1990 tests; P-51/F6F/P-47/FG-1; all corner speeds close to max. level speed?

[Gaston]

    Robert Johnson DID use the term "mushing" in his interview, and he DID say "no mushing" after rolling in the opposite direction to his turn...  I don't think he even moved the nose up to get some "oblique turn" gravity help. I think the maneuver helped the weaker "high" wing get more bite in the turn transition... That's what it sounded like to me. Ask Widewing.

     Gaston.

    P.S. BTW, kind of interesting how the anecdotes are piling up on the side of those 1990 tests that the P-47D and FW-190A were better-turning than the lighter P-51Ds and Me-109Gs, isn't it?

     Oseau also had trouble believing it, and this explains the frustration of Ofw Leo Schuhmacher who said, in reference to a turnfight; "Several times I had said to Oseau that the FW-190 was better than the Me-109..."

     It is counter-intuitive, but it was generally true.

    The higher altitude fighting and the climb rate still made the 109 necessary, in any case, but by the end of 1944 it was only 30% of the Western Front fighter strenght.

     G.

     

     

[BnZs]

I have yet to come across any interview where he mentions mushing in relation to this move. I do know this maneuver was a form of lag roll. This is easier for me because I actually know what a "lag roll" is and its place in the ACM repetoir. Geometry is more the point here to avoid the overshoot and move to a position more to the rear quarter, "gravity assist" is incidental. "Higher wing getting more bite" is arrant nonsense. You don't get uneven AoA without rotation. This incident does not describe Johnson attempting to practice his spin recovery techniques during the middle combat. If he had executed a snap-roll, he would have said snap-roll.

   

    P.S. BTW, kind of interesting how the anecdotes are piling up on the side of those 1990 tests that the P-47D and FW-190A were better-turning than the lighter P-51Ds and Me-109Gs, isn't it?

Too bad every single actual flight-test, and the opinion of WWII pilots disagrees with that conclusion. The plural of anecdote is NO data.

In the case of 109G vs. Fw-190A, it is literally physically impossible for the 190A to have a tighter sustained radius of turn or better sustained radius of turn, unless perhaps the loading is very biased, a very late-war high-wingloaded 109G laden with gondolas against an early-model 190 with the outer MG/FFs removed. But even there it is unlikely.

 The things that would make it possible for a heavier wing-loaded plane to have a tighter sustained turn radius are: 1. A higher Clmax, either because of the airfoil itself or lift-increasing devices such as flaps superior to that of the 109G, which the 190A does not have or 2. A *much* superior power loading, which the 190A also does not have. A superior sustained *rate* for the heavier wing-loaded aircraft can be a product of a superior ratio of thrust/induced drag, which is also not the case for 190 vs. 109G. The physics here are not debatable.

Everything resembling a valid flight test that the rest of the world has heard of  agrees that the 190A's rate and radius of turn are poor. British tests of captured examples say this. German tests say this. It could not match a Corsair or Hellcat in tight maneuvers. The Russians, fighting against both, say the 190's maneuverability was considerably inferior to the 109s. The only way a 190 ever even achieved relative neutrality against a 109 was likely by being tested/flown by someone who believed the 109 slots opening=imminent stall and thus never achieved Clmax while turning the 109, which was often the case even with green Luftwaffe pilots, to say nothing of Allied testers.

Every flight test anyone *besides* you has ever heard of confirms that the 109s controls become heavy at speeds starting at around ~280mph IAS, while the 190s was good to at least 350. This, along with firepower, cockpit size and visibility, ease of take off/landing, and ease of management constitutes the primary reason the 190 was preferred by the Allies.

[Widewing]

Bob Johnson did comment on the P-47 mushing...

CCJ: What about a situation where you end up in rolling scissors with a Focke Wulf? Do you follow him by reversing the turn too?

RSJ: No. Whenever you get into a series of reverses, the airplane tends to mush-out a bit when you reverse your turn. The Jug tended to mush a bit more than the 190. The way to avoid this was roll into the reverse.

CCJ: I'm not sure I follow you.

RSJ: Picture this in you mind. The 190 rolls into a hard left. You follow, firing as he crosses your guns. Suddenly, he reverses his turn, hard right. Rather than reverse, you continue rolling left until you are in a right bank, just like the 190. Now, pull hard. No mushing. If he reverses again, you roll left and fire as he crosses your guns. If he doesn't reverse, I pull the nose high and roll out behind him.


My regards,

Widewing

[BnZs]

It sounds like "mushing" in this case refers to the effect of inertia in the roll. Which is a new use of the word on me, but not anything outside of the laws of aerodynamics.

Bob Johnson did comment on the P-47 mushing...

CCJ: What about a situation where you end up in rolling scissors with a Focke Wulf? Do you follow him by reversing the turn too?

RSJ: No. Whenever you get into a series of reverses, the airplane tends to mush-out a bit when you reverse your turn. The Jug tended to mush a bit more than the 190. The way to avoid this was roll into the reverse.

CCJ: I'm not sure I follow you.

RSJ: Picture this in you mind. The 190 rolls into a hard left. You follow, firing as he crosses your guns. Suddenly, he reverses his turn, hard right. Rather than reverse, you continue rolling left until you are in a right bank, just like the 190. Now, pull hard. No mushing. If he reverses again, you roll left and fire as he crosses your guns. If he doesn't reverse, I pull the nose high and roll out behind him.


My regards,

Widewing

[Gaston]

    Thanks for the quote, Widewing.

    It seems mushing in this case is due to the momentum of the turn being one way, reversing the turn aggravates this, and thus the pilot is well aware of it.

    R. Johnson-"Now pull hard. No mushing." That is clearly meant as ELEVATOR-related mushing, and that is exactly how I took it.

    The P-47, especially the razorback, was known for its crisp aileron reversal, which probably is why Johnson makes the strange statement that the P-47 "rolled as quickly" as the FW-190; the good reversal probably gave a better impression than the actual number performance.

    Now consider this logically; which has the greater mass and leverage, and is the more likely as such to cause some delay to an action; the front of a 30 foot fuselage loaded with a P&W 2800 engine, or the tip of a wingtip on the end of a 15 foot wing?

    In addition, there may be mushing the pilot is not aware of, if WW II footage is any guide; mushing the way I understand it does not necessarily imply a lack of immediate turning; Johnson clearly states the 190 does not mush as much in reversed turns as the P-47, however the FW-190's prolonged turn performance at high speed is poor, so that even if it pulls an impressive 4-5 Gs in the turn, if the theoretical "perfect" circle would have allowed 7 Gs, then there could still be two full G's lost to "mushing" in an "elongated" turn.

    It could also be that the response is immediately to a full 7G potential for the first 90°, then as the attitude of the aircraft reaches close to 90° to the original trajectory, the aircraft would then "sink" horizontally in the same direction as its starting trajectory, decelerating into a wider turn while still imposing on the pilot 7Gs for a short time. The pilot could very well not be aware of it.

    Given how not-so-crisp a lot of WW II footage elevator pitch responses look, I don't think it is outlandish to say "mushing" has some effect on turn performance...

    As for the 190 turn performance, I already posted in a previous thread a test that illustrates PERFECTLY the point that the 190A performs better in turns relative to the P-47D at lower speeds, and not at higher speeds. The same P-47D that out-turns the 109G according to the Germans themselves... (See "On Special Mission"; Kg 200)

    Gaston.

[BnZs]

    As for the 190 turn performance, I already posted in a previous thread a test that illustrates PERFECTLY the point that the 190A performs better in turns relative to the P-47D at lower speeds, and not at higher speeds. The same P-47D that out-turns the 109G according to the Germans themselves... (See "On Special Mission"; Kg 200)

    Gaston.

Johnson could roll his P-47 as quickly as the 190 pilots because a primary limitation on roll rate at speed in WWII airplanes with unboosted controls was how much the pilot could deflect his ailerons, and Johnson was quite the athlete. But that would not keep the 47 from having more inertia in a roll due to say 4 .50 cals and ammo in each wing, in an aircraft double the mass of the Fw-190. Whereas whether he is reversing his turn by rolling right/left or by continually rolling one direction, it is still a reversal  and wing lift must still be used to change the aircrafts flight path in the same way.

The 190A has a similar wing loading to the P-47 and a superior power loading at low altitudes. It is not at all like comparing it to the 109G, which is superior in every trait related to turning and which is acknowledged to be the better turner of the two. You continually fail to understand how a combat reports are not useful for giving us any concrete data about aircraft performance because of the unknowns. And this "2G's lost to mushing"...again BS. G forces are induced when lift being used to turn the aircraft. A 747 and an RC model, if they could be at the same speed, at the same bank angle, pulling the same Gs would be producing *the same rate and radius of turn* Once again this is not up for debate.

[hitech]

    It seems mushing in this case is due to the momentum of the turn being one way, reversing the turn aggravates this, and thus the pilot is well aware of it.

No he is referring to roll responsiveness I.E. rolling one way, then rolling the other, nothing about what your are referring to as mushing.
2nd even though he does not state it, this roll reversal sounds like it is well below corner speed. I.E. he is at the Top of the lag roll. Because at corner speed I would have a very hard time believing the Ailerons felt soft.

    Now consider this logically; which has the greater mass and leverage, and is the more likely as such to cause some delay to an action; the front of a 30 foot fuselage loaded with a P&W 2800 engine, or the tip of a wingtip on the end of a 15 foot wing?

Once again you are incorrect, the mass of a motor that is in the center of the airplane will have very little to do with the planes total rolling moment as compared to gas and other things mounted in the wings.

  It could also be that the response is immediately to a full 7G potential for the first 90°, then as the attitude of the aircraft reaches close to 90° to the original trajectory, the aircraft would then "sink" horizontally in the same direction as its starting trajectory, decelerating into a wider turn while still imposing on the pilot 7Gs for a short time. The pilot could very well not be aware of it.

Say WHAT?

If the pilot is maintaining 7 g's for the turning circle to become "wider" the plane would have to accelerate. (This is not debatable).


HiTech

[Gaston]

    Agreed on this last point; if the aircraft mushes at the mid-way point of a 7G 180° turn, the turn can no longer be 7 Gs; my mistake... The point I wanted to make was that if the mushing occurs, with the aircraft pointing at close to 90° to the starting trajectory, BEFORE the halfway-point of the semi-circle (implying pointing the nose INSIDE its turn "perfect" circle, while skidding past the "perfect" circle itself), then the mushing would feel like a near-vertical deceleration that would seem to the pilot like close to the same thing as "normal" turn-related Gs.

   But then you said that the degrees per second of pivoting made by a fighter's nose cannot be at a different rate than that implied by the turning circle itself...

   It was one of the characteristics of the Spitfire that it could do this, mushing with full 3-axis control and shooting "inside" its own turn.

   I don't see how it can be denied that the Spitfire flew like this...

   The "scientific" term might be an accelerated stall, but if full 3 axis control remains, I think calling this a stall is a factor of confusion rather than clarity...

    As for the Jonhson interview, look at the wording; "the airplane tends to mush-out a bit when you reverse your turn" He did NOT say:  " the airplane tends to mush-out a bit when you reverse your ROLL"

    Also; "Now, pull hard. No mushing."

    I will concede his words could be interpreted either way, but my impression is that he felt reversing the roll affected the turn response, and that by continuing the same roll he sensed that his turn response was more immediate.

    Also, if mushing in the roll response was what was in question, this mushing loss was unlikely to be as great as continuing through 270° to roll "the long way around". On the other hand, mushing in the turn response could well be worth rolling 270° to avoid.

    Even if it turns out the intended meaning was for roll only, it still remains that one of the tactical advantages of the Spitfire was to be able to shoot inside its own turn, and even the Mustang had to resort to it (with difficulty) because of its noticeably wider (if faster) turn...

    As for the relative turn rates, I think the real-life results are often counter-intuitive to calculated values, and the fact that the 1990 tests were done by real test pilots, and caused a surprise as to the expected outcome, means we should not dismiss them as unimportant. The fact that Warbirds were not their area of primary interest, since they in fact mostly tested other kinds of aircrafts, actually increases their credibility. Their comments about lower speed sustained turns do seem speculative... I plan to order the complete report eventually...

                       
   Gaston.

[Charge]

"then the mushing would feel like a near-vertical deceleration that would seem to the pilot like close to the same thing as "normal" turn-related Gs."

More likely it will feel like relaxation of Gs due to loss on "foot hold" due to mushing i.e stalling through turn. Maybe you meant this by saying "deceleration" as deceleration generally means less Gs.

"It was one of the characteristics of the Spitfire that it could do this, mushing with full 3-axis control and shooting "inside" its own turn. I don't see how it can be denied that the Spitfire flew like this..."

I'm not sure what this means but I'm willing to claim that Spit, of all planes, cannot do such thing. Due to wash-out it can enter a controlled half-stall where root of the wing has stalled but the wing tips have not, but if the critical AoA for its wingprofile is around 13 degrees, with wash-out it would be around 15 deg but considering the shape of the leading edge it is still dangerously on the verge of a full span stall. On the other had Bf109 probably could do this because of the wingtip slats which make such radical maneuver possible, although not from a 7G turn...

-C+

[hitech]

  I will concede his words could be interpreted either way, but my impression is that he felt reversing the roll affected the turn response, and that by continuing the same roll he sensed that his turn response was more immediate.

    Also, if mushing in the roll response was what was in question, this mushing loss was unlikely to be as great as continuing through 270° to roll "the long way around". On the other hand, mushing in the turn response could well be worth rolling 270° to avoid.

    Even if it turns out the intended meaning was for roll only, it still remains that one of the tactical advantages of the Spitfire was to be able to shoot inside its own turn, and even the Mustang had to resort to it (with difficulty) because of its noticeably wider (if faster) turn...

Read again, why do you think he continued to roll in the same direction when he needed to reverse his turn, I.E. you can roll 180 left or 180 right and the the out come is exactly the same. It is simply because of the slow roll reversal, it is very obvious that is what he is speaking about.

But then you said that the degrees per second of pivoting made by a fighter's nose cannot be at a different rate than that implied by the turning circle itself...

While this is mostly correct, I did not say this. During the time you are increasing AOA, the 2 rates can be different. But this time span is very short, and for most purposes can be ignored.

Even if it turns out the intended meaning was for roll only, it still remains that one of the tactical advantages of the Spitfire was to be able to shoot inside its own turn

All planes can do this.  When flying at max AOA, all planes are shooting inside their turning circle . The exact degree inside the circle is simply AOA - (wing incidence measured from the guns).  This would normally be in the 14 - 16 degree range.


HiTech

[Gaston]

    I have just remembered a combat anecdote that MAY prove Johnson's "mushing" description refers to a mushing TURN, NOT a mushing roll;

    He encountered a FW-190D at a fairly high altitude; 25 000 ft. +.

    He approached the FW-190D from behind, which saw him late; the FW-190D broke LEFT at the last moment.

    Jonhson then rolled RIGHT 270°, and pulled-in in a continuous turn that the 190D never changed for a long period. (I assume this was his razorback, because on his second tour he never scored)

    Now if the roll rate "mush" was what he wanted to avoid, he could have rolled left, and if the German reversed right he could easily have CONTINUED his left roll a further 180°, until being in a right bank. This is EXACTLY what he described doing in his interview with Widewing. However, this is NOT quite what he did in this actual combat...

    In actual combat he started his roll OPPOSITE the FW-190D's left turn. My theory why he did this is this; the high altitude (25 000 ft. +) introduced different priorities; roll speed and reverses are LESS important, mushing in turns MORE important.

    A full opposite RIGHT roll equals a "pull hard. no mushing" turn to the LEFT, his top priority at this high altitude. He even describes how the P-47 responded "beautifully" to the turn...

    The loss of time implied by rolling opposite; here at LEAST 2-3 seconds (more at high altitude) compared to a 1-2 second 90° left roll, means he hoped to gain by some other means than roll, unless the P-47 rolled so much better to right always that he always rolled right no matter what...

    But then he would not have described to Widewing doing a left roll, continuing it through 270° against a left-breaking, then reversing, 190, if that's NEVER what he did...

    I think if the 190 had broken to the right at this high altitude, he could very well have rolled left to take out the "mushing" of his subsequent right turn, after the usual full 270° roll. It would make sense as this would be the exact mirror-image of what he actually did at this altitude.

   At a lower altitude it could have been a different tactic; roll rates would be faster and "mushing" in turns less pronounced. It could even be that at lower altitudes the slower P-47 right turn is more apparent, so he would roll right with a right-breaking 190, and left with a left-breaking one, continuing the roll 270° IF a reverse occurred; exactly what he described to Widewing.

   So it does seem the grammatical meaning of what he said is closer, since he never applies "mushing" to the word roll, but to turn.

   Gaston.

[Widewing]

    I have just remembered a combat anecdote that MAY prove Johnson's "mushing" description refers to a mushing TURN, NOT a mushing roll;

    He encountered a FW-190D at a fairly high altitude; 25 000 ft. +.

    He approached the FW-190D from behind, which saw him late; the FW-190D broke LEFT at the last moment.

    Jonhson then rolled RIGHT 270°, and pulled-in in a continuous turn that the 190D never changed for a long period. (I assume this was his razorback, because on his second tour he never scored)

    Now if the roll rate "mush" was what he wanted to avoid, he could have rolled left, and if the German reversed right he could easily have CONTINUED his left roll a further 180°, until being in a right bank. This is EXACTLY what he described doing in his interview with Widewing. However, this is NOT quite what he did in this actual combat...

    In actual combat he started his roll OPPOSITE the FW-190D's left turn. My theory why he did this is this; the high altitude (25 000 ft. +) introduced different priorities; roll speed and reverses are LESS important, mushing in turns MORE important.

    A full opposite RIGHT roll equals a "pull hard. no mushing" turn to the LEFT, his top priority at this high altitude. He even describes how the P-47 responded "beautifully" to the turn...

    The loss of time implied by rolling opposite; here at LEAST 2-3 seconds (more at high altitude) compared to a 1-2 second 90° left roll, means he hoped to gain by some other means than roll, unless the P-47 rolled so much better to right always that he always rolled right no matter what...

    But then he would not have described to Widewing doing a left roll, continuing it through 270° against a left-breaking, then reversing, 190, if that's NEVER what he did...

    I think if the 190 had broken to the right at this high altitude, he could very well have rolled left to take out the "mushing" of his subsequent right turn, after the usual full 270° roll. It would make sense as this would be the exact mirror-image of what he actually did at this altitude.

   At a lower altitude it could have been a different tactic; roll rates would be faster and "mushing" in turns less pronounced. It could even be that at lower altitudes the slower P-47 right turn is more apparent, so he would roll right with a right-breaking 190, and left with a left-breaking one, continuing the roll 270° IF a reverse occurred; exactly what he described to Widewing.

   So it does seem the grammatical meaning of what he said is closer, since he never applies "mushing" to the word roll, but to turn.

   Gaston.

A couple of points... Bob never encountered a 190D as they didn't enter service until he was long gone from combat. He may have run into a prototype... Maybe, but not likely.

Johnson only did one tour, which was extended for a few additional missions to get 27 kills (he was going to be pulled from combat when he reached 27). Johnson was on his way home in May of 1944.


My regards,

Widewing

[BnZs]

Lag Roll



An appropriate maneuver whenever one has energy and excess lead on the bandit. But where does this condition come up most in actual combat? When one is pursuing a bandit who reverses his turn, which automatically converts any lag or pure pursuit approach you may have been following into lead pursuit, thus making a lag roll an appropriate response if you don't want to try just shooting him as he crosses.. Obviously a good way to counter an opponent with a fast roll-rate scissoring willy-nilly....whether he ends up going right, or going left, you can enter smoothly into an appropriate maneuver that retains the offensive.

Now you know what a lag roll is. If you knew the name, form, and purpose of the rest of the BFMs, you might be able to cease converting good honest combat reports into walls of text composed primarily of equine exhaust product.

[hitech]

No. Whenever you get into a series of reverses, the airplane tends to mush-out a bit when you reverse your turn.

To reverse a turn is to state roll the other way.

rather than reverse, you continue rolling left until you are in a right bank,

Why would rolling an addition 180 degrees left and then pulling for a right hand turn, vs rolling right and then pulling for a right hand turn make any different to the turn performance.

Answer it would not, but it would make a substantial difference to the roll performance.

Hence why the turn mush simply refers to the roll response.

If you do not wish to see this simple fact, then all hope of you understanding the basics of ACM is hopeless. Because roll performance and reversal timing is what wins a scissors as he describes.


HiTech
HiTech

[Angus]

From HiTech:
"If the pilot is maintaining 7 g's for the turning circle to become "wider" the plane would have to accelerate. (This is not debatable)."
HiTech has it, mathematically completely true. If may humbly add to this, none or few aircraft of WW2 could do this without the loss of altitude, and neither could the pilots. (Pressure suit issue etc). Basically you'd say 5 G's for 5 seconds, or tops 6 for 6, and you're ... out.
I think many on the boards actually forget about the vertical factor in turns though.
Just the cents.