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.
XP-39 II - The Groundhog Day Thread
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MiTasol
1st Lieutenant
yep and that video clearly shows that prompt recovery takes many thousands of feet of precious altitude. If you do not have the altitude you hit the silk, if there is time, or die.
MiTasol
1st Lieutenant
Drip under pressure... 
Peter Gunn
Master Sergeant
Well it has been an entertaining thread, I'm still laughing over this whopper:
The Mustang I didn't see combat until April 1943 with the Brits. It already weighed 8600lbs clean. With two 75gal drop tanks it would have weighed 9600lbs and likely couldn't leave the ground with its 1150hp engine.
What I don't understand is why race cars today blow so many tires at a measly 200 mph +/- when, being able to leave a P-39 in the dust means the Mustang was running on the roads at 400 mph, man Goodyear technology must have been really something in 1942!
The Mustang I didn't see combat until April 1943 with the Brits.
It already weighed 8600lbs clean. With two 75gal drop tanks it would have weighed 9600lbs and likely couldn't leave the ground with its 1150hp engine. What I don't understand is why race cars today blow so many tires at a measly 200 mph +/- when, being able to leave a P-39 in the dust means the Mustang was running on the roads at 400 mph, man Goodyear technology must have been really something in 1942!
Peter Gunn
Master Sergeant
Hey Greg,
Agreed, I had a 1995 Seville STS back in the nineties that was about as fast in the stoplight wars and absolutely better on the highway. Heck, my XT-6 is probably faster with a 6 cylinder, but nothing can beat the "Cool" factor of those old beasts, and the sound. I'm going to see if I can hunt up some snaps of it, don't think I have any but might be cool to see.
Nice 'stang by the way, except who's the old dude in the drivers seat?
Trust me, I don't look any younger than that either.
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.
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.
.......
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.
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.
.......
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.
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.
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.
....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.
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.
.......
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.
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.
.......
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.
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.
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.
FLYBOYJ
"THE GREAT GAZOO"
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.
FLYBOYJ
"THE GREAT GAZOO"
Or both engines weren't. To avoid the adverse yaw you powered back the good engine. This was SOP on the aircraft (and some other twins) and it worked fine if the pilot was well trained.
P-39 Expert
Non-Expert
Please expand above.
DarrenW
Staff Sergeant
Yes, this was true for the P-51D and F4U-1, but the P-47D could intentionally spin up to one-half turn and the F6F-3/5 up to two full turns.
DarrenW
Staff Sergeant
Snip:
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.
Looks like Bell was the only company endeared to the weapon.
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.
Looks like Bell was the only company endeared to the weapon.
There was a redesign of the wing, it was called the P-63 Kingcobra. The problem was that when the P-63 arrived in October 1943, the USAAC already had the P-38 working in the Pacific and the P-47 in the ETO, Med and Pacific, and there was no real requirement for the P-63 that those other fighters didn't already meet.
P39 Expert,
Here are a couple of opinions from my perspective.
Overheating: If during the taxi out 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 experience, 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 experience 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
Here are a couple of opinions from my perspective.
Overheating: If during the taxi out 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 experience, 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 experience 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
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FLYBOYJ
"THE GREAT GAZOO"
Biff - always appreciate your perspectives, this forum is blessed to have you (and a few others) around!!!
glennasher
Senior Airman
There's no need to expand further, you either get it, or you don't. By now, if you don't get it, you ain't gonna get it. Quit trolling.
Let's keep it civil gents.
P-39 Expert
Non-Expert
Biff, was your post addressed to me? Just asking. Thanks.
Yes, I abbreviated your screen name. My bad. Fixed.
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P-39 Expert
Non-Expert
Thank you, just making sure.
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