P-39: N or Q? VVS?

[SnakeEyes]

Actually, I don't have it Verm... my wife saw the pricetag.  

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SnakeEyes
o-o-o-
=4th Fighter Group=

[Vermillion]

Think Christmas SnakeEye's <G>

And drop lots of hints  

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Vermillion
WB's: (verm--), **MOL**, Men of Leisure,
"Real men fly Radials, Nancy Boys fly Spitfires "

[funked]

Keep in mind that the AHT acceleration figures are calculated - not measured.  Also they are at 250 mph, a fairly high speed.  Acceleration varies greatly as a function of speed, so an acceleration ranking at one speed can not be generalized to "better acceleration".

Just doin' my job as NerdBoy.    

P.S.  I forgot acceleration also varies greatly with altitude.  The higher you go, there is less drag for a given IAS, so weight is more important.  And of course the ability to make power up high (P-47 and P-38 are the kings) is critical.

[This message has been edited by funked (edited 11-15-1999).]

[Vermillion]

Hey, O Funky Smelling One  

Hey, what have you heard back from Wright Patt? Still willing to meet you up there to do some research.

Have you seen the flight test data that the US Naval Aviation Historic Center has up? Looks to be primary test data quality to me. Not enough probably to do a flight model, but still good quality data.
 http://www.history.navy.mil/branches/org4-8.htm

Includes data for: F4F-4,F9F Panther,F4U-4 Corsair, F6F-5 Hellcat,F2H-2 Banshee,F3D-2 Skyknight,F7F-3N Tigercat, AD/A-1 (AD-4) Skyraider, AD-5 Skyraider, A3D/A-3 Skywarrior, PBM-5 Mariner, P2V-4 Neptune, PBY-6A Catalina, P2V-5 Neptune, PB4Y-2 Privateer, PV-1 Ventura, PB2Y-5R Coronado, TBF-1 Avenger, SB2C-5 Helldiver, SBD-5 Dauntless, OS2U-3 Kingfisher, PBJ-1H Mitchell (B-25), R5C-1 Commando (C-46), and many many more. All from declassified Navy source sheets.
 
What I have looked at so far is really good.
 


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Vermillion
WB's: (verm--), **MOL**, Men of Leisure,
"Real men fly Radials, Nancy Boys fly Spitfires "

[funked]

Yeah that Navy stuff is cool!

It looks like I will be going to WPAFB the day after Thanksgiving.  I still have to confirm with the research guy.

[SnakeEyes]

Please excuse my ramblings but...

 

And of course the ability to make power up high (P-47 and P-38 are the kings) is critical.

Um... P38???  Allison engines???  You sure???

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SnakeEyes
o-o-o-
=4th Fighter Group=

[Sundog]

The Yak-9T did have very powerful cannon, however, read this paragraph from `Soviet Combat Aircraft of the Second World War: Volume 1: Single Engined Fighters' by Yefim Gordon and Dmitri Khazanov
ISBN 1 85780 083 4

`Pilot V. Khomyakov and armament engineer A. A. Aronov, who conducted flight tests of the Tak-9TK in October 1943, noted that the flying weight, centre of gravity position, handling qualites and performance varied in accordance with the gun installed (They were testing the 20mm ShVAK, the 23mm VYa, and the 37mm and the 45mm NS). When firing the ShVAK and VYa cannon the recoil was imperceptible even at minimum maneuvering speeds, whereas the recoil of the NS-37 greatly affected handling. At an indicated airspeed of 186 to 217 mph (300 to 350 km/h) the aircraft swung violently, and it was only possible to aim the first salvo.  With the NS-45, only a single shot could be fired at near top speed.' pp-146

However, they began adding muzzle brakes to the cannons, and the Yak-9K was built with the 45mm NS. (29 shells). However, the plane wasn't very maneuverable in the vertical plane, and the book states that the great recoil caused many servicing problems, such as leaks etc. However, it could set a building, a ground vehicle, or locomotive on fire with a single shot! Ouch!

The Yak-9UT went into production with the 37mm cannon, but only saw action the last few days of the war over berlin according to the authors.

[funked]

Snakeyes:

The P-38 used turbosuperchargers, which don't lose performance with altitude as much as a mechanical supercharger.  

The down side is that they are bulky, so you need a large plane (like a B-17).  On the P-38 the turbos and all the plumbing occupied most of the aft part of the booms.  The P-47 used a mechanical supercharger AND a turbo which is the reason for the fat belly on the Jug - it's full of turbo plumbing.

Anyways the turbos allowed the P-38 to maintain full power up to 25k plus.  The V-1710-111/113 in the P-38L could make 1600 hp Combat Power from the deck up to 28700 feet, and it could make 1100 hp Normal Power up to 33800 feet.

Likewise the R-2800-59 in the P-47D-20 (and later) could do 2300 hp Combat Power from the deck right up to 31000 feet with no drop off.

Mechanically supercharged engines, even ones with two stages like the later Merlins and the R-2800's in the F4U and F6F, could only make full power up to 20k or so before losing power.

[juzz]

Of course, early P38's couldn't make the full power at alt because of the engine cooling problems. The occurrence of backfires reshaping the wing leading edge is pretty annoying too