Spitfire IX v. FW 190A

[Gaston]

The Spitfire got more power per unite than Fw-190 and its Wing Load much lower than Fw190 how do you guys possibly convinced that Fw.190 are capable to overwhelming the Spitfire?

Above is the wing load ranking list you can see.

How about listening to the opinion of a 32 kill ace: Would that change anything?:

http://img30.imageshack.us/img30/4716/jjohnsononfw190.jpg

Or Hurricane pilot John Weir:

"The Hurricane was more manoeuvrable than the Spit and, and the Spit was probably, we (Hurricane pilots) could turn one way tighter than the Germans could on a, on a, on a Messerschmitt, but the Focke Wulf could turn the same as we could and, they kept on catching up, you know."

Or(ad nauseam)...: -Squadron Leader Alan Deere, (Osprey Spit MkV aces 1941-45, Ch. 3, p. 2: "Never had I seen the Hun stay and fight it out as these Focke-Wulf pilots were doing... In Me-109s the Hun tactic had always followed the same pattern- a quick pass and away, sound tactics against Spitfires and their SUPERIOR TURNING CIRCLE. Not so these 190 pilots: They were full of confidence..."

8:1 for the FW-190As that day...



Note that all British and Soviet tests have widely indicated (especially the British ones), that there was NO significant differences in sustained turn rates between the Spitfire Mk V and the Mk IX, this even remaining true (with a bit of difficulty) at 30 000 ft...

So given that, the Johnny Johnson outcome above would have been nearly identical with a Mk IX... It is his tactics that were wrong...

The British Mk V/Mk IX tests even described that the only advantage the Mk IX could use, to gain the upper hand over the Mk V, was to use its tremendous climb rate on the vertical, and then dive on the Mk V... :

Spitfire IX Tactical Trials

Quote: "Manoeuvrability

20......... The Spitfire IX was compared with a Spitfire VC for turning circles and dog-fighting at heights between 15,000 and 30,000 feet. At 15,000 feet there was little to choose between the two aircraft although the superior speed and climb of the Spitfire IX enabled it to break off its attack by climbing away and then attacking in a dive. This manoeuvre was assisted by the negative 'G' carburettor, as it was possible to change rapidly from climb to dive without the engine cutting. At 30,000 feet there is still little to choose between the two aircraft in manoeurvrability, but the superiority in speed and climb of the Spitfire IX becomes outstanding. The pilot of the Spitfire VC found it difficult to maintain a steep turn without losing height, whereas the pilot of the Spitfire IX found that he had a large reserve of power which enabled him to maintain height without trouble. The all-round performance of the Spitfire IX at 30,000 feet is most impressive."

No doubt this is exactly the same tactics that were successfully used by the Mk IX to redress the balance with the FW-190A... NOT turn-fighting... Note Eric Brown's claim to the opposite from his own personal combat with the FW-190A proved so ineffective for both fighters, holding to their supposed respective "best" tactics, that they both decided to call it quits...

No hits, or even danger of hits, from either side is NOT a sign of effective use of their respective aircrafts... They called it quits because they were both getting nowhere, and of course the FW-190A is pathetic in vertical maneuvers, as the "sinking" dive pull-out and so-so climb rate should make obvious...

I'll re-iterate again that I am not argueing the Spitfire does not have a tighter unsustained turn radius than the FW-190A... The mistake here is to assume that this tighter radius necessarily translates into sustained turns when pulled from the nose over several 360s... It doesn't...

Gaston

 

[Gaston]

Gaston the major problem with these discussions are three fold.

First, you don't display the requisite math and physics to question your assumptions ('ie throttle down in successive 360 degree constant altitude turns - pursuing or being pursued.) Based on that you have no reason to question why the physics and aerodynamics prove that the tightest possible turn with fastest rate of turn is at the stall speed of that airplane at say, 3g, for the high performing fighters of WWII... and the stalling speed for a high G banked turn is considerably higher than for level, low rpm flight. It is also operating at CLmax and pushing the bank angle or reducing the thrust is a recipe for disaster. Dropping flaps increases CLmax, but also increases induced drag and 'moving pitch to coarse' further increases drag - and therefore the stall speed moves to a higher point...

Second, you select a portfolio of USAAF Encounter Reports that present you with the perspective of the 'winning pilot' but have no ancillary facts like a.) the skill of the opposing pilot, b.) the attitude of the aircraft in the manuever (climbing, level, spiral down, turn roll, turn, reverse, turn, enemy fighter conditions (engine not 100%, using lower boost than achievable, thereby losing power from optimal), etc, etc. In other words you don't have any validation or verification of the combat parameters other than the singular perspective of the winning pilot.

A very good example of questions that could be asked is in the May 24 Encounter report from Hanseman. It "Seems Like" Hanseman enters the combat going after the Me 109 approaching the runway (gear down, on final, and low Rpm, flaps deployed, etc) causing Hanseman to 'throttle down' just to slow down for a good shot at the sitting duck without over running him.

Coming out of that engagement, he spotted the second one. It was high when he made his pass on the one on final. Where was it now? above and in front? off to one side at same altitude? Did he throttle up to get airspeed and turn to engage or what?

If he entered the turn with the 109, was it trying to turn on him, or escape and try to out turn Hanseman? What was the relative airspeed and altitude when the engagement began and each pilot had the other in sight.

Was the 109 pilot a low timer, or a pro, did he panic instead of throttling up and making for the airfield to get hanseman in range of the AA?

When Hanseman 'down throttled' how much airspeed did he have and was it significantly higher than his opponent. If so, the 109 would initially out turn him w/o much effort and if he wished to turn with the guy he needed to slow down. If he was in a high g, near max turn, he was skirting disaster with reducing power (which also reduces thrust, which in the case of near stall - takes you into stall unless you quickly push forward on the stick to stabilize.

As the turn continued, was the 109 pilot taking advantage of good acceleration and better angle of climb to try to corkscrew out of the manuever and get himself some energy or even room to bail out?

Did the 109 pilot see the other 51s and alter his turn accordingly knowing he had very little time left for survival. How did he adjust, accordingly?

Can you plot with high confidence what each flight path and energy state was for each aircraft? Do you know that both ships and pilots were operating at max capability for their respective fighters?

Ditto for every Encounter Report you have read.

Last, there is little enough fact based information regarding competitive performance among the various aircraft - and the engineering precision to record the data (dash number of engine, boost, WI/No WI, engine rpm and Hp, engine spec'd or as recovered when captured for enemy aircraft, pilot skill (i.e willing to push an airplane to stall speed at low altitude where there is no hope of recovering from a violent stall departure)..

I'll post again here the Hanseman combat report, so that anyone loosely following here can judge for themselves if the situation Hanseman describes is clear...:
http://www.spitfireperformance.com/mustang/combat-reports/339-hanseman-24may44.jpg


Fully correlating this are at least 6 other Merlin P-51 combat reports with the exact same 3 downthrottling steps at low speed, including the strange coarser prop pitch at low speeds...

Further correlating the use of downthrottling is a FW-190A-8 Western Ace describing using the FW-190A-8 ONLY as a downthrottled low speed horizontal turn fighter, preparing for the merge with P-51Ds by downthrottling and popping the flaps long before the merge... Doing this "I feared no other aircraft in my FW-190A-8"... And he described the three ailerons type he could choose from, how he chose the widest chord for low speed performance at all costs, and added field-installed hinge "spacers" to widen the aileron chord further to catch better the low speed stall while turning...

He then described how, with the wider wood prop, reduced throttle and wider ailerons he reversed a tailing P-51D on the deck in two 360 turns, the formerly-tailing P-51D almost straining into a stall just before being hit and shot down...

The relative who posted this direct from the pilot's mouth did not say the pilot's name, and this Aces High thread was pulled by "Hitech" after many pages as it wasn't in line with his obviously well-set notions on the issue... (Note Hitech is also a recent P-51D pilot)

But even if you think that this above FW-190A-8 ace thing was all a fraud, including all that business about spacers on the aileron hinges, you still have a third aircraft type to deal with, along with another multiple ace pilot singing the praises of downthrottling...:

virtualpilots.fi: 109myths

Quote:

"I learned to fly with the "Cannon-Mersu" (MT-461). I found that when fighter pilots got in a battle, they usually applied full power and then began to turn. In the same situation I used to decrease power, and with lower speed was able to turn equally well. I shot down at least one Mustang (on 4th July 1944) in turning fight. I was hanging behind one, but I could not get enough deflection. Then the pilot made an error: he pulled too much, and stalling, had to loosen his turn. That gave me the chance of getting deflection and shooting him down. It was not impossible to dogfight flying a three-cannon Messerschmitt."
" When the enemy decreased power, I used to throttle back even more. In a high speed the turning radius is wider, using less speed I was able to out-turn him having a shorter turning radius. Then you got the deflection, unless the adversary did not spot me in time and for example banked below me. 250kmh seemed to be the optimal speed."
- Kyösti Karhila, Finnish fighter ace. 32 victories.


Notice the extraordinary quoted "optimal sustained turn speed" for the Me-109G-6: A measly 160 MPH (250 km/h) or barely 60 MPH above stall was optimal...

Now downthrottling, in the sadly confused currently accepted theory sense, should apply only if you are above "Corner Speed"... Below that it makes no sense to downthrottle for the highest turn rate...

"Corner Speed", the lowest speed at which a given amount of Gs can be reached, reached, ie: regardless of sustainability, is for WWII aircrafts usually given for 6 Gs, since that is pretty much the pilot's practical limit without G suit...

For most if not all prop WWII fighters, the 6 G "Corner Speed" is calculated to be between 220 MPH and 280 MPH: They almost all fall, according to aeronautic engineer math, in between these two values... Sort of a high mid-range of speeds: Makes sense intuitively...

So 220-280 MPH is the range of the lowest speed to reach 6G...

Does anyone know how well the aeronautic engineer math did when that value was actually looked for and tested in flight for the P-51D, FG-1, F6F-5, P-47D?

I await the answer I am sure someone has out there... Hint: The aeronautic engineer math didn't do too well...

Gaston

 

[drgondog]

I'll post again here the Hanseman combat report, so that anyone loosely following here can judge for themselves if the situation Hanseman describes is clear...:
http://www.spitfireperformance.com/mustang/combat-reports/339-hanseman-24may44.jpg

Gaston - use YOUR intellect and quit trying to use someone else's narratives

Fully correlating this are at least 6 other Merlin P-51 combat reports with the exact same 3 downthrottling steps at low speed, including the strange coarser prop pitch at low speeds...

If an airplane is entering a turn at relatively high speed, with an equally performing aircraft in a turn at lower speed - and he wishes to pursue it - then he must reduce his speed to enter the turn. If he doesn't lower his speed he will remain 'faster' but his RATE of turn will be slower (to you that means it will take Longer to complete a 360 degree turn) and his Radius of turn will be greater. If he engages under these circumstances the Other aircraft will eventually end up on His tail.

So, if he wishes to slow down fast he not only reduces throttle (that is reducing power to the prop), but he increases drag by changing pitch from Fine to Coarse-(er). The latter changes the angle of attack to Increase the blade pitch creating more drag on the propeller disk - which slows the airplane down rapidly.

Hence - not 'Strange' if you want to slow down.

Further correlating the use of downthrottling is a FW-190A-8 Western Ace describing using the FW-190A-8 ONLY as a downthrottled low speed horizontal turn fighter, preparing for the merge with P-51Ds by downthrottling and popping the flaps long before the merge... Doing this "I feared no other aircraft in my FW-190A-8"... And he described the three ailerons type he could choose from, how he chose the widest chord for low speed performance at all costs, and added field-installed hinge "spacers" to widen the aileron chord further to catch better the low speed stall while turning...

He then described how, with the wider wood prop, reduced throttle and wider ailerons he reversed a tailing P-51D on the deck in two 360 turns, the formerly-tailing P-51D almost straining into a stall just before being hit and shot down...

The relative who posted this direct from the pilot's mouth did not say the pilot's name, and this Aces High thread was pulled by "Hitech" after many pages as it wasn't in line with his obviously well-set notions on the issue... (Note Hitech is also a recent P-51D pilot)

But even if you think that this above FW-190A-8 ace thing was all a fraud, including all that business about spacers on the aileron hinges, you still have a third aircraft type to deal with, along with another multiple ace pilot singing the praises of downthrottling...:

virtualpilots.fi: 109myths

Quote:

"I learned to fly with the "Cannon-Mersu" (MT-461). I found that when fighter pilots got in a battle, they usually applied full power and then began to turn. In the same situation I used to decrease power, and with lower speed was able to turn equally well. I shot down at least one Mustang (on 4th July 1944) in turning fight. I was hanging behind one, but I could not get enough deflection. Then the pilot made an error: he pulled too much, and stalling, had to loosen his turn. That gave me the chance of getting deflection and shooting him down. It was not impossible to dogfight flying a three-cannon Messerschmitt."
" When the enemy decreased power, I used to throttle back even more. In a high speed the turning radius is wider, using less speed I was able to out-turn him having a shorter turning radius. Then you got the deflection, unless the adversary did not spot me in time and for example banked below me. 250kmh seemed to be the optimal speed."
- Kyösti Karhila, Finnish fighter ace. 32 victories.


Notice the extraordinary quoted "optimal sustained turn speed" for the Me-109G-6: A measly 160 MPH (250 km/h) or barely 60 MPH above stall was optimal...

Ah Grasshopper, stall speed for a banked turn is much higher than for level flight. 160mph is also the approximate stall speed for a P-51D at 9800 pounds, 1600 hp, 3000 rpm, 3g turn... whereas the stall speed for the same P-51D in level flight is approximately 94mph. Your would not be so great if you understood trig, and the relationship between CLmax and stall, and further understood that in a turn the airplane increase relative angle of attack as the bank angle increases..I will post a few images below to help you work throught these concepts visually.

Now downthrottling, in the sadly confused currently accepted theory sense, should apply only if you are above "Corner Speed"... Below that it makes no sense to downthrottle for the highest turn rate...

Ah, Grasshopper - 'Corner Speed' is a very meaningful term describing the maximum G versus velocity which the airplane is intended to remain 'intact' - that speed may be reached in a near terminal dive and pullout for WWII fighters (i.e' 'vertical turn for you)... but no WWII fighter had the thrust to sustain a 360 degree turn at much more than 2.8 to 3.1 G - and the velocity in that turn (just before stall) would be ~150 to 170 mph. An F-16? different story.

In your spare time look up V-n Diagram to further explain Corner speeds (two) for positive and negative design limits for each airframe/engine combination.

Simply, exceed Corner Speed at your own risk sayeth the manufacturer, for to exceed such risketh loss of critical components of your metal steed - like your wing...

When you wish to dabble in the arcane art of science and math, and begin to understand the relationships between Weight, Lift, Wing Area and Density of air, you may find pearls of wisdom to bridge ignorance of the laws of the universe (Newtons laws at least)

V*=Sqrt [2*nmax*(W/S)/({Rho@Sl*CLmax)] at sea Level

Where V*=corner Speed
nmax = airframe mfr Limit Load factor (positive and negative)
CLmax = maximum Lift Coefficient (stall break point)
W= weight
S= wing area
rho@SL=density of air at seal level


"Corner Speed", the lowest speed at which a given amount of Gs can be reached, reached, ie: regardless of sustainability, is for WWII aircrafts usually given for 6 Gs, since that is pretty much the pilot's practical limit without G suit...

Correct, as noted above - and has nothing to do with any WWII aircraft in a sustained 360 degree turn.

For most if not all prop WWII fighters, the 6 G "Corner Speed" is calculated to be between 220 MPH and 280 MPH: They almost all fall, according to aeronautic engineer math, in between these two values... Sort of a high mid-range of speeds: Makes sense intuitively...

So 220-280 MPH is the range of the lowest speed to reach 6G...

So V*= Sqrt {[2*6.83/(.0023769*1.72)]*(W/S)} for SL in feet per sec. Remember to divide the final answer by 1.467fps/mph toget speed in miles per hour.

For a P51D at 9800 pounds, in a 6.83 G (Limit Load for a D at 9800lbs), CLmax=1.72, Wing Area at 233.2 sq ft, sea level density = .0023769 slugs

V*=Sqrt(140413) = 374.71fps = 255mph for the P-51D for limit load and 312mph for ultimate load at sea level. At 15000 ft the corner velocity = 322 mph for limit load and 394 mph for ultimate load.

At 10,000 feet, 6g (NOT G limit load for P-51D at 9800 pounds GW), the same velocity calculates to 278.6 mph - note, increasing the 'n' to 6.83 G Limit load for same GW, the CORNER Speed then is 297.2 mph.


You are parroting what you think you learned on the other threads but that is the math behind the discussion. Incidently the P-51A had a higher Corner Speed because it was lighter and had the same CLmax and wing area. The original design limit load by NAA was based on 8G at 8000 pounds gross weight

Does anyone know how well the aeronautic engineer math did when that value was actually looked for and tested in flight for the P-51D, FG-1, F6F-5, P-47D?

I await the answer I am sure someone has out there... Hint: The aeronautic engineer math didn't do too well...

Gaston

See Dean's "America's Hundred Thousand" for the results of the turn factors for the P-51D-15, P-47N, F4U-1, F6F-5 following the October 1944 Convention at Patuxent River.

And 'hint' the aero math worked very well in correlation with flight results. Also 'hint' Dean is an Aeronautical Engineer.

Pay particular close attention to the lift vector in a banked turn - which must increase as the aircraft banks at a steeper angle - necessary to provide a component of lift equal and opposite the vertical weight vector. To get that increase in lift vector for a given speed, the angle of attack on the wing has to increase to give a higher Coefficient of lift.. (that's when the pilot pulls on the stick 'thingy').. at some point in the stick pulling exercise, the pilot will pull the stick too far back - reach CLmax (stall) and his metal steed falleth out of the sky. Hope that helps!!

 

[claidemore]

How about listening to the opinion of a 32 kill ace: Would that change anything?:

http://img30.imageshack.us/img30/4716/jjohnsononfw190.jpg

Gaston

Johnsons story changes nothing. We don't know what altitudes the 190 and Mk V were at when combat began, we don't know if Johnson was above the 190? or level? We don't know what speeds they were at, we don't know who was flying the 190. We know 610 Sq was bounced earlier on at 10000 feet, but that's it so far as actual numbers.

Johnson was alone, had already made a decision to bug out, had used a large part of his ammo already (long burst at previous 190). He 'eased' towards the solitary plane and it 'snaked' towards him. He mentions greying out as he turned, indicating high G, which indicates high speed. You simply don't grey out when turning at low speed close to the stall. So... the Spitfire was pulling a lot of G in a fairly high speed turn with resulting large radius.

Johnson doesn't mention making a decision to attack the 190, he just says that he spotted it over the town and 'eased' towards it. Given his usual documented and successful tactic of attacking with alt advantage, we can make an assumption that he was above the 190. Alone, low on ammo, and being an extremely intelligent fellow, he would not have even approached an unknown fighter from below. So the 190 had to make a quick zoom climb to meet him head on (good tactic for a FW 190), thus bleeding off speed. Consequently when they went into that left hand turn, the 190 was turning at a much lower speed with a resultant small turn radius.
As soon as Johnson saw the 190 getting inside of him, he attempted to disengage. He was high enough to try a near vertical dive, and mentions the warning they had not to fly below 4000 feet, so the combat probably took place between 10000 and 4000 feet.
He makes another hard turn at the end of his dive, (indicating he had not given up on the Spits turn ability as a defensive move), and he makes another hard turn after he gets past the destroyer which he used to facilitate his escape. Johnson used two breaking turns after he had lost the initial turn fight, but the two breaking turns occurred during pursuit, when the 190 was at the same speed, or more likely closing with superior speed.

What this story does do is illustrate the weakness of relying on level turning in the initial stages of the fight. Had Johnson done just about any vertical manuever he would have ended up on the 190s tail, but he used a level turn and gave away the advantage to the slower plane.

Derating and downthrottling limits one to turnfighting, giving the advantage to the opposing fighter, ie it's a dumb thing to do.

 

[parsifal]

Guys excellent critiques, but I fear your efforts are being wasted. Somebody is just not listening, except to himself.

 

[drgondog]

I had an email exchange with RCAF pilot Warren Peglar who came to the 355th FG in July 1944, shot down a 109 and a 190 on August 3 and then two 109s on Sept 11.

During the latter mission, he shot down his first one at medium altitude, then chased and shot down a second on the deck when a third one got on his tail. He pulled into a hard turn but the 109 stayed inside his turn and had deflection on him.

In desparation Peglar dropped, and just as quickly, retracted his flaps.. then actuated his gear, but stopped from deploying and retracted. The effect was the 109 was finally forced 'outside' the turn but Peglar had run out of moves, was in a stall turn at near stall, full power - when his wingman slid in behind the 109 and terminated his fun.

Peglar said simply 'there was no way' he ever contemplated reducing power as he knew that would lead to a full blown stall.

 

[timshatz]

I've been in and out of this topic for a while and it seems to me the idea proposed is to slow down in an air brawl to allow the lower speed to give you a smaller turning radius. While I see the point, I wouldn't do it. Not if I wanted to go home in the airplane I came in.

Here is why:
- Against one other aircraft, you might get away with it. But dogfights tended to be slashing events where the guy who go you was not seen until too late (if at all). So while you're lowering your speed to get the edge on the guy, his wingman or some other guy swings down out of nowhere and pastes you. Not good.

-Dogfights are relatively rare events, most kills are "shoot and scoot" affairs. A low speed turn is a very limited value event in that world. It is more of desperation option than a skilled setup. It is not for nothing that many a "There I was, flat on my back..." starts with "I was out of AIRSPEED, altitude and ideas.".

-Even if you avoid the guy behind you with a low speed turn, you are still in an area full of hostile aircraft (most likely), flying slowly, the picture of fat, dumb and happy (even if you are thin, sharp and neurotic). Not conductive to a long life span.

The math says a slower aircraft will turn tighter. Ok. But it also makes you more of a target for other birds. Nice idea in theory, not smart in practice.

Just my .02 on it.

 

[Gaston]

See Dean's "America's Hundred Thousand" for the results of the turn factors for the P-51D-15, P-47N, F4U-1, F6F-5 following the October 1944 Convention at Patuxent River.

And 'hint' the aero math worked very well in correlation with flight results. Also 'hint' Dean is an Aeronautical Engineer.

Pay particular close attention to the lift vector in a banked turn - which must increase as the aircraft banks at a steeper angle - necessary to provide a component of lift equal and opposite the vertical weight vector. To get that increase in lift vector for a given speed, the angle of attack on the wing has to increase to give a higher Coefficient of lift.. (that's when the pilot pulls on the stick 'thingy').. at some point in the stick pulling exercise, the pilot will pull the stick too far back - reach CLmax (stall) and his metal steed falleth out of the sky. Hope that helps!!

-Yes I have read Americas hundred thousands....

Those turn comparison figures are nothing more than weight divided by wing area plus another few -crude- considerations: They are supported by no flight tests, as even the pilot preferences on the elevators performance make clear in the very same pages...


Overwhelmingly, such Aeronautic engineer math calculation peg WWII aircraft 6G Corner Speeds at between 220 MPH and around 270-280 MPH at most: The P-51D being usually quoted at 2.44 stall or 240 MPH, the Me-109G being the same but sometimes quoted a bit lower at 220-230 MPH...

Confirming this notion is a set of two complex 1940 graphs depicting turn "performance" of a Spitfire Mk I and a Me-109E... As expected these charts display the familiar "Doghouse" curve appearance which has NO, I repeat NO relevance to a piston-engine nose-driven WWII aircraft... Availability of a still barely in service Me-109E to the Brits in shape for months of testing in 1940 is also doubtful...

These two charts, very tellingly, have no later war counterparts: This is obviously because they were found to be complete aeronautic engineer nonsense and of no practical value for combat, otherwise 1944 pilots would have had them for every fighter type in existence...

Basically, if they cannot even locate correctly the 6G Corner Speed, they (engineers and test pilots of that fairly primitive time) know very little about turn behaviour (or how downthrottling may or may not help)... The front line pilots were the ones doing the real "testing" in other words, which is why so little is officially left of whatever their dicoveries were...

In 1989 an ACTUAL test was done by "The Society Of Experimental Test Pilots" , with MODERN instruments, allowing up to 6Gs at METO Power (Normal Power in WWII speak), or 325 MPH maximum speed for the P-51D Mustang at 10 000 ft.

The results: "Corner Speed is very close to the Maximum Level Speed on all 4 types: This meant an actual 6G "Corner Speed" of 320 MPH for the P-51D!!!!

This is 80 MPH above any previous "calculated" estimation... Confirming this, the same was true of the P-47D, FG-1 and F6F, all tested at the same time by the same team of modern professional test pilots in 1989...

IF full WEP had been allowed, I have the impression the prop load would have delayed the minimum speed to reach 6Gs even higher, maybe 340 MPH, and I think they noted the "Corner Speed" went up with more power, because they chose to put this "adjustable" statement on it: "Corner Speed is very close to the Maximum Level Speed"... Hint: Whatever that maximum level speed the power level might be set at...

So you can see what all those little WWII "doghouse" charts are worth when confronted with the actual reality...

This underlines what nonsense it is to claim downthrottling is in any way beneficial to the turn rate for the "accepted" reasons of being "above" Corner Speed (besides of course not overshooting, like in a straight line for instance): To be above the 6G "Corner Speed", in those old aircrafts, you have to be nearly in a steady dive!!!!!

Therefore the benefits of downthrottling in sustained level turns can ONLY be for some other reason: Not an issue of speed but of prop load in my view, which is why, in the Hanseman account, the benefit is clearly described as instantaneous, not delayed by a time-consuming deceleration to a lower speed...

Gaston

 

[drgondog]

-

Overwhelmingly, such Aeronautic engineer math calculation peg WWII aircraft 6G Corner Speeds at between 220 MPH and around 270-280 MPH at most: The P-51D being usually quoted at 2.44 stall or 240 MPH, the Me-109G being the same but sometimes quoted a bit lower at 220-230 MPH...

Let us take the above paragraph a piece at a time. First of all airframe weight has to be stated, as well as power applied, as well as altitude for anything you state to have relevance.

Second - you do not yet grasp 'Corner Speed'. To help you out it is a CALCULATED maximum speed for an applied load, such load being the CALCULATED maximum allowable limit load per the manufacturer's 'Do Not Exceed' instructions. When flight tests result in a broken bird, the engineers are trying to figure out whether the excessive stresses were due to sub maximum flight conditions (back to the drawing board), or in fact due to exceeding manufacturer's specifications.

Third - the number of WWII fighters that could ATTAIN anything near Corner Speed in a horizontal turn - is ZERO. The Corner Speed (Velocity at G load-Limit) could only be achieved in a manuever like a dive pull out or a very hard turn from a diving state where the velocities were far above level flight capability


These two charts, very tellingly, have no later war counterparts: This is obviously because they were found to be complete aeronautic engineer nonsense and of no practical value for combat, otherwise 1944 pilots would have had them for every fighter type in existence...

You may not conceive of the possibility, but fighter pilots were 'busy' in a fight and had little time to calculate whether they were near some design wall. Additionally, there were no accelerometers or a head's up display to present for the interested party what his current G load and speed were, along with a pretty red line to alert him that he was entering a 'deep kimchi' zone.

Basically, if they cannot even locate correctly the 6G Corner Speed, they (engineers and test pilots of that fairly primitive time) know very little about turn behaviour (or how downthrottling may or may not help)... The front line pilots were the ones doing the real "testing" in other words, which is why so little is officially left of whatever their dicoveries were...

Hogwash. Bovine Fecal matter.

In 1989 an ACTUAL test was done by "The Society Of Experimental Test Pilots" , with MODERN instruments, allowing up to 6Gs at METO Power (Normal Power in WWII speak), or 325 MPH maximum speed for the P-51D Mustang at 10 000 ft.

Show the report - and state the gross weight.. and the method of recording the accelerations.. .

The results: "Corner Speed is very close to the Maximum Level Speed on all 4 types: This meant an actual 6G "Corner Speed" of 320 MPH for the P-51D!!!!

Actual Flight Test results for P-51D-15 44-15342 dated June 15, 1945
P 51D Performance Test

Show 417mph at 67"/3000rpm at 10,000 feet - critical altitude for the 1650-7 Packard Merlin.

For this altitude and GW condition the Vmax should be:

V= sqrt {(6*2)/[.0023769*.7386*1.72]) *W/S}
= sqrt {12/[.00302]*(9660/233.2)}=sqrt (115920/[.704])=sqrt[164659] fps
=405.78fps = 276.6 mph @ 6G.

Actual 'Corner Speed' for max G allowable of 8G*8000/9660 = 6.62G

V= sqrt [6.62*2*9660/(.0023769*.7386*1.72*233.2)]=sqrt[181774] fps
=426.35fps =290.6 mph @6.62G

290/417 =~ .69 max speed at 10,000 feet... hardly 'near top speed'




This is 80 MPH above any previous "calculated" estimation...

Show sources for this statement? Since you are using data allegedly extracted for P-51D, please refer those only for comparison purposes

Confirming this, the same was true of the P-47D, FG-1 and F6F, all tested at the same time by the same team of modern professional test pilots in 1989...

You haven't confirmed' anything. Produce the report and all associated parameters


IF full WEP had been allowed, I have the impression the prop load would have delayed the minimum speed to reach 6Gs even higher, maybe 340 MPH, and I think they noted the "Corner Speed" went up with more power, because they chose to put this "adjustable" statement on it: "Corner Speed is very close to the Maximum Level Speed"... Hint: Whatever that maximum level speed the power level might be set at...

Corner Speed is strictly a function of the maximum allowage limit load per structural calculations (yes - that 'math thingy' again) and Wing Loading - assuming the aircraft HAS the power to produce the velocities in such a turn. Has nothing to do with the power applied FOR this Calculation. It varies with sqrt of max permissible Limit load and Wing loading.

So you can see what all those little WWII "doghouse" charts are worth when confronted with the actual reality...

This underlines what nonsense it is to claim downthrottling is in any way beneficial to the turn rate for the "accepted" reasons of being "above" Corner Speed (besides of course not overshooting, like in a straight line for instance): To be above the 6G "Corner Speed", in those old aircrafts, you have to be nearly in a steady dive!!!!!

Babble. Theoretically when you exceed Corner Speed, do not compalin to the manufacturer when your aircraft disintegrates or loses key parts. Downthrottling in a turn to gain an advantage is YOUR mantra.

Therefore the benefits of downthrottling in sustained level turns can ONLY be for some other reason: Not an issue of speed but of prop load in my view, which is why, in the Hanseman account, the benefit is clearly described as instantaneous, not delayed by a time-consuming deceleration to a lower speed...

Gaston

Babble and more babble. If Hanseman increased pitch it would have a quick increase to prop drag but woe unto the pilot that does this on ragged edge of stall.

Produce your Test Pilot report please - re: Corner Speed for P-51D

 

[Gaston]

You have never heard of "The Society of Experimental Test Pilots", or of their 1989 side-by-side tests of the P-47D. P-51D. FG-1, F6F...

Badboy here has the full test: Badboy's BootStrap Calculator...

Or you can order it directly from their website or by contacting them...

Badboy's explanation for the mysterious non-math approved 320 MPH 6G Corner Speed was that they "went easy" on the planes to avoid stalling... Laughable when you consider that they do not mention this at all, while they do for every aspect they did that was not full wartime, like limiting to METO or weights for instance, and that an 80 MPH lay off is quite substantial... In fact ridiculous... Also they did test the stall anyway...

Oh the powers of self-delusion...

Note I have little doubt you can pull 6Gs at a lower speed than 320 MPH IF you have less power than METO pulling... Which is what they likely meant when they said "close to the maximum level speed", INSTEAD of saying the fixed speed of 320 MPH on their graph...

I also have to point out the P-51D Mustang test you linked says nothing about turn rate or even turning at all, and I would be interested in hearing the to me totally inscrutable reason why you posted it...

Gaston

 

[Gaston]

Link to SETP site:

SETP Home

Gaston.

P.S If you want to know how serious is the America Hundred thousands turn rate hierarchy, note the relative position of the F4U...

G.

 

[Njaco]

Gaston, I would suggest that if you want to talk about the merits of the P-51, you should start a thread and discuss it. If I remember correctly, this thread is about the Spit vs the Fw 190 and is starting to grow tiresome with all the off-topic Mustang tidbits.

 

[drgondog]

You have never heard of "The Society of Experimental Test Pilots", or of their 1989 side-by-side tests of the P-47D. P-51D. FG-1, F6F...

Badboy here has the full test: Badboy's BootStrap Calculator...

Or you can order it directly from their website or by contacting them...

Badboy's explanation for the mysterious non-math approved 320 MPH 6G Corner Speed was that they "went easy" on the planes to avoid stalling... Laughable when you consider that they do not mention this at all, while they do for every aspect they did that was not full wartime, like limiting to METO or weights for instance, and that an 80 MPH lay off is quite substantial... In fact ridiculous... Also they did test the stall anyway...

If YOU have a copy, I would like to see the pages which a.) summarize the test conditions, b.) the instrumentation and c.) the flight profiles (weights, altitude, the Bhp assumed for the profiles), etc.

If they tested a high speed turn stall departure please supply that also.

If you are quoting from memory - say so.

Oh the powers of self-delusion...

Note I have little doubt you can pull 6Gs at a lower speed than 320 MPH IF you have less power than METO pulling... Which is what they likely meant when they said "close to the maximum level speed", INSTEAD of saying the fixed speed of 320 MPH on their graph...

In Corner Speed, the value has nothing to do with power available - it has everything to do with the energy available as you initiate the manuever to generate a load greater than 1G.

For example a P-51B without prop, as NAA tested in dive tests to derive data to correlate NACA wind tunnel test vales with actual flight recorded data, dove to .75M. When the pilot pulled out of this near terminal dive he probably came close to 6G on the Pullout. Had he wished to do so he could probably have pulled up to 7G, without seriously endangering the structure as the limit load for that weight was close to 7G. The Speed he was generating during the pullout had an initial value of say 400-450 mph when he started the pull out, and he would lose speed as the angle of attack increased and drag increased, as he pulled through say 3G his speed would be reducing rapidly. If he then really pulled back the stick he could rapidly increase the load on the airframe - possibly up to 6G. Possibly more -

At any rate he could come close to Corner Speed/Limit Load without ONE OUNCE of Thrust or a small percent of one flea power!

Gaston - SLOWLY - None of those WWII fighters are capable of pulling 360 "6G" turns. They do Not have the thrust available. Pylon racers like Strella or Rare Bear May be close and may actually be able to pull it off with 2x the Hp available during WWII.

You ought to have 'serious doubt' that they (WWII fighters -stock) can even do "3.0 to 3.5G" in a sustained 360 degree turn.

BTW - Bootstrap Calculator is not a bad approximation. In fact, considering that he is attempting a level playing field for simulators it is pretty good. The issue is most the input data and the assumptions regarding Oswald efficiency, which is a value incorporating lift related effects to Induced Drag due to planform of the wing, tip geometry, twist, etc plus he does not attempt to incorporate trim drag at high and form drag at angles of attack. Each of those are relatively small - in the order of say 2% but are cumulative and important when predicting behavior of two closely matched aircraft in a turn.

Additionally, prop efficiency at max power/low speed near stall is up to 10-15% less than at medium to high speed. That directly affects Thrust in the turn equations. He uses a constant.

You should play with the numbers and pay close attention to the various outputs at Max CL where the best rate of turn occurs at stall speed.

You should also pay attention to the bank angles and radius as a function of speed.

Last, but not least, you should note that an airplane stalls out at a much higher speed in a sustained turn than in level flight. When you comprehend these factors you will be embarrased to review your many illucid posts.

I also have to point out the P-51D Mustang test you linked says nothing about turn rate or even turning at all, and I would be interested in hearing the to me totally inscrutable reason why you posted it...

Gaston

No Gaston - no turn rates - but an extremely well planned and recorded sets of tests at many important power settings at many different altitudes with tabulated speeds, Bhp, Gross weight and external stores (wing racks only, 2x110 gallon tanks, 2x500 pound bombs, 2x250 pound bombs, etc). The latter is crucial to cruise settings at different altitudes, engine boost/rpm and Bhp for each adjustment.

The subtle point I was making is that the P-51D-15 tested, and report submitted on June 15, 1945 recorded for ~9660 pounds gross weight the following

10,000 Feet
War Emergency Power 3000rpm/67" Hg --------------> 417mph
Military Power (your METO) 3000rpm/61"-------------> 413mph

You will note, Grasshopper, that both of those speeds are considerably Higher velocity than the "320 mph 6G Corner Speed" you quoted from your source 'as near top speed' is only 77% of 'top speed' - at least for GW around 9700 pounds. Now, if the tests were made, for extremely odd and dangerous reasons, at 12,500+ pounds GW then a.) you might be able to get a Corner Speed at 6G at 10,000 feet.

At 12600 the Limit Load for a P-51D is 8x8000/12600 = 5.07 G

In fact, given that the Definition of Corner Speed is the velocity 'not to exceed' is calculated based on the Gross Weight and Limit Load. By definition for that P-51D tested in your source, would have to be

6=8*8000/"X" -----------> "X" =64000/6 = 10,666 pounds for a Limit of 6G.

The Calculated Corner Speed = 290.6 mph

Whether my math is correct or not the DEFINITION of Corner Speed is a Calculated one - not a flight test 'measured' value. Flight Test instruments can tell you what you actually experienced in flight - but NOT what you Should (or Should Not) experience if you wished to be home in time for supper!

Look it up.

V= K*sqrt(Nmax*2*[W/S]/{Rho*(Rho@10000/Rho@SL)*CLmax})

K=1.467 for conversion to mph from fps
Nmax = Maximum Limit Load (see above)=6 @10,666 pounds
Rho=.0023769 pound seconds>>2 per ft>>4
Rho@10000/Rho@SL=.7386
W=10,666
S=233.2 ft>>2

 

[Gaston]

I see you are hell bent on complicating very simple things, and posting links devoid of relevant content to obfuscate clear issues like the P-51D tests without turn tests, despite turn tests being the only subject here...

Here is the "condensed" version of the SETP 1989 test which is all I, or anyone else, needs to know that traditionnal calculations are worthless for estimating the turn performance for nose traction aircrafts...:

F6F, FG-1, P-51, P-47 comparison

The P-51 was lighter than normal according to Badboy, which I have no trouble believing...

The one useful added detail provided by Badboy was that the complete graph has the 6G Corner Speed at 320 MPH precisely, which is indeed very close to maximum level speed at METO and 10 000 ft. for the P-51D...

I do not have to care about the (higher weight) calculated "Corner Speed" you mention as being 290 MPH on the P-51D, because I always specified my figure was at 6G (for an unusually light weight: Ask Badboy what the weight actually was, but it was somewhat below normal WWII service, which is basically all we need to know...) The structural limit is therefore irrelevant to my 6 G quote... You therefore don't have to tell me that the Corner Speed is defined as calculated, since I qualified the statement correctly (minus actual weight which was very light anyway), and you are not argueing that calculated is superior to real life, are you?...

That 290 MPH is the "calculated" minimum speed for 6G at 10 660 pounds, when in reality 6G can only BEGIN to be touched at 320 MPH at METO at around 9000 lbs, in actual modern tests with an actual pilot at the controls, shows just how off base these calculations are...

In fact previous "calculated" figures I have seen were much lower: 270-280 MPH for 7 Gs at normal load....

I am sure that at full WEP the actual minimum 6G Speed is at least 340 MPH and maybe more... If "Close to the maximum Level Speed" is taken at face value, then a 400 MPH minimum is not impossible...

Your assumption that the aircraft is aerodynamically unaffected by engine nose traction power is what prevents you (and apparently aeronautic engineers throughout the world!), of understanding that the prop power does indeed load the wing up with at least a thousand pounds, or maybe much more, of extra weight through the position of the raised nose leverage... (The elevator does not heavy up a lot in spite of this extra load, because of the wing's "pulley assist" effect when the wing angle of attack is increased; the same "pulley effect" which, in addition to the inherent stability resistance or lack of thereof, allows a reasonably low force on the elevator to create 6Gs on the 9 000 lbs aircraft as a whole (54 000 lbs of force total) without tearing away the elevator under thousands of pounds of force...)

That extra prop disc-created load is what pushes back the 6 G Corner Speed (The lowest speed at which 6 G can be reached), from a "calculated" roughly 270 MPH to 290 MPH (according to you at a comparatively high weight of 10 600 lbs) to 30 MPH higher at 1600 pounds lighter... Or, according to me, up to maybe 50-100 MPH higher than calculated if the power is all out at WEP...

The basic point why this is relevant to any discussion is that your notions of the benefits downthrottling make no sense in the context of an "optimal" 6 G "Corner Speed" being that high even at light weights...

How long can you turn level above such speeds for it to be worth downthrottling?

Compare Karhila's own quoted "optimal" downthrottled sustained turn speed of 160 MPH in a Me-109G-6, whose 6 G "Corner Speed" was probably close or similar to the Mustang (In fact in dive pull-outs, trimmed tail heavy, the Me-109G-6 outperformed in dive pull-outs at least the fabric elevator P-51D at 400 MPH +, to the surprise of many combat pilots...).

In theory, sustaining turns should be as close as possible (maximum power then) to the Corner Speed: 220-240 for most types at 3-3.5 Gs... 160 MPH on a Me-109G means this obviously wasn't the case, which is why the whole edifice falls down where nose-traction is concerned...

Gaston

 

[Glider]

Your assumption that the aircraft is aerodynamically unaffected by engine nose traction power is what prevents you (and apparently aeronautic engineers throughout the world!),

This sums up the problem with all his postings. He an untrained, inexperienced, unqualified person who knows what is correct and that all the trained, experienced and qualified engineers throughout the world of all nations, are wrong. Simple really.

 

[Milosh]

Because of the age of the aircraft, structural loads were kept to 6g max.

F6F, FG-1, P-51, P-47 comparison

Nowhere did I see 6G mentioned for turns. 4G was the only mentioned. When a 4.5G turn was attempted, a spin resulted.

Nowhere was the weight of the a/c mentioned.

 

[DerAdlerIstGelandet]

I see this thread is going to go down hill again...

 

[drgondog]

chris - I will quit responding..this is way off topic

 

[drgondog]

F6F, FG-1, P-51, P-47 comparison

Nowhere did I see 6G mentioned for turns. 4G was the only mentioned. When a 4.5G turn was attempted, a spin resulted.

Nowhere was the weight of the a/c mentioned.

Milosh are you talking about the Experimental Test Pilot report of the Bootstrap model?

edit - i just signed up at Aces High so I will peruse and see if I can find data..I can see why Gaston so clueless - he doesn't know how to interpret what he reads...

 

[Gaston]

F6F, FG-1, P-51, P-47 comparison

Nowhere did I see 6G mentioned for turns. 4G was the only mentioned. When a 4.5G turn was attempted, a spin resulted.

Nowhere was the weight of the a/c mentioned.

4-4.5 Gs was only for the sustained tracking after a turn reversal part of the test at a lower speed of 220 knots... For "Corner Speed", you don't have to sustain the 6G turn or follow an opposite turn reversal...

What does this mean to you?
: "Corner speeds of all were very close to the maximum level flight speed,
implying very rapid energy loss when turning at the structural limit.
The F6F was in light airframe buffet at 6g at Vmax; the P-47 experienced
light buffet at 4.8g. The FG-1 and P-51 were buffet-free up to 6g."

Do you really think the original version of these tests does not have the weights? It does and includes several charts too... Ask Badboy for the weight details... They were in no way heavy and in fact were all very light...

These tests were, after all, run by modern professional test pilots in 1989, as part of the publication of a book by the "Society of Experimental Test Pilots", which you can still order from them...


These were four separate types and they all displayed the minimum speed to reach 6G as being very close to their METO maximum level speeds, despite the inevitable variations in that level speed among the types...

They all posted these very high minimum 6G speeds while being all seriously underweight; No real guns or ammo I am fairly sure... In doing so they without question demonstrated that calculations are not accurate. I don't know what else needs to be said about 220-280 MPH 6G Corner Speeds for WWII single engine piston fighters at normal or even light weights: Four different types show these ranges to be completely fictional even for underweight aircrafts... This basic notion likely remains mostly true for the entire family of high power post 1940 low-wing monoplanes piston fighters of the WWII period...

Kurt Tank correlates this by quoting a minimum speed of 400 MPH for 7Gs on the FW-190A, but considering the stick forces showed only 2 pounds per G at 400 MPH (abnormally light), I am sure the FW-190A was in fact incapable of real 7G turns or dive pull-outs: It was Gs from high speed nose-up deceleration "sinking"; the mushing still going up or down in Gs as the elevator still could change the pitch up or down, but the actual trajectory was likely little above 5 Gs or maybe less, the rest being the deceleration mushing: More or less nose-up meant more or less deceleration vs the actual tightness of the trajectory's curve... See Eric Brown comment on FW-190A pull-outs: "Care had to be taken not to kill speed by "sinking" on dive pull-outs, or the FW-190A would be very vulnerable on dive exits"... Or the Russian evaluation: "After diving at 40 degrees from 1400 m, the FW-190A, when pulling-out of the dive, will fall an extra 220 M. (660 ft.)" The "extra" here means after nose-level or up...They describe this behaviour as "hanging"...

So to conclude, the SETP tests show the "Doghouse" to have a roof slanted quite some way to one side: Not a symmetrical doghouse shape at all...

You can choose to look at the facts or ignore them, but I don't know why you would expect your credibility to rise above that of a clearly objective and unbiaised institution like the "Society of Experimental Test Pilots", doing such tests with far more modern instruments than WWII evaluations...

Gaston