Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: F4UDOA on May 01, 2000, 12:32:00 PM
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I'm down on the deck in my F4U with less than 50% fuel and ammo when a freshly spawned 109G-10 rears his ugly head and starts making high overhead runs on me. I evade, evade, evade until finally I get him were I want him. He loses e and flat turns on the deck in an atempt to get on my 6. I engage WEP and drop two notches of flap and brake left with the stall buzzer blowing in my ear. I see him directly above my conopy and I assume within two turns I should be looking at his tail in my sights. But then ping blam boom I'm dead.
Why, assuming I weight 12,000lbs (At that point I surely did not) and he was fresh from the hanger with say half fuel and ammo at 6740LBS (A full load would be 7410lbs).
His wing loading would be 6740/173.3= 38.9
My F4U would be 12,000lbs/314=38.21.
Ok thats too close to call right, wrong.
I had half fuel and ammo plus two notches of flap. So what gives? If I'm wrong then somebody explain why. But from everything I have read about the ability of the Bf-109 compaired to the Fw-190 and the P-51 the F4U should turn behind it quite easily. And the relative wing loading agree's with me as well. I am not trying to out turn a spitty here, I am fighting a bloated G-10 with Dragster tires and a blower sticking out of the hood.
Pyro, how to you calculate the sustained turn radius on these birds? I would luv to know?
Also I have seen Jekyll's web pages on this topic and it would seems to match my finding as well.
Thanks F4UDOA
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If you are trying to get your guns to point at your opponent, it's turn rate you need to worry about, not radius. Even with a larger circle, the 109 can use yo-yo's to get his nose on you with a better rate of turn (he has flaps too!). I can almost guarantee that using flaps will reduce your radius but the drag far outweighs the lift and your rate will fall off even more (the only exceptions being the P-38 with one notch and maybe the George). The plane with the lowest stall speed has the smallest radius.
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Actually Wells,
It is the radius that I am speaking of. The F4U was carrier plane and had very good low speed lateral control as well as a low stall speed. Like I said the loaded or empty wing loading of a F4U is much better than a late model 109 with high wing loading. In head to head test with a P-51 and a FW-190 the F4U could turn circles around both of them. And both of those A/C could out turn a 109. Also a Hi yo yo is one thing but thats not what happened. I watched him fly right up my tail pipe. Flat on the deck. Not a yo, yo in the sky. As far as the flaps adding drag. Well 20%flap seeting in an F4U is called a maneuver flap and is meant to reduce the turning circle. According to the Arodynamic text that I have wing loading is the best indicator of turn radius. Then that number is divided by the lift coefficient of the wing to give you an "index" of turning capabilty. So for instance the turning index of a F4U-1D would be 11,803lbs/314=37.6 divided by the lift coefficient which is 1.88 (2.33 prior to the leading edge spoiler strip). Which gives you an index number of 19.99. The lower the better. A P-51D would be
9500/233.19=40.73 divided by lift coeficient of 1.89=21.55 or a little worse than the F4U-1D. If anybody knows the lift coefficient of the Bf-109 just figure it out and post it please. But wing loading is your best off the cuff indicator.
Thanks
F4UDOA
[This message has been edited by F4UDOA (edited 05-01-2000).]
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And did you think in the chance of it being a 109F4?...its not so different from a G10
Anyway, what wells says. If you turn with a 109 down in the deck with a F4U...well you saw the results (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif).
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Ram, out
Fw190D9? Ta152H1? The truth is out there
JG2 "Richthofen" (http://www.busprod.com/weazel2/)
(http://nottosc.tripod.com/ram190.gif)
[This message has been edited by RAM (edited 05-01-2000).]
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EEEEKSSS!! <COUGH COUGH!!!>
AAAARG!!!!
A FW190 OUT TURNIGN A Me109?!?!?!??! WTF!??!?!?!
you are GROSSLY wrong!!!!
and, again...wasnt it a 109F4? why are you so sure it was a G10?
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F4u,
A smaller radius does not mean 'turn circles around'.
Here's some math for you...
One plane has a turning radius of say 500' and a sustained turning speed of 150 mph
Another plane has a turning radius of 600' but a sustained turning speed of 200 mph. Which one turns 'faster'?
A hint...not the first one
Flaps should only be used as an offensive tool (or when landing) to 'ensure' a kill. They will increase your turn rate temporarily, until the speed loss outweighs the turn rate, so only a few seconds, after which, your turn rate will be lower than before. The exceptions to this are those which have flaps that increase wing area before increasing the Cl, such as the P-38's fowler flaps and maybe the butterfly flaps on the George.
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RAM,
Yes I am very sure it was a G-10.
I asked as soon as I pick the shrapnel out of my arse. The offending pilot was glad to tell me what he was flying. No problem really.
If you are sure about the capabilities of the 109G-10 could you please post what you think the correct wing loading ad lift coefficient should be? I have the G-10 listed at 7410lbs loaded with a wing area of 173.3ft.
I am also looking at the empty wing loading which is even more slanted toward the F4U-1D.
Empty weight being 8971lbs wing area 314 wing loading=28.57.
BF-109G10 empty weight=6070lbs and wing area
=173.3 wing loading=35.02.
Maybe the F-4 fairs better in this comparison but the G10 does not.
F4UDOA
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Wells,
Stay with me on this because I think you understand what I'm saying. If I am turn slower I will have a smaller radius faster will have a larger radius but will exit the turn faster. Fine. But for the puposes of getting a tail shot I want a smaller radius.
Which should bring me into firing position.
Being faster in a turn in that case would be a disadvantage because it woud lead him in front of me or just plain overshoot. But their is no way he should get a "six" shot from a conopy to canopy start.
By your logic a faster circle is better than a smaller circle for ACM. If so why would the Zero be such and effective fighter at low speed. I was at 120IAS, we were in a slow left turn. In two turns he was on my 6. Why???
F4UDOA
Please don't turn this into a flame fest.
I just want a conversation with out the BS
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Personally, I would rather be the 109 in that situation...
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Clmax of 109 is about 1.4
Cdimax = 0.10
F4u Clmax = 1.88
F4u Cdimax = 0.21
Cdimax * WA (109) = 0.10 * 173 = 17.3
Cdimax * WA (F4u) = 0.21 * 314 = 65.9
So the F4u has almost 4 times as much drag in a max rate turn than a 109 (at a given speed). Does it have 4 times the power to overcome that drag? Not even close. The sustained turning speed of the F4u is going to be much lower than the 109's.
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F4U,
Turn 'rate' means getting ones nose pointed in the right direction faster. The plane with the faster turn 'rate' can always get it's nose on target. It's a delicate balance though, being too fast will result in too larger a radius and rate will be slower, likewise, the inverse is true (this is what I think happened to you in that fight). Your speed was simply too slow for the radius and your turn rate suffered. Time for some offline testing, I guess.
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Here's what I measured in AH (50% fuel loads)
109G10, sustained turn speed 180 mph, 28s for 360 degrees
F4u-1D, 140 mph, 30 s
Radii are
109G10 - 1176'
F4u-1D - 980'
The 109 does indeed get it's nose around a bit faster, albeit with a larger radius.
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Wells,
Great job of explaining. I am a long time aviation guy but a newbie in the aerodynamic calculations. I am reading my text to keep up with you but you seem to be giving me the info I am looking for. I was trying not to get into a pissing match with the flame artist on this board. I will respond as soon as I run some calculations on some other A/C for contrast.
Thanks Again
F4UDOA
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Wells,
How did you measure radius from your offline testing? How did you determine your best sustained turn speed? Was it 3G speed turn you were measuring?
F4UDOA
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I just looked at the IAS while pulling as much as I dared with the stall horn blaring in a level turn. The radius can be figured by timing the turn at a constant speed.
For the F4u, it flew at 140 mph for 30 seconds, so it flew a distance of 1.1666 miles (the circumference of the circle). Divide by pi to get diameter, then divide that by 2 to get the radius.
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F4UDOA;
Some thing to consider, aside from the mathematics of turn radii.
Assume that you and your opponent have the same center for your turn radii. Both have the same center point of their respective turn circles. This situation plugs well into your formula from above.
Now assume that you and your opponent did not have the same center point. This now becomes an issue of "How did it appear?" and "How was it really?".
If you sketch this out and run it in your head you can see how an A/C with a slower rate or a larger turn radius appears to turn faster. This is do to the intersection piont of the two A/C flying in seperate circles.
Just something to consider. Good Luck! (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Mino
The Wrecking Crew
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Minotaur,
I see your point. However the F4U should still have the smaller radius. I have been reading all evening and I can't get past the lower wingloading and lower stall of the F4U.
The equation is F=mv2/r (when realigned for radius) which basically says that the lower the volocity the smaller the circle. I was at 120IAS. Or even just say hypothetically I am at 120IAS on the deck turning at only about a 60degree angle pulling 1.8G's. The slower the airplane the smaller the circle. Especially since the V is squared in that equation the speed accounts for much of the radius. Plus the fact that the F4U wing accounts for quite a bit more lift than the 109 meaning a lower stall speed.
So if I picture two A/C as dots one inch apart from one another and then draw two circles at the same time starting from these two positions the smaller circle will always be in better position that the larger regardless of how fast I draw either.
Oh well, Its late and I'm tired. I'll let the Gods of ACM worry about this one for now.
Thanks All
F4UDOA
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Ah,
but F is also directly related to V^2.
If r = mV^2/F
reducing V also reduces F and r remains constant!
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Also, apart from the mathematical point of view, in the real world the speed in the turn and better climb of the 109 will let him do a hi yoyo to get a shot even if his turn rate and radius doesn’t allow him to ‘catch your tail’.
If you are at stall speed on the deck and he is outside your turn but faster he can use speed and climb, pointing the nose up over the circle, rudder into the turn and drop back into the circle. This will let him cut across the circle in the vertical plane using gravity assist to tighten the turn in the horizontal plane. He is still flying a longer way from his point of view, but in the plane of your circle he has decreased his turning radius a lot and cut inside you and pulled lead for the shot.
A way to defeat him is with scissors instead of a sustained turn, the hard part is to keep him down and turning hard instead of doing what he should do and use his climb to extend over your nose.
Turn radius is a very effective tool to deny the attacker the shot by keeping inside his turn, but doing just this will never provide you with an offensive opportunity unless the attacker mess up and pull to hard, trying to force the shot, which seems to happen a lot.
(I think everyone who posted to this thread are well aware of all this, so this is just for the benefit of others)
-Jinx
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Being a 109 pilot with a little experience:
unless you in a spit/niki/205/202/p38/la5 dont flat turn with a 109
especially the g10: why you ask? the g10 is superior with its engine thus making low speed cornering feasible. As i start to lose angles i kick the rudder a good bit to adjust my radii to my opponents, then combined with the awesome accel i gain angles thru lag pursuit on you before you get to accelerate to my corner velocity.
just becuase its a g10 dont underestimate its ability to turn...its engine keeps its at a better corner velocity in sustained flat turns...
most 109 pilots dont trim there aircraft right so maybe you have experienced some victories in the past but against a experienced pilot who knows how to use the rudder you have no chance. My personal trim settings in knife fight are 3/4 full trim allowing me a very energy efficient turn by barely pulling on the stick.
Rudder is key to the 109, use it live by it...
me and Hristo experimented one day i was p38 he was g10 believe it or not he was able to set up some snap shots on me(now this is a tight fight not a e fight so i was very impressed.. I use the same technique and have had much success)
regards,
DoctorYO
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yo is correct the 109 with 20 mm will turn unbelievably if you use the rudder and eng torq ( like a gyroscope) but it is pretty much a experten thing . i.e. you fight a 109 hope it aint a expert they are real dangerous .
and the hog was refered to as the ensign eleminator. good low speed handelin is a laugh. they turn like zeeks here when slow.
get out of the hog it is visably stuntin the growth of many pilots with its lazer guns and wild low speed loops(not to metion breakin the sound barrier and livin).you fly that thing you get lazy ( pongo and i took out a force of 7 panzers and a wad of m16s in um last nite just silly.)
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Towd,
That ensign eliminator stuff is a little silly. Yes it did have a reputation for ground looping but if you ever read Marion Carl or Tommy Blackburn 's auto-biography you will find that the F4F had a horrible reputation as well. Everytime the HP increased people would scream ground loop.
But Blackburn's squad the VF-17 carrier qualified no problem in the early model F4U.
He volenteered to fly from a ground base because he didn't want to give up flying the F4U to fly the F6F. He also commanded and A/C carrier in his career and swore the only reason the F4U did not make on the decks the first time was because of the lack of spare parts avaiable to the Navy logistics for Corsairs. The F6F was easy because it used alot of the same parts as the F4F already in use. Many Marine avaitors had problems late in the war landing because unlike there Navy counter parts they were not Carrier qualified but were forced to fly off of carriers prematurely.
In fact the F4U has lower wing loading than the Bf109g-10, P-51D, P-38L, P-47D and FW-190. It proved it could outturn these A/C in numerous flight test. Check the thread under general discussion for SpitIXvrsFW190 for more information I have already posted.
Later
The Truth is out there
F4UDOA
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F4UDOA,
first, thanx for the test data, their just great info.
second, No offense, but (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif).
We all have our favorite plane, well i haven't decided that (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif), so it's natural that we are looking for arguments why it should be superior over another plane.
I followed the wingloading arguments in another thread where people were squeaking why the spit is supposed to be superior over the 190.
I am no expert, but i just can't believe that wingloading is the single answer to a planes maneuver ability.
The thing i figured at AH is that 90% is the pilot. If I am flying a spit and i.e. I have Hristo in a 109 I am just dead (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif).
Again no offense, but i just wanted to bring that in mind.
<S>
Maik
(http://saintaw.tripod.com/maik.jpg)
[This message has been edited by maik (edited 05-12-2000).]
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Maik,
I just grew a brain and posted some more test data on get this. My own web page. WooHoo!!
Anyway you are very right about I have my favorite plane thing. I guess we all do.
But because I do it makes my data seem one sided and my opinion seem a little childish.
But I am a little obsessive complusive when it comes to flight models.
The one airplane that I know more than the ohters is the F4U so I point out any inaccuracies. However I was doing offline testing and I find things like all of the A/C with a couple exceptions all stall at the same speed. So not only is the F4U porked but many others are as well. The Spitty on the ohter hand can pull 3g turns down to 140mph and is almost impossible to stall at low speed in the flat turning arena. So I just want to say that I'm not looking for an uber plane. I just can't stand when people say that the F4U couldn't turn well. It just couldn't turn well against a Zero. But then again either could a Spitfire. If it had seen
action in Europe I think it would have a completely different reputation based on it's advisaries. Also wing loading isn't everything in turning ability but it is the best of hand gauge for radius of a A/C turning ability. Rate may vary.
Anyway check my test data out at
http://members.home.net/markw4/index.html (http://members.home.net/markw4/index.html)
Thanks
F4UDOA
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Just one question....
Wife or Mistress?
hehehe
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Vermillion
**MOL**, Men of Leisure
"Real Men fly Radials, Nancy Boys fly Spitfires"
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An important thing to understand is that I'm not inputing things like turn rate or turn radius into the model. Those are based on the physical attributes of the plane, i.e. lift, drag, thrust.
As to all planes having the same stall speed, that's not correct, but most of the planes we have so far fall into the same area. Stall speed will just be a factor of weight, wing area, and max lift coefficient.
BTW, thanks for the navy vs FW report. I've seen it before but no longer had a copy.
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Doug "Pyro" Balmos
HiTech Creations
The road to hell is paved with good intentions.
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Pyro,
Please answer one question and I'll never complain again. (Did I really just say that?)
What are you using for a maximum lift coefficient for the F4U?
Is it...
A. 2.30 which is the pre-spoiler coefficient from early model F4U-1's
B. 1.88 Which is the post spoiler Max lift Coefficient.
C. 1.48 Which is totally porked and I can't figure out were it comes from.
Also Vermillion,
The lovely lady is me Wife. (Boss)
Thanks F4UDOA
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Note: The following data has no relation to flight performance in AH.
Level stall speeds for corresponding CLmax using 12000 lbs airframe and 314 sq ft wing.
2.30 = 81 mph (70 knts)
1.88 = 89 mph (78 knts)
1.48 = 100 mph (87 knts) <---this matches the flight manual data as well as airfoil analysis of NACA 23018 and NACA 23009 airfoils used in the F4u wing (no washout).
Results for Rn = 10M (flaps up) are as follows:
23018 (root airfoil) = 1.75 @ 19 degrees (2d flow)
23009 (tip airfoil) = 1.16 @ 12 degrees (2d flow)
23018 @ 12 degrees = 1.45
Average for the wing (60% root + 40% tip due to taper est.) @ 12 degrees ~ 1.33
With 50 degrees of flaps on 23018:
CL = 3.47 @ 12 degrees
If flaps span 45% of the wing surface (my own estimated measurement from a small drawing), then average CL with flaps down is approximately 2.20. It can be estimated that the body contributes another 0.1 - 0.15 or so to the lift coefficient. The reason the angle is limited to 12 degrees in these calculations is because that is when the tip stalls and aileron control would be lost. For 3d flow, factoring in aspect ratio, the induced angle of attack is about 4-5 degrees. What this means is that the above calculated lift coefficients actually occur at a higher angle of attack than 12 degrees, or rather 16-17 degrees. Low aspect ratio wings have higher angle of attack capability than high aspect ratio wings (check f18, f15, f16, Su-27).
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F4UDOA
if found some lift coefficients for the BF109 V24. It´s a predecessor machine of the 109F.
Tests were done in chalais meudon /france.
It did not have the rounded wingends, but this should not have too much influence on max Cl
Cl_max: 1,46 without flaps
Cl_max: 1,98 with flaps
have a look at:
http://www.stud.mw.tum.de/~sl1/f4_windkanal.html (http://www.stud.mw.tum.de/~sl1/f4_windkanal.html)
niklas
P.S.: when will we see here smiliar charts from spits, P51, P38 instead of phrases like "elliptical wing", "laminar wing", "high aspect ratio" ????
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Wells,
Err, I think your may be right? However the Max lift is what it is flaps or no. It still does not correspond to the flight model in AH. That's why I keep asking Pyro what numbers he is using. Test for yourself. A full loaded F4U-1D or C 50% flap and see where you stall. Also the F6F, P-51 and other A/C were also tested by NACA in the same format. This must also mean that there Max lift coefficients are proportionally lower. By the way, the Naval requirement for landing and takeoff speeds aboard carriers is not dependant on a head wind. Since wind nor a funtional engine in the carrier could be depended on in combat.
Niklas,
Thanks very much for the info on the 109.
That information is hard to come by.
I want to see this info posted as well. Pyro must have it somewhere since he did the FM's.
I hope they post it in the A/C section.
Later
F4UDOA
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I got a clean stall speed with full fuel and ammo (no ord) of 102 mph for F4u-1D. I don't see a problem. Flaps down, I was unable to get an accurate reading (trim speed only works down to 100), but I noticed a total lack of drag with flaps full down. I maintained altitude without having to add any power at all. There's your secret, don't dump 1 or 2 notches of flap, use FULL flaps when turning!
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thanks guys now my brain hurts (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
just fly the damn planes and have fun...btw if you can calculate that lot why not put your minds to good use and give me next lottery numbers :P
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Aerodynamic calculations work in the air, we are not in the air. In a perfect virtual enviorment, this could be, and actually MAY be modeled, however netlag could be working in this situation, negating the validity of any real-world mathematics. If this was mentioned, pardon me, I missed it. Whatever factors may or may not have been at work , a very informative discussion, and more than I want to think about (or am able to).