MIflyer
1st Lieutenant
You don't understand! Something is because it is, it is, it is!
Or so say the 6 year olds.
XP-39 II - The Groundhog Day Thread
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You don't understand! Something is because it is, it is, it is!
Or so say the 6 year olds.
I used to do that in one of the very old flight simulators! (SubLogic Jet)
Taxi around at high speed, blast a few targets with tracking missiles....
Taxi through the hangar for a reload.
It got to be kind of boring.
- Ivan.
P39 Expert said:
Weight influences climb more than any other factor.
Negative! Run the numbers. A 10% change in Thrust Available will have a greater effect on RoC than 10% change in weight. They advocated weight reduction because thrust was already maxed out in practical terms.
Weight influences climb more than any other factor.
Negative! Run the numbers. A 10% change in Thrust Available will have a greater effect on RoC than 10% change in weight. They advocated weight reduction because thrust was already maxed out in practical terms.
GregP
Major
Hi Stig1207. What book did Claringbould write? I ask becasue:
1) I have the Statistical Digest of World War II. The total victories are shown, but not by model of aircraft.
2) I have Naval Aviation Combat Statistics for WWII. The Navy didn't fly P-39s, so it is of no help.
3) I have many WWII aviation books, including Frank Olynyk's Stars and Bars. It is ovr 650 pages, but the data are there. It is just a bear trying to get through it. I may well make the effort, but finding such a treasure for other nations is impossible to date.
4) I have a file with more than 68,000 German claims, but the claim file doesn't tell you the aircraft being flown. It shows the pilot name, unit, victim, and location and date, but not the airplane being flown. I don't know how to find out what dates the various units were flying what aircraft.
So, I'm curious, but not curious enough to buy a book to settle a P-39 question. It was not a very good airplane during the war and is of interest, but not to the point of spending much money on it, specifically. I might change my mind if I OWNED a P-39, but I don't. It would be quite nice to fly one.
1) I have the Statistical Digest of World War II. The total victories are shown, but not by model of aircraft.
2) I have Naval Aviation Combat Statistics for WWII. The Navy didn't fly P-39s, so it is of no help.
3) I have many WWII aviation books, including Frank Olynyk's Stars and Bars. It is ovr 650 pages, but the data are there. It is just a bear trying to get through it. I may well make the effort, but finding such a treasure for other nations is impossible to date.
4) I have a file with more than 68,000 German claims, but the claim file doesn't tell you the aircraft being flown. It shows the pilot name, unit, victim, and location and date, but not the airplane being flown. I don't know how to find out what dates the various units were flying what aircraft.
So, I'm curious, but not curious enough to buy a book to settle a P-39 question. It was not a very good airplane during the war and is of interest, but not to the point of spending much money on it, specifically. I might change my mind if I OWNED a P-39, but I don't. It would be quite nice to fly one.
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This why it is a groundhog thread, weight influences climb when you cant change anything else, neither a Jumbo Jet nor a Saturn V rocket had any trouble getting to 40,000 ft faster than a P-39 and they were a little heavier as far as I remember.
I think this is the only thing we can all agree on, well almost all of us.
All but one, maybe.
GregP
Major
Hi P-39 Expert. Post #1616! You hit the nail on the head! EXACTLY.
Except for the propeller, there was little aerodynamic difference, yet the climb rate is 37% higher for the P-39C and that is impossible if both planes were making 1,150 hp as stated in the reports. It just won't happen that way. EXACTLY my point.
Since the climb difference was noted, then either the P-39C was making more hp (extra MAP that, handily, is unreported) than indicated, or the P-39D was making less hp (my assumed rated power rather than military power) than indicated, or the pilot mis-timed it. Let's give the test driver the benefit of the doubt and say he timed it correctly. If so, then I am left with the first sentence of this paragraph, without the assumption that the pilot mis-timed it.
Except for the propeller, there was little aerodynamic difference, yet the climb rate is 37% higher for the P-39C and that is impossible if both planes were making 1,150 hp as stated in the reports. It just won't happen that way. EXACTLY my point.
Since the climb difference was noted, then either the P-39C was making more hp (extra MAP that, handily, is unreported) than indicated, or the P-39D was making less hp (my assumed rated power rather than military power) than indicated, or the pilot mis-timed it. Let's give the test driver the benefit of the doubt and say he timed it correctly. If so, then I am left with the first sentence of this paragraph, without the assumption that the pilot mis-timed it.
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wuzak
Captain
The guns in the wing would have some effect.
The fuselage was longer, which would have had some effect, albeit small.
And then there was the different propeller - not sure how different they were, so hard to know what effect that would have.
Why would that be? They are the same engine, right?
One would expect that the P-39C, being faster than the P-39D, would have greater ram effect and therefore a higher critical altitude. Assuming the same engine and rating.
We don't know what actual power the two planes had, the power numbers having been taken from two different charts. The charts also are unlikely to include ram effect.
windhund116
Senior Airman
- 360
- Jul 3, 2017
I think Stig1207 meant this book. P-39/P-400 Airacobra versus A6M2/3 Zero-Sen. New Guinea 1942. Michael John Claringbould. Osprey Publishing, 2018. ISBN 978-1472823663.
Amazon link.
As an Amazon Associate we earn from qualifying purchases.
GregP
Major
Looks like a decent book ... we'll see. 
MIflyer
1st Lieutenant
Well, some models of the P-39 had significantly better performance than did others.
GregP
Major
Wherever did you find THAT, Miflyer? Never saw that one before!
Those sure are BIG cannons in the wings! What are they, 15" inch Bazookas?
And it still has a big pushbutton on the nose, too! Or it that a nipple and it needs a bra?
Those sure are BIG cannons in the wings! What are they, 15" inch Bazookas?
And it still has a big pushbutton on the nose, too! Or it that a nipple and it needs a bra?
It gets cold at altitude...
GregP
Major
Perhaps it would have made a good "American Meteor."
Wonder if it would have faster or slower than the F.9/40?
The cockpit on the P-39 jet is farther back than on the F.9/40, so it should be more streamlined, right? After all, the Gee Bee was fast:
But, the P-39 jet doesn't have that innovative, Mach-capable cruciform tail. Maybe it wouldn't need a jack under the wing trailing edge to stop it from falling back on the tail, though. The aerogodamnics might be tricky, too.
Wonder if it would have faster or slower than the F.9/40?
The cockpit on the P-39 jet is farther back than on the F.9/40, so it should be more streamlined, right? After all, the Gee Bee was fast:
But, the P-39 jet doesn't have that innovative, Mach-capable cruciform tail. Maybe it wouldn't need a jack under the wing trailing edge to stop it from falling back on the tail, though. The aerogodamnics might be tricky, too.
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vikingBerserker
Lieutenant General
Looking for that I came across a Soviet copy that was to have mated two together ala F-82. The Belyayex OI-2
Powered by 2 x 1,800 hp engines and armed with 2 x 23mm in the hubs, 4 x .50 cals in the left fuselage and 4 x 30 cal in the center wing and up to 1,100 lbs of bombs
Powered by 2 x 1,800 hp engines and armed with 2 x 23mm in the hubs, 4 x .50 cals in the left fuselage and 4 x 30 cal in the center wing and up to 1,100 lbs of bombs
GregP
Major
Vikes, Picture? Maybe this?
or this:
Well, at least it follows the rule: If it is wierd, it is British; if it is ugly, it is French; it it is weird AND ugly, it is Russian.
Not that the U.S.A didn't have wierd and ugly airplanes:
We DID! It has a face that would make a train want to take a dirt road on a rainy night. Note the not-quite-fully-enclosed nosewheel. That is so it can double as a big wheelbarrow?
Whoever designed that should be slapped, hard ... sort of like Moe slaps Curly:
Well, at least it follows the rule: If it is wierd, it is British; if it is ugly, it is French; it it is weird AND ugly, it is Russian.
Not that the U.S.A didn't have wierd and ugly airplanes:
We DID! It has a face that would make a train want to take a dirt road on a rainy night. Note the not-quite-fully-enclosed nosewheel. That is so it can double as a big wheelbarrow?
Whoever designed that should be slapped, hard ... sort of like Moe slaps Curly:
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vikingBerserker
Lieutenant General
The link windhund116 provided; originally referenced by jmcalli2, to which I replied here #1025. Can't blame you for having missed or forgotten it, it's some 30 pages back!
1. There is this Warbirds and Airshows, but the victories by model given here don't really agree with the Statistical Digest, see USAAF figher victories. Ray Wagner provided stats by model for the ETO and MTO, which do agree with the Statistical Digest and at the same time noted that stats by model for the theatres vs Japan do not exist.
Unfortunately, his website is no longer available, but Eagledad at one time posted an attachment on this site with the numbers in them.4. I have downloaded your file, it's good work by you, my own Excel skills are rather limited. You could possibly match the aircraft with the claims by trawling through this site ww2.dk, but that too would be a major undertaking.
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