# Insight into the magnitude of forces involved in dogfights during WW2



## Soren (Feb 7, 2008)

Insight into the magnitude of forces involved in dogfights during WW2

By 1942 the old WW1 style of dogfighting where one aircraft tries to outturn the other in a prolonged slow speed turn fight was long gone, the speed regimes had moved hugely upward to the point where wing loading no longer was anywhere near being as important a factor as earlier. By 1942 the speeds at which most dogfights were taking place were so high that the lightness harmony of the controls plus the structural integrity of the a/c became the two dominant if not the only factors for achieving success. This is the main reason behind the FW190’s huge success against the Spitfire in the ETO and the F6F F4U Corsair’s against the Zero in the PTO. 

I have chosen to use the FW190 as an example to demonstrate the forces which a pilot of the type had to endure in the high speed, wild confusing dogfights taking place in the mid to late war period.

*Lift equation (FW190): *

CL * A * .5 * r * V^2 = X Newtons

1.58 * 18.3 * .5 * 1.225 * 112^2 = 222152.045 N

*Convert result in Newtons into kgf:*

222152.045 Newtons = 22653.2 kgf

*Divide result with a/c weight to get Max G:*

22653.2 / 4270 = 5.3

*Max G at 112 m/s (400 km/h):*

5.3 G
________________________________

Using the same equation the Max G at 125 m/s (450 km/h) is 6.6 G, so already at this speed the pilot will be blacking out in a full performance turn. 

At 500 km/h which would be the average speed in a dogfight in 1944-45 the G-forces in a max performance turn will exceed 8.25 G's!

At 650 km/h which would quickly be reached in a dive the G-forces the FW190 is capable of pulling are staggering, a massive 13.8 G’s! This is way beyond even the structural load limit.


*I hope this gave some insight into why the style of dogfighting evolved as it did and why B&Z tactics became dominant in the mid to late war period.*

PS: I can add other a/c for comparison reasons by request.

All the best!


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## Soren (Feb 8, 2008)

Here's the P-51D put in for comparison:

1.45 * 21.64 * .5 * 1.225 * 112^2 = 241083.45 N

241083.45 N = 24583.67 Kgf

24583.67 / 4587 = 5.35 

*Max G at 112 m/s (400 km/h):* 5.35 G

So as you can see in terms of instantanous turn rate the FW190 P-51 are very close, it is only in sustained turn rate that the FW190 holds a marked advantage, and this is only at low to medium alt for the Anton. Ofcourse at very high speeds the FW190 will be able to accellerate into a turn allot more quickly because of its much better elevator authority.


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## Soren (Feb 8, 2008)

Bf-109 K-4 Max G at 112 m/s (400 km/h) = 6.4 G
Spitfire Mk.XIV Max G at 112 m/s (400 km/h) = 6.22 G
Ta-152H-1 Max G at 112 m/s (400 km/h) = 6.15 G
Spitfire Mk. IX Max G at 112 m/s (400 km/h) = 7.14 G


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## davparlr (Feb 8, 2008)

Great post Soren! Very informative, I never really thought of this.

I am a bit uncertain regarding your comment


> By 1942 the speeds at which most dogfights were taking place were so high that the lightness harmony of the controls plus the structural integrity of the a/c became the two dominant if not the only factors for achieving success.


. While most of the aircraft I looked at that are known as great fighters (American, since the only source on this was the Joint Fighter Conference), all had light and effective controls, it seems to me that the big effort in aircraft design was for more powerful and faster aircraft than the enemy, and not one with lighter controls and stronger airframe. The effort on the P-51H, for example, was to lighten the structure (lower g limits) for speed and maneuverability. Higher speed and more power allow better use of energy management, which, without a doubt, is one of the major factors in successful air-to-air combat. Due to its much higher power, it was much easier for an F6F to maintain airspeed in a turn than an F4F in the same situation.


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## drgondog (Feb 8, 2008)

davparlr said:


> Great post Soren! Very informative, I never really thought of this.
> 
> I am a bit uncertain regarding your comment . While most of the aircraft I looked at that are known as great fighters (American, since the only source on this was the Joint Fighter Conference), all had light and effective controls, it seems to me that the big effort in aircraft design was for more powerful and faster aircraft than the enemy, and not one with lighter controls and stronger airframe. The effort on the P-51H, for example, was to lighten the structure (lower g limits) for speed and maneuverability. Higher speed and more power allow better use of energy management, which, without a doubt, is one of the major factors in successful air-to-air combat. Due to its much higher power, it was much easier for an F6F to maintain airspeed in a turn than an F4F in the same situation.




Dave, the reduction in limit loads on the 51H from D was from 12g to 11g on Ultimate and 8g to 7.4 on Limit Load, which in a turning high G fight was still below the Berger poopy suit capability in 44 and 45.

Your point about power loading is a good one re: energy as the H was nearly 900 pounds lighter and had the more powerful -9 Merlin. It had better acceleration, roll, turn and climb than the D


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## davparlr (Feb 8, 2008)

drgondog said:


> Dave, the reduction in limit loads on the 51H from D was from 12g to 11g on Ultimate and 8g to 7.4 on Limit Load, which in a turning high G fight was still below the Berger poopy suit capability in 44 and 45.
> 
> Your point about power loading is a good one re: energy as the H was nearly 900 pounds lighter and had the more powerful -9 Merlin. It had better acceleration, roll, turn and climb than the D



Indeed. From what I understand the reduction in load factor was to make it similar to the Spitfire. Apparently, the British thought that the P-51 was overdesigned in regards to stress levels.


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## drgondog (Feb 8, 2008)

davparlr said:


> Indeed. From what I understand the reduction in load factor was to make it similar to the Spitfire. Apparently, the British thought that the P-51 was overdesigned in regards to stress levels.



That is what I believe Schmeud quoted in Mustang Designer - and makes sense. 

Having said that, 8/12 is pretty much Aero Structure as practiced today (oops -at least 20 years ago).. NASTRAN and Stardyne type finite modelling make those numbers more consistent (and believable) than the old 'hand hack' methods because these computer models will incorporate realistic deflections and interplay with shear panels, etc.

As to the Brits, they probably were right to focus on more realistic loads based on ACM. Having said that, they experienced a bit of a 'boo boo' in the wing design which had some serious control reversal issues when the wing deformed under high aileron loads... so maybe they went to 8/12 for the spar and torsion box design?? I don't know specifically what they did to fix it.


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## Soren (Feb 9, 2008)

Davparlr,

Regarding my comment on the lightness harmony of the controls and the structural integrity of the airframe being the dominant factors for succes, well usually this was a feature of the faster more powerful a/c over the previous lighter but less powerful a/c. When the FW190 arrived on the scene the Spitfire pilots were at a complete loss as the FW190 ws not only much faster, it also climbed much faster and was unbelievably agile at all speeds, esp. at speeds of 400 km/h and above where pulling lead on one was near impossible without blacking out.

Bill,

The FW190 BF109 were both designed to withstand 13 G's fully loaded, this was the ultimate load limit no doubt, but it is still pretty staggering.

The load limit for the P-51D is 6.59 G fully loaded, now as to the ultimate I don't know but.

The load limit for the Dora-9 fully loaded is 6.9 G.


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## syscom3 (Feb 9, 2008)

US fighter pilots had gee suits in which to tolerate the high speed turns.


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## Soren (Feb 9, 2008)

And the German pilots had tilted seats plus heightened footrests, in the end this probably cancelled out the difference with the early G-suit.


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## syscom3 (Feb 9, 2008)

Soren said:


> And the German pilots had tilted seats plus heightened footrests, in the end this probably cancelled out the difference with the early G-suit.



Not hardly.


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## FLYBOYJ (Feb 9, 2008)

Soren said:


> And the German pilots had tilted seats plus heightened footrests, in the end this probably cancelled out the difference with the early G-suit.



It helps but not even close Soren. Take a guy with a tilted seat and heightened footrests and put him against a guy with a g suit at say 7 or 8 Gs. There is no doubt the guy with the G suit is not going to black out first, and this even includes the early USAAF G suits. If it was a matter of tilting a seat back and adding stirrups to overcome blacking out, there's been a lot of wasted money spent in developing anti g technology since WW2.


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## drgondog (Feb 9, 2008)

Soren said:


> Davparlr,
> 
> Regarding my comment on the lightness harmony of the controls and the structural integrity of the airframe being the dominant factors for succes, well usually this was a feature of the faster more powerful a/c over the previous lighter but less powerful a/c. When the FW190 arrived on the scene the Spitfire pilots were at a complete loss as the FW190 ws not only much faster, it also climbed much faster and was unbelievably agile at all speeds, esp. at speeds of 400 km/h and above where pulling lead on one was near impossible without blacking out.
> 
> ...



Soren the Limit load in the Mustang Manual is 8G at 8,000 pounds gross. You can extrapolate whatever you want from that as it is linear basically.

According to Gruenhagen's "History of Mustang" the Mustang A-D (and K) was 12 Ultimate) and the G,J H and M (Light weigh re-design) were 11 Ultimate at 8,000 pounds - consistent with RAF design doctrine.

US airframe standards and practices in WWII all the way through my own career, at the time NASTRAN and Stardyne became industry standards for Structural and Frequency analysis, used 1.5 limit load (usually at 'yield' for LOWEST single point of stress attaining Yield level), for Design Ultimate and tested analytically if there were discrete 'points of failure' that would fail before 'ultimate' stress point was reached. 

Obviously a C-47 flight load limits was 3g positive and 1 1/2 g negative (i think) for normal ops and gross, while the US fighters (exceptions noted) were 8g for nominal (not max) gross weight. Landing loads were considerably higher.

For practical purposes the Manual is right for a 51 after burning the fuse tank over Germany.

I think we have had this discussion before, but I haven't seen anyone including Kurfurst present one LW source specifying limit and ultimate loads for any LW fighter or other a/c.. Have you found a source yet for the above Fw 190 and Me 109 figures?


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## Soren (Feb 9, 2008)

Bill,

I extrapolated the load limit from the 9700 lbs gross weight, which is with an empty fuselage tank. (Simply divide 64,000 with weight of a/c) With a full fuselage tank the P-51D weighed in at 11,000 lbs. So 8,000 lbs is not anywhere near a representive figure, esp. since this is considering that atleast 80% of the internal fuel has been used up, which in turn would mean no return trip. Remember than the empty weight of the P-51D is ~7,400 lbs. Also the P-51's would mostly run on the external drop tanks to the frontline and then drop them to run on internal once the enemy was sighted.

The load limit figure for the FW190 is from the Dietmar Hermann's book on the plane and is the minimum figure for a fully loaded a/c.

What is your source for the 11 G ultimate load limit for the -51 ?


FLYBOYJ,

Is there any proof that these early G-suits helped much in any way ? From what I've heard the heightened footrests and tilted seats did just as much good as these early G-suits. Remember the US pilots were just sitting in what resembled a straight chair by comparison. 

Anyway the best way to survive high G's between the early G-suit and the heightened footrest tilted seat is with lots of practice with muscle straining. 

Today the G-suit is ofcourse the no.1 reason pilots aren't blacking out above 7 G's, but the design effectiveness is also a good deal different than the early G-suits of WW2.


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## FLYBOYJ (Feb 9, 2008)

Soren said:


> FLYBOYJ,
> Is there any proof that these early G-suits helped much in any way ?


100% YES - there were extensive tests done at Wright Patterson AFB around 1943 or early 1944 if I remember right. I think the museum there has a whole display of these test and the first implementation of the G suit.


Soren said:


> From what I've heard the heightened footrests and tilted seats did just as much good as these early G-suits. Remember the US pilots were just sitting in what resembled a straight chair by comparison.


It didn't matter, again if it was a matter of just reclining the seat and using foot rest a lot of extra "junk" could of been omitted from fighters over the past 60 years...


Soren said:


> Anyway the best way to survive high G's between the early G-suit and the heightened footrest tilted seat is with lots of practice with muscle straining. The G-suits are of course the no.1 reason pilots aren't blacking out above 7 G's. The G-suits helps allot.


The physical training (especially leg muscle weight training) is a big part of it. the inclined seat will help but in the end the guy wearing the g suit has a BIG advantage.


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## syscom3 (Feb 9, 2008)

Soren, the early g-suits were designed for dive bomber pilots, that had an annoying habit of blacking out after pulling from a dive.

They worked like a charm, and soon found use in the fighters.


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## DerAdlerIstGelandet (Feb 9, 2008)

Soren said:


> And the German pilots had tilted seats plus heightened footrests, in the end this probably cancelled out the difference with the early G-suit.



Your proof and source that the tilten seats were better than G-suits please.

The tilted seats and all probably helped but I find it very hard to believe that it was better than a G-Suit, even an early one.


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## davparlr (Feb 9, 2008)

Soren said:


> Davparlr,
> 
> The FW190 BF109 were both designed to withstand 13 G's fully loaded, this was the ultimate load limit no doubt, but it is still pretty staggering.
> 
> ...



The loaded weight of a Bf-109G is 7480. For 13 “gs” the Bf-109G must be tested to withstand an equivalent of 97240 lbs of force. For the P-51D, if, as you say, has a load limit of 6.59 gs, and, as I remember g limits on aircraft, they are tested to 1.5 times limit load, as drgondog has also said, then the test level must be 9.9 gs. Now the P-51D has a loaded weight of 10100 lbs., so for a load limit 6.59 gs, then it must be tested to an equivalent of 99990 lbs. In other words the aircraft structure of the P-51D must be tested to a higher stress level than the structure of the Bf-109.


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## davparlr (Feb 10, 2008)

Soren said:


> Bill,
> 
> What is your source for the 11 G ultimate load limit for the -51 ?



This is not surprising at the 8000 lb number. Again, to meet the 6.59 gs at loaded weight, the P-51 must be tested at an equivalent 99990 lbs of force. Dividing this by 8000 lbs, you get 12.5 gs. The 8000 lbs number is obviously a design-to number and is not meant to be any combat weight value.

These g levels are not that far off modern fighter designs where g suits are worn. These numbers are probably over design for the environment in which they fought, which is also probably why the Brits wanted to relax the P-51 specs.


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## Soren (Feb 10, 2008)

Davparlr,

There seems to be something you don't understand;

The load limit of 6.59 G's is for the P-51D at 9,700 lbs, which is with an empty fuselage tank. At 10,100 lbs with full internal fuel the load limit is 6.33 G's. 

So this means that the P-51's airframe has a 9.85 G ultimate load limit at 9,700 lbs, and 9.47 G ultimate at 10,100 lbs. 

Now as to how mouch force the airframe has to withstand, well what does this matter ?? The a/c which can withstand the most G-forces is what matters. So while the P-51 is able to withstand ~96,000 lbs of force it is also heavier than both the 109 190 and therefore has to cope with more weight for every increase in G-forces.


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## Soren (Feb 10, 2008)

DerAdlerIstGelandet said:


> Your proof and source that the tilten seats were better than G-suits please.
> 
> The tilted seats and all probably helped but I find it very hard to believe that it was better than a G-Suit, even an early one.




Again why is it necessary to twist what I say ?? I never claimed that the tilted seat heightened footrests were better than the G-suit, just that they about cancelled out the advantage given by the early G-suit. Besides at that period exercise was the best way to withstand G-forces.


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## Soren (Feb 10, 2008)

Anyway getting back on track the point here is that all the fighters above could take G-loads which would black out the pilot quite quickly, and this just illsutrates why a/c-wise light harmonized controls at all speeds plus high perofmance was the dominant factor for success, if these were close however the pilot experience became the absolute dominant factor for success.


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## FLYBOYJ (Feb 10, 2008)

Soren said:


> Again why is it necessary to twist what I say ?? I never claimed that the tilted seat heightened footrests were better than the G-suit, just that they about cancelled out the advantage given by the early G-suit. Besides at that period exercise was the best way to withstand G-forces.


Again 100% wrong - tilting a seat back and adding food rest WILL NOT cancel out the advantage of the G suit - even the early ones (which aren't much different from the ones we see today), and I don't care if the pilot was sitting on a milk crate.

I've flown in jets and pulled Gs with and without a g suit and there is a HUGE differance. Again an angled seat will help, but its not cancelling out the advantage, even if the guy in the tilted seat is in exceptional shape.


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## davparlr (Feb 10, 2008)

Soren said:


> Davparlr,
> 
> There seems to be something you don't understand;



Maybe I didn't understand because you said


> The load limit for the P-51D is 6.59 G fully loaded, now as to the ultimate I don't know but.



You didn't define your numbers very well, who would have known you were using an empty tank.




> The a/c which can withstand the most G-forces is what matters. So while the P-51 is able to withstand ~96,000 lbs of force it is also heavier than both the 109 190 and therefore has to cope with more weight for every increase in G-forces.



This is true, but then you said


> Anyway getting back on track the point here is that all the fighters above could take G-loads which would black out the pilot quite quickly


This is also true and since all of these planes would exceed the pilots ability to perform and were very effective in combat, I scratch my head wondering why we always end up discussing load limits.


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## Soren (Feb 10, 2008)

Davparlr,

I made it quite clear that I extrapolated the 6.59 G figure from a weight of 9,700 lbs, but nevermind cause you obviously missed this, so no point in argueing over it.

As to your last point, well that is alo my point; All of the fighters above could pull G's that the pilots couldn't stand and this at below the normal speed at which dogfighting was taking place by then. 

What becomes important in a prolonged dogifght however is the ability to sustain high G's, and here the higher powered FW-190, Bf-109 Spitfire have a significant advantage over the heavier P-51, although unlike the Dora the Anton only has this advantage at low to medium alt. The P-51 was a hottie at high alt, no doubt about it.


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## drgondog (Feb 10, 2008)

davparlr said:


> This is not surprising at the 8000 lb number. Again, to meet the 6.59 gs at loaded weight, the P-51 must be tested at an equivalent 99990 lbs of force. Dividing this by 8000 lbs, you get 12.5 gs. The 8000 lbs number is obviously a design-to number and is not meant to be any combat weight value.
> 
> These g levels are not that far off modern fighter designs where g suits are worn. These numbers are probably over design for the environment in which they fought, which is also probably why the Brits wanted to relax the P-51 specs.



Soren - the source for the Mustang design loads in Gruenhagen's Mustang and Wagner's Mustang Designer - about Edgar Schmeud.

The former discusses in some depth the RAF design teams dialog with Schmeud and NA engineers in 1942 and early 1943 when the P-51 was undergoing a severe weight analysis for future production versions. 

The 11 g target was discussed specifically as one of the considerations to examine to see in US aircraft were a.) over designed, and b.) would point to areas in conventional design of serious concern.

Thus 11g was the design Ultimate for all the Light weight fighters.

The P-51A,B and C was Design limit at 8,000 which was a high (but not max) Gross weight for the 51A, but the 8,000 pound target upon which a 8G limit load kept moving into the normal flight profile, meaning ammo and most internal wing fuel but no fuselage tank (with most of the extra pounds along with heavier Merlin from the P51A)

The F-16 is designed to higher stress limits than the P-51 and the G suits are pushing 9g (I think) which is at the threshold of endurance for a fighter pilot with that G suit in manuever. I don't recall where I pulled the 9g number... but if correct indicates the Ultimate number of the airframe to be well into 13-14G range. Someone else may have a definitive number on this.

IIRC the typical 'high side' of G achievement for un augmented fighter pilot was around 4G? and the Berger moved that peg to 5-6G for limited time?


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## DerAdlerIstGelandet (Feb 10, 2008)

Soren said:


> Again why is it necessary to twist what I say ?? I never claimed that the tilted seat heightened footrests were better than the G-suit, just that they about cancelled out the advantage given by the early G-suit. Besides at that period exercise was the best way to withstand G-forces.



Okay then can you please post proof and sources that show that they cancel each other out.

I am sorry but I find it very hard to believe, for the same reasons that Joe has allready stated.


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## Soren (Feb 10, 2008)

A 1 - 1.5 G improvement with the early G-suit sounds very reasonable Bill.

The pressure points, pressure itself and design of later G-suits is quit different from the early G-suits.

The tilted seat heightened footrests helped allot according to the pilots, and according to NACA a 30 degree tilt gives a huge increase in tolerable G.


From here: Physiological Effects of Positive G Forces

_"The last method has not effectively been used in military aircraft to any extent to date but which is probably the system of the future. It is reclining the pilot in the cockpit. 

Consider a subject sitting erect in the seat of an aircraft. The average distance from his heart to the base of the brain is 30 cm and it takes approximately 24 mm of mercury pressure to raise a column of blood 30 cm in a normal standing environment of one G. It would, of course, take the same pressure to raise a column of blood from the heart to the wrist if the wrist is held at eye level as it takes to de- liver blood to the brain. 

In a study in which 250 centrifuge runs were made on human volunteers, it was demonstrated that systolic blood pressure in the radial artery held at eye level was reduced by 32 mm of mercury for every G added to the ± G2 force. Visual disturbances occurred when the systolic blood pres- sure at the base of the brain was reduced to 50 mm of mercury and complete loss of vision occurred when the pressure was reduced to 20 mm of mercury. Loss of consciousness occurred when the systolic pressure at brain level was reduced to zero. This would be equivalent to a five ± G pull, i.e., 5 x 32 = 160, where the blood pressure at the base of the brain would be reduced to zero if the systolic blood pressure in the subject was 160 at the heart level. 

These forces were sustained in the study for a period of 15 seconds and the time to recovery unfortunately was not reported. It was noted, how- ever, that under a load of five G’s, the systolic blood pressure was reduced by five mm of mercury and the diastolic pressure was unaffected if the head is lowered to the level of the heart. To extrapolate from that information a positive G force in itself would not produce unconsciousness or blackout if the head is lowered to heart level. 

Tables 2 and 3 show the time of exposure to ± G loads when pulling from horizontal flight to vertical (Table 2) and from vertical down to vertical up (Table 3) as in an inverted humpty at various speeds from 100 to 300 MPH and at varying G loads from two G’s to 12 G’s. Table 1 shows blood pressure at the base of the brain with varying seat tilt angles and 0 loads up to 12 G’s. Remember that L.O.C"_


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## drgondog (Feb 10, 2008)

Soren said:


> The load limit of 6.59 G's is for the P-51D at 9,700 lbs, which is with an empty fuselage tank. At 10,100 lbs with full internal fuel the load limit is 6.33 G's.
> 
> So this means that the P-51's airframe has a 9.85 G ultimate load limit at 9,700 lbs, and 9.47 G ultimate at 10,100 lbs.
> 
> ...



Soren just some more thoughts.

In most combat situations the 51 had burned away external and some internal (ie. fuse tank). The max take off weight for no stores on the A was 8200, the B/C was 9000 (with 184 wing plus internal 85 gal tank) and 9540 for D/K. The H was 8500 (with 205 wing and 50 fuse cells)

So if combat was engaged after 'drop' tanks, fuselage tank dry, but all wing fuel and ammo intact - the B was at approx 8500 and the D was at 9,000.. the H in that same conditionwas at 8100 

PS the Gruenhagen discussion about 12 and 11 g ultimate load change for the lightweight design is on page 119


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## FLYBOYJ (Feb 10, 2008)

Soren said:


> A 1 - 1.5 G improvement with the early G-suit sounds very reasonable Bill.
> 
> The pressure points, pressure itself and design of later G-suits is quit different from the early G-suits.


Again, the early pneumatic g-suits aren't much different from the ones today - I've seen both - the biggest difference is comfort and the material used.


Soren said:


> The tilted seat heightened footrests helped allot according to the pilots, and according to NACA a 30 degree tilt gives a huge increase in tolerable G.
> 
> 
> From here: Physiological Effects of Positive G Forces
> ...



All fine and dandy - but still gives no indication that an angle seat will cancel out the g suit advantage. BTW the angle of the seat (which is referred as "pitch) has to be factored into the location of the flight controls. A 30 degree pitch is huge - and what Luftwaffe fighter had "pitched" seats????


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## Soren (Feb 10, 2008)

drgondog said:


> Soren just some more thoughts.
> 
> In most combat situations the 51 had burned away external and some internal (ie. fuse tank). The max take off weight for no stores on the A was 8200, the B/C was 9000 (with 184 wing plus internal 85 gal tank) and 9540 for D/K. The H was 8500 (with 205 wing and 50 fuse cells)
> 
> ...




I just used the fully loaded weight with empty fuselage tank for the P-51D, expecting that they ran on external tanks to begin with and on internal on the home trip.

The German fighters were often carrying half full internal fuel tanks, there not being enough fuel to go around. I used the fully loaded weight for all the fighters though.


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## Soren (Feb 10, 2008)

FLYBOYJ said:


> All fine and dandy - but still gives no indication that an angle seat will cancel out the g suit advantage. BTW the angle of the seat (which is referred as "pitch) has to be factored into the location of the flight controls. A 30 degree pitch is huge - and what Luftwaffe fighter had "pitched" seats????



FLYBOYJ,

The LW fighters have pitched seats, around 25 degrees, and the heightened footrests allowed the pilot to increase the pitch of his body even further. The raising of his legs also helps the heart push blood up to the brain.


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## FLYBOYJ (Feb 10, 2008)

Soren said:


> FLYBOYJ,
> 
> The LW fighters have pitched seats, around 25 degrees, and the heightened footrests allowed the pilot to increase the pitch of his body even further. The raising of his legs also helps the heart push blood up to the brain.


And agree there - I don't know the pitch of say a P-51 or P-38 (I've sat in both). I wouldn't guess they weren't as high 25 degrees but there was a "pitch" there. 

Even at 15 degrees, throw a g suit in there and there is a great advantage.

BTW - I sat in "White 14" and I could tell you that seat back was pretty straight.


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## Soren (Feb 10, 2008)

Roger that FLYBOYJ, the FW190's seat has more pitch than the BF109's, far more.

As to the early G-suits, have you ever tried one ? Also is there a study which compares the early G-suit's effectiveness vs not wearing one ?


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## FLYBOYJ (Feb 10, 2008)

Soren said:


> As to the early G-suits, have you ever tried one ? Also is there a study which compares the early G-suit's effectiveness vs not wearing one ?


I've seen a WW2 Berger suit, tried on Korean war vintage suits and personally own a CSU-138 that I have used on several occasions. The Berger suit I seen from what I remember was made from "canvas" (possibly something else) and rubber and seemed to have little room to get adjusted when you would put it on. The Korean War suit was very similar to a modern suit and used a nylon material - more "wiggle room' to make it easier to get on. The suit I own is around a post VietNam era suit and had all kinds of zipper and snaps that make it a little easier to put on and adjust, but from the operational standpoint they were about the same in where pressure would be placed on the legs and stomach - the biggest difference I seen from the early suit was comfort and ease of putting it on.

I think you could see that this is an area I'm very "into." Several years ago I did work on a T-33 and the owner and I got his g suit system working so we went out and tested it - this prompted me to buy my own. Additional at the same time I was occasionally getting T-33 and F-4 rides at my full time employer. I went up a few times and was blacked out when we were pulling maneuvers. At later times I used my g suit and it made all the difference in the world.

BTW - not being prepared for accelerated Gs - I blacked out at 4Gs while trying to take pictures in the back of an L-29. One minute we were above the airport in formation - we did a "pitch out" that I was not prepared for, the next thing I know we were on final - out for about 20 seconds.


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## Glider (Feb 10, 2008)

Its interesting but if I remember correctly the first use of an anti G suit was by British Seafires in 1942. They were also used by British test pilots to help them in their analysis of new designs.

I will dig around and see what I can find.


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## pbfoot (Feb 10, 2008)

Glider said:


> Its interesting but if I remember correctly the first use of an anti G suit was by British Seafires in 1942. They were also used by British test pilots to help them in their analysis of new designs.
> 
> I will dig around and see what I can find.


I think the first G suits were made in Toronto by a gent named Franks who worked under Banting(insulin guy) the RAF used the MK 1 the USAAF and RCAF the MK2 it used water instead of the modern air models


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## Glider (Feb 10, 2008)

Found something that I think will be of interest
Whatever Happened To...?: Catching ... - Google Book Search


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## Soren (Feb 10, 2008)

Does anyone have an exact number on how many Allied pilots wore the G-suit ?


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## DerAdlerIstGelandet (Feb 10, 2008)

FLYBOYJ said:


> All fine and dandy - but still gives no indication that an angle seat will cancel out the g suit advantage. BTW the angle of the seat (which is referred as "pitch) has to be factored into the location of the flight controls. A 30 degree pitch is huge - and what Luftwaffe fighter had "pitched" seats????



I also agree that a tilt seat will make it easier but I would still like to see actual proof that it cancels out a g-suit.


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## drgondog (Feb 10, 2008)

Soren said:


> Does anyone have an exact number on how many Allied pilots wore the G-suit ?



The 355th received full supply in October 1944 to start of November and used them on all missions forward. The 4th tried the water filled version on a limited basis in April 1944, liked the benefit but didn't like the water aspect. They got theirs along with 56th, 361st and 479th at the same time the 355th got theirs. I think the 65th FW was first (all the above) but all 8th FC had them in November.

So, multiply approximately 100 fighter pilots by 15 Fighter groups to get 8th AF FC suit wearers at any one time, although only 70% flying on a given day in late 1944. I don't know when the 9th, 12th and 15th Fighter Groups got them - or RAF and RCAF... Real short on PTO knowledge here.

My father and three others 'pioneered' them in mid October for 355th. He spoke very highly of them in contrast to pre G suit and felt he was good for 6+ as contrast to 4-5(max) w/o G suit.


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## drgondog (Feb 10, 2008)

DerAdlerIstGelandet said:


> I also agree that a tilt seat will make it easier but I would still like to see actual proof that it cancels out a g-suit.



It just won't cancel out a G suit - which is why F-16 and F-15 and F22 all have both reclined seats AND G suits for pilot. I do believe the add't recline slant on an Fw 190 probably helped a little. I think the 51/47 and 38 seats had about a 15-20 degree slope from headrest to butt location.


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## FLYBOYJ (Feb 10, 2008)

Interesting stuff Bill! The early British ones did work with water - Pb nailed it about the company in Toronto. I could tell you first hand the difference it makes.


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## Soren (Feb 10, 2008)

Excellent info Bill, thank you very much!


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## FLYBOYJ (Feb 10, 2008)

As we've been discussing this I just noticed I had this sitting on my desk!

Right after the T-33 flight were we "tried out" the g suits. I think we were only pulling about 4 Gs. the suit helped but it still felt like I spent an afternoon working out with weights, and back then I was in real great shape, about 15 pounds less than I am today.


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## Soren (Feb 10, 2008)

The tilted seat + the heightened footrests is what leads me to the conclusion that this about cancels out the advantage of the early Berger suit. The raising of your legs I know will help allot plus the fact that it allows you to further increase the pitch of your own body.


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## FLYBOYJ (Feb 10, 2008)

Soren said:


> The tilted seat + the heightened footrests is what leads me to the conclusion that this about cancels out the advantage of the early Berger suit. The raising of your legs I know will help allot plus the fact that it allows you to further increase the pitch of your own body.


Believe what you want Soren, the Berger suit worked very similar to today's suits and unless the bulk of Luftwaffe pilots were either in super condition or 30 to 40 pounds overweight (The two body types that could actually take high g forces well) a 25 degree pitch seat is not going to have an advantage over a g suit, even a Berger - if they weren't effective the AAF wouldn't of pushed their use.


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## Soren (Feb 11, 2008)

Thx for that back handed remark.

I never questioned the effectiveness of the G-suit, however the effectiveness of the early G-suit I don't believe to be much more effective than the tilted seat heightened footrests. There's no doubt that wearing a G-suit is an advantage, never claimed otherwise, but a tilted seat heightened footrests is also an advantage. Having both would've been the best.


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## FLYBOYJ (Feb 11, 2008)

Soren said:


> Thx for that back handed remark.


Sorry Soren, wasn't meant to come out that way...


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## Soren (Feb 11, 2008)

No worries.


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## DerAdlerIstGelandet (Feb 11, 2008)

drgondog said:


> It just won't cancel out a G suit - which is why F-16 and F-15 and F22 all have both reclined seats AND G suits for pilot. I do believe the add't recline slant on an Fw 190 probably helped a little. I think the 51/47 and 38 seats had about a 15-20 degree slope from headrest to butt location.



I agree, that is what I am getting at.


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## DerAdlerIstGelandet (Feb 11, 2008)

Soren said:


> Thx for that back handed remark.
> 
> I never questioned the effectiveness of the G-suit, however the effectiveness of the early G-suit I don't believe to be much more effective than the tilted seat heightened footrests. There's no doubt that wearing a G-suit is an advantage, never claimed otherwise, but a tilted seat heightened footrests is also an advantage. Having both would've been the best.



But how is it an advantage over the early G-Suits. I dont buy it. 

Until I see proof it is nothing more than an opinion to me. Ang this is not supposed to be an insult or a back handed remark to you either Soren so please dont take it that way.


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## Soren (Feb 12, 2008)

I never claimed the tilted seat heightened footrests to be an advantage over the G-suit, never. Both were advantages, a means of delaying black outs. Hence why modern fighters feature both.

What I've been saying from the start is that the tilted seat + heightened footrests probably cancels out the advantage given by the early berger G-suit, that's all, both were advantages. The chart I provided demonstrates a ~1G improvement in tolerance with 25 degree's of tilt, and with your feat raised aswell this would've been increase to the same degree I believe, which means a 1.5 to 2G improvement in tolerance, the same as the early Berger G-suit.


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## Soren (Feb 12, 2008)

Anyway I added some more a/c;

Bf-109G-2 Max G at 112 m/s (400 km/h): 7.49 G 
A6M5 Max G at 112 m/s (400 km/h): *9.61 G* !! (Holy moly! )
FW-190 A-5 Max G at 112 m/s (400 km/h): 5.52 G
F4U-4 Max G at 112 m/s (400 km/h): 5.49 G ( At 6,000 kg weight)
F6F-5 Max G at 112 m/s (400 km/h): 6.5 G

I think it's a pretty good thing that the Zero had heavy stick forces at high speeds!


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## DerAdlerIstGelandet (Feb 12, 2008)

Soren said:


> I never claimed the tilted seat heightened footrests to be an advantage over the G-suit, never. Both were advantages, a means of delaying black outs. Hence why modern fighters feature both.




Okay then I ask again, how does it cancel out the G-Suit?


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## Soren (Feb 12, 2008)

By delivering roughly the same increase in G tolerance as the early Berger suit. Against the modern G-suit's there's no contest.


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## FLYBOYJ (Feb 12, 2008)

Soren said:


> By delivering roughly the same increase in G tolerance as the early Berger suit. Against the modern G-suit's there's no contest.


I think you're missing the point that the Berger suit will do about the same as a modern suit. The only real improvement I find over G suits in the past 60 years is construction material and comfort. Bottom line a 25 or 30 degree seat pitch WILL NOT be as effective as a G suit, even if we speak in terms of WW2...


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## DerAdlerIstGelandet (Feb 12, 2008)

Soren said:


> By delivering roughly the same increase in G tolerance as the early Berger suit. Against the modern G-suit's there's no contest.



Proof please?


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## Soren (Feb 12, 2008)

The early G-suit delivered about a 1.5 - 2 G improvement to tolerance, and so did the heightened footrest + tilted seat according to the chart I presented, that's the proof Adler.

I severely doubt that the Berger suit was as effective as modern G suits, infact I know it isn't.


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## Soren (Feb 12, 2008)

Art Friedler in his P-51D also failed to follow a FW190A in a couple of the tight pull outs because he greyed out, the German pilot being able pull more G's and get away.


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## FLYBOYJ (Feb 12, 2008)

Soren said:


> The early G-suit delivered about a 1.5 - 2 G improvement to tolerance, and so did the heightened footrest + tilted seat according to the chart I presented, that's the proof Adler.
> 
> I severely doubt that the Berger suit was as effective as modern G suits, infact I know it isn't.


They work the same way and applied the same pressure, how were that not as effective? I don’t have any references in font of me (Bill might have a few) but I have seen testimony from P-51 drivers where they have stated that the G suit made the difference in air battles they were in.


The big difference is the g suit worked automatically, in the seat with stirrups you had to prepare for the g loading. In the height of battle that one or 2 seconds could mean everything....


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## DerAdlerIstGelandet (Feb 12, 2008)

FLYBOYJ said:


> They work the same way and applied the same pressure, how were that not as effective? I don’t have any references in font of me (Bill might have a few) but I have seen testimony from P-51 drivers where they have stated that the G suit made the difference in air battles they were in.
> 
> 
> The big difference is the g suit worked automatically, in the seat with stirrups you had to prepare for the g loading. In the height of battle that one or 2 seconds could mean everything....



Agreed. I am still not convinced that it canceled out the G-Suit.


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## drgondog (Feb 12, 2008)

DerAdlerIstGelandet said:


> Agreed. I am still not convinced that it canceled out the G-Suit.



There is no question that the G-suit was accepted as a 'diiference maker' by US fighter pilots in ETO.

A bigger question to me is why it was not universally adapted by RAF and LUftwaffe? 

Joe - my data on the G-suit is strictly anecdotal both from personal comments and encounter reports. Physiologically speaking the simple act of applying pressure to abdomen and Upper thighs restricts flow of blood to lower body, which a reclined seat will facilitate - but not duplicate until some very advanced reclining state (I don't know the assymptotic approach migh be.)

I am sure the USAF studied it but I haven't put my fingers on any tables.


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## DerAdlerIstGelandet (Feb 12, 2008)

drgondog said:


> There is no question that the G-suit was accepted as a 'diiference maker' by US fighter pilots in ETO.
> 
> A bigger question to me is why it was not universally adapted by RAF and LUftwaffe?



Agreed

I dont think it can be truthfully argued either.


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## Soren (Feb 14, 2008)

I feel that the weight I used for the F4U-4 is too high, does anyone have some info on its cleanly loaded weight (Full internal fuel ammunition) ??


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## drgondog (Feb 14, 2008)

Soren said:


> I feel that the weight I used for the F4U-4 is too high, does anyone have some info on its cleanly loaded weight (Full internal fuel ammunition) ??




Vought F4U Corsair - USA

Soren - This source has the following for F4U-4

9,205 Empty
12,400 'normal load', no external stores, full internal fuel and ammo
14,670 'Max gross TO'

The web sites are all over the place but I think this set is close.


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## Soren (Feb 14, 2008)

Roger that Bill, those figures look far more reasonable and right in the ballpark of what I suspected. I actually have the POH on my stationary but I'm currently out of town so I couldn't look it up. 

Thanks mate! 

The new figure: 

F4U-4 Max G at 112 m/s (400 km/h): 5.88 G

Awesome a/c! Right up there alongside the FW190!


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## renrich (Feb 14, 2008)

F4U4-empty-9205 lbs, combat-12420lbs, fighter, one extra tank-13530 lbs, bomber-two extra tanks(1000lb bomb)-14515 lbs, bomber-one extra tank(2000 lb bomb)-14412 lbs, rocket-one extra tank, 8 HVAR-14670 lbs


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## Soren (Feb 14, 2008)

I used 5,600 kg (12,400 lbs).


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## drgondog (Feb 14, 2008)

Soren said:


> I used 5,600 kg (12,400 lbs).



Soren - all the loads you are presenting are based on G for Design Limit loads, aren't they?

Interesting but the most likely situation for experiencing a limit G load in any of those fighters is pulling out of a dive. Quite a few pilots would lose consciousness quickly near that level, particularly w/o G suit. 

Having said that I suppose it is nice to think I still have wings and tail after I regain my senses?

Out of curiosity, what does the F4U Flight Manual say is the weight the Limit Load limit is tagged to? ie. for the 51 it was 8,000 for the 8G limit... which was neither empty nor normal mission profile (but closer to 51B w/o fuse tank than to P-51D).


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## Soren (Feb 14, 2008)

No the G-loads I'm presenting are the max the a/c can pull at the specified speed, in this case 112 m/s (400 km/h). And 400 km/h was below the average speed at which dogfighting was taking place by 42 and onwards. In a pull out from a dive much higher G forces could be pulled, forces way exceeding the maximum load limit of the airframe.

I don't know the load limit for the F4U, but I'll look for it in the POH when I get home.


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## drgondog (Feb 14, 2008)

Soren said:


> No the G-loads I'm presenting are the max the a/c can pull at the specified speed, in this case 112 m/s (400 km/h). And 400 km/h was below the average speed at which dogfighting was taking place by 42 and onwards. In a pull out from a dive much higher G forces could be pulled, forces way exceeding the maximum load limit of the airframe.
> 
> I don't know the load limit for the F4U, but I'll look for it in the POH when I get home.



I got that Soren. 

I think what I meant was, that very few fighters were going to go very far in the horizontal at 400mph. They might enter at that speed but wouldn't have the power to sustain it. On the other hand it's easy to find 400mph and 6 G's recovering from a dive. You might find it in a rolling pull out (and be delighted you kept your tail)

Gene/Crump did an excellent job showing the G limits in sustained turns for all the important birds which you noted also. From recall I seem to remember 3-3.5 G's for both the 51 and the Fw 190 in the 280mph range as 'peak' for some sustained period. I think the curves were representative for the energy available to sustain such high G turns. 

Again, I dealing only from my faulty and ancient memory. I could look those up but I'm too lazy right now.


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## Soren (Feb 14, 2008)

Yes Crumpp did an excellent analysis.

The P-51D was able to sustain a max of ~3 G, the FW190A8 slightly more, the Dora-9 much more. The FW190 is esp. superior in sustained turn rates at slow to medium speeds. His charts also demonstrated how close the 109 Spit are in terms of turn performance.


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## Soren (Feb 14, 2008)

drgondog said:


> I got that Soren.
> 
> I think what I meant was, that very few fighters were going to go very far in the horizontal at 400mph. They might enter at that speed but wouldn't have the power to sustain it. On the other hand it's easy to find 400mph and 6 G's recovering from a dive. You might find it in a rolling pull out (and be delighted you kept your tail)
> .




Roger that Bill, that is why timing is so important in real dogfights. A P-51 might be straight behind a FW190 and chasing it, and then the FW190 suddenly knives hard left pulling 6 G, the P-51 is completely unable to follow this maneuver as not only does the 190 start off first but it also enters the bank angle much faster. The P-51 will overshoot. It's the same if you close on an enemy fast and he suddenly turns into you, forcing a lead you can't possibly pull at that speed.

The best thing to do in both situations is climb, esp. when you're up against a more agile fighter such as the 190.


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## drgondog (Feb 14, 2008)

Soren said:


> Roger that Bill, that is why timing is so important in real dogfights. A P-51 might be straight behind a FW190 and chasing it, and then the FW190 suddenly knives hard left pulling 6 G, the P-51 is completely unable to follow this maneuver as not only does the 190 start off first but it also enters the bank angle much faster. The P-51 will overshoot. It's the same if you close on an enemy fast and he suddenly turns into you, forcing a lead you can't possibly pull at that speed.
> 
> The best thing to do in both situations is climb, esp. when you're up against a more agile fighter such as the 190.



A good manuever, except the Fw 190 stalled badly trying to pull a turn so tight he was pulling 6 g's.. or he misjugdged the distance and pulled into his turn too soon, and as he stalled out pulling the high g's the pesky 51 pilot nailed him in recovery (just kidding Soren)

More likely the 51 pilot pulls into a high scissor and cuts the circle or keeps on going, but shouln't waste his energy trying to stay in a turn like that when he has so much more energy? At least I hope I wouldn't. Might be like a F-4 trying to stay horizontal with a Mig 17..

And, if the Fw 190A is at 25,000 feet trying this he is having less fun than he wants today - pilot skill being similar. He is having more fun with a Dora but still at an energy disadvantage with an aircraft equal or nearly equal..

All in fun

Bill


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## renrich (Feb 15, 2008)

To me, I believe that many of us on this forum tend to use the term "dogfight" incorrectly in the context of WW2. If, for instance,  you look at flight tests done by USN of A6Ms versus Navy fighters, they say "DO NOT DOGFIGHT WITH A ZERO," which, to me, means getting into a slow, turning fight in the horizontal. All this discussion about pulling Gs at 300 or 400 mph in WW2 means to me that the ACM in that particular fight was not "dogfighting" If you read Bob Johnsons's book, few, if any kills he had were "dogfights" I know these are modern terms but in Shaw's book on ACM (it is packed so I can't remember the name of the book) he uses the terms "angles or energy fights" It would be interesting to know how many encounters in WW2 in the ETO were angles(dogfights) or energy fights. There may be another category which I believe was the by far dominant category, find oneself on an unsuspecting enemies six with a no deflection shot and shoot him down (maybe that is called a sniper fight). My point is (if there is one) that we may put too much emphasis on "dogfighting" qualities when not that much of that category was done.


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## Soren (Feb 15, 2008)

drgondog said:


> A good manuever, except the Fw 190 stalled badly trying to pull a turn so tight he was pulling 6 g's.. or he misjugdged the distance and pulled into his turn too soon, and as he stalled out pulling the high g's the pesky 51 pilot nailed him in recovery (just kidding Soren)
> 
> More likely the 51 pilot pulls into a high scissor and cuts the circle or keeps on going, but shouln't waste his energy trying to stay in a turn like that when he has so much more energy? At least I hope I wouldn't. Might be like a F-4 trying to stay horizontal with a Mig 17..
> 
> ...



The FW190 stalled no more badly in a turn than the P-51 (The Laminar airfoils means sharp and unpredictable stalls in high G turns), infact there'd be more warning in the FW190 if the ailerons are correctly adjusted. If you read the reports made by the RAE AFDU whilst flying the FW190G3 Jabo it notes the very mild stalling characteristics of the a/c and the ample amount of warning given. (Post war USAAF tests note the same with a underpowered Dora)

The problem with the FW190 is that its got so light controls that if you're not used to it you can easily pull too much and cause the a/c to stall, while an experienced pilot would know exactly how much to pull before stalling. FW190 pilots all note they easily felt the buffeting when pulling high G turns and knew when not to pull any tighter.

At low to medium alt the P-51 is better off not trying to dogfight a FW190 as the FW190 turns tighter and has a better sustained turn rate, so climbing would be the best choice. At 25,000 ft I agree completely that a FW190A would be allot better off doing Split S's and head for the deck instead of hanging around in Mustang territory, whilst a Dora-9 could stay and fight with its better performance. (You'd have to go bloody high for the P-51 to gain a power advantage over the Dora-9)


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## drgondog (Feb 15, 2008)

Soren said:


> The FW190 stalled no more badly in a turn than the P-51 (The Laminar airfoils means sharp and unpredictable stalls in high G turns), infact there'd be more warning in the FW190 if the ailerons are correctly adjusted. If you read the reports made by the RAE AFDU whilst flying the FW190G3 Jabo it notes the very mild stalling characteristics of the a/c and the ample amount of warning given. (Post war USAAF tests note the same with a underpowered Dora)
> 
> The problem with the FW190 is that its got so light controls that if you're not used to it you can easily pull too much and cause the a/c to stall, while an experienced pilot would know exactly how much to pull before stalling. FW190 pilots all note they easily felt the buffeting when pulling high G turns and knew when not to pull any tighter.
> 
> At low to medium alt the P-51 is better off not trying to dogfight a FW190 as the FW190 turns tighter and has a better sustained turn rate, so climbing would be the best choice. At 25,000 ft I agree completely that a FW190A would be allot better off doing Split S's and head for the deck instead of hanging around in Mustang territory, whilst a Dora-9 could stay and fight with its better performance. (You'd have to go bloody high for the P-51 to gain a power advantage over the Dora-9)



Soren - My only point in pulling your leg is that BOTH would pretty much stall out in a 4G turn at any altitude at 400mph, much worse as the G's (attempted) increased. 

F-16s with inclined seats, great T/W ratio (>1) and G suits can pull more sustained G's than the pilot. 

By comparison the 51 and 190 had minimal power(and Thrust) to weight ratios and could only achieve even 3-3 1/2 Gs for limited time before stalling out. Even then the air speed would be bleeding away at an alarming rate 

As to the other judgements, the airplane was not as much a factor as the pilots and tactical advantage... all the airplanes we are talking about had areas of superiority and inferiority in pure flight test scenarios in comparison.

Regards,

Bill


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## Glider (Feb 15, 2008)

Soren, 
Can I ask where you get the information that the Laminar airfoils in a P51 would means sharp and unpredictable stalls in high G turns.

The Pilots notes disagree pointing out that its stall is mild and there is little tendancy to drop into a spin.


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## renrich (Feb 15, 2008)

Hmmmmm, I know we all have problems with Eric Browns 's extreme bias toward certain AC but in "Duels in the Sky" he is an unabashed fan of the FW190, saying when it first appeared it was the most advanced fighter in the world. He says the A4 appearing a year later maintained that status for a while. However, "stalling speed in clean configuration was 127 mph. The stall came suddenly and virtually without warning, the port wing dropping so violently that the Ac almost inverted itself. This proved to be the fighters Achilles heel, for if it was pulled into a "g" stall in a tight turn, it would flick into the opposite bank and, unless the pilot had his wits about him, into an incipient spin." Interestingly, the USN flight test comparing the A4 to Navy AC reported the same characteristics-stall with little warning, aileron reversal in tight turns to left, turning to right tends to drop nose and dive.


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## drgondog (Feb 15, 2008)

Glider said:


> Soren,
> Can I ask where you get the information that the Laminar airfoils in a P51 would means sharp and unpredictable stalls in high G turns.
> 
> *I can tell you from personal experience that a LOW speed stall in a turn for a 51 will get your attention. *
> ...



Glider - The classic stall in level or climbing flight is gentle and predictible. 

The danger (to both a Fw 190 and a 51 in a high speed turning/manuever stall) is that you can end up in a flat spin if you aren't on your toes. I think the Fw 190 had the reputation of recovering from a spin better and faster than a 51. 

You do not want to be tinkering with spins in 51s if avoidable


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## Glider (Feb 15, 2008)

From the other postings the 190 doesn't seem to be much better


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## Soren (Feb 15, 2008)

Bill,

We agree.

Glider,

Bill is right, the P-51 suffers from unpredictable and dangerous stalls in high G turns. Unlike the FW-190 which recovers emmidiately from a stall a P-51 will often loose 9,000 - 10,000 ft in a spin.

The FW-190 has a very predictable stall if the ailerons are correctly adjusted, something which clearly demonstrated with EB-104 and the Dora tested by the USAAF:

From RAE report (G3 Jabo):
_G. Stalls Stall Warning.

The airplane has a gentle stall and controls remain effective up to the stall. Adequate warning of the stall is given by shaking of the airplane and controls._

From post war USAAF report (Dora):






The above agrees completely with what LW veterans say.

Eric Brown notes the aileron reversal which in itself is a clear sign of ill adjusted ailerons, and so is the unpredictable stall as proper adjustment would ensure ample warning of a stall. The waaay premature stalling speed of the airplane at 127 mph is also yet another clear indication of ill adjusted ailerons.


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## drgondog (Feb 15, 2008)

Soren said:


> Bill,
> 
> We agree.
> 
> ...



Soren - I would doubt seriously that there is much to choose from at medium and high speed manuevers in context of stall and stall warning betweeen these two ships.


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## Soren (Feb 15, 2008)

I agree Bill, the only difference would be the nasty spin the P-51 has a habbit of entering, quite a few -51 pilots have lost their lives to this, one very recently.

Bottom line however is, the FW190 P-51 both give plenty of warning of a stall.


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## drgondog (Feb 15, 2008)

Soren said:


> I agree Bill, the only difference would be the nasty spin the P-51 has a habbit of entering, quite a few -51 pilots have lost their lives to this, one very recently.
> 
> Bottom line however is, the FW190 P-51 both give plenty of warning of a stall.



I basically agree - don't push the Mustang into a spin, especially an inverted one.. but I wouldn't describe it as a habit except for possibility that lesser skilled/time pilots would be more prone to this before they had a feel for the airplane. 

I would have classified myself this way. This is NOT an airplane a 200 hour total time pilot should be yanking all over the sky. There are consequences.

Having said that, my experience with it was that it was a Delight to fly - with few nasty surprises. The low speed turning stall was one, and the 20+ degree flap condition, torque stall at low speed is a killer at low altitude.


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## FLYBOYJ (Feb 15, 2008)

Soren said:


> quite a few -51 pilots have lost their lives to this, one very recently.


There have been 2 spin stall P-51 accidents in the past 10 years, the last two in Hampstead, NC in November of 2000, the other in Urbana, IN in Feb. 2003. In the first accident the pilot was taking off and stalled, spun when turning crosswind - the NTSB attributed that to the pilot not maintaining a speed above Vso on takeoff. In reading the NTSB report it seems the pilot was "shoving" the aircraft into the air as he lifted off within 1000'. This was confirmed by witnesses on the ground. The Second accident occurred because the pilot spun the aircraft at 1,500 feet AGL. He was seen doing low altitude aerobatics by several witnesses. According to the NTSB report the POH for this aircraft allowed power off spins only if they are started above 12,000 feet.

In both cases this seems to be attributed to pilot error and not the fault of any characteristic of the aircraft.


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## Soren (Feb 15, 2008)

Glider said:


> Soren,
> Can I ask where you get the information that the Laminar airfoils in a P51 would means sharp and unpredictable stalls in high G turns.



Common aerodynamics buddy. The unpredictable dangerous stallling characteristics of a laminar flow airfoil is one of the very well known facts about this type of airfoil.

Laminar flow airfoils have rather sharp leading edges, leading to a low critical AoA and the sharp and unpredictable stalls.

Some basic info:
_"Laminar flow airfoils were originally developed for the purpose of making an airplane fly faster. The laminar flow wing is usually thinner than the conventional airfoil, the leading edge is more pointed and its upper and lower surfaces are nearly symmetrical. The major and most important difference between the two types of airfoil is this, the thickest part of a laminar wing occurs at 50% chord while in the conventional design the thickest part is at 25% chord.

The effect achieved by this type of design of a wing is to maintain the laminar flow of air throughout a greater percentage of the chord of the wing and to control the transition point. Drag is therefore considerably reduced since the laminar airfoil takes less energy to slide through the air. The pressure distribution on the laminar flow wing is much more even since the camber of the wing from the leading edge to the point of maximum camber is more gradual than on the conventional airfoil. *However, at the point of stall, the transition point moves more rapidly forward*."_


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## kool kitty89 (Mar 11, 2008)

The High 'G' stall characteristics of the Fw-190 were caused by the wings warping which resulted in eliptical lift distribution. Correct? Similar to laminar flow wings eliptical wings have sudden stalls as the wing tends to stall "all at once" along the entire span. 

However this was not as pronounced on a/c with semi-eliptical wings such as the P-47 with an eliptical trailing edge and a straight leading edge. (unlike the Spitfire which had a near fully eliptical wing, the He 112 even moreso)

The P-51's wing though wasn't a "true" laminar flow airfoil iirc as it was adjusted to be a semi-laminar flow type with the chord farther foreward than 50% (closer to 35%) with a being a compromise between low drag and stall characteristcs. Iv'e read on this on here (on the forum) but haven't seen many sourses though.


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## drgondog (Mar 12, 2008)

FLYBOYJ said:


> There have been 2 spin stall P-51 accidents in the past 10 years, the last two in Hampstead, NC in November of 2000, the other in Urbana, IN in Feb. 2003. In the first accident the pilot was taking off and stalled, spun when turning crosswind - the NTSB attributed that to the pilot not maintaining a speed above Vso on takeoff. In reading the NTSB report it seems the pilot was "shoving" the aircraft into the air as he lifted off within 1000'. This was confirmed by witnesses on the ground. The Second accident occurred because the pilot spun the aircraft at 1,500 feet AGL. He was seen doing low altitude aerobatics by several witnesses. According to the NTSB report the POH for this aircraft allowed power off spins only if they are started above 12,000 feet.
> 
> In both cases this seems to be attributed to pilot error and not the fault of any characteristic of the aircraft.



Joe - that very accurately summarizes the cautions and the consequences. 

I got caught in the low speed stall once and only once and snapped it but avoided a spin. It scared the living bejeesus out of me - but I had warning as the stick was 'shuddering' and I wanted to see how far I could push it in a turn. My father was in front and guiding me through the process. It was dramatic but easily recoverable

I also experienced the torque stall with same consequences that I think I told you about earlier.

Both would havce been fatal at low altitude but not a problem otherwise.

Too much is being made about P-51 Wing. It was a sweet and honest airplane and even with my relatively low time a fairly easy airplane to fly. 

I always thought, and still think the AT-6 was harder to fly from context of a.) taking off in a straight line and b.) landing in a straight line with a little cross wind.


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## drgondog (Mar 12, 2008)

kool kitty89 said:


> The High 'G' stall characteristics of the Fw-190 were caused by the wings warping which resulted in eliptical lift distribution. Correct? Similar to laminar flow wings eliptical wings have sudden stalls as the wing tends to stall "all at once" along the entire span.
> 
> However this was not as pronounced on a/c with semi-eliptical wings such as the P-47 with an eliptical trailing edge and a straight leading edge. (unlike the Spitfire which had a near fully eliptical wing, the He 112 even moreso)
> 
> The P-51's wing though wasn't a "true" laminar flow airfoil iirc as it was adjusted to be a semi-laminar flow type with the chord farther foreward than 50% (closer to 35%) with a being a compromise between low drag and stall characteristcs. Iv'e read on this on here (on the forum) but haven't seen many sourses though.



KK _ the two best books on this subject are Mustang by Gruenhagen and the other book (can't remember title) written about Edgar Schmeud who was the Mustang Design engineer.

Both books discuss the evolution of the Mustang airfoil from a NACA series laminar flow airfoils with max thickness at 40% chord. It was an EVOLVED and uniques design but very close to the 40 series with a 15% maximum thickness.

It had a lower CL than classical airfoils with some camber but it DID delay boundary layer separation over those comparative airfoils


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## Soren (Mar 12, 2008)

> It had a lower CL than classical airfoils with some camber but it DID delay boundary layer separation over those comparative airfoils



In straight flight. The Critical AoA was lower.


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## kool kitty89 (Mar 15, 2008)

The P-39 also had a good warnig before a stall (buffetting) but if you jerked the controls or pused too close to a stall you could enter a nasty spin. The P-51 was similar but much less sensitive to sharp imputs by comparison. Though a snap stall (and spin) could still be entered from rapid elevator force and this could also be used as an escape tactic if the pilot knew how to handel it and had enough altitude. (the plane could loose several thousand feet before recovering)


_View: https://www.youtube.com/watch?v=NlfOWZHEGNk_


_View: https://www.youtube.com/watch?v=mdCm5z2RpI8_


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## kool kitty89 (Mar 19, 2008)

Just because the WWII G-suit used the same mechanism as Korea/Vietnam/Modern suits doesn't necessarily mean they will be as effective or efficient in operation. (though they may have been)

That said, does anyone have figures or knowledge on the effectiveness of the G-suits in question?


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## FLYBOYJ (Mar 19, 2008)

kool kitty89 said:


> Just because the WWII G-suit used the same mechanism as Korea/Vietnam/Modern suits doesn't necessarily mean they will be as effective or efficient in operation.
> 
> That said, does anyone have figures or knoledge on the effectiveness of the G-suits in question?


Not so much effectiveness, more comfort than anything else, but in principal they worked the same way and the net result was probably the same as well.


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## alejandro_ (Apr 14, 2010)

I will post my question here to avoid opening another topic. I am looking for data on anti-gravity suits fielded by US aircraft during World War 2. Barret Tillman gives some information oin his book "Hellcat, the F6F in World War 2". In the US Navy they were known as "zoot suits", and were first tried by three instructors at Cecil field (Florida) in early 1943. One of them, Lt. E.S McCuskey, a tactical officer in VF-8, immediately recognized the value of the suit, as it allowed to pull 1/1.5g more, and without any penalty weight.

McCuskey then inquired about the Z suits and was told that the west coast evaluation team had decided against their use. He then contacted the manufacturer directly (Berger Brothers), and got the suits. Permission was obtained to equip VF-8 with the Z suits, and this made them the only unit in the US Navy to be equipped with them.

Russell Kyler, a P-47 pilot, also mentions the use of G suits in 56 FG (20:00). It seems that Berger suits were available in large numbers since June 1944.

Timeless Voices

Few questions:

- What is the difference between Berger and Z suit?
- Why did the Navy rejected the Z suit when it was so highly regarded by the unit who tried it?


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