Now having said that, I believe this thread has run its course. No amount of facts will change any opinions or lack of understanding present here.
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"Normal spin characteristics with prompt recovery if proper technique is used." I had seen this film before, thanks for posting.
The only thing refuting is your "expert" status.
Hey Greg,Hey Peter Gunn
Maybe we could fix the P-39 with some Chevrolet "SS" letters along the lower nose in front of the door? And might as well install a Hurst "pistol-Grip" shifter handle on the control stick, too, along with a push-button radio.
I had a Burgundy 1970 Chevelle SS 454 LS-7 with rock crusher 4-speed and have been weeping about it for 50 years. I've heard people say they had an LS-7, but they always miss when I ask them about the axle ratio. It only came with ONE axle ratio in 1970, and that was a 4.11 . My ex-wife wrapped it around a Police car when she ran a stop sign. Nobody was killed, but the car was a total loss.
At least my 2019 Ford Mustang GT PP1 6-Speed with more horsepower than the Chevelle (not as much torque, though) helps a bit.
View attachment 597984
It's actually quicker than the old Chevelle and very definitely handles better, but I loved that old Chevelle and the cowl induction. The Mustang is unrelated to the P-39, but likely has a better drag coefficient at sea level!
Reminds me of my favorite kitplane. Take a garden-variety Vans RV-4 kitplane as below:
View attachment 597985
Remove the 4-cylinder 160 hp and add a six-cylinder 285 hp Lycoming and chop off one wing bay from each side to get a fire-breathing Harmon Rocket:
View attachment 597986
Outclimbs a stock P-51 handily, at least in the lower altitudes. Just shy of 4,000 fpm (3,950)!
Cheers!
P-39 had no trouble operating in squadron or group strength.
The AAF didn't buy many Allison powered Mustangs. Less than 1000 P-51s and only a little over 600 Mustang I.
Perhaps the equivalent of 1.5 regular .50cal.
.......
Too low for what? You make it sound like the 37mm was hand loaded after every round. Ballistics very good (flat) out to 400yds.
.......
37mm was not more widely used because it had to be a centrally mounted weapon on a single engine plane. Could not be mounted out on the wing like all the other AAF/USN planes required.
20mm was used in the P-39 only briefly because of early shortages of the 37mm, and because the Brits specified it on the P-400. 20mm would have been just fine on the P-39 given more ammunition capacity. Either gun could have been used.
And if you observe some of those recoveries show the aircraft with the tail low because of the aft CG, not a desirable characteristic. A well trained pilot will deal with this accordingly."Normal spin characteristics with prompt recovery if proper technique is used." I had seen this film before, thanks for posting.
I understand the critical engine. That refers to a conventional twin engined plane with both propellers turning the same direction. If both props are turning right as viewed from behind then the right engine would be the critical engine. If the left engine is lost then the right engine torque (and the drag of the dead left engine) tends to pull the plane into a left bank. If the right engine is lost the left engine torque works against the inclination of the plane to bank right offering more stability.
On the P-38 both engines turned outward so the loss of either one made the plane want to bank/turn violently toward the dead engine. Both engines were critical.
Hello P-39 Expert,
....except that it created situations in which a little extra idling on the ground would cause the P-39 to overheat and abort.
The original discussion was about the inadequacy of the cooling system in the P-39 even for the engines that were already installed and the tendency to exceed temperature limits in sustained high power operation at existing altitudes thus making it unsuitable for installation of a ASB and operation at higher altitudes.
The tendency to run hot and overheat has been documented by numerous test reports and pilot accounts.
Your refusal to acknowledge these issues is quite extraordinary.
I have continually acknowledged this but maintain it was not nearly as serious as you are making it out to be.
The production of the last Allison powered P-51, the P-51A stopped because production began of the Merlin powered P-51B with superior altitude performance.
Even 1.5 regular .50 cal MG is pretty inadequate unless you happen to be designing fighters for the Soviets. Not when used with a 37mm cannon.
.......
A gun with a 2000 fps muzzle velocity has a rather looping trajectory at any range. It doesn't fly flat out to a specific distance. Flat trajectory out to 400yds from "Cobra" by Birch Matthews.
Check back to your high school physics which should have explained all this.
The problem is when you have a battery of guns with significantly differing ballistics, you can get them to all line up within a certain distance when flying straight and level such as in a bomber intercept but that doesn't work so well when pulling G in a deflection shot. It should out to 400yds.
.......
If the 37 mm M4 were such a fantastic weapon, then there were many aircraft such as twin engine attack aircraft, night fighters, the P-38 that could have used it. Please tell us how many actually did.
P-39, P-59, P-63.
If it were so easy a solution, then some of the operators of P-39 with 20 mm cannon in New Guinea or Guadalcanal should have done something to address the issue. These folks operating the aircraft probably figured out pretty early that 6 seconds of firing time is really about two good squirts before the ammunition is gone. I suspect increasing the ammunition supply might not have been so easy. Should have been easy to reduce the weight also. I have no idea why it wasn't implemented.
From what I can tell, both the 37 mm and 20 mm guns used magazines that sat above the gun and there may not have been the room above the gun to put in a larger ammunition supply. Remember that this space is also shared with the .50 cal cowl MG.
- Ivan.
...As you know, spins were prohibited in the pilot's manual on all AAF and USN fighters.
Hello P-39 Expert,
However long it would have taken to design a new wing, this was a basic design flaw in the P-39 that was a serious limitation. The symmetrical airfoil had a pretty low coefficient of lift relative to more modern airfoils.
The wing retained good lateral control because the tips did not stall with the rest of the wing, but the rest of the wing tended to stall all at once. (from NACA Report)
If the aircraft had any directional misalignment during the stall, the stall was asymmetrical and the aircraft would flip.
This was described in NACA testing.
Even with equipment shifts to attempt CoG corrections, the problem appears to be a significant rear weight bias and there are not that many places equipment can be moved with such a small airframe.
The CoG may have been fine with the aircraft loaded but was not so fine when loads were expended. Both conditions need to be addressed.
As for taking a year to design a replacement wing, that is a pretty sad commentary. The Soviets managed to do this kind of a thing much quicker.
Roll at a MAXIMUM of 80 degrees per second was hardly adequate. Whether or not a new wing is involved, this should have been improved.
As for turn rates, the Hurricane typically also turns better than the Spitfire.....
I suspect some of the Soviet fighters did better as well.
- Ivan.
P39E,
Here are a couple of opinions from my perspective.
Overheating: If during the taxi out flight a member of your flight has a mechanical fault and returns to the chocks for a quick fix. The rest of the flight has two choices, wait or go. Fighter tactics are built around mutual support. Two aircraft are much more effective / deadly than two. Three are more effective than two in some cases, and can be a serious detriment if split. Four are way more effective than three. Yes, we practice 3 ship ops but it has it's detriments. Again, four is way more effective than three. So while you are waiting the opportunity for overheating becomes are serious reality, which might take more assets out of the mission. No or not enough assets could cause mission cancel or failure. Also, if there are complaints of overheating, then the P39s peers aren't experiencing the same problems or the guys would not be mentioning it.
CG: What type of car do you drive and how old is it? The reason I ask is most modern cars understeer when at the limits. Oversteer is when the tail slides around, under steer is when the nose plows or slides. The latter is what is standard today, and the reason is it's easier to handle as control degrades. Great for masses, doesn't require above average skills at the limit. Did you watch the spin video? There were a few that I would describe as violent and I did spin training in the T-37. Also realize that the AAF was expanding exponentially at times. So your instructors are all young aviators. Young aviators have less experience to draw on and pass along to neophytes. Next look at all the other single engine fighters / trainers the USAAF had. All of them had engines in the front. Next think about where are the mass is in a single engine piston fighter. Not surprisingly it's centered on the engine. Now your spin training, from your young instructors, as you came up the pipeline, has been in nothing but nose engined aircraft, and they all behaved in a similar fashion. The P39, can under controlled circumstances, be recovered from a spin. And the CG is within limits. There is a reason they are limits, and exceeding them is NOT a safe way to operate. Yes, the video showed several different spins, and they were recovered from (well except one). I wonder if the AAF made spin videos about the other fighters.
Someone posted comments by a pilot regarding doing intentional spins. The comment talked about pulling on the stick and letting go, and how the plane behaved would determine whether a spin would be accomplished. If I remember correctly, the pilot made comment about if the plane returned quickly to it's pre-pull on the stick status it was okay, and if it didn't it wasn't. What the pilot was doing was checking the dynamic stability of the plane. Dynamically stabile aircraft will return to "normal" fairly quickly, dynamically unstable will not. Guess what, the F16 is dynamically unstable, which is what makes it very maneuverable. However, it requires a computer (it has 3) to keep it flyable. The closer to unstable a plane is, the more maneuverable it can be, however the more easily it can be departed (put out of control). Approaching dynamically unstable in 1940s, with neophyte pilots with low experienced pilots, without years of history and procedures to fall back on, is / was a recipe for problems.
Regarding the expended ammo and acrobatics. You mentioned if I remember correctly, that a guy would know not to do loops after expending his ammo. That works in peace time. In combat, you are shooting and being shot at. Run out of ammo but not adversaries, and the option of going home or no acrobatics will not always be there.
Looking at the video, and reading quite a bit what's been posted on here, I can see how you would think it's no big deal to recover from a spin. However, from the perspective of the late 30s, to mid 40s, the USAAC / USAAF had exponentially grown, had young pilots, low experienced instructors, and not much history of procedures, and the benefit of owning a plane for decades to fall back on. Also the P39 sits outside the standard due to it's mid engine layout as compared to all the trainers or other SE fighters. The guys on this forum have been doing an admirable job of walking you through the CG limits and ramifications, as well as it's combat record with the Soviets (IE how it compared in quality to their indigenous planes. Add as well their willingness to overboost the engine (works if you are fighting over LAND, and it's your land (DEFENSIVE), which gives much more opportunity to WALK home vice become a casualty / POW. It was a decent plane, just didn't fit in with it's peers.
Cheers,
Biff
Please expand above.
Biff, was your post addressed to me? Just asking. Thanks.P39E,
Here are a couple of opinions from my perspective.
Overheating: If during the taxi out flight a member of your flight has a mechanical fault and returns to the chocks for a quick fix. The rest of the flight has two choices, wait or go. Fighter tactics are built around mutual support. Two aircraft are much more effective / deadly than one. Three are more effective than two in some cases, and can be a serious detriment if split. Four are way more effective than three. Yes, we practice 3 ship ops but it has it's detriments. Again, four is way more effective than three. So while you are waiting the opportunity for overheating becomes are serious reality, which might take more assets out of the mission. No or not enough assets could cause mission cancel or failure. Also, if there are complaints of overheating, then the P39s peers aren't experiencing the same problems or the guys would not be mentioning it.
CG: What type of car do you drive and how old is it? The reason I ask is most modern cars understeer when at the limits. Oversteer is when the tail slides around, under steer is when the nose plows or slides. The latter is what is standard today, and the reason is it's easier to handle as control degrades. Great for masses, doesn't require above average skills at the limit. Did you watch the spin video? There were a few that I would describe as violent and I did spin training in the T-37. Also realize that the AAF was expanding exponentially at times. So your instructors are all young aviators. Young aviators have less experience to draw on and pass along to neophytes. Next look at all the other single engine fighters / trainers the USAAF had. All of them had engines in the front. Next think about where are the mass is in a single engine piston fighter. Not surprisingly it's centered on the engine. Now your spin training, from your young instructors, as you came up the pipeline, has been in nothing but nose engined aircraft, and they all behaved in a similar fashion. The P39, can under controlled circumstances, be recovered from a spin. And the CG is within limits. There is a reason there are limits, and exceeding them is NOT a safe way to operate. Yes, the video showed several different spins, and they were recovered from (well except one). I wonder if the AAF made spin videos about the other fighters.
Someone posted comments by a pilot regarding doing intentional spins. The comment talked about pulling on the stick and letting go, and how the plane behaved would determine whether a spin would be accomplished. If I remember correctly, the pilot made comment about if the plane returned quickly to it's pre-pull on the stick status it was okay, and if it didn't it wasn't. What the pilot was doing was checking the dynamic stability of the plane. Dynamically stable aircraft will return to "normal" fairly quickly, dynamically unstable will not. Guess what, the F16 is dynamically unstable, which is what makes it very maneuverable. However, it requires a computer (it has 3) to keep it flyable. The closer to unstable a plane is, the more maneuverable it can be, however the more easily it can be departed (put out of control). Approaching dynamically unstable in 1940s, with neophyte pilots with low experienced, without years of history and procedures to fall back on, is / was a recipe for problems.
Regarding the expended ammo and acrobatics. You mentioned if I remember correctly, that a guy would know not to do loops after expending his ammo. That works in peace time. In combat, you are shooting and being shot at. Run out of ammo but not adversaries, and the option of going home or no acrobatics will not always be there.
Looking at the video, and reading quite a bit what's been posted on here, I can see how you would think it's no big deal to recover from a spin. However, from the perspective of the late 30s, to mid 40s, the USAAC / USAAF had exponentially grown, had young pilots, low experienced instructors, and not much history of procedures, and the benefit of owning a plane for decades to fall back on. Also the P39 sits outside the standard due to it's mid engine layout as compared to all the trainers or other SE fighters. The guys on this forum have been doing an admirable job of walking you through the CG limits and ramifications, as well as it's combat record with the Soviets (IE how it compared in quality to their indigenous planes. Add as well their willingness to overboost the engine (works if you are fighting over LAND, and it's your land (DEFENSIVE), which gives much more opportunity to WALK home vice become a casualty / POW. It was a decent plane, just didn't fit in with it's peers.
Cheers,
Biff
Biff, was your post addressed to me? Just asking. Thanks.
Thank you, just making sure.Yes, I abbreviated your screen name. My bad.