davebender
1st Lieutenant
I think historical records will show that most WWII era aerial combat took place well below 25,000 feet.
MW-50 Bf 109s Vs Fw 190 A
- Thread starter Jenisch
- Start date
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I think historical records will show that most WWII era aerial combat took place well below 25,000 feet.
Shortround6
Major General
You are right but for the Luftwaffe to ignore the 25,000 ft and up area of the sky would mean giving up any hope of controlling air combat in the West now matter how well they do in the East.
Even the West much of the "combat" was below 25,000ft but the guys who could fly well at above 25,000ft often controlled the "Bounce" and thus the engagement as a whole.
Designing equipment for "average" conditions can leave you very vulnerable to less than average conditions even without going to extreme conditions.
Even the West much of the "combat" was below 25,000ft but the guys who could fly well at above 25,000ft often controlled the "Bounce" and thus the engagement as a whole.
Designing equipment for "average" conditions can leave you very vulnerable to less than average conditions even without going to extreme conditions.
davebender
1st Lieutenant
The Luftwaffe page , Daimler-Benz DB 605
Isn't that what the DB605AS engine was for? 1,200 hp @ 8,000 meters. The DB605D was even better with 1,300 hp @ 8,000 meters. That provides a decent power to weight ratio for the lightweight Me-109G.
Isn't that what the DB605AS engine was for? 1,200 hp @ 8,000 meters. The DB605D was even better with 1,300 hp @ 8,000 meters. That provides a decent power to weight ratio for the lightweight Me-109G.
Shortround6
Major General
Yep, but it doesn't do much for the Fw 190 does it? which was a large part of this discussion.
It also means it took the Germans until 1944 to equal what the Merlin 61 was offering in 1942.
1390hp at 7150 meters ,without ram.
Max cruise of 990hp at 7700 meters compared to the DB 605 ASM 1040ps at 7100 meters.
It also means it took the Germans until 1944 to equal what the Merlin 61 was offering in 1942.
1390hp at 7150 meters ,without ram.
Max cruise of 990hp at 7700 meters compared to the DB 605 ASM 1040ps at 7100 meters.
davebender
1st Lieutenant
What difference does that make? Except for recon and pathfinders the RAF didn't normally fly above 20,000 feet. 1943 model P-47s weren't terribly impressive.
The P-51B showed up about a month before the DB605AS engine. Perhaps that not a coincidence. The U.S. finally had a high performance bomber escort which Germany needed to counter with a high altitude version of the Me-109G.
The P-51B showed up about a month before the DB605AS engine. Perhaps that not a coincidence. The U.S. finally had a high performance bomber escort which Germany needed to counter with a high altitude version of the Me-109G.
Shortround6
Major General
Try telling that to the Luftwaffe during the battle of Britain. Both sides were flying fighters at 25-28,000ft if not higher at times in order to get the bounce. The Luftwaffe knew that combat altitudes against the British were not going to go down.
The American turbo-chargers were not a secret to anybody who had a subscription to any worth while aviation magazine of the 1930s.
While fitting the Merlin XX to the Hurricane only boosted the speed at 25,000ft from 290mph to 313 it did change the rate of climb from 1260fpm to 1840fpm at 25,000ft and at 30,000ft the change was from 660fpm to 1120fpm.
Figures for the 109E are a speed of 328mph and climbs of 1340fpm at 25K and 740fpm at 30K. Granted the 109F more than addressed the problem but the idea that British fighters would make no further progress in altitude performance seems pretty silly. Not having an engine in hand to counter a British change in tactics (wither they choose to fly at 25,000ft+ or not the aircraft could do it) seems a bit short sighted. It taking months if not a year or two to develop a major variant of an existing engine. It is certainly not done in weeks.
You might want to tell that one to the dozens of Luftwaffe pilots shot down those not terribly impressive P-47s. Even cutting the claims numbers to 1/3 leaves the P-47s shooting down Luftwaffe fighters at about 2:1 to 3:1.
And that is with the Americans gaining experience while the Luftwaffe has yet to reach the steep downward spiral of 1944/45.
GregP
Major
Lightweight Me 109G? Please!
The Me 109C weighed in about 5,065 popunds.
The Me 109D weighed in at about 5,345 pounds.
The Me 109E weighed in at about 5,519 pounds. See a trend here?
The Me 109F, widely regarded as the best of the breed by the Aces, weighed in at 6,054 pounds.
The Me 109G weighed in at about 6,942 pounds (normal, not max). Max was 7,053 pounds!
The Me 109K weighed in at about 6,832 pounds normal and 7,493 pounds max.
The Me 109G could outweigh the F model by a whopping 1,000 pounds, all without an increase in wing area. In truth, it was the heavyweight of Me 109's and had the heaviest wing loading.
Also, I said the performance of the radial-powered Fw 190's fell off about 20,000 feet and it does. I did not mention the Fw 190D or the Me 109 in performance fall-off above 20,000 feet, though the performance DOES fall off eventually, as it does for all WWII fighters. While the Me 109 COULD get high and fgast, it was unmaneuverable in the extreme when going fast ... but it could get there and fly intercepts on bombers effectively. I don't think any Me 109 pilot was eager to fight a Spitfire or Mustang at 28,000 feet. They were MUCH more likely to try to get the Allied fighters to descend and fight in the teens or LOW tewnties, where they were more maneuverable, than fight in the high twenties or higher. As I recall .. possibly wrongly, the Me 109G was at critical altitude for high blower at about 19,600 feet. Above that, the performance was still good, but falling off. That was with the DB 605 and was, I believe, the G-2. So the Me 109G pilot wanted to fight at about 19,600 feet (6,000 meters) if possible, where he had the best performance from his powerplpant.
The Me 109C weighed in about 5,065 popunds.
The Me 109D weighed in at about 5,345 pounds.
The Me 109E weighed in at about 5,519 pounds. See a trend here?
The Me 109F, widely regarded as the best of the breed by the Aces, weighed in at 6,054 pounds.
The Me 109G weighed in at about 6,942 pounds (normal, not max). Max was 7,053 pounds!
The Me 109K weighed in at about 6,832 pounds normal and 7,493 pounds max.
The Me 109G could outweigh the F model by a whopping 1,000 pounds, all without an increase in wing area. In truth, it was the heavyweight of Me 109's and had the heaviest wing loading.
Also, I said the performance of the radial-powered Fw 190's fell off about 20,000 feet and it does. I did not mention the Fw 190D or the Me 109 in performance fall-off above 20,000 feet, though the performance DOES fall off eventually, as it does for all WWII fighters. While the Me 109 COULD get high and fgast, it was unmaneuverable in the extreme when going fast ... but it could get there and fly intercepts on bombers effectively. I don't think any Me 109 pilot was eager to fight a Spitfire or Mustang at 28,000 feet. They were MUCH more likely to try to get the Allied fighters to descend and fight in the teens or LOW tewnties, where they were more maneuverable, than fight in the high twenties or higher. As I recall .. possibly wrongly, the Me 109G was at critical altitude for high blower at about 19,600 feet. Above that, the performance was still good, but falling off. That was with the DB 605 and was, I believe, the G-2. So the Me 109G pilot wanted to fight at about 19,600 feet (6,000 meters) if possible, where he had the best performance from his powerplpant.
- Thread starter
- #49
I already read an interview with a Fw 190 pilot, were he told just this. He said to like more the 190 because it was "easy to maneuver". While the 109, you would need "muscles from a gigant" if wanted constant maneuvers.
The late 109s had servo tabs in the ailerons which at least diminished this disadvantage. However posterior Doras introduced hidraulically boosted ailerons.
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GregP
Major
I have heard that before Jenisch, from actual Me 109 pilots, but thanks for the corroboration. They were astounded to sit in a P-51 and be able to see out as well as you can. After sitting in the P-51, they both said the Me 109 cockpit needed massive redesign for forward visibility.
The heavy controls (at speed) were the result of mechanical advantage, or lack thereof, and were correctable, as was the lack of rudder trim and aileron trim. Unbelievable, but true.
The Me 109, to me, was many good things combined with some bad things ... and ALL the bad things were fixable, but were never fixed!
The heavy controls (at speed) were the result of mechanical advantage, or lack thereof, and were correctable, as was the lack of rudder trim and aileron trim. Unbelievable, but true.
The Me 109, to me, was many good things combined with some bad things ... and ALL the bad things were fixable, but were never fixed!
The rudder got a Flettner tab but the number of 109s with the tabs on the ailerons is questionable.
I think the K was the heaviest, which natural with all the bigger engines, cannons, MW boost, electric equipment etc. added. It weighted 3362 kg. Early G-1 weighted 3037 kg, F-4 2890 kg, F-1 2728 kg, E-3 2540 kg, the 109B around 2000 kg. All data from kurfurst site orginal papers. so there was not that much increase between late F and early G really. The G just gained the same weight as the others before. By far greatest increase was going from Jumo 109 to DB 109 because of the largest engine.
Besides increasing weight during a long used fighter is true for all WWII fighters. Allison Mustangs were much lighter than Merlin Mustangs, Griffon Spitfires were much heavier than Merlin Spitfires, late Yak 9 was much heavier than early Yak 9 etc. of course "all without increase in wing area", since it would be a major redesign. But that is important if there would be no increase in output of engine, since greater output engine can cancel more drag, allowing wing to use high angle of air flow and provide more lift.
GregP
Major
Hi Tanta Ju,
My post was in response to the "lightweight Me 109G" comments earlier.The fact that the Me 109 gained weight is not as important as how much it gained. Once the wing loading got past a certain point, perhaps some increase in size would have been better. In any case, the Me 109 was and is a great plane, ir ever there was one.
My post was in response to the "lightweight Me 109G" comments earlier.The fact that the Me 109 gained weight is not as important as how much it gained. Once the wing loading got past a certain point, perhaps some increase in size would have been better. In any case, the Me 109 was and is a great plane, ir ever there was one.
davebender
1st Lieutenant
I disagree.
What counts is power to weight ratio @ the most common combat altitude. Even that "overloaded" Me-109G6 had a good power to weight ratio compared to contemporary fighter aircraft.
Shortround6
Major General
Power to weight and wing loading are both important. Increasing the power to weight ratio increases certain aspects of performance but increasing wing loading can decrease others. It is not only turn radius, which can and was compensated for to some extent by tactics but field length, both take-off and landing and handling at low speeds.
Increasing the power to weight ratio while the plane becomes harder for low time pilots to handle increases the accident rate.
Getting back to turning, it is not just turn radius but the the higher speed at which a high speed stall occurs at high G's.
Higher weight also affects altitude performance. The higher weight requires a higher minimum speed just to stay in the air, which requires some of the extra power.
Increasing the power to weight ratio while the plane becomes harder for low time pilots to handle increases the accident rate.
Getting back to turning, it is not just turn radius but the the higher speed at which a high speed stall occurs at high G's.
Higher weight also affects altitude performance. The higher weight requires a higher minimum speed just to stay in the air, which requires some of the extra power.
To comment first on what another poster added: The correlation between wing bending loads and slow speed turning at various power levels was likely never done on WWII fighter aircrafts. As he points out: all WWII fighters wing bending data is likely static in nature...
Yes that is exactly it: I'll go back to the power level issue just below...
To bridge the gigantic gap in wingloading between the Spitfire and the FW-190A, and to still give a significant sustained low-speed turn advantage to the FW-190A, I figure the Spitfire's wing at a 3G turn at full power is really being bent as if it was almost at a "theoretical" 6G in actual in-flight wing bending force, while the FW-190A's wing at the same 3 G would be bent as if it was at say 4G: The gap between the 4G bending stress on the FW-190A wing (at 3G of "true" turn felt on the pilot) and the 6G bending stress on the Spitfire wing (also at 3G of "true" turn felt on the pilot) would overcome the Spitfire's theoretical wingloading advantage: In fact the Spitfire's wing real in-flight wingloading seems higher than a FW-190A, as RCAF pilot John Weir observed when he said "The Spitfire has a higher wingloading": It was observable experience to him, not theoretical numbers: I think those Spitfire wings are much more heavily stressed in low-G sustained turns than current flight physics theory considers, because there must be a loophole or error in basic flight physics that may not be scaleable to lesser power (or high-wing) prop aircrafts...
At 6Gs the Spitfire's wing would, according to this, be bent like if it was at 9G, but the airframe is rated around 12-14Gs so there is room in there for the effect...
The root of the phenomenon (that I presume to exist) is something I call now the "CL collapse", but is in fact a CL displacement down and forward of CG as the elevator tries to raise the nose.
This displacement is caused by the prop's resistance to be forced below its potential forward speed in an assymetrical way (which prop "resistance" insures continuing directional stability, even with the CL suddenly displaced forward of CG).
A valuable counter-argument to that is that common drag, like a simple external mirror, also puts the whole prop surface below its potential forward speed, but linearly, and thus to my mind in a benign way: My argument is that the real prop resistance starts only with the assymetrical necessity of a turn. In other words the prop doesn't react strongly to being slowed down as long as it is done evenly on its whole surface, but leverage-wise there is hell to pay if you want to slow it down unevenly, as in a turn, because the length of the aircraft's nose suddenly intrudes, with leverage, as soon as any tilt to the trajectory is introduced...
If tail and nose are close in lenght, as in a P-51, then the CL collapses more down and moves less forward. On a longer tail and shorter nose type, like a FW-190A, the CL collapse is less down but moves more forward: That is the engine of the system. It is largely an issue of how taxing for the CL is the leverage of the tail vs the nose: A long tail with a short nose is less taxing to the CL: The CL will go less down but strangely enough it will consequently want to move more forward, giving the CL more leverage to lift the nose as the turn increases the CL's lift.
CL collapse is a very small, perhaps micro-second event. The "pivot axis" of the CL collapse I situate in the prop face: It "sets" everything that follows: The more the CL collapses, the lower the prop's "pivot point" for that collapse, the lower the prop's "pivot point", the larger the prop surface brought below its forward speed potential: The larger the prop surface brought below its forward speed potential, the greater the disparity in incoming air speed between the outside turn of that area and the inside turn of that area. The larger that disparity in incoming airspeed, the greater the amount of thrust slanting for 1° of "normal" pilot-induced AoA increase.
In effect, for a micro-second the prop is "pulled" back assymetrically from the top as the CL collapses a very minor amount, then the prop rises as it rotates up, as the now forward CL relieves the pilot of the effort of lifting it in an upward movement, as the turn actually begins to tighten... There is a "scissor" action, with the CL being now forward of the CG, that is favourable to lifting the nose as the turn tightens (unlike if the CL had not moved forward of the CG).
This is why huge prop forces at the nose cannot be felt by the pilot in the elevators: The collapsed CL moved forward and its action took over like a pulley, still responding to the pilot's touch but nullifying 90-99% of the effort to lift the nose, and thus lightening the load just like a pulley does.
Say the pivot point of the CL "collapse" is set in the lowest 10% of the prop, then 90% of the prop moves back compared to the trajectory: This may be equivalent to +0.9° of thrust slanting for each 1° of "pilot induced" AoA increase: 1.9° worth of lift for 1° AoA, 13.3° for 7° AoA, but probably after that no more than 20.6° for 14° AoA.
There must be an extra cost in drag in all that extra "added" thrust slanting angle, but if the rule is the same for all, how do you know there is an "anomaly"?
So the "kind" of CL collapse ("deep" and "short" vs "shallow" and "long") sets the "boost" to the AoA by lowering the initial pivot point in the prop's face (which pivot point may exist for barely a micro-second to "set-up" what follows), and it also sets the amount of extra void above the wing needed to actually bend the wings beyond what the "visible" AoA could in theory accomplish.
Now I have to say I don't know how that extra void above the wing balances itself with the thrust slanting, as the AoA is gradually increased or decreased by the pilot, and even how it remains in place: How can that extra void (initiated by the CL collapse) not be washed away by the airflow?
The only explanation I can come up with is that as the aircraft turns, the difference in the speed of the air above and below the wing is exacerbated, and some of that faster air below the wing "leaks" around the trailing edge as the CL collapses, this faster airflow moving then forward(!) and under the boundary layer on top of the wing, keeping the boundary layer higher and thus the void above the wing proportional to the "boosted" value of the AoA + thrust slanting.
The proportional aspects would be as such: A tighter turn would make a greater air speed disparity on the top and bottom of the wing, "leaking" comparatively faster air from below the trailing edge, and lifting the boundary layer higher, creating a larger void. A slower turn would "leak" comparatively slower air and cause less lift of the boundary layer, for a lesser void.
That is a stretch, even for me, but if it has remained ignored for so long it cannot be that simple to figure out...
This is the only way I could figure how the engine's power could in fact increase or decrease the bending of the wing independantly of the turn's G force.
How many WWII types report faster sustained turn rates with seriously lowered power? The P-51D is most prominent, as is the FW-190A, with just one Me-109G pilot (Karhila) also mentionning the best sustained turn speed for the Me-109G-6 as being 160 mph with a strong emphasis on reducing the throttle to achieve this best sustained turn performance.
Absolutely no mention of reduced throttle sustained turning for the P-47D and Spitfire, and relatively little for the Me-109: Why? I think the convenience of the flap "set up" plays a big role in how pilots will risk experimenting with lower throttle settings: The flap set-up for the P-47D must not have encouraged exploring lower speed turning performance at reduced power, and neither did the size and weight... The Me-109G could not really use its laborious flaps in combat, and the Spitfire had only full up or full down flap positions, a huge limitation in my view...
The SETP "Society of Experimental Test Pilots" tested the corner speed of 4 WWII US types in 1989, at maximum continuous power ("normal power") and found the P-51D's "Corner Speed" in horizontal turns to be a surprisingly high 320 MPH, close to the maximum level speed at this power level at 10 000 ft for ALL four types: P-47, P-51D, F4U, F6F: This was due in my opinion to the loading of the prop in horizontal turns...
At War Emergency Power, the "Corner Speed" (minimum speed allowing 6Gs) in level turns would probably have been even higher: 350 mph?
Did you ever achieve 6 G in horizontal turns at full power below 300 mph? At normal power? Remember you cannot unload the prop by spiralling down: It has to be a true level turn.
Gaston
Yes that is exactly it: I'll go back to the power level issue just below...
To bridge the gigantic gap in wingloading between the Spitfire and the FW-190A, and to still give a significant sustained low-speed turn advantage to the FW-190A, I figure the Spitfire's wing at a 3G turn at full power is really being bent as if it was almost at a "theoretical" 6G in actual in-flight wing bending force, while the FW-190A's wing at the same 3 G would be bent as if it was at say 4G: The gap between the 4G bending stress on the FW-190A wing (at 3G of "true" turn felt on the pilot) and the 6G bending stress on the Spitfire wing (also at 3G of "true" turn felt on the pilot) would overcome the Spitfire's theoretical wingloading advantage: In fact the Spitfire's wing real in-flight wingloading seems higher than a FW-190A, as RCAF pilot John Weir observed when he said "The Spitfire has a higher wingloading": It was observable experience to him, not theoretical numbers: I think those Spitfire wings are much more heavily stressed in low-G sustained turns than current flight physics theory considers, because there must be a loophole or error in basic flight physics that may not be scaleable to lesser power (or high-wing) prop aircrafts...
At 6Gs the Spitfire's wing would, according to this, be bent like if it was at 9G, but the airframe is rated around 12-14Gs so there is room in there for the effect...
The root of the phenomenon (that I presume to exist) is something I call now the "CL collapse", but is in fact a CL displacement down and forward of CG as the elevator tries to raise the nose.
This displacement is caused by the prop's resistance to be forced below its potential forward speed in an assymetrical way (which prop "resistance" insures continuing directional stability, even with the CL suddenly displaced forward of CG).
A valuable counter-argument to that is that common drag, like a simple external mirror, also puts the whole prop surface below its potential forward speed, but linearly, and thus to my mind in a benign way: My argument is that the real prop resistance starts only with the assymetrical necessity of a turn. In other words the prop doesn't react strongly to being slowed down as long as it is done evenly on its whole surface, but leverage-wise there is hell to pay if you want to slow it down unevenly, as in a turn, because the length of the aircraft's nose suddenly intrudes, with leverage, as soon as any tilt to the trajectory is introduced...
If tail and nose are close in lenght, as in a P-51, then the CL collapses more down and moves less forward. On a longer tail and shorter nose type, like a FW-190A, the CL collapse is less down but moves more forward: That is the engine of the system. It is largely an issue of how taxing for the CL is the leverage of the tail vs the nose: A long tail with a short nose is less taxing to the CL: The CL will go less down but strangely enough it will consequently want to move more forward, giving the CL more leverage to lift the nose as the turn increases the CL's lift.
CL collapse is a very small, perhaps micro-second event. The "pivot axis" of the CL collapse I situate in the prop face: It "sets" everything that follows: The more the CL collapses, the lower the prop's "pivot point" for that collapse, the lower the prop's "pivot point", the larger the prop surface brought below its forward speed potential: The larger the prop surface brought below its forward speed potential, the greater the disparity in incoming air speed between the outside turn of that area and the inside turn of that area. The larger that disparity in incoming airspeed, the greater the amount of thrust slanting for 1° of "normal" pilot-induced AoA increase.
In effect, for a micro-second the prop is "pulled" back assymetrically from the top as the CL collapses a very minor amount, then the prop rises as it rotates up, as the now forward CL relieves the pilot of the effort of lifting it in an upward movement, as the turn actually begins to tighten... There is a "scissor" action, with the CL being now forward of the CG, that is favourable to lifting the nose as the turn tightens (unlike if the CL had not moved forward of the CG).
This is why huge prop forces at the nose cannot be felt by the pilot in the elevators: The collapsed CL moved forward and its action took over like a pulley, still responding to the pilot's touch but nullifying 90-99% of the effort to lift the nose, and thus lightening the load just like a pulley does.
Say the pivot point of the CL "collapse" is set in the lowest 10% of the prop, then 90% of the prop moves back compared to the trajectory: This may be equivalent to +0.9° of thrust slanting for each 1° of "pilot induced" AoA increase: 1.9° worth of lift for 1° AoA, 13.3° for 7° AoA, but probably after that no more than 20.6° for 14° AoA.
There must be an extra cost in drag in all that extra "added" thrust slanting angle, but if the rule is the same for all, how do you know there is an "anomaly"?
So the "kind" of CL collapse ("deep" and "short" vs "shallow" and "long") sets the "boost" to the AoA by lowering the initial pivot point in the prop's face (which pivot point may exist for barely a micro-second to "set-up" what follows), and it also sets the amount of extra void above the wing needed to actually bend the wings beyond what the "visible" AoA could in theory accomplish.
Now I have to say I don't know how that extra void above the wing balances itself with the thrust slanting, as the AoA is gradually increased or decreased by the pilot, and even how it remains in place: How can that extra void (initiated by the CL collapse) not be washed away by the airflow?
The only explanation I can come up with is that as the aircraft turns, the difference in the speed of the air above and below the wing is exacerbated, and some of that faster air below the wing "leaks" around the trailing edge as the CL collapses, this faster airflow moving then forward(!) and under the boundary layer on top of the wing, keeping the boundary layer higher and thus the void above the wing proportional to the "boosted" value of the AoA + thrust slanting.
The proportional aspects would be as such: A tighter turn would make a greater air speed disparity on the top and bottom of the wing, "leaking" comparatively faster air from below the trailing edge, and lifting the boundary layer higher, creating a larger void. A slower turn would "leak" comparatively slower air and cause less lift of the boundary layer, for a lesser void.
That is a stretch, even for me, but if it has remained ignored for so long it cannot be that simple to figure out...
This is the only way I could figure how the engine's power could in fact increase or decrease the bending of the wing independantly of the turn's G force.
How many WWII types report faster sustained turn rates with seriously lowered power? The P-51D is most prominent, as is the FW-190A, with just one Me-109G pilot (Karhila) also mentionning the best sustained turn speed for the Me-109G-6 as being 160 mph with a strong emphasis on reducing the throttle to achieve this best sustained turn performance.
Absolutely no mention of reduced throttle sustained turning for the P-47D and Spitfire, and relatively little for the Me-109: Why? I think the convenience of the flap "set up" plays a big role in how pilots will risk experimenting with lower throttle settings: The flap set-up for the P-47D must not have encouraged exploring lower speed turning performance at reduced power, and neither did the size and weight... The Me-109G could not really use its laborious flaps in combat, and the Spitfire had only full up or full down flap positions, a huge limitation in my view...
The SETP "Society of Experimental Test Pilots" tested the corner speed of 4 WWII US types in 1989, at maximum continuous power ("normal power") and found the P-51D's "Corner Speed" in horizontal turns to be a surprisingly high 320 MPH, close to the maximum level speed at this power level at 10 000 ft for ALL four types: P-47, P-51D, F4U, F6F: This was due in my opinion to the loading of the prop in horizontal turns...
At War Emergency Power, the "Corner Speed" (minimum speed allowing 6Gs) in level turns would probably have been even higher: 350 mph?
Did you ever achieve 6 G in horizontal turns at full power below 300 mph? At normal power? Remember you cannot unload the prop by spiralling down: It has to be a true level turn.
Gaston
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wuzak
Captain
Do what?
Since wing loading is defined as mass divided by wing area, does the Spitfire gain mass in flight, or does its wing area reduce?
Well, not sure what aircraft Mr Weir was comapring the Spitfire to - maybe he was saying its wingloading was greater than that of the Wright Flyer!
GregP
Major
I'll say one thing for you Gaston, you don't go in for short posts, do you? I'll have t read that one awhile ... 
By the way, at 8,000 pounds or less, the corner speed of a P-51D is very close to 265 mph and 8g. At 320 mph you can easily break a P-51D. If you exceed these limits, you may get away with it, but you have structurally compromised the aircraft. The desgn safety factor is 1.5, but the flight limits are the flight limits. Exceed them and you are a test pilot.
The Society of Experimental Test pilots does not have the authority to change the manufacturer's pilot manual. If they want to allow a higher speed, they have to do the engineering, the testing and verification, get approval and release the FAA-approved new flight limits. That has not happened and will not. The liability is WAY too high for anyone to be that stupid.
The guys running at Reno have increased the max speed with design work and streamlining (and that is allowed in the Experimental and Experimental Exhibition categories), but the structural limits are the same ... 8g at 8,000 pounds or less. Most of the P-51's running at Reno, including the National Champion, run at Reno at about 8,200 pounds, and their structrual limit is 7.8 g at 8,200 pounds. Even Strega, the current US National Champion has a pure stock P-51D structure underneath the streamlining and new cowling and small Formula 1 canopy. The engine may be putting out more than 3,000 HP, but the structure is stock P-51.
Jimmy Leeward's The Galloping Ghost taht crashed at Reno last year violated that and had a modified elevator trim system. He paid the ultimate price for that.
To get the g limit at other than 8,000 pounds, you divide 64,000 by the weight in pounds ... and that is straight from the pilot's manual.
You might not want to argue too hard about this one. Our museum operates two P-51D's, and I have been working the past month with the current Reno National Champion, Steven Hinton Jr, pilot of Strega, while we overhauled the left hand Allison from the Museum's P-38. We have discussed P-51's at length and Strega in particular. I think he knows the P-51's limits VERY well, and his structural numbers come right from the North American P-51 manual that was the wartime bible for the aircraft and still is. The numbers for Strega in particular come from the Tiger Destefani manual and are not public, but it is quite a bit faster than a stock P-51D. While the speed is faster, the structural limits remain the same and are calculated the same.
By the way, at 8,000 pounds or less, the corner speed of a P-51D is very close to 265 mph and 8g. At 320 mph you can easily break a P-51D. If you exceed these limits, you may get away with it, but you have structurally compromised the aircraft. The desgn safety factor is 1.5, but the flight limits are the flight limits. Exceed them and you are a test pilot.
The Society of Experimental Test pilots does not have the authority to change the manufacturer's pilot manual. If they want to allow a higher speed, they have to do the engineering, the testing and verification, get approval and release the FAA-approved new flight limits. That has not happened and will not. The liability is WAY too high for anyone to be that stupid.
The guys running at Reno have increased the max speed with design work and streamlining (and that is allowed in the Experimental and Experimental Exhibition categories), but the structural limits are the same ... 8g at 8,000 pounds or less. Most of the P-51's running at Reno, including the National Champion, run at Reno at about 8,200 pounds, and their structrual limit is 7.8 g at 8,200 pounds. Even Strega, the current US National Champion has a pure stock P-51D structure underneath the streamlining and new cowling and small Formula 1 canopy. The engine may be putting out more than 3,000 HP, but the structure is stock P-51.
Jimmy Leeward's The Galloping Ghost taht crashed at Reno last year violated that and had a modified elevator trim system. He paid the ultimate price for that.
To get the g limit at other than 8,000 pounds, you divide 64,000 by the weight in pounds ... and that is straight from the pilot's manual.
You might not want to argue too hard about this one. Our museum operates two P-51D's, and I have been working the past month with the current Reno National Champion, Steven Hinton Jr, pilot of Strega, while we overhauled the left hand Allison from the Museum's P-38. We have discussed P-51's at length and Strega in particular. I think he knows the P-51's limits VERY well, and his structural numbers come right from the North American P-51 manual that was the wartime bible for the aircraft and still is. The numbers for Strega in particular come from the Tiger Destefani manual and are not public, but it is quite a bit faster than a stock P-51D. While the speed is faster, the structural limits remain the same and are calculated the same.
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Shortround6
Major General
I am not sure why we have to throw out all the data that was collected with static testing.
I mean those engineers/designers knew how much wing bend/deflection they were getting at certain given loading's. Any major discrepancies (like being off by 50%) would probably have been noticed.
As far as "Did you ever achieve 6 G in horizontal turns at full power below 300 mph? At normal power? Remember you cannot unload the prop by spiralling down: It has to be a true level turn."
I don't think ANY WW II fighter was going to pull 6 "G"s in a horizontal turn for very long ( a couple of seconds?) without spiraling down.
If you haven't seen them try these charts for starters.
http://www.spitfireperformance.com/spit109turn.gif
Please note the Spitfire has to be doing 250mph in a 6 G turn or it stalls. also please note how far the Spitfire is from being able to maintain a 6 G turn. It has descend at rate equal to 27.5-28 degree descent in level flight in order to maintain the 6 G turn.
Later Spitfires with more powerful engines will do better but then later Spitfires also weigh more and will have a a higher stalling speed limit which will affect the tightest turn radius.
Please also note that turn radius varies with speed and G's pulled.
Which Spitfire is out turning which?
A. taking 19 seconds at a 1600ft radius at 375mph.
B. taking just under 16 seconds at a 1200ft radius at 325mph.
C. taking 13 seconds at 800ft radius at 265 mph.
All are pulling 6 Gs and all are loosing thousands of ft/min altitude.
The Spitfires "best" turn performance seems to be a 23-23.5 second turn at 225mph at 1200ft radius at 3gs. it may actually hold height at that turn "rate" and speed.
Obviously starting position between two aircraft could be critical to a turning fight. a little altitude advantage helps, the pursuing airplane starting on the outside of the target plane has to pull more Gs ( or turn tighter, momentarily trading speed for turn radius)to get the target in the sights while starting from inside the turn (target turns across the pursuer) makes things easier for the pursuer. initial bank can affect results.
Blacking out in a sustained 6 G turn can really affect the results
I mean those engineers/designers knew how much wing bend/deflection they were getting at certain given loading's. Any major discrepancies (like being off by 50%) would probably have been noticed.
As far as "Did you ever achieve 6 G in horizontal turns at full power below 300 mph? At normal power? Remember you cannot unload the prop by spiralling down: It has to be a true level turn."
I don't think ANY WW II fighter was going to pull 6 "G"s in a horizontal turn for very long ( a couple of seconds?) without spiraling down.
If you haven't seen them try these charts for starters.
http://www.spitfireperformance.com/spit109turn.gif
Please note the Spitfire has to be doing 250mph in a 6 G turn or it stalls. also please note how far the Spitfire is from being able to maintain a 6 G turn. It has descend at rate equal to 27.5-28 degree descent in level flight in order to maintain the 6 G turn.
Later Spitfires with more powerful engines will do better but then later Spitfires also weigh more and will have a a higher stalling speed limit which will affect the tightest turn radius.
Please also note that turn radius varies with speed and G's pulled.
Which Spitfire is out turning which?
A. taking 19 seconds at a 1600ft radius at 375mph.
B. taking just under 16 seconds at a 1200ft radius at 325mph.
C. taking 13 seconds at 800ft radius at 265 mph.
All are pulling 6 Gs and all are loosing thousands of ft/min altitude.
The Spitfires "best" turn performance seems to be a 23-23.5 second turn at 225mph at 1200ft radius at 3gs. it may actually hold height at that turn "rate" and speed.
Obviously starting position between two aircraft could be critical to a turning fight. a little altitude advantage helps, the pursuing airplane starting on the outside of the target plane has to pull more Gs ( or turn tighter, momentarily trading speed for turn radius)to get the target in the sights while starting from inside the turn (target turns across the pursuer) makes things easier for the pursuer. initial bank can affect results.
Blacking out in a sustained 6 G turn can really affect the results
GregP
Major
Hi Shortround,
I agree and do not think ANY WWII fighter can complete a 6g level 360° turn. I seriously doubt a 4g level 360° turn since the power surplus is just not there to sustain it. Any 8+g encounters were momentary.
They CAN sustain 4 - 6 g if descending. Gravity works all the time, regardless of nationality.
We KNOW a P-51D can achieve 11-12 g at 495 mph without structural failure, but the survival rate is 50%.
I agree and do not think ANY WWII fighter can complete a 6g level 360° turn. I seriously doubt a 4g level 360° turn since the power surplus is just not there to sustain it. Any 8+g encounters were momentary.
They CAN sustain 4 - 6 g if descending. Gravity works all the time, regardless of nationality.
We KNOW a P-51D can achieve 11-12 g at 495 mph without structural failure, but the survival rate is 50%.
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