage the plane without flaps start to turn more tight and much faster, than the more slow flying plane with flaps. Simply cause the plane with flaps have problems to bank, without to lose altitude. As result the "excess lift" is smaler than that of the plane without flaps. As faster the planes fly, as less important the gravity get, cause the ammount of produced lift get much higher than the needed lift to overcome the -1g.

btw, where do you got the thrust values from??

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: dtango on August 01, 2007, 10:24:31 PM

Knegel:

It’s included in the Cl (lift coefficient) term in the equation:
(http://brauncomustangs.org/images/eq1-4.jpg)

By definition in a turn Cl must be greater than Cl at 1g. Thus:

(http://brauncomustangs.org/images/delta-cl.jpg)

Therefore another way to represent the turn rate equation is:

(http://brauncomustangs.org/images/eq1-4c.jpg)

This would be rather unconventional and simply redundant so we just leave Cl as....well simply Cl and not as Cl1g+delta_Cl_turn. :)

Quote
Although the full flap condition have a much better lift coefficient as result, the plane fly much more slow, as result the produced lift isnt in the same relation, while the needed lift to overcome the -1g (gravity) remain the same. As result the more slow flying plane suffer more by the -1g, than the faster plane.
This gets best visible when the planes fly with much reduced power. At one stage the plane without flaps start to turn more tight and much faster, than the more slow flying plane with flaps. Simply cause the plane with flaps have problems to bank, without to lose altitude. As result the "excess lift" is smaler than that of the plane without flaps. As faster the planes fly, as less important the gravity get, cause the ammount of produced lift get much higher than the needed lift to overcome the -1g.

You should be careful in how you’re characterizing the physics in these statements. There is only a portion of the flight envelope where this is true so be careful not to oversimplify this and apply it universally. This only applies when the reduction in lift coefficient to satisfy where thrust=drag in a turn at higher velocities becomes pronounced compared to the aircraft without flaps.

2ndly remember not to confuse turn rate with load-factor.

---------------------------
Thrust…

thrust = engine BHP * prop-efficiency *550 / velocity

So if we know engine BHP, prop efficiency and velocity we can find thrust. Engine BHP for the F4U is readily available from various sources. The prop-efficiency curve was derived from calculations based on momentum theory. You can find all these listed above in my previous post discussing my original calculations (page 7 of this thread).

Cheers!

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: nooblet187 on August 02, 2007, 06:48:37 PM

Hey, do we need all this math? lol. I'm going to try to explain this since I'm not so good at math.

While climbing thrust is the 'mostly' the limiting factor, not lift. It doesn't matter if your going max speed at max climb or 110 mph climbing fast as possible without stalling. Thrust is limiting you in both these cases. If you increased lift by adding more wing area or engaging flaps you're also increasing drag.

Increasing wing area will increase lift and drag, it will help with turning and allow for slower stalls and slow your plane down overall :lol . Flaps also increase lift & drag, except alot. Which isn't very usefull when there is already plenty of lift in a climb. Excess lift will only create excess drag, ALSO the thrust is unable to take advantage of all that lift! If you increase lift and drag you must increase thrust to be able to maintain the same speeds.

Also important to point out. While climbing flaps have the tendency to push your nose upwards, which the elevators have to fight against. Which makes your wings fly in a weird angle that they dont like! If you didn't lower your nose after engaging flaps you would stall out soon. Basically you're adding much more drag to the plane when combining these factors, then you are lift. This is basically what you want though in a turn.

When doing a sustained turn at full throttle, lift and thrust are factors. Without flaps, your wings AOA and lift will max out at a certain point, and you will stall. Your wings lose lift as the AOA is too high. Flaps will increase your AOA and lift at the cost of drag and speed, allowing tighter turns to stay on that spitfires arse. Now your flaps are actually doing something useful !!

Also you keep saying something about lift is worse at slower speeds and its less efficient to fight the earths gravity. Thanks to someone(sorry I'm too lazy to go back! nice math I dont get any of it:cry) here is nearly 1G of pull saved by slowing down and going in a tighter turn:
mph   g   rate
170   2.90   20.1
110   2.02   20.1

I hope this makes sense somewhat to you, if you think I've left anything out let me know. :D

Title: Corsair Turning Ability in AH
Post by: rednex21 on August 02, 2007, 08:52:53 PM

i have no clue what you guys are talking about but i love the Corsair. And btw...the F4U-4 turns great without flaps.:aok

Title: Corsair Turning Ability in AH
Post by: SgtPappy on August 02, 2007, 09:26:47 PM

Quote
Originally posted by nooblet187

Increasing wing area will increase lift and drag, it will help with turning and allow for slower stalls and slow your plane down overall :lol .

Wing area is only increased in aircraft with Fowler flaps like the P-38 or the Ki-84 'Frank'. Next the F4U's flaps help increase lift co-efficient and then you have smelly flaps on the Spitfire. IMO the otherwise awesome Spit's main fault was it's 'crap flap' which was a split flap designed ONLY to increase drag.

Title: Corsair Turning Ability in AH
Post by: nooblet187 on August 02, 2007, 10:52:24 PM

Ok, this should clear some things up.

When flaps are engaged in level or climb, the planes nose is at a lower angle. The wing tips(past the flaps) produce little or no lift and are causing drag and worsens at higher speeds. Also the elevator causes drag keeping the nose down. This may be more or less extreme in AH or real life though.

While turning the wings tips past the flaps is at a high enough angle to help produce lift. At 20 degrees of flaps the elevator causes alittle drag, at 40 degrees there is more drag on the elevator. As the f4u pilots stated I noticed the best results at 20 or less degrees.

I did some tests in X-plane, and frapsed them with flight model enabled, with a f4u-1a corsair. In the video you will see in the scenes first 'no flap climb', then 'full flap climb', 'no flap turn', 'half flap turn', 'full flap turn'.

Video: http://www.mediafire.com/?4i4wdh3dtyd

Title: Corsair Turning Ability in AH
Post by: Knegel on August 04, 2007, 07:09:52 AM

Quote
Originally posted by dtango
Knegel:

Therefore another way to represent the turn rate equation is:

(http://brauncomustangs.org/images/eq1-4c.jpg)

This would be rather unconventional and simply redundant so we just leave Cl as....well simply Cl and not as Cl1g+delta_Cl_turn. :)

Cheers!

Tango, XO
412th FS Braunco Mustangs

Hello Tango,

after a bit more reading in this article, it got clear to me that the effect i did describe is already included in your formula, but its hidden and only got visible to me while looking to the other fomulas, which at the end result in your formula.
http://flighttest.navair.navy.mil/unrestricted/FTM108/c6.pdf

But in this articel i found another agument against a that good turn at very slow speed(same weight, fuselage, wingspan etc), its the effect of a increased sideforce, which work against the lift. This sideforce effects need a higher rudder variation(or smaler bank angle) at slower speeds, cause the Fuselage/Rudder work somewhat like a wing while a banked flight, so the slower flying plane need a higher rudder variation to overcome this sideforce and this add drag and reduce the excess thrust. This specialy count for high bank angles.

This article also confirm the influence of Alpha-t to the thrust lift(lift = wing lift + thrust lift) and of course the thrust lift also influence the turn performence(more AoA = more thrust lift).

In all this calculations is the bad influence of a higher torque(specialy at max power) at slower speeds not included, which result in the need of a higher aleron and maybe rudder deflection, what will have a higher drag and a more bad stall speed(smaler CLmax than expected) as result.

Anyway, your last calculation with alpha-t included already show what i assume and what the F2A also show. A slower turn rate with max flaps than without in a sustained turn, already at sea level and max Power(best case).
19,3 sec/360° 160mph(Radius 722ft) without flaps and 21,8sec/360°(Radius 492ft) with full flaps seems to be more credible, while the absolutly easy and stable full flap flight at stall speed seems to be a bit off(max up trim alone keep almost the most tight turn, torque effects dont disturb, while the stall edge at higher speeds is more difficult controllable, at least for me).

Only few planes in AH show a turn rate penalty due to full flaps of 2,5sec/360° at sea level, while the F4U seems to have rather outstanding flaps.

I still keep my opinion, the flaps in AH are overdone while turning, while they give the right penalty while climbing.

The reason for this discrepancy might be that the thrust lift got included while climbing, while it got neglected for the horizontal turning part.

Title: Corsair Turning Ability in AH
Post by: Knegel on August 04, 2007, 07:15:13 AM

Quote
Originally posted by SgtPappy
......................... IMO the otherwise awesome Spit's main fault was it's 'crap flap' which was a split flap designed ONLY to increase drag.

In AH the Spit´s turn great with full flaps, it show a better radius reduction due to full flaps than the Ki84 or P38(both with fowler flaps). :rolleyes:

Title: Corsair Turning Ability in AH
Post by: Knegel on August 04, 2007, 08:08:59 AM

Quote
Originally posted by nooblet187
Ok, this should clear some things up.

When flaps are engaged in level or climb, the planes nose is at a lower angle. The wing tips(past the flaps) produce little or no lift and are causing drag and worsens at higher speeds. Also the elevator causes drag keeping the nose down. This may be more or less extreme in AH or real life though.

While turning the wings tips past the flaps is at a high enough angle to help produce lift. At 20 degrees of flaps the elevator causes alittle drag, at 40 degrees there is more drag on the elevator. As the f4u pilots stated I noticed the best results at 20 or less degrees.

I did some tests in X-plane, and frapsed them with flight model enabled, with a f4u-1a corsair. In the video you will see in the scenes first 'no flap climb', then 'full flap climb', 'no flap turn', 'half flap turn', 'full flap turn'.

Video: http://www.mediafire.com/?4i4wdh3dtyd

Hi,

at a climb speed of 100mph, the full flaps AH F4U-4 elevator is absolut level, so the drag is perfect regarding this and also the wingtips stand good in the "wind". At max AoA(around 75mph), the climb is worse.
The slower climb speed with full flaps result in a rather similar drag, like the same plane without flaps at 170mph, despite the drag coefficient got increased by the flaps and at same time the effective thrust is better at slow speed than at higher speeds.

One reason for the so much worse climb with full flaps must be the smaler thrust lift due to a disadvanced angle between airfoil and engine, while flying with full flaps. The engine points relative more downward in combination with fhe "full flaps airfoil", this is wanted to provid a better sight while landing. And the max AoA is also worse with full flaps.
Roundabout like this:
(http://www.raf-roy.com/share/knegel/Screenes/Thustline.JPG)

While climbing and turning at max AOA the discrepancy is most big, resulting in a smaler thrust lift.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: SgtPappy on August 04, 2007, 04:02:28 PM

This thread is still alive?
Bump! heheh.

Title: Corsair Turning Ability in AH
Post by: dtango on August 04, 2007, 05:37:58 PM

Knegel:

"The definition of insanity is doing the same thing over and over again and expecting different results."

I now realize that I'm stuck in this loop thinking if I try to reason with you with all the different ways that I know how you will see the aerodynamics.

I would continue try to answer your questions and objections but I'm convinced now that you really aren't interested in understanding the aerodynamics. Instead you have an agenda which presupposes that the AH flight model is wrong and are looking for anything to grasp in order to prove this.

You are demonstrating the classic signs of selection bias:
[list=1]
You are cherry picking concepts that you think support your position vs. trying to understand the whole. I have purposely avoided dissecting the thrust angle issue because I'm not out to discredit you by pointing out where you're wrong about this. Now you bring up rudder drag to offset sideforce as another "proof". This only shows that you don't understand the fundamental relationships for turn rate in this equation
(http://brauncomustangs.org/images/eq1-4.jpg)

and how the variables in the equation themselves change.

I could bring up a bunch of other things like the impact of viscous separation, lift degradation due to compressibility effects at moderate airspeeds with high aoa, differentials in airspeeds between the outboard and inboard wings in a turn, etc etc.

I don't because they wouldn't serve any purpose but to confuse people. I enjoy posting about aerodynamic topics because I like to understand the "why?" and want to help others to understand the "why?" too. It serves no purpose to drill into details that only obscure the central principles.

You are misinterpreting the F2A-3 report by only picking parts of it that (you think) support your argument but have ignored and continue to ignore the parts that don't.
Aerodynamically the bottom line is that we cannot conclude anything about turn-rate performance from steady climb performance which was your central point in believing something is wrong with the AH flight model. I've tried to explain why in the best ways that I can.

And BTW, I'm glad you found the Naval Flight Test Manual. There's great information there! I've used it as a reference for years :).

Cheers!

Tango, XO
412th FS Braunco Mustangs

Title: Corsair Turning Ability in AH
Post by: nooblet187 on August 05, 2007, 07:24:50 AM

Quote
Originally posted by Knegel
Hi,

at a climb speed of 100mph, the full flaps AH F4U-4 elevator is absolut level, so the drag is perfect regarding this and also the wingtips stand good in the "wind". At max AoA(around 75mph), the climb is worse.
The slower climb speed with full flaps result in a rather similar drag, like the same plane without flaps at 170mph, despite the drag coefficient got increased by the flaps and at same time the effective thrust is better at slow speed than at higher speeds.

One reason for the so much worse climb with full flaps must be the smaler thrust lift due to a disadvanced angle between airfoil and engine, while flying with full flaps. The engine points relative more downward in combination with fhe "full flaps airfoil", this is wanted to provid a better sight while landing. And the max AoA is also worse with full flaps.
Roundabout like this:

While climbing and turning at max AOA the discrepancy is most big, resulting in a smaler thrust lift.

Greetings,

Knegel

While full flaps are down, if you do not input any elevator control you will continue to do circles/loops until you stall and/or crash. This means the elevator while climbing must constantly push the nose down, this causes drag on the elevator. Which means a significant amount of lift from the flaps is being fought against.

Also with full flaps in a climb the plane is near horizontal which seems very inefficient when climbing, meaning airflow is going downwards on the wings causing drag.

Title: Corsair Turning Ability in AH
Post by: Knegel on August 08, 2007, 04:16:50 AM

Hi Tango,

this was my initial argumentaion:
----------------------------------------------------------------------------------------
"Another risk factor of steep turns is that bank angles beyond 30° rapidly increase the load factor and stall speed. For example, the load factor in a 30° bank is only 1.15 G with a 7.5% increase in stall speed. However, a 60° bank imparts a 2G load factor and a 41% increase in stall speed".

But our AH F4U-4 turn with less than 100mph, with full flaps and around 60 degree banking, absolutly alone, without the need to pull the elevator, only with a very smooth correction with the alerons.
----------------------------------------------------------------------------------------
Another point of my argumentaion regarding the climb/turn-comparison was/is that weather the climb or the turn relation is wrong, but of course both could be wrong and lead to the discrepancy i still see.

Although the climb/turn results dont allow a exact conclusion, the different results give a good hint to the drag/lift relation at give speed. Since we can find the position of the max AoA in a graphic(look below) and cause we need a rather similar CL at same speed to overcome the gravity and cause the thrust is similar at same speed, we can see how the drag at this speed should look like.

(http://www.badz.pwp.blueyonder.co.uk/images/Flaps.jpg)

If its like this graphic show, then the F4U w/o flaps with 100mph climb at "C", while the full flaps F4U climb at roundabout where the both lines cross, resulting in a smaler drag for the full flap F4U and this should then result in a better climb ratio.
Now we have the disadvanced thrust angle with full flaps, resulting in a smaler thrust lift, but will this help the no flaps F4U so much, to overcome the full flap F4U by 30% regarding the climb ratio?

The turn in AH seems to follow the logic of this graphic rather close, whats about the climb??

The climb test with 100mph make me belive its rather this curve for full flaps:
(http://www.raf-roy.com/share/knegel/Screenes/Flaps_02.JPG)

Will it be possible to keep the turn ratio with full flaps with the relation of this curves??

My main point, a discrepancy between climb and turn, still remain from my point of view.

Believe me, i wanna see the whole and of course i pic the parts out of the F2A test that support my assumtion, the other parts already got offered here by you and others, to support your point of view.

So maybe its not only the turn that is not correct, but also particular the climb?

nooblet187,

with 100mph the AH F4U-4 100% fuel and full flaps provide a nice exact steady climb. The tail wing and elevator stand almost exact in one line then.

Of course i dont wanna climb with 170mph, at this speed there is a big nose up moment.

With 100mph, the no flap F4U-4(close to max AoA, big elevator input) climb better than the full flaps F4U-4.

Greetings,

Knegel

Title: Corsair Turning Ability in AH
Post by: nooblet187 on August 09, 2007, 06:43:29 PM

I already said in 100 mph climb with no flaps, you are limited by lift and power. Your using 100% power and 100% lift or close to it.

With full flaps at 100 mph you are using 75%( just a guess) of lift and 100% power. Therefore the flaps are adding drag, and lift you cannot use since your already at 100% power(well you could use the lift, just pull back on the elevator more even though you would slow down..).

In a turn you use 100% or close to it of the additional lift that the flaps add.

Title: Corsair Turning Ability in AH
Post by: TequilaChaser on August 09, 2007, 09:15:32 PM

Quote
Originally posted by nooblet187
While full flaps are down, if you do not input any elevator control you will continue to do circles/loops until you stall and/or crash.

why would you continue to do circles/loops? what is causing it to loop? trim? Combat Trim?
Quote
Originally posted by nooblet187
This means the elevator while climbing must constantly push the nose down, this causes drag on the elevator. Which means a significant amount of lift from the flaps is being fought against. [/B]

if the elevator is constantly pushing the nose down, then how could you be doing loops as you stated in the 1st sentence?

the 1st sentence , sounds like you are using CT ( Combat Trim turned on ), yet your second sentence cancels this out.........

where are you getting your #'s? , data?, information? got any charts/URL links? NEVERMIND THIS QUESTION - NOTICED U USING X-Plane to find knowledge

looking for something to explain your statements, just reading it without pictures or charts is hard to visualize.......

Title: Corsair Turning Ability in AH
Post by: nooblet187 on August 10, 2007, 08:16:48 PM

Quote
Originally posted by TequilaChaser
why would you continue to do circles/loops? what is causing it to loop? trim? Combat Trim?

The flaps cause the airplane to turn on its own.

Quote
if the elevator is constantly pushing the nose down, then how could you be doing loops as you stated in the 1st sentence?

It was just to say what the flaps are doing, and what you must do when climbing.

Quote
the 1st sentence , sounds like you are using CT ( Combat Trim turned on ), yet your second sentence cancels this out.........

It was just explaining what you must do in a high speed climb because the full flaps keep pushin the nose up, just tested and even at 100 mph, the flaps are pushing up on the nose past the max climb rate with full flaps, meaning you gotta keep using elevators to point nose down.

Title: Corsair Turning Ability in AH
Post by: SgtPappy on August 10, 2007, 09:49:29 PM

TC is like the God of aerodynamics math here, sooo I would not advise you saying anything against him.. but then again being wrong is one way of learning.

Title: Corsair Turning Ability in AH
Post by: Saxman on August 10, 2007, 10:42:06 PM

Nooblet:

If you're having to manually push the stick forward something's not right. You should be able to trim the nose down to cancel out the tendency of the nose to pop up when you begin dropping flaps. I'm no aerodynamics guru and far from a math whiz, but I fly the F4U in here almost exclusively, and at no airspeed do I ever have to push the stick forward to keep the plane from flopping over on its back.

Now if you have COMBAT TRIM enabled as TC suggested, THAT will cause you problems. Combat trim tries to automatically trim your plane for level flight, one of the little allowances HTC has made to account for the fact that a real pilot would have trimming so second-nature he can trim without thinking, and also because we don't have the capability of "feeling" how the plane is handling and trimming accordingly. However if you're near stall speeds with full flaps deployed this will cause you problems because the aircraft's natural tendency is to lose altitude, so combat trim is trying to compensate by continuously trimming the nose up, which will generate the exact same effect you're describing. This is why using combat trim while trying to land the F4U is IMO a BAD thing.

However at low speeds once you have full flaps deployed, you can actually trim the nose so far down that you need BACK PRESSURE on the stick to maintain a nose-high attitude for landing.

This is the flaw in what you describe, because the elevators on the REAL aircraft wouldn't come into play keeping the nose down at all, only the trim tabs.

Title: Corsair Turning Ability in AH
Post by: TequilaChaser on August 11, 2007, 01:42:26 PM

Quote
Originally posted by SgtPappy
TC is like the God of aerodynamics math here, sooo I would not advise you saying anything against him.. but then again being wrong is one way of learning.

ROFLMAO............that right there is the funniest thing I have ever read......

you must have me mixed up with the Elite engineers group

all I everwas, was simply an Aviation Machinist ( AD ) jet mechanic.......in my Navy career. different engine types I worked on were TF-34-GE-400B's, F-110-GE-400's, F404-GE-400's, TF-30P-414A's, TF41-A-400's, J-52-P-408A's, J79-GE-8B/-8C's mainly the "O" level but had time in both "I" & "D" levels of maintenance as well.....
and I learn things everyday concerning the aero engineering , and I learn from this particular forum as well as other areas, but I am no aerodynamic mathmatical god by no means.......ROFL.......

dtango, Widewing, Brooke, Hitech, Badboy, gripen, among some others are the "gods of aerodynamics math" as far as Aces High is concerned.......

I simply could not understand his statement, it was canceling itself out 1st sentance to 2nd setance.......

Title: Corsair Turning Ability in AH
Post by: nooblet187 on August 11, 2007, 02:49:57 PM

As my name suggests, its true when it comes to aerodynamics. :D

I never considered trim, but it should still be true that theres not enough power to use all the extra lift while it adds more drag.

Title: Corsair Turning Ability in AH
Post by: SgtPappy on August 13, 2007, 10:23:32 AM

heh, well TC, your doing very well and a little idiot like myself who hasn't taken his gr 11 physics course yet needs a helluva lot to learn.

I meant however, that you were our mathematician (in addition to Tango, of course) in this particular thread. Also that the 'being wrong and learning' applied to those who question you and Tango :D

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