GregP
Major
Watching this thread is better than watching The Big Bang Theory, unless Penny is in the scene. If she is, I'd go with Penny and her assets as better.
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XP-39 II - The Groundhog Day Thread
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glennasher
Senior Airman
It's like talking (typing) to a brick wall, or trying to teach a pig to sing.
While this is frustrating, lets all try and keep it civil.
FLYBOYJ
"THE GREAT GAZOO"
So if a "Test Pilot" submitted a "pilot report" would it be "factual and comparable" or "hearsay and opinion"?
Hello P-39 "Expert",
I guess you really do have a comprehension problem.
Have you actually figured out how adjusting the mixture control for best power actually works? There isn't a "Best Power" label.
Trying to do this in maneuvering flight while also trying to avoid catching bullets is just not an intelligent thing to do.
You will never have a chance for conditions to stabilize enough.
You obviously didn't read the rest of the memorandum or don't understand what achieving 335 MPH on partial power really means.
.....
ONE P-39K achieved 370 MPH, just like a P-39D achieved only 358 MPH. The big difference in the tests I am quoting for the P-39s as versus the A6M2 is that the P-39 were aircraft deemed to be in good condition and the tests were representative of their type by the service that normally operated them.
The A6M2 was a crashed aircraft repaired but never had all its systems working properly and tested by its captors who didn't really know how to run it properly.
Glad it is comparable to a A6M2 running at partial power with a poorly working carburetor.
Probably because the only service that had the opportunity to test the A6M2 to determine the actual maximum speed apparently never cared to do so. They only listed the speed at "Normal Power". This is pretty typical for Japanese aircraft.
.....
Actually we are talking about more like 15 MPH. The claim is 345 MPH as maximum speed for the A6M2.
The USN apparently agreed with this assessment and issued a memorandum to that effect later in the war.
I have not yet found the document though it is mentioned in Mr. Dunn's article.
I did not ask what the listed weight of he P-39D-1 was. I asked if you had any proof that the test aircraft was loaded to that weight. You are making an assumption here. Please observe that in many other test reports specifying a specific model of aircraft, the weight, CoG, loads and other specific details are mentioned and most of the time they do NOT agree with the standard details of the aircraft being tested.
I believe he was a good pilot trying to use a few tricks to make his aeroplane look better than it should have.
First of all, I am not trying to "prove" anything other than the fact that you can't do math.
Even when I claim that the A6M2 was probably faster than 335 MPH, I qualify what I claim as a GUESS.
Perhaps the Aleutian A6M2 rebuilt after a crash and with a poorly rebuilt carb and running at part throttle was the fastest Zero ever built. I don't think so, but maybe SOME people do. People also tend to write books very often without primary sources by just quoting from others who have written books. Just because a statistics is often repeated doesn't mean it is correct.
You might observe that Richard Dunn, who certainly knows more about the A6M2 than I do, does not state his conclusion as an absolute but just as "very likely". Saburo Sakai states that 345 MPH was the maximum speed of the A6M2 based on his personal experience but you will note that Dunn did not take that as conclusive evidence either though it certainly was a strong data point.
You are also making claims for performance when:
1. The client DIDN'T WANT the changes you propose.
2. The operators didn't agree that those changes were a good idea. They wanted more armour, not less.
3. You are using techniques to estimate performance that do not follow good aerodynamic principles.
I guess you really do have a comprehension problem.
Have you actually figured out how adjusting the mixture control for best power actually works? There isn't a "Best Power" label.
Trying to do this in maneuvering flight while also trying to avoid catching bullets is just not an intelligent thing to do.
You will never have a chance for conditions to stabilize enough.
You obviously didn't read the rest of the memorandum or don't understand what achieving 335 MPH on partial power really means.
.....
ONE P-39K achieved 370 MPH, just like a P-39D achieved only 358 MPH. The big difference in the tests I am quoting for the P-39s as versus the A6M2 is that the P-39 were aircraft deemed to be in good condition and the tests were representative of their type by the service that normally operated them.
The A6M2 was a crashed aircraft repaired but never had all its systems working properly and tested by its captors who didn't really know how to run it properly.
Glad it is comparable to a A6M2 running at partial power with a poorly working carburetor.
Probably because the only service that had the opportunity to test the A6M2 to determine the actual maximum speed apparently never cared to do so. They only listed the speed at "Normal Power". This is pretty typical for Japanese aircraft.
.....
Actually we are talking about more like 15 MPH. The claim is 345 MPH as maximum speed for the A6M2.
The USN apparently agreed with this assessment and issued a memorandum to that effect later in the war.
I have not yet found the document though it is mentioned in Mr. Dunn's article.
I did not ask what the listed weight of he P-39D-1 was. I asked if you had any proof that the test aircraft was loaded to that weight. You are making an assumption here. Please observe that in many other test reports specifying a specific model of aircraft, the weight, CoG, loads and other specific details are mentioned and most of the time they do NOT agree with the standard details of the aircraft being tested.
I believe he was a good pilot trying to use a few tricks to make his aeroplane look better than it should have.
First of all, I am not trying to "prove" anything other than the fact that you can't do math.
Even when I claim that the A6M2 was probably faster than 335 MPH, I qualify what I claim as a GUESS.
Perhaps the Aleutian A6M2 rebuilt after a crash and with a poorly rebuilt carb and running at part throttle was the fastest Zero ever built. I don't think so, but maybe SOME people do. People also tend to write books very often without primary sources by just quoting from others who have written books. Just because a statistics is often repeated doesn't mean it is correct.
You might observe that Richard Dunn, who certainly knows more about the A6M2 than I do, does not state his conclusion as an absolute but just as "very likely". Saburo Sakai states that 345 MPH was the maximum speed of the A6M2 based on his personal experience but you will note that Dunn did not take that as conclusive evidence either though it certainly was a strong data point.
You are also making claims for performance when:
1. The client DIDN'T WANT the changes you propose.
2. The operators didn't agree that those changes were a good idea. They wanted more armour, not less.
3. You are using techniques to estimate performance that do not follow good aerodynamic principles.
GregP
Major
Mea Culpa, DerAdler. I was trying to make a funny and perhaps got carried away. Will correct it. Cheers to all.
Was not directed at you, but at all of us. As frustration settles in, we all run the risk of going overboard.
wuzak
Captain
The V-1650-3 and V-1650-7 had different rated altitudes. The -7 was adopted as it gave better performance in the lower to mid altitudes, while maintaining good performance at the higher altitudes.
I believe that is how most kill ratios for US aircraft are traditionally calculated; all combat losses vs combat kills of the enemy. As I remember the book, there were some records of Zeros disappearing on their homeward flights, well after combat. Don't know how many.
My overall take was this; USAAC had to figure out how to maintain a new type of engine (V-1710 - almost all previous aircraft had radials) in a jungle under attack. They also had to fight a more experienced foe with little advanced warning of the attacks. Add to that conservative engine use doctrine developed from a time when funding was scarce (priority given to reducing maintenance over performance) and you see they had an uphill battle. Yet, they managed to hold the Japanese at bay for the first two 'lean' years of the war.
As for the P-39, there was not a USAAC fighter that would have faired any better at that time.
Also interesting, and something I don't see many talking about, is that of the USAAC single seat fighters, the P-38, P-39, P-40, P-47, and P-51, the P-39 was by far the smallest of the lot, for whatever that's worth.
FLYBOYJ
"THE GREAT GAZOO"
I've heard similar, somewhere I think it was calculated a 1 to 1.45 kill/ loss ratio, Zero to P-39
If you want to include all causes
Some points made, the P-39, despite it's reputation in the SWP did hold it's own but at the same time look at some of the P-39 units that transitioned into the P-38 in the later part of 1942 and the leap in combat victories. Those same early P-38 units operated under dismal conditions as well and had the P-38 been available earlier it would have made a huge difference. Research the 39th and 80th fighter squadrons and some of the aces that emerged from those units and how things turned around into 1943, all occurring when they got the P-38.
FLYBOYJ
"THE GREAT GAZOO"
P-38, P-39 and P-40 ops in New Guinea. Note comments at 4:35 and 19:35
The First Fighters in New Guinea 1942-1944
The First Fighters in New Guinea 1942-1944
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Hello jmcalli2,
The most effective Japanese Naval Fighter Unit that was fighting from Lae was the Tainain Air Group.
The unit was formed in October 1941, so it was hardly a veteran unit.
Although they had some experienced pilots from the war in China, that war was hardly comparable to a modern war.
Here are a couple questions for you regarding inexperience with the V-1710:
How much more experience would the AVG have had with their P-40s in China?
Did it make a difference that all the USAAC personnel in New Guinea were at least US Army instead of a mix of USN, Marines, US Army and civilians? Would these other people have had better experience working on V-1710 engines?
Would their supply chain have been any better than a base in New Guinea that was within shipping distance of Australia?
How well did P-40s do in New Guinea?
Did the Australians have the same problems with Allison equipped aircraft?
They could not possibly have had any more knowledge than the service that gave them the aircraft or could they?
- Ivan.
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GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The RAAF was operating out Milne Bay, as well - so it wasn't just the USAAF that was contesting Japanese air power.
Did you note how the P39s taking off had to rotate to an exaggerated nose high attitude to break ground, and climbed out in the same exaggerated attitude? Betcha a high speed high positive lift airfoil would have performed better than the symmetrical one they had. The only true benefit of a symmetrical airfoil is a better L/D in inverted flight or negative G maneuvering, performance arenas that are not tactically or doctrinally relevant to the P39. Did it even have a pressure carb and inverted fuel and oil header tanks? If not, then why the symmetrical airfoil? AFAIK it was a positive G airplane, and could have benefited from a positive lift wing. I believe most planes of the era that were inverted capable had header tanks of limited (seconds rather than minutes) endurance, though I've read of Zeroes flying inverted for extended periods when exuberant young pilots were (in the vernacular) "showin their ass".
The T34 I used to fly (a 1954 product) had a high lift Bonanza wing and DID have a syllabus reason to engage in inverted flight, which required an exaggerated nose high attitude and a lot of forward stick pressure to maintain altitude and stay out of a split S. Its header tanks were good for 90 seconds inverted, but Grandpa NATOPS said not over 60. Kinda cool looking "down" at the soft blue and "up" at the hard blue with waves and boats and whitecaps on it. Letting it pitch down into a split S when your personal discomfort limit was reached (well before 60 seconds) was a real blast! Makes you appreciate a tight 5 point harness and stirrups on your rudder pedals.
Hello XBe02Drvr,
I have been commenting on why the symmetrical airfoil was a bad idea for quite some time.
Considering that the outer wing sections about even with the inboard side of the main gear wells were detachable, it would not have been too difficult to integrate a new outer wing section to the rest of the aeroplane and also add some sweep similar to IL 2/M3 or P-39E to push the center of lift back a bit and correct the CoG issues.
The outer wing sections already had a NACA 23000 series airfoil at the tip to try to prevent a stall from affecting aileron control, but apparently it wasn't enough to prevent the aircraft from flipping if the stall were slightly asymmetrical. This was shown by a tuft test in the L-602 report.
- Ivan.
I have been commenting on why the symmetrical airfoil was a bad idea for quite some time.
Considering that the outer wing sections about even with the inboard side of the main gear wells were detachable, it would not have been too difficult to integrate a new outer wing section to the rest of the aeroplane and also add some sweep similar to IL 2/M3 or P-39E to push the center of lift back a bit and correct the CoG issues.
The outer wing sections already had a NACA 23000 series airfoil at the tip to try to prevent a stall from affecting aileron control, but apparently it wasn't enough to prevent the aircraft from flipping if the stall were slightly asymmetrical. This was shown by a tuft test in the L-602 report.
- Ivan.
The only drawback to this approach is likely higher torsional loads on the center section to wing panel attach points, which the center section points may not be stressed to handle. IIRC, that problem arose with the Sturmovik, and turned out to be more than a simple bolt-on field mod.
It is all losses in engagements between P-39's and Zeros ; 44 P-39's lost vs 15 Zero's. Both sides suffered other losses in combat and operational non-combat losses so the overall totals are higher for both sides.
Peter Gunn
Master Sergeant
I. AM. SPEECHLESS.
FLYBOYJ
"THE GREAT GAZOO"
You said 15 P-39s were shot down by zeros, 44 lost total, this against 15 zeros lost to P-39s, this is a 1 to 1 ratio in the air. If you include the total 44 lost P-39s this comes out to 2.9 to 1
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