S/R I was just referring to peoples "intuition" the 750 turbo had more power and torque than a normally aspirated 900cc. It should have been quicker but was actually about 2 seconds a lap slower. The turbo lag was actually short but enough to make a telling difference regardless of what the charts and graphs said. In aircraft terms there is a difference between what an aircraft should do and what it actually does in practice because the pilot cannot get the best out of it
F4U vs. P-51 essay
- Thread starter magnocain
- Start date
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Whoa! Didn't these planes have constant speed props? If they're cruising at any power setting within the prop's governing range (which is from a little above idle all the way to max power), it's the prop governor, not the throttle controlling the RPM. If a sudden acceleration is needed, both prop and throttle get pushed to the stops. As soon as the governor sees the demand for max RPM, it flattens the propeller pitch, sharply reducing its rotational resistance. At the same time, the engine is being fed gobs more fuel, increasing its power output. Admittedly the propeller is heavy, but by reducing its rotational drag, it's helping the engine accelerate its RPM. I have a difficult time envisioning 2000+ HP being much impeded by flywheel effect, especially with the "flywheel" helping the engine accelerate.
Cheers,
Wes
PS: Once the governor sees its target (max) RPM, it abruptly coarsens the propeller pitch to change engine torque into increased thrust and minimize RPM overshoot. ("WWOWWWW"!) The Curtiss electric was not as fast-acting as the Ham Standard Hydromatic, and more prone to slower accelerations and RPM overshoots.
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Please forgive my personal rant, but IMHO, electric propellers were a bad idea from the get-go. (Zipper, you want to talk about "flop or not", try electric propellers!)
Not too-too bad on low, slow and dirty aircraft of the thirties, and maybe even marginally acceptable on transports and heavy bombers and other straight-and-level WWII aircraft, but they had no business on fighters, fighter-bombers, attack aircraft, or anything else subject to strenuous maneuvering.
Their electrical contact sliprings were easily corroded/eroded, making the propeller pitch changes even more sluggish and sometimes unresponsive. This could result in engine overspeeds, overtorques, or in extreme cases, runaways. (Remember, the propeller is controlling engine RPM by adjusting its pitch to balance propeller resistance to engine torque at the desired RPM.) At sea and at high altitude, these effects were more pronounced, due to salt corrosion and arcing due to the reduced electrical insulation capabilities of thinner air. An aircraft engaged in strenuous maneuvering needs to have its propeller(s) responding instantaneously to the various loads imposed on them if the engine(s) are to be kept within their operating limits.
Electric propellers caught on early largely because they were relatively simple, cheaper to build, the promotional horsepower of Curtiss, and the fact that early hydraulic propellers had their share of problems. I think it's a tribute to the market power of Curtiss-Wright Aeronautical that electric propellers held on as long as they did. Once the Hydromatic became available, that should have been the end of the electric, IMHO.
Cheers,
Wes
Not too-too bad on low, slow and dirty aircraft of the thirties, and maybe even marginally acceptable on transports and heavy bombers and other straight-and-level WWII aircraft, but they had no business on fighters, fighter-bombers, attack aircraft, or anything else subject to strenuous maneuvering.
Their electrical contact sliprings were easily corroded/eroded, making the propeller pitch changes even more sluggish and sometimes unresponsive. This could result in engine overspeeds, overtorques, or in extreme cases, runaways. (Remember, the propeller is controlling engine RPM by adjusting its pitch to balance propeller resistance to engine torque at the desired RPM.) At sea and at high altitude, these effects were more pronounced, due to salt corrosion and arcing due to the reduced electrical insulation capabilities of thinner air. An aircraft engaged in strenuous maneuvering needs to have its propeller(s) responding instantaneously to the various loads imposed on them if the engine(s) are to be kept within their operating limits.
Electric propellers caught on early largely because they were relatively simple, cheaper to build, the promotional horsepower of Curtiss, and the fact that early hydraulic propellers had their share of problems. I think it's a tribute to the market power of Curtiss-Wright Aeronautical that electric propellers held on as long as they did. Once the Hydromatic became available, that should have been the end of the electric, IMHO.
Cheers,
Wes
Shortround6
Major General
I guess it depends on the time span we are talking about. Compared to a motorcycle/race car accelerating out of a corner an aircraft can take quite a while to get up to speed, yes a large part is aerodynamic drag ( and a difference of 150-200mph in speed instead of 50-100mph) but a 450lb prop with a diameter of 12 ft or so ( average weight at what distance from prop center?) running at, say 900rpm ( engine doing 1800rpm with 2:1 reduction gear) is going to take some effort to get up to 1350rpm (engine doing 2700rpm), regardless of what pitch the blades are at. Obviously the engine will pick up speed quicker in fine pitch vs coarse pitch but it isn't this "flywheel" effect that causes problems at low speeds and large throttle changes? sudden increase in throttle has the plane rolling the opposite way the prop turns ?
This maybe one reason some US pilots were using the wrong engine settings for cruising (high rpm and low boost) as they thought it would help them get to high speed quicker.
This maybe one reason some US pilots were using the wrong engine settings for cruising (high rpm and low boost) as they thought it would help them get to high speed quicker.
S/R I was only talking about human perception. The guy concerned was an old schoolmate of mine and was a top rider at club level. He is still (as far as I know) a motorcycle journalist. Everybody including me thought it would be a class winner, harmony of controls beat brute horsepower every time.
Yes, the inertial reaction of accelerating a heavy prop is a contributor to the infamous "torque roll", but it's only a minor player in what amounts to a veritable "perfect storm" of forces at work. The major players are "P" factor and gyroscopic precession, both resulting from the fact that at speeds down in the "danger zone" the aircraft is at a relatively high angle of attack and the thrust line is at an acute angle to the relative wind and the direction of flight. In addition the air flow over the stabilizers and control surfaces is slow and "soft", reducing their effectiveness in keeping the pointy end forward and the oily side down. It starts with a P factor driven yawing moment which through differential lift and gyroscopic precession quickly induces a rolling moment. The pilot's startled reaction of full opposite aileron only serves to stall the downward-traveling wing, accelerating the roll. What you have here is a classic snap roll, initiated by a surge of "P" factor and gyroscopic precession rather than a pilot's rudder stomp, and aided by torque reaction.
The speed range in which this becomes a danger is generally well below even the slowest speed at which the aircraft might cruise.
Cheers,
Wes
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CORSNING
Tech Sergeant
magnocain,
Are you still out there after 9.5 years? If you are still interested
you will want to read;
F4U Corsair vs P-51 Mustang
Are you still out there after 9.5 years? If you are still interested
you will want to read;
F4U Corsair vs P-51 Mustang
Except Corsair had way more non combat losses than the Mustang.
The F4U5 was grounded replaced by the -4 because the plane used electrical relays that failed due to corrosion.
Corsair operated better from airstrips.
Mustang has a much longer loitering period exposing them to small arms fire.
Corsair could become a flame trap because the oil cooler was not shielded.
drgondog
Major
Dan - you have put your finger on loss per sortie ratios for P-51s in WWII. The 2x flight time until the P-47D-25 entered service surely contributed to more losses for the ustang.
DarrenW
Staff Sergeant
I'm not so sure if the average Luftwaffe pilot was "far more deadly and dangerous" when compared to their Japanese counterparts (by 1944 anyway). Both aircrew training and aircraft quality were slowly deteriorating as the war progressed, on par with the situation in Japan. Maybe the Germans had more aircraft and better radar which obviously improved their situation some, but the aerial prowess that the Luftwaffe enjoyed earlier in the war was largely gone by mid 1944.
I do agree though that the loss rates for the Corsair would have gone up in Europe, but in my opinion probably not as much as some are being led to believe.
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Peter Gunn
Master Sergeant
Hmm... by mid '44 the P-38, P-47, P-51, F6F, F4U all had a decent performance advantage over just about anything the IJA or IJN could throw at them, in the ETO not so much. Also I don't see the Japanese fielding any jets in mid '44 either.
Would the Corsairs loss rate increase with ops in the ETO? Most definitely. If loss rates for Korea are any indication, you would probably lose just as many Corsairs as Mustangs in CAS roles, although I doubt the Corsair is going to range as far afield as the P-51, so perhaps that would play into the numbers somewhat.
Hell, JoeB posted numbers several years ago that showed the F6F was tougher v ground fire than the F4U.
Would the Corsairs loss rate increase with ops in the ETO? Most definitely. If loss rates for Korea are any indication, you would probably lose just as many Corsairs as Mustangs in CAS roles, although I doubt the Corsair is going to range as far afield as the P-51, so perhaps that would play into the numbers somewhat.
Hell, JoeB posted numbers several years ago that showed the F6F was tougher v ground fire than the F4U.
GregP
Major
I'm not sure the average German pilot was ever better than the average Luftwaffe pilot. The German pilots had many more targets, to be sure, but the average Japanese pilot, at least at the start of the war, was well-trained and a combat veteran, much as was the core of the Luftwaffe. My bet is they were pretty close in training and experience.
The top scorer against western front pilots for the Germans was Hans Joachim Marseille with 185 victories mostly against the British in the desert. The top-scoring Japanese ace of the war was Hiroyoshi Nishizawa with 102 at the time of his death. The spread is not all that great, and most of Nishizawa's victories were against Allied Navy fliers, mostly. The difference could well be the availability of targets since most of the Allied targets available to Nishizawa were in and around Naval battles, which were not very frequent relative to Marseille's target population.
By the end of the war, the average German pilot was nowhere NEAR as experienced as his pre-war and/or early-war counterparts and neither were the average Japanese pilots.
The top scorer against western front pilots for the Germans was Hans Joachim Marseille with 185 victories mostly against the British in the desert. The top-scoring Japanese ace of the war was Hiroyoshi Nishizawa with 102 at the time of his death. The spread is not all that great, and most of Nishizawa's victories were against Allied Navy fliers, mostly. The difference could well be the availability of targets since most of the Allied targets available to Nishizawa were in and around Naval battles, which were not very frequent relative to Marseille's target population.
By the end of the war, the average German pilot was nowhere NEAR as experienced as his pre-war and/or early-war counterparts and neither were the average Japanese pilots.
pinehilljoe
Staff Sergeant
- 754
- May 1, 2016
given the choice, I'd rather be in a P-47N
I'll take a P-51H...
Peter Gunn
Master Sergeant
Me too.
The P47 was not used in Korea for a few reasons.
First the P47 loaded required a bomber base with a long airfield to get off the ground.
Early in the war Pusan was surrounded by NK army.
Only bases available were short airfields left by the Japanese.
Perfect for Mustang and Corsair.
They could have flown out of Japan but P47 was a pig on fuel and maintenance.
CAS role P47 would have the same loss ratio as the Mustang and Corsair.
Had huge oil plumbing to cool the turbo and engine.
Plus 40 mm AA was far more abundant than WW2.
Another reason seems that Formosa got the remaining available P47s for Chennault and Chang Kia Shek.
