How superior climb rate is used in air combat ?.

[Steamed_Banana]

The film was original negative B/W and was on reels for wartime recce training. I doubt that it was ever released for general viewing and I was not in a position to do that.

I certainly never suggested that you were. I'm just noting if they are sitting on all this film they are perhaps missing an opportunity. Just establishing an idea, not assigning blame, let along putting it on you.

The point is that it was possible for combat trials aircraft to film engagements in an accurate way that could have better defined the combat abilities of different aircraft. I would still say that much of the British trials performance data is of mixed value. OTOH, some original manufacturers' aircraft performance data is quite detailed but it is not always the performance used in combat, before the BoB there was little or no mention of the serious Merlin negative-G cut problem, despite all the performance trials.

Every nation and armed services branch had their blind spots, pretty clearly. Progress in the war was largely a matter of the painful process of figuring these out and gradually fixing them, often after a very frustratingly long time (and after the loss of many lives). Look at the US torpedo problems, the issues with the early and mid-war P-38s, etc.

But this is the data we have. On the upside, new data does seem to keep emerging. For example based on what you said there are probably hundreds or thousands of gun camera clips that someone may finally put online. As flawed as this type of footage is, after analysis in aggregate it could be very helpful in understanding air combat.

Furthermore, the format and scope of British tactical trials with enemy aircraft was very variable. Precise definitions or the quantifying of combat performance were often loose, how about this British tactical trials quote, "if the "X aircraft" flicked over into a diving turn in the opposite direction the "Y aircraft" had great difficulty in following this manoeuvre". Did it manage to follow , why was it difficult, what was the implication in combat? Who can tell? From my POV, following any other aircraft in combat is difficult! The point of tactical trials briefs is to quantify the difficulties and promote the understanding.

Totally agree, again the same problem is notable with the US tests especially of the A6M. Wrong fuel, poor maintenance, aircraft running rough (not just the captured one either). As more wartime tests keep emerging sometimes the picture becomes clearer over time.

I don't see the point of fretting about flaws in testing standards and so on in historical documents from 80 years ago. Historical analysis is based on learning what we can from what we get. Testing standards could certainly have been better, I'm also not sure that any level of testing will necessarily conclusively measure merits of one plane vs another in an absolute sense.

What was unsaid in this quote is that aircraft Y could not use aileron rolls to shake aircraft X off his tail!

Eng

It seems pretty clear that this was in fact done. Certainly Fw 190 pilots did it to early Spit Vs among many others. It appears to have been a tactic used by the Kittyhawk pilot in that Australian test between Kittyhawk and Spit V as well. And it's described by many pilots on both sides in personal anecdotes.

None of which necessarily proves anything. It just helps us form (hopefully provisional) theories in one direction or another. That's really all you can do with history, it's a journey with no end-point.

 

[Steamed_Banana]

A minor point: When roll rates are discussed, remember that roll rate is basically not affected by moment of inertia, i.e. if there are guns and ammunition in the wings or not.

The aircraft will still reach basically the same roll rate in the end but it will take longer to get there. This point is often missed in these discussions. And it's important to remember that the end roll rate attained is basically only determined by aerodynamic factors, not by moment of inertia.

However, what is affected is the roll acceleration. This is why for example the P-38 with boosted ailerons may have a very good roll rate at higher speeds. However, the roll acceleration will always suffer due to the horrendous moment of inertia the engines out on the wings cause.

And of course roll rate is important: But what really counts is how fast you can attain a certain bank angle: As an example, a P-38 chasing a Bf 109 jinxing left and right by rolling, will always have a harder time due to roll acceleration than a single engined fighter which as the same roll rate performance.

yes all true though some of the roll rate tests measure roll achieved in a certain amount of time (as well as at a certain stick force etc.) I think the ultimate roll rate does in fact matter because it doesn't take that long to reach maximum roll rates (even in the P-38)

 

[Holtzauge]

Roll varied not just by stick force and speed, but also by altitude. Some aircraft like the P-47 seem to have rolled better at higher altitude. I don't know the full breakdown of this for aircraft in general, maybe someone who knows the physics / aerodynamics / engineering very well (I know y'all are in here) can chime in.

This effect is not limited to the P-47. All aircraft roll better at higher altitudes:

If one considers that the end roll rate will be achieved when the rolling moment of the ailerons is balanced by the counter moment of the roll caused by the induced angle of attack on the wings, one can intuitively understand that for a certain roll rate, the induced angle of attack will be less the higher you go because you need to go faster to attain a certain force, and hence a smaller induced angle of attack.

So in practice, this means that you will be able to roll a bit faster before you attain the induced angle of attack you had as a limit at SL. So say that you at SL can manage 90 deg/s at a certain IAS, you will at 20,000 ft roll 37% faster, i.e. 123 deg/s at the same IAS. (The 37% figure comes from a 1945 article in the RAE Journal by British aerodynamicist M B Morgan).

The same article goes on to say that at 40,000 ft, you will have double your SL turn rate!

 

[GregP]

Perhaps a better roll rate. Definitely NOT a better turn rate.

A WWII fighter that can pull 8 g at 10,000 feet is lucky to be able to pull 3.5 - 4 g at 25,000 feet. Many can pull only 3 - 3.3 g or so, if that when there or higher. Most cannot sustain much turn rate at high altitudes without stalling since the stall speed goes up with desceasing air density as altitude goes up, but the weight doesn't change except for fuel burned and ammunition expended. Since WWII fighters don't have large excess power (relative to modern jets, anyway), they can't add enough power to maintain speed while also maintaing altitude when nearing a stall up high.

Dogfights at 30,000 feet are large, lazy-looking. slow-turning affairs, that always move downward, especially when the pilot needs to maneuver hard and doesn't have the power To do it, he lowers the nose to add the power of gravity and pulls until he feels a stall nibble. When you approach the ground and can't afford to lose more altitude, then the actual maximum turn performance comes more into play since turning hard and losing attitude at 50 feet usually means hitting the ground. Most pilots choose not to do that.

 

[Steamed_Banana]

Thanks for the explanation. But anecdotally, some aircraft with small wings seem to have performed / handled fairly poorly at high altitude and had a sluggish response, P-39s and I-16s come to mind for example. Does this make sense in terms of aerodynamics etc.?

 

[Steamed_Banana]

Perhaps a better roll rate. Definitely NOT a better turn rate.

A WWII fighter that can pull 8 g at 10,000 feet is lucky to be able to pull 3.5 - 4 g at 25,000 feet. Many can pull only 3 - 3.3 g or so, if that when there or higher. Most cannot sustain much turn rate at high altitudes without stalling since the stall speed goes up with desceasing air density as altitude goes up, but the weight doesn't change except for fuel burned and ammunition expended. Since WWII fighters don't have large excess power (relative to modern jets, anyway), they can't add enough power to maintain speed while also maintaing altitude when nearing a stall up high.

Dogfights at 30,000 feet are large, lazy-looking. slow-turning affairs, that always move downward, especially when the pilot needs to maneuver hard and doesn't have the power To do it, he lowers the nose to add the power of gravity and pulls until he feels a stall nibble. When you approach the ground and can't afford to lose more altitude, then the actual maximum turn performance comes more into play since turning hard and losing attitude at 50 feet usually means hitting the ground. Most pilots choose not to do that.

This would help explain why P-47s apparently had comparatively good agility at altitude, due to power from the turbo... ?

 

[Holtzauge]

yes all true though some of the roll rate tests measure roll achieved in a certain amount of time (as well as at a certain stick force etc.) I think the ultimate roll rate does in fact matter because it doesn't take that long to reach maximum roll rates (even in the P-38)

Well before you said "Weight in the wings could affect roll rate" so good to know we are now on the same page. And I never said the end roll rate does not matter. I merely tried to nuance a discussion which was only talking about roll rates and comparing charts of aircraft's ultimate roll rates.

And I think you are missing an important point about the P-38: When you have attained that maximum roll rate, matching that of say a Fw 190, when the 190 decides to roll in the opposite direction, the P-38 has to stop its roll, and now accelerate in the opposite direction. This is much harder to do in a twin which as two huge engines out on the wings compared to a single engined fighter. This is simple physics.

 

[Holtzauge]

Thanks for the explanation. But anecdotally, some aircraft with small wings seem to have performed / handled fairly poorly at high altitude and had a sluggish response, P-39s and I-16s come to mind for example. Does this make sense in terms of aerodynamics etc.?

The example I gave for improvement in roll over altitude is valid for a certain aircraft type, and says that the roll rate at a certain IAS will improve as the altitude goes up. Certainly, if you have a smaller wing (e.g. Bf 109 versus Spitfire) you will start to feel the effects at higher altitudes, but IAS is the determinator, and the altitude as such is not the problem, but that you seldom have the power to be able to keep your IAS up at higher altitudes and hence the sluggishness.

 

[Steamed_Banana]

Well before you said "Weight in the wings could affect roll rate" so good to know we are now on the same page. And I never said the end roll rate does not matter. I merely tried to nuance a discussion which was only talking about roll rates and comparing charts of aircraft's ultimate roll rates.

No, I totally agree, I think I'm thinking in terms of an 'effective roll rate' that you can achieve in combat, i.e. in a very limited amount of time. What is your 1/2 second or 2 seconds or 3 second roll rate might be a very interesting metric.

And I think you are missing an important point about the P-38: When you have attained that maximum roll rate, matching that of say a Fw 190, when the 190 decides to roll in the opposite direction, the P-38 has to stop its roll, and now accelerate in the opposite direction. This is much harder to do in a twin which as two huge engines out on the wings compared to a single engined fighter. This is simple physics.

No, I do get that as well. I think a P-38 trying to out roll a Fw 190 is going to get in serious trouble. Outrolling a Bf 109 in a dive might work however, and outrolling an A6M, especially an A6M2 (and though these were the early types, they were still fighting well into 1944). In both cases their roll rate and roll acceleration are poor at higher speeds, especially going against the engine torque, so a P-38 with the boosted ailerons might still be competitive.

 

[Holtzauge]

No, I do get that as well. I think a P-38 trying to out roll a Fw 190 is going to get in serious trouble. Outrolling a Bf 109 in a dive might work however, and outrolling an A6M, especially an A6M2 (and though these were the early types, they were still fighting well into 1944). In both cases their roll rate and roll acceleration are poor at higher speeds, especially going against the engine torque, so a P-38 with the boosted ailerons might still be competitive.

Sure: At really high speeds like in power dives, I'm sure the P-38 could very well keep up with a Bf 109 in roll. Probably even if the Bf 109 tries to jinx left and right by rolling because at really high speeds, the roll rates for aircraft with conventional ailerons was very poor and a P-38 with boosted ailerons probably had a huge advantage here.

 

[GregP]

Thanks for the explanation. But anecdotally, some aircraft with small wings seem to have performed / handled fairly poorly at high altitude and had a sluggish response, P-39s and I-16s come to mind for example. Does this make sense in terms of aerodynamics etc.?

Yes. Turn perfomance at altitude can be tied to span loading (lbs of aircraft per foot of span, or kg per meter). Not entirely, but directly related. Lower span loading turns better, sometimes by far, at higher altitudes, everything else being equal.

If a U-2 had more structural limit strength, it could easily out-turn almost anything at 50,000 feet. But, the U-2 is not very structurall strong since the span is ridiculously large. Basically, it is an F-104 with sailplane wings. But they aren't stressed for fighter maneuvering.

In WWII., one of the best at high altitude has to have been the long-wing Ta-152H, though it never got a chance to SHOW that since it came into service late in the fray, and really started to turn into a service aircraft in April 1945, right about the same time the Luftwaffe collapsed as a viable fighting force.

 

[Steamed_Banana]

Sure: At really high speeds like in power dives, I'm sure the P-38 could very well keep up with a Bf 109 in roll. Probably even if the Bf 109 tries to jinx left and right by rolling because at really high speeds, the roll rates for aircraft with conventional ailerons was very poor and a P-38 with boosted ailerons probably had a huge advantage here.

Of course, only later model P-38s with the lift device could even dive at high speed. Fw 190 i believe had boosted ailerons too. P-40s could still roll at very high speed but had to use rudder trim tabs (or have the leg of a brontosaurus) which put a mental load on the pilot... needless to say pulling out of a dive you have to quickly reverse that trim setting. Apparently the longer tail helped with overall stability and handling and was mentioned in this context.

 

[Engineman]

Fw 190 i believe had boosted ailerons too.

Can you explain, please?

Eng

 

[Steamed_Banana]

Can you explain, please?

Eng

I double checked, I was wrong, only some late D model version had boosted ailerons.

 

[bada]

Of course, only later model P-38s with the lift device could even dive at high speed. Fw 190 i believe had boosted ailerons too. P-40s could still roll at very high speed but had to use rudder trim tabs (or have the leg of a brontosaurus) which put a mental load on the pilot... needless to say pulling out of a dive you have to quickly reverse that trim setting. Apparently the longer tail helped with overall stability and handling and was mentioned in this context.

To my knowledge, the p-38 was never to exceed 0.68M, lift device, airbrakes or whatever plasma shield. This allowed the P-38 to not desintegrate in the dive, but the plane was aerodynamically unable to go faster without serious consequences. The Shrike was tested till 0.79M without any structural issue, if the pilot was slightly more kamikaze, it could push it even further, as at M0.79, only 27kg was needed to recover. (without using the horizontal tail trim). But Test pilots are not kamikaze.

But, about the spit roll rate, am i the only one that interpret this report on the clipped spit as a direct questioning about the quality of production?
Better Roll rate seems more like a lotery, depending on the airframe "build-qualities".

The results being absolutely not reproductible,
On both the Mk5 and 9, clipping the wings didn't change the aileron responsiveness, the Mk5 having good ailerons and the Mk9 having "bad ailerons" at start.
But on the MK12 (note that both mk12 airframes tested were originally Mk5 airframes and were the first two MK12 from the factory) the one airframe with originally poor ailerons got an amelioration in roll, but the other with "good" ailerons no difference was found.

In conclusion, can we apply here the fact that cutting the wingtips doesn't per se make the spit a rolling beast?
What means no generalisation of the roll performance found in the different charts can be applied to all concerned spits and that manufacturing quality was not , well, very qualitative?
Can we push further and say that pilots never complained to the grease monkeys about the sloppy ailerons (2 of4 airfranes in the test had poor ailerons before testing) and ask them why and demand to correct it? if i'm a pilot that knew an airframe with good ailerons, and got one sloppy, wouldn't i request to check the issue? or is it just because most spits had sloppy ailerons and actually no pilot ever got one with good ailerons?
I can not imagine a Wurger pilot going on mission with unbalanced ailerons , giving flutter and serious vibrations in turn and maneuvering.

The conclusion by the raf reminds me of the Meteor III Evaluation: "hmmm, ok, but actually it's not, there is much room for improvement."

PS: Just like Clostermann, Bogdan Arct from the Sq306-303-145PFT had nothing good to say about the clipped Mk5 they used for a few weeks in the MTO, and not only because is was a Cropped, but mostly because it was Clipped.

 

[PAT303]

Oh yeah, this keeps coming up.

There is an ongoing debate as to what caused the vast improvement in roll-rate, either the clipped wings or the metal ailerons, or some combination of both. There seems to have been considerable range of quality in the Spit Vs that were being produced by various factories, and specifically with the fabric covered ailerons, some appearing to be very 'loose' and some 'tight', and possibly some rigged differently. The memo you are referring to notes that one of the aircraft (N.221) had 'bad' ailerons, which clearly affected the test:

View attachment 884399

and nevertheless the pilot seemed to note that clipping the wings did improve roll rate on the second aircraft.

I don't know if the difference was the 'clipped' wings or the ailerons or both, (which is why I wrote "Clipped wing and / or metal aileron" in the post you replied to) but something clearly improved later production Spit Vs and subsequent Merlin marks, which did get the metal ailerons, and it's notable that clipping the wings became common practice at least from what I understand.

View attachment 884400

The famous NACA 868 chart shows two different roll rates for the Spitfire as you can see, both peaking at about 200 mph and falling off fairly sharply after that, but early Spit V (indicated as 'normal wing' on the chart, correctly or otherwise) peaked at about 105 degrees per second (quite good), fell to about 85 by 280 mph (average), and dropped to 45 by 380 mph (poor), indicating a relatively low roll rate in a dive. The later Spitfire (indicated as 'clipped wing' on the chart, probably later Mk V with clipped wings and metal ailerons) peaks at a superb 150 degrees per second, drops to a still superb 130 at 280 mph, and is still a respectable 85 at 380 mph. That's a huge difference.


It's notable that aside from the rather epic roll rate of the Fw 190, the next best are the P-40F and the P-51B. Other tests of P-40s show higher roll rate than indicated here, while early P-51 (P-51A, NA 73 etc.) had a quite sluggish roll rate. The difference for the P-51 seems to be related to how the ailerons were rigged and mounted. Spitfire roll rates improved dramatically between 1940-43, and P-40 roll rates also seem to have improved in most tests. Later model P-40s had lengthened tails which improved handling, I don't know if any changes were made to ailerons or aileron rigging.

View attachment 884402

In this early (1941 I believe) test, P-36 peaks at 90 degrees roll at about 180 mph, (probably early Hawk 81 / Tomahawk type) P-40 peaks at 110 at 290 mph, while (probably Mk I) Hurricane and (early Mk I or II) Spitfire peak similarly at around 60 degrees.

View attachment 884401

On this 1944 test for example, (late model) Spit V peaks at 150 degrees per second at 200 mph, drops to 115 at 300 mph, and hits 70 at 400 mph, while the (late model) P-40 peaks at 135 degrees per second at 360 mph, then drops rapidly to 80 by 450 mph (which is close to it's dive speed limit). The P-51B peaks at 95 degrees per second at 300 mph and drops off more slowly. Fw 190 peaks at 160 degrees per second at 260 mph, drops to a still quite brisk 105 degrees at 350 mph, and drops to 65 at 450.

Worth pointing out that in this test that the (certainly clipped and / or metal aileron) Spit V can out roll the Fw 190 at low speed, while only the P-40 can out-roll it above ~320 mph, i.e. in a dive of any significance, something which was noted by some USAAF P-40 pilots flying over Sardinia, Sicily, and Italy in 1943-44.

And just to add more confusion into the argument it was the reprofiling of the ailerons that made the single biggest difference to the Spitfires handling, they also changed to piano hinges for the moving surfaces with winkle Brown doing a lot of flight testing with different bob weights after a few Mk V's lost their tails, you could almost say there isn't a ''normal'' Spitfire considering the constant development happening the them.

 

[PAT303]

View attachment 884403

A couple of other points on roll rate:

• Roll varied not just by stick force and speed, but also by altitude. Some aircraft like the P-47 seem to have rolled better at higher altitude. I don't know the full breakdown of this for aircraft in general, maybe someone who knows the physics / aerodynamics / engineering very well (I know y'all are in here) can chime in.
• Weight in the wings could affect roll rate, which is one of the reasons why Soviet designed fighters rarely had wing guns.
• The Soviets often (not always) removed one or more pairs of wing guns from many Lend Lease aircraft including Hawker Hurricane, Spitfire, P-39, and P-40s. Many Tomahawk type P-40s had all wing guns removed, leaving only the two 12.7mm machine guns in the nose.
• Italian units often removed the 7.7mm wing guns from MC. 202 fighters, leaving only the two 12.7mm machine guns in the nose. In part this was to improve roll rate.
• Some RAF and USAAF units fighting in the early days in the Pacific War (Burma / Malaya / Java / Philippines) removed some wing guns from their Buffalo, Hurricane, and P-40 fighters.
• USAAF units in North Africa so routinely removed a pair of wing guns from their P-40Fs that the next model, P-40L, came with four guns instead of six (though two more could easily be put back in by field mechanics, and they often did when doing mostly strafing / fighter bomber missions). The early P-40N also had four guns.
• The (four gun) P-51B/C apparently had a bit better roll rate than the (six gun) P-51D.
• The two-cannon Fw 190A-5, which had the outer pair of wing cannon removed to help carry the weight of bombs, apparently had a better roll rate than the (four cannon) A4 and A8 etc. variants. Though the A-5 was designed as a fighter-bomber type some very high scoring pilots (Otto Kittel - 267 victories, Josef Wurmheller -102 victories, notably in the West, Hermann Graf 212 victories) preferred the A-5 due to in part to slightly better handling and roll rate.
• Apparently one whole gruppe, JG 54, stuck with Fw 190 A-5 when the A-8 came out because they preferred the agility of the A-5.
• The HF (high altitude) Spitfire variants with extended wingtips apparently had significantly inferior roll rate, to the point that they were often disliked by pilots (though this wasn't the only reason)
• The Japanese clipped the wings of the A6M "Zero" fighter, which went from 39' 4" / 12m in the A6M2, to a 36' 1" / 11m on the A6M3 and A6M5. This was in part to improve rate of roll, as well as to improve acceleration and dive speed.
• Generally speaking, later war fighters tended to improve in rate of roll, while remaining the same or sometimes declining in rate of turn.

Winkle Brown mentioned the 109's roll rate as effected by stick restrictions, when pulling max turns the stick was hard into his thighs limiting movement which is probably why Mitchell made the Spits control stick hinged.

 

[Steamed_Banana]

To my knowledge, the p-38 was never to exceed 0.68M, lift device, airbrakes or whatever plasma shield. This allowed the P-38 to not desintegrate in the dive, but the plane was aerodynamically unable to go faster without serious consequences. The Shrike was tested till 0.79M without any structural issue, if the pilot was slightly more kamikaze, it could push it even further, as at M0.79, only 27kg was needed to recover. (without using the horizontal tail trim). But Test pilots are not kamikaze.

But, about the spit roll rate, am i the only one that interpret this report on the clipped spit as a direct questioning about the quality of production?
Better Roll rate seems more like a lotery, depending on the airframe "build-qualities".
View attachment 884491

The results being absolutely not reproductible,
On both the Mk5 and 9, clipping the wings didn't change the aileron responsiveness, the Mk5 having good ailerons and the Mk9 having "bad ailerons" at start.
But on the MK12 (note that both mk12 airframes tested were originally Mk5 airframes and were the first two MK12 from the factory) the one airframe with originally poor ailerons got an amelioration in roll, but the other with "good" ailerons no difference was found.

View attachment 884492

In conclusion, can we apply here the fact that cutting the wingtips doesn't per se make the spit a rolling beast?
What means no generalisation of the roll performance found in the different charts can be applied to all concerned spits and that manufacturing quality was not , well, very qualitative?
Can we push further and say that pilots never complained to the grease monkeys about the sloppy ailerons (2 of4 airfranes in the test had poor ailerons before testing) and ask them why and demand to correct it? if i'm a pilot that knew an airframe with good ailerons, and got one sloppy, wouldn't i request to check the issue? or is it just because most spits had sloppy ailerons and actually no pilot ever got one with good ailerons?
I can not imagine a Wurger pilot going on mission with unbalanced ailerons , giving flutter and serious vibrations in turn and maneuvering.

The conclusion by the raf reminds me of the Meteor III Evaluation: "hmmm, ok, but actually it's not, there is much room for improvement."
View attachment 884493

PS: Just like Clostermann, Bogdan Arct from the Sq306-303-145PFT had nothing good to say about the clipped Mk5 they used for a few weeks in the MTO, and not only because is was a Cropped, but mostly because it was Clipped.

There was a lot of variability in build quality of WW2 fighters in general. Spitfires were built in several different factories and over a long period of time with many changes made. There certainly are a lot of anomalies like this that show up with US aircraft in US testing. Do you think a 'Wurger' pilot never faced any quality control issues for some specific reason? I don't know about quality control of German aircraft during the war, but I know they definitely had a lot of trouble with their tanks breaking down (and spontaneously catching fire) right and left. It didn't help to be using slave labor, which can have some curious side effects.

 

[Holtzauge]

To my knowledge, the p-38 was never to exceed 0.68M, lift device, airbrakes or whatever plasma shield. This allowed the P-38 to not desintegrate in the dive, but the plane was aerodynamically unable to go faster without serious consequences. The Shrike was tested till 0.79M without any structural issue, if the pilot was slightly more kamikaze, it could push it even further, as at M0.79, only 27kg was needed to recover. (without using the horizontal tail trim). But Test pilots are not kamikaze.

But, about the spit roll rate, am i the only one that interpret this report on the clipped spit as a direct questioning about the quality of production?
Better Roll rate seems more like a lotery, depending on the airframe "build-qualities".
View attachment 884491

The results being absolutely not reproductible,
On both the Mk5 and 9, clipping the wings didn't change the aileron responsiveness, the Mk5 having good ailerons and the Mk9 having "bad ailerons" at start.
But on the MK12 (note that both mk12 airframes tested were originally Mk5 airframes and were the first two MK12 from the factory) the one airframe with originally poor ailerons got an amelioration in roll, but the other with "good" ailerons no difference was found.

View attachment 884492

In conclusion, can we apply here the fact that cutting the wingtips doesn't per se make the spit a rolling beast?
What means no generalisation of the roll performance found in the different charts can be applied to all concerned spits and that manufacturing quality was not , well, very qualitative?
Can we push further and say that pilots never complained to the grease monkeys about the sloppy ailerons (2 of4 airfranes in the test had poor ailerons before testing) and ask them why and demand to correct it? if i'm a pilot that knew an airframe with good ailerons, and got one sloppy, wouldn't i request to check the issue? or is it just because most spits had sloppy ailerons and actually no pilot ever got one with good ailerons?
I can not imagine a Wurger pilot going on mission with unbalanced ailerons , giving flutter and serious vibrations in turn and maneuvering.

The conclusion by the raf reminds me of the Meteor III Evaluation: "hmmm, ok, but actually it's not, there is much room for improvement."
View attachment 884493

PS: Just like Clostermann, Bogdan Arct from the Sq306-303-145PFT had nothing good to say about the clipped Mk5 they used for a few weeks in the MTO, and not only because is was a Cropped, but mostly because it was Clipped.

Very interesting snippets of info here. Thanks for posting.

Manually controlled aircraft are very much individuals. And while WW2 fighters are not gliders, I'm old enough to have flown gliders with wooden wings and fabric covered ailerons. We had three different Bergfalke IIIs we used for training, and they were all very much individuals when it came to stick forces: You could not see any differences between them really, but they all had very different control characteristics in roll, with some being lighter than others. So I'm not surprised that different Spitfires individuals of the same version were either "good" or "bad" in roll.

The British test pilot Jeffrey Quill mentions in his book "Spitfire: A test pilot's story" that all Spitfires before delivery were tested and evaluated when it came to control and trim in roll, and that this often on the fabric covered versions involved doping small strips of string to the trailing edge of the ailerons to balance them. So you did a test flight, landed, and told the ground crew to dope on a strip and tested again, and repeated until the aircraft was deemed OK. For the most part this could be tuned, but some ailerons would simply not work with some wings and had to be exchanged. Interestingly though, Quill mentions that these "discarded" ailerons would even so work on another Spitfire! It was all a matter of finding the right combination. In addition, he says that Supermarine sometimes received reports of "rogue" aircraft from Squadrons, which in fact turned out to be caused by someone fitting on a new aileron on an airplane, and not understanding that this meant that it had to be "tuned" again.

According to Quill, very small differences in size and shape of the overhang, the shape of the trailing edge etc, could make huge differences. In addition, how the slot in the wing was shaped also mattered. So even if both wing and aileron were within production tolerances, it seems that it was not until you tried the two together that you knew if you had a happy marriage or not.

Quill goes on to say that metal skinned aileron were a huge improvement, but it still seems that aircraft were very much individuals. IIRC then I've read that this was also visible on Squadron/Geschwader level: Aces and higher ranks picked the best aircraft, while newcomers were left with the "lemons".

 

[Steamed_Banana]

One of the things I learned about the P-40 was that Curtiss had one test pilot who used to 'check out' new planes every day, I forgot his name but he has a wiki IIRC. And he would among other things put the plane into a 'Split S' and dive up to 500 mph TAS to verify that everything was working Ok (which is interesting because the manual indicated 460 and later 480 mph as max dive speed). Many times aircraft would be deemed unacceptable and sent back into the factory for modifications, sometimes due to problems with specific subsystems (engine, control systems, etc.) or with instruments, or with build quality issues.

It seems like build quality was iffy / highly variable at first, was tightened up significantly, and then got quite 'iffy' again around the time the P-40N came out, to the point that many squadrons reported basically doing substantial rebuilding and modifications to aircraft at field locations before they were deemed combat worthy. Curtiss was having various problems by then.