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Thoughts on the K-4 Manouverability


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Richomer

Hey pilots,

 

Generally speaking, I find it very pleasant to fly the K-4 with its strenghts and flaws. However every plane must be measured in regards to other plane availible and something bugs me a little bit. Are you convinced by the fact that the tempest, a plane about 2 tons heaviers, without leading edge slats, a draggier frame and higher wing loading outturns the K-4 ?

 

This question is especially relevant for two reasons, firstly other sims with great emphasis on flight models propose a much more manoeuverable K-4. Secondly, I belive historical pilots impression on the K-4 manoeverability has often been misinterpretted, some squadrons complained about it because they were endowed with unremovable 20mm wing mounted gun pods.

 

If there is any data backing this loss of agility, let me know as well.

 

Cheers

Edited by Richomer
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II/JG17_HerrMurf

It's a fair question but your last line is gonna draw a lot of heat and adds nothing to the conversation.

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Mitthrawnuruodo
1 hour ago, Richomer said:

Are you convinced by the fact that the tempest, a plane about 2 tons heaviers, without leading edge slats, a draggier frame and higher wing loading outturns the K-4 ?

 

You're not the first to question the Tempest's turning abilities. See this thread for some relevant discussions.

 

Note that the Tempest actually has a lower wing loading than the K-4. The K-4 is heavier than the earlier 109 variants, so it loses some turn performance. The question is therefore somewhat nuanced.

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QB.Shallot

AS @Mitthrawnuruodohas said, its not so much the K4's performance. When compared to the Tempest, pretty much every other A/C pales in comparison due to its questionable turn rate. 

Edited by QB.Shallot
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CountZero

Yes its obvious that problem is in questionable turn ability of Tempest, i would think thats gona get another look when they do Typhoon FM or that airplane will also turn like crazy, if they take complains serious.

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von_Tom
1 hour ago, CountZero said:

Yes its obvious that problem is in questionable turn ability of Tempest, i would think thats gona get another look when they do Typhoon FM or that airplane will also turn like crazy, if they take complains serious.

 

Obvious?  Tempest could out-turn a G and there is no reason why it could not out-turn a K4.  Typhoon FM should be different as they had a different wing, but their turn performance was similar.  Fuel limits taken by respective pilots may also be a factor.


I love this as an explanation of turning circles:

ytte562x0u521.jpg.9ee5fe31d03f2b5912a8bcacc95f7e32.jpg

 

As with all of these things, as has been shown in the past, detailed and evidenced FM issues are considered.

 

von Tom

 

Edited by von_Tom
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CountZero
1 hour ago, von_Tom said:

 

Obvious?  Tempest could out-turn a G and there is no reason why it could not out-turn a K4.  Typhoon FM should be different as they had a different wing, but their turn performance was similar.  Fuel limits taken by respective pilots may also be a factor.


I love this as an explanation of turning circles:

ytte562x0u521.jpg.9ee5fe31d03f2b5912a8bcacc95f7e32.jpg

 

As with all of these things, as has been shown in the past, detailed and evidenced FM issues are considered.

 

von Tom

 

I read trough topic posted in 3rd post and it makes it obvious that tempest turn is problme not lasck of turn of 109.

Also tempest is one who can brake its own wings if you turn to hard and no combat or post war report says anything about pilots braking their wings trying to turn at high speed, so something is fishy with its elevators to me.

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von_Tom
32 minutes ago, CountZero said:

...something is fishy with its elevators to me.

 

This has happened to me a few times.

 

I don't know if something is wrong.  I can understand some things never being mentioned because training stopped pilots doing certain things, or if wings came off the pilots died so couldn't report it.

 

But, it does not seem correct that such a big control surface can be controlled at high speed so easily.  Then again, some aircraft did have light elevator controls.

 

von Tom

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[DBS]Browning
1 hour ago, CountZero said:

Also tempest is one who can brake its own wings if you turn to hard and no combat or post war report says anything about pilots braking their wings trying to turn at high speed, so something is fishy with its elevators to me.

 

The Tempest is far from the only plane ingame capable of this. The majority of planes can break their own wings through manurers.

 

This is how it should be. All planes have a g-limit and the vast majority planes are capable of breaking it from a 747 to an Extra 300.

That you don't often have reports of it happening is largely a result of pilots knowing the danger and also because such manurers are, in reality, very uncomfortable for the pilot to perform; something we don't experience ingame.

 

Also, the Tempest does have an unusually thin wing.

Edited by [DBS]Browning
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III/JG52_Otto_-I-
19 hours ago, Mitthrawnuruodo said:

Note that the Tempest actually has a lower wing loading than the K-4. The K-4 is heavier than the earlier 109 variants, so it loses some turn performance. The question is therefore somewhat nuanced.

Low wing loading means slow airplane, and lower turn radius, but in other hand more parasite drag at high speed. The best aerodynamic solution for these problems, is a design with a high wing loading and low parasite drag, for flying at highter speed with less engine power, but equiped with lift augmetation devices ( automatic slats) for better turning radius at low speed, ... casually as Bf-109 K4 had. :umnik2:

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von_Tom

 

Tempest wing had low wing loading and low parasitic drag albeit no slats.  I'd have thought that the slats only come out when the AoA is high so either he 109 bleeds speed rapidly or it is already at very low energy/slow speed.

 

von Tom 

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Denum

Tempest turns tighter then it should no doubt.


But the K4 is pretty heavy for a 109. So in a turning match on the deck vs a Spitfire or P-38, its not going to go well. 

 

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II/JG17_HerrMurf

Spitfire, no but I have little problem handling a P-38 in any version of the 109.

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Denum

Not referring to single player. Even on hard they are... well... turkey shoot?

Some of the better Lightening players online can do some pretty impressive maneuvers in it. Thing has enormous wing area once it drops the flaps

 

I'm putting my money on the lightening.  

Edited by Denum
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II/JG17_HerrMurf
10 minutes ago, Denum said:

Not referring to single player. Even on hard they are... well... turkey shoot?

Some of the better Lightening players online can do some pretty impressive maneuvers in it. Thing has enormous wing area once it drops the flaps

 

I'm putting my money on the lightening.  

 

Why did you assume I was talking about single player? I haven't flown offline in this game, except to test new aircraft, since EA.

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Denum
1 minute ago, II/JG17_HerrMurf said:

 

Why did you assume I was talking about single player? I haven't flown offline in this game, except to test new aircraft, since EA.

Most people play single player. I did take the time to check the two most popular servers for your tag before suggesting that. 

I assume you're on Berloga then mostly? 

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II/JG17_HerrMurf
12 minutes ago, Denum said:

Most people play single player. I did take the time to check the two most popular servers for your tag before suggesting that. 

I assume you're on Berloga then mostly? 

 

I no longer fly with this handle. It's a forum persona only now.

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Denum

Fair enough!

I found the K-4 to be race horse on cocaine. I didn't feel like I was struggling with it any point. Just had to know who to turn with and who not to. Tempest, Spitfire, Yaks. Risky. P-38 was a maybe but had to be careful because they can reverse the fight fast if they know whats up. 

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von_Tom

 

Don't turn with anyone.  Never turn to death - if you do have to turn, make it a climbing turn that you gradually tighten and make steeper.

 

If you're in a horizontal plane turn it comes down to the pilot but in a K4 I would avoid turning with anything other than a P47.  The P38 can be nasty if you're not careful.  There are too many variables for everything else, for example with equal fuel loads a K4 should be able to turn with a P51, but if the P51 has 10% fuel and you have 50% it gets very tough,

 

That is my opinion anyway.  I usually rely on squad mates to save me anyway.

 

von Tom

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Panthera

In reality everything speaks to the K4 being a stellar turn fighter, small, low weight, lots of power, very low span loading etc., and that is how it is simulated in for example DCS as well, where it easily beats for example the P-51 in any form of turning contest with the same fuel load in both (400L), as it should. In IL2 however it is curiously quite the opposite.

 

I've brought up this issue earlier, where I tested the K4 against the P-51D in terms of sustained turn performance in IL2, and the K4 is soundly beaten here, which I can't see justified in any way from a physics/aerodynamic PoV. As mentioned is the exact opposite in DCS, dramatically so, where the aircraft fly more as expected.

 

From a real world perspective, even if we assume the best possible scenario for the P-51, i.e. same fuel load of 400 L, and 1.8 ata vs 75" Hg, the K4 should still be the clear winner in any turn fight, esp. if it involves more than a single turn.

 

Bf-109 K-4 vs P-51 (400 L fuel)

Weight: 3362 kg vs 4205 kg

Wing area: 16.15 sqm vs 21.83 sqm

Wing span: 9.92 m vs 11.28 m

Power: 1823 hp vs 1820 hp (1.8ata vs 75" Hg)

Cd0: 0.0205 vs 0.0161

AR: 6.09 vs 5.82

Span loading: 327 kg/m vs  372 kg/m

 

As for Clmax vs mach curves (instantaneous performance), based on the data I've seen the 109 most likely comes out noticably better here than the P-51 at any WW2 dogfighting speeds, it not being until around 0.5 mach where the laminar profile starts coming into its own. In addition to this the 109 should enjoy an overall lift increase from its outboard slats allowing the outboard wing section to match the energized (prop wash) root section in lift during power on conditions (something it seems DCS simulates very well). Importantly the difference here is supported by pilots who fly both types today. The Clmax debate is however a contentious one amongst some on this board (and elsewhere I've learned), but to me it seems the DCS deverlopers got it right, where'as the IL2 ones didn't (the Tempest & P51 stick out to me).

 

Just my two cents

 

Edited by Panthera
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LukeFF
4 hours ago, Panthera said:

In reality everything speaks to the K4 being a stellar turn fighter

 

Uh...ok? What reality? What test report(s)? The K-4 was hardly a light plane. What makes you think it would be any more maneuverable than a G-6 or G14? You're going to need more than "your two cents" if you want something to change.

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Panthera
7 hours ago, LukeFF said:

 

Uh...ok? What reality? What test report(s)? The K-4 was hardly a light plane. What makes you think it would be any more maneuverable than a G-6 or G14? You're going to need more than "your two cents" if you want something to change.

 

Well I'm struggling to find a western allied fighter that was lighter, and I don't remember mentioning the G6 or G14 anywhere.

 

Also "maneuverability" is a broad term, so I'm not sure what you're refering to here either. If we're talking turn performance, are you aware that sustained turn performance relies on specific excess power? 

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ACG_Cass
16 hours ago, Panthera said:

Span loading: 327 kg/m vs  372 kg/m

How come the choice of span loading here? Wing loading tends to be more relevant to sustained turn performance and in this configuration it's significantly lower on the 51.

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LukeFF
11 hours ago, Panthera said:

 

Well I'm struggling to find a western allied fighter that was lighter, and I don't remember mentioning the G6 or G14 anywhere.

 

Also "maneuverability" is a broad term, so I'm not sure what you're refering to here either. If we're talking turn performance, are you aware that sustained turn performance relies on specific excess power? 

 

My points and questions still stand - on what are you basing your assertion that the K-4 should have "stellar" maneuverability? I brought up the G-6 and G-14, because they are contemporaries of the K-4, and neither of those are regarded as having "stellar" maneuverability. 

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ZachariasX
6 minutes ago, LukeFF said:

My points and questions still stand - on what are you basing your assertion that the K-4 should have "stellar" maneuverability? I brought up the G-6 and G-14, because they are contemporaries of the K-4, and neither of those are regarded as having "stellar" maneuverability. 

 

I guess the point is here that when looking at excess power vs span loading, the K4 has a very good sustained turn and becuae it has more power it is considerable better than the G-6/14, depending on engine mod of course. Also better than the Mustang.

 

The K4 in this sim is an extremely good dogfighter, but it is much harder to make most out of it than with the P-51, and that is why you usually win a fight a close in fight against a K4 in this sim. At least I feel like that. In "the other sim", it is very easy to control the K4 to the edge of the enveloppe. Hence, you can readily mop the floor with it.

 

True or not, I prefer how it is in this sim. The F4 is probably the most liked 109 for fast food dogfighting and it was the most liked 109 back then. It is nice seeing this point reflected in the general behavior of the players. I really appreciate how it is in this game. It is of no use if in theory you have everything you need to easily win a fight, but if it is not really there, like just put on the top drawer in your kitchen. And easy to handle aircraft can indeed give you more at hand immediately than a difficult to control aircraft. And in this department the Mustang is just on another level than the 1930's comeptition, no matter how pimped.

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Panthera
7 hours ago, Cass said:

How come the choice of span loading here? Wing loading tends to be more relevant to sustained turn performance and in this configuration it's significantly lower on the 51.

 

Wing loading is more relevant to instantaneous performance, but it does help reduce the required lift coefficient, problem is the P-51 is much larger & heavier, and thus in the end it just isn't enough, and the difference in span loading squared indicates how much more thrust the P-51 will require to sustain the same load factor as the 109. Also I didn't cite wing loading as in this case we're talking two aircraft with no similarity in airfoil designs, with the 109's 2R1 profile (similar to NACA 5 digit series) having a noticably higher Clmax at the normal WW2 dogfighting speeds, where'as the laminar flow airfoil with its sharper LE and max thickness much further back doesn't get into its own until around 0.5 mach. The 109 is helped a long even further by the overall increase in lift provided by the slats allowing the outboard wing section to match the energized root section in both Clmax & critical AoA during power on conditions, and this effect increases the slower the airrcaft goes and vice versa.

 

 

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Mitthrawnuruodo
7 hours ago, Cass said:

How come the choice of span loading here? Wing loading tends to be more relevant to sustained turn performance and in this configuration it's significantly lower on the 51.

 

Induced drag depends on span loading, giving most of the thrust/power required in a best rate sustained turn using the basic lift/drag model.

 

Di = q S CDi = q S CL^2 / (pi AR e) = q S [n W / (q S)]^2 / (pi e b^2 / S) = n^2  / (pi e q) (W / b)^2

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Panthera
14 minutes ago, ZachariasX said:

The K4 in this sim is an extremely good dogfighter, but it is much harder to make most out of it than with the P-51, and that is why you usually win a fight a close in fight against a K4 in this sim. At least I feel like that. In "the other sim", it is very easy to control the K4 to the edge of the enveloppe. Hence, you can readily mop the floor with it.

 

I must say it doesn't take much skill to hold a level sustained load factor (you can even turn on automatic rudder if you're having issues holding the ball in the middle), and here the P-51 curiously comes off noticably better in IL2, which isn't realistic. In DCS it's the opposite way round, the K4 can sustain a significantly higher load factor than the P-51 here, as the aerodynamic specifications also suggest it should. 

 

IMO there can be little doubt which sim got it right in this case.

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ZachariasX
17 minutes ago, Panthera said:

I must say it doesn't take much skill to hold a level sustained load factor (you can even turn on automatic rudder if you're having issues holding the ball in the middle), and here the P-51 curiously comes off noticably better in IL2, which isn't realistic. In DCS it's the opposite way round, the K4 can sustain a significantly higher load factor than the P-51 here, as the aerodynamic specifications also suggest it should. 

 

IMO there can be little doubt which sim got it right in this case.

 

Looking at the spec tables, it lists the 109K4 with 24 sec for a full turn (3361 kg) and the Mustang 20 sec, the Mustang (4578.6 kg). The hardest data i have on this is Hotzauges simulation, and there the K4 beats the Mustang. So I wouldn't mind if the K4 would turn a bit better. The F4 is specified with 20.3 s after all.

 

But I do contest your statment that a rate fight is a trivial thing to do.

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Panthera
29 minutes ago, ZachariasX said:

 

Looking at the spec tables, it lists the 109K4 with 24 sec for a full turn (3361 kg) and the Mustang 20 sec, the Mustang (4578.6 kg). The hardest data i have on this is Hotzauges simulation, and there the K4 beats the Mustang. So I wouldn't mind if the K4 would turn a bit better. The F4 is specified with 20.3 s after all.

 

Well the K4 in IL2 would need quite an increase it would seem, as it is beaten by the P-51 even at 67" Hg (added the G14 as well, which also oddly gained nothing despite being 150 kg lighter than the K4 with the same power):

 

IL2 @ 370 km/h sea level:

P-51D, 400 L, 67" Hg: 3.4 G's sustained

109K-4, 400 L, 1.8ata: 3.3 G's sustained

109G14, 400 L, 1.8ata: 3.3 G's sustained

 

DCS for comparison:

 

DCS @ 370 km/h sea level:

P-51D, 400 L, 67" Hg: 3.0-3.1 G's sustained 

109K-4, 400 L, 1.8ata: 3.6-3.7 G's sustained

 

 

In short the K4 is performing much worse in IL2 than it does in DCS, whilst the P-51 is performing noticably better in IL2 than it does in DCS. 

 

That the P-51 in IL2 is not only able to match, but actually surpass the K4 in sustainable load factor at 67" Hg, suggests something is seriously amiss simulating these two in IL2. 

 

Based on span loading squared alone the P-51 would need ~29% more power to just match the K4 in sustainable load factor, where'as in reality it actually has less power, noticably less at 67" Hg. In DCS this is properly reflected, in IL2 it's mysteriously opposite.

Edited by Panthera
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=621=Samikatz

I don't think it's wise to use other sims as a benchmark, especially when that other sim is far from immune from getting aircraft performance completely wrong in the past.

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Panthera
2 hours ago, ZachariasX said:

I'm not sure the spec sheet is always up to date.

 

Those figures are not from the spec sheet though, they are tested values.

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Panthera
15 hours ago, =621=Samikatz said:

I don't think it's wise to use other sims as a benchmark, especially when that other sim is far from immune from getting aircraft performance completely wrong in the past.

 

Haven't had DCS for that long, but I've litterally only had positive experiences with their FM's so far (Got all the warbirds now, and a few fast movers). They probably also work off a bigger budget, considering the fidelity of their modules.

 

That said I'm not just simply comparing the two sims and then going "that ones better" with nothing to back up the statement, I consider the DCS FM more realistic based on both pilot testimony and most importantly the actual physical specifications of the real aircraft. 

 

That said, I didn't really start getting this impression until the release of the later war aircraft in IL2, and actually felt the FMs to be quite believable in the BoM days. So to me it feels like either something went wrong along the way, or it was always wrong and I just didn't notice it as the BoM aircraft seemed to perform comparatively as expected.

Edited by Panthera
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Aurora_Stealth

Just to say - I still haven't heard a sound argument [from a technical perspective] why a P-51 would be able to outmaneuver a G-14 or K-4 in terms of turning performance below 300mph (co-energy) when its been demonstrated in almost every metric (with the exception of drag) that its turning performance would have been inferior.

 

Apart from satisfying the US inclined user base (which I can understand from a business perspective), this viewpoint seems to originate from survivor-ship bias. Usually when I hear an argument about the P-51 turning well, it derives from quotes from Bud Anderson (note: with his 850 pre-combat flight hours, versus the 1/8 average of the Jagdwaffe of 1944).

 

Regarding the K-4 there's little adequate explanation for this whatsoever (weight, lift, thrust, wing profile - even when the '51 is at lower fuel levels) and even the models that Holtzauge presented indicated that most of the advantage is at higher mach no's.

 

I do however appreciate and did notice many months ago that tweaks were made so that judging the P-51's stall from sounds including the gunports was made more vague and in real life you obviously cannot judge an impending stall in such a way; which is a lot more realistic. I appreciate that and want to say thanks for adjusting that.

 

I'd like to leave you all with the following quote from the U.S. Air Forces, Flight Test Engineering, which assessed the Mustang B on 24 April 1944:

 

"The airplane is very maneuverable with good controllability at indicated speeds up to 400 MPH. The stability about all axes is good and the rate of roll is excellent; however, the radius of turn is fairly large for a fighter."

 

This is the same USAF / USAAF that employed the P-47 and P-38 as their typical ETO fighters through 1943. I would interpret that statement in the same way I would interpret the Fw 190 being maneuverable - its good in everything other than turning circle.

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LukeFF
10 hours ago, Aurora_Stealth said:

Apart from satisfying the US inclined user base (which I can understand from a business perspective)

 

Well, as has already been said, making statements like that is going to get you nowhere good, which leads us to...

 

10 hours ago, Aurora_Stealth said:

I'd like to leave you all with the following quote from the U.S. Air Forces, Flight Test Engineering, which assessed the Mustang B on 24 April 1944:

 

"The airplane is very maneuverable with good controllability at indicated speeds up to 400 MPH. The stability about all axes is good and the rate of roll is excellent; however, the radius of turn is fairly large for a fighter."

 

That statement really means nothing without context and is akin to pilots saying their plane "flew like a bat out of hell." Proper context here is going to mean of course things like fuel loading, ammo weight, ability of the pilot, condition of the plane, altitudes and temperatures on the day the tests were performed, etc. "It's turn radius is fairly large" doesn't really tell us much, especially when the former sentence tells us that it has good maneuverability.

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6./ZG26_Klaus_Mann
15 hours ago, LukeFF said:

Snip

Ask 2 Pilots on the same Day for their Opinions and you wouldn't be able to tell that they were flying one and the same Plane.

To one Pilot "Going like a Bat out of Hell" means good low Speed Acceleration, steep Climb and short Take-Off Runs (I-16), to the other it means being able to achieve high Speeds in shallow Dive Angles with little Trim Change, light and precise Controls at High Speeds.

 

Good "Manouverability" is also a weird Term, because many things go into it and each Pilots values different things differently.

 

Even "Stable" is a term open to interpretation and can mean opposite things. For one Pilot it means that you can aim effectively using Rudder, without having to correct a lot with aileron and elevator. To the other it means the Aircraft is Rock steady on the Yaw Axis and can aim with Ailerons easily.

It can mean that the Aircraft doesn't have aggressive Stall Characteristics, to another it means that it will hold Speed set by Trim very precisely without oscillation.

 

Radius of Turn can also be interpreted to mean different things. There is a natural Speed Range Airframes want to achieve, a P-40 is naturally about 100km/h slower than a Mustang and when doing a 180° turn out of Cruise will achieve a very small radius even without forcing it.

A Mustang will, at the same G-Load take much longer to achieve a 180° turn, as it is naturally faster. So even if the Mustang had the same Turning Radius as the P-40 (which it doesn't) a Pilot would still feel that the Mustang wasn't as good of a turner.

 

I could go on for days, but the gist of it is, judge a Plane by the Numbers, Pilots are unreliable sources.

Edited by 6./ZG26_Klaus_Mann
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Panthera

Yes, pilot opinion is a tricky one, esp. if it comes from a source without lots of experience flying either of the aircraft compared. Hence why I tend to trust more in the assessments by modern pilots, as they're much better trained and also taught most of the aerodynamic principles at work. WW2 pilots by comparison had very little flight training and education in aerodynamic principles. 

 

That said, as you correctly point out the numbers/physical properties of the aircraft are the most important, as they give us an unbiased view as to how the aircraft should compare. 

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gimpy117

I also wanna throw out, are we also taking extra wing slat drag into account? there's no such thing as free lift... 

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