Corsair Turning Ability in AH

[HoseNose]

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.

[Benny Moore]

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?

[HoseNose]

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

Page 41 - F4U manual

[Knegel]

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

[HoseNose]

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.

[Benny Moore]

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

[Knegel]

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.

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.

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

[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.

[Benny Moore]

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.

[TequilaChaser]

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


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

[SgtPappy]

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!

[mtnman]

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

[Vulcan]

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

[Benny Moore]

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.

[Knegel]

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