XP-39 II - The Groundhog Day Thread

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The P-39, P-40 and F4F over the Solomons barely scraped over a 1 to 1 kill/ claim ratio.
Which we could afford and the Japanese could not. That our less experienced pilots in lower performing planes could manage that ratio against the experten of IJNAF is an amazing achievement itself.
Probably partly due to our "overweight" and overbuilt aircraft. They didn't call Grumman "the Iron Works" for nothing.
 
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Without the racks, the P-51B was probably faster, not slower. With racks on, the positions switched. P-51D used more streamlined racks, 4 mph cost vs. 12 mph on the B.
A quick overview from Joe Baugher:
 
And the lack of a supercharger is another myth that has been perpetuated for 75 years.
C'mon, man, the guy was a maintenance officer. He wasn't that ignorant. All the engine types in question had integral gear driven superchargers built in. Part of the engine, in wrench twister jargon. None of these guys had probably ever seen an external extra stage supercharger like European engines had, so to them an outboard turbocharger was just "a supercharger". "Turbo" was understood. The fact that in our ex post facto concise semantics we misconstrue their words is our (the modern world's) fault, not theirs.
 
I doubt very much any Allied pilot fighting the Japanese during the calendar years 1942 and 1943 would be very inclined to agree with you. A case could even be made for the first several months of 1944, but then again, it would only be pilots reports, not actual test data.
 
Hi Reluctant Poster.

Show me a list of vetted kills. The only ones I know of are the USAAF Report 85 and Naval Aviation Combat Statistics - World War II, and people fight over those.

So, we are left with claims only. I have zero confidence in someone who says they have the kill information unless they state: 1) exactly what IS a "kill" (widely differing opinions), 2) where did they get their kill numbers exactly and how? (who did the vetting? Is it "official" and recognized by anyone).

When I think about it, all I see to really use is acknowledged losses versus claims because claims is all we really have. I have a great file of German claims ... 68,000+ claims. I don't have and have not seen a list of vetted German victories. As far as I know, Hartmann is sill at 352 victories.
 
Biff,

Please accept my apology, I should never have said that pilot reports were heresay and opinion. But any report from an individual will contain some opinion.

I am neither a pilot, mechanic or engineer. I just like to read about history. I will be 70 in February and my Dad served in WWII, so that is my favorite period.

You are correct, I'm just gleaning through piles of old contradictory information trying to sort out what happened and why. I became more interested when M. Williams started publishing the actual performance reports in wwiiaircraftperformance.org. This information cleared up a lot of confusion for me, since most prior published information was very contradictory, meaning some of it was wrong.

I'm just expressing my opinions based on that newer information, and getting almost 100% pushback from everyone who would rather believe what they have heard for 75 years rather than newer factual information and recently released information from the fall of the Soviet Union.

I'm not worried about credibility, I know I don't have any. But I do have a lot of facts that nobody else wants to believe.

I always enjoy your posts and please feel free to contact me anytime.

Thanks.
 
Agree with you about WEP. Your crew chief was not to happy to see that wire broken and would want to know why you abused HIS airplane. And it was for EMERGENCY only as using it risked engine damage or failure.
 
P-39 Expert,

No one thinks you are dumb. No one thinks you don't have facts. We don't think you are putting it together right.

When you make comments such as saying mixture adjustment is simple, and that simply removing weight will make something better, and then completely blow off people with actual experience explaining how things in the real world work, you kind of lose them.

You are a valued member here, but maybe try listening a lil more...
 
The early planes were attriting Japanese pilots, whether it be from combat losses, accidents, weather or mechanical problems. Not just victory claims. The Japanese lost those planes and pilots because of combat, if not actually from combat. And those losses were the best of the best, since their pilot training fell off as the war progresses and they didn't rotate their pilots back home to teach the trainees. The P-38, Corsair and Hellcat pilots had it easier because of the work done before they arrived.

I'm just saying that early work would have been a lot more productive if the P-39 was made lighter.
 
I have never blown off anyone on here, never told them they didn't know what they were talking about, and certainly never even mentioned the word stupid. I have always been as courteous as I possibly can to everybody on here that disagrees with me, which is everybody.

But how anyone can say that removing weight will not make an airplane perform better is someone I'm going to disagree with every time.
 
I'm just saying that early work would have been a lot more productive if the P-39 was made lighter.
Nobody's quibbling with the idea that a lighter P39 would have performed better. The devil is in the details, and the real world impracticality of most of the solutions you suggest are what is generating the pushback. The personnel at Port Moresby and Milne Bay were stuck with playing the hand they were dealt, and from the perspective of 3/4 century later, I think we can say they played that hand as successfully as was possible under the circumstances.
 
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Like you, I am not an engineer, A&P or a pilot. I don't disagree with everything you say. I have not posted in this thread up until this point, as I didn't think I had anything to add.

Having said that, you are dealing with many knowledgable individuals here and yet you continue to use very simplistic language which continues to get you in trouble. So...

I think an Allison V-1710 weighs about 1400 lbs. dry. If I remove that weight from the P-39 I can state categorically that the airplane will not perform better...

So maybe going forward; "But how anyone can say that removing weight, while maintaining proper weight and balance, will not make an airplane perform better is someone I'm going to disagree with every time."
 
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You're making a generalization that spans about 8 months, in some cases I can agree, but in other areas no. Again, the JAAF did not lose it's best pilots during the first 6 months and there plenty of them still around when better aircraft showed up.
 
How you going to define "performance"; miles/hour, ft/min, degrees/sec, OR total losses during a period of combat ops (including operational) vs VERIFIED enemy combat losses?
Quite likely that which you sacrifice in pursuit of weight reduction will negatively effect your victory/loss ratio. (IFF, protection, firepower, etc) It's not just an airplane, it's a weapons system.
 
So maybe going forward; "But how anyone can say that removing weight, while maintaining proper weight and balance, will not make an airplane perform better is someone I'm going to disagree with every time.

And this statement is about 98/99% correct. Depending WHERE in the weight and balance envelope the aircraft falls will also be a determining factor. Tail heavy aircraft (within the envelope) will generally fly faster but be less stable, nose heavy aircraft (within the envelope) may be a little more stable, require more elevator back pressure to maintain level flight (to be trimmed out) but may not gain maximum lift efficiency (slower flight at a given power setting). Removing weight will of course make the aircraft lighter (and will more than likely make the aircraft perform better) but you also have to consider WHERE you are removing that weight from, thus this IS NOT a linear calculation and I think GregP even gave the correct equation to figure this out about 100 posts ago!

PS - I actually witnessed this when I crewed a Jet at Reno. In once case the weight removed didn't make a difference until we got the C/G aft and then we saw results.
 
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I think you are not listening. People are telling you that you can't just remove the weight and it will magically get better. Removing weight also affects things such as CG. Depending on where that CG now lies will effect how it performs as well. Thats a real simple view of it. There is much more to it than that. Engineers sit down, perform calculations, and together with test pilots figure it out. You cannot simply modify an aircraft and think it will make it better. Trust me I have done countless modifications, and currently work in retrofit and modification engineering. This stuff has to be carefully evaluated.


Thank you. Said much better than I have.


And this as well.

Again no one is saying reducing weight will not improve performance. But has to be done correctly.
 
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It is my understanding that American aircraft were designed to higher stress standards than the British so that for a similar size aircraft the American craft would be heavier. I also understand that part of the lightening of the P-51H was designing to the lighter standards which worked quite well. However to do so was a major impact and the P-51H is a significantly different aircraft than the P-51D. I do wonder if the P-39 was originally designed to the lighter British standards, how would it have performed.
 
Something new!
 
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