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That might be consistent with a "max performance takeoff/unrestricted climb" profile where the aircraft cleans up, accelerates in ground effect to a predetermined zoom climb speed, than pops up into a climb, slowly bleeding back to Vy. This will give an exaggerated "time to climb" performance value, if someone is trying to prove a point, but is not practical in a combat situation, especially if you're trying to get multiple fighters into the air in close proximity as quickly as possible.I see the fuel consumption was noted as "excessive" and instructions for correcting that were forthcoming from the Power Plant Laboratory (!). If the carburetor needed adjustment to the point where it was noted in the test report, I wonder how much different the actual power delivered was from the Tech Order power table that was used for the report.
No one would do such a thing just to post a better result would they? Surely not. British tests are sometimes criticised because of the state of the planes tested, that was the state of the planes pilots were flying. What is the point in testing something hotted up just for the test, another issue that has dogged the P-39 since the P-400 tag was made.That might be consistent with a "max performance takeoff/unrestricted climb" profile where the aircraft cleans up, accelerates in ground effect to a predetermined zoom climb speed, than pops up into a climb, slowly bleeding back to Vy. This will give an exaggerated "time to climb" performance value, if someone is trying to prove a point, but is not practical in a combat situation, especially if you're trying to get multiple fighters into the air in close proximity as quickly as possible.
Possibly to justify expenditure on a plane seen as having potential, but in danger of being labeled "a dog"? IAC, hoist on its own petard when the combat ready D1 came along.What is the point in testing something hotted up just for the test
The P-39D is lighter?Actually the P-39 pilot would not attempt to turn with the A6M2, that had been drummed into him since he arrived in theater. In his lighter P-39 he would have the choice of outclimbing the A6M2 or diving away as he had previously done.
.....
I was using the formula from Aerodynamics for Naval Aviators agian: RC = 33,000 * [(Pa - Pr)/W].
That's why I think the P-39D test was run at normal rated power, not military power.
There were 60 P-39D-BE's and 336 P-39D-1's. It had the 37 mm cannon, two 50-cals in the upper nose, four 30-cals in the wings, and no 30-cals in the bottom of the nose. They went to a V-1710-63 engine with 1,325 hp for the P-39D-2. The test airplane had the V-1710-35 engine, so it was either a P-39D-BE or P-39D-1. With wheels up, it was at 25.8% MAC, so it definitely has some ammunition in the nose. The P-39D had 30 cannon rounds, not 15 like the P-39C.
I was using the formula from Aerodynamics for Naval Aviators agian: RC = 33,000 * [(Pa - Pr)/W].
But could the P-39 nuke Japan?
Wait...is this the wrong thread?
They can have a fuel truck waiting there to top it off after it's run-upThat depends on whether it uses 2% or 20% of its fuel between engine start and takeoff.
Hot fueling avgas with a gravity nozzle? Not me, friend!They can have a fuel truck waiting there to top it off after it's run-up
Bet they had no idea they were creating a historical document that "historians" 78 years hence would be scratching their heads over.
Now let's take a little walk back to Peter Gunn's post #1381 on page 70 for an apples-to-apples comparison of three different blade sets on the same model hub, same engine, same airplane (in this case, a P40F, same s/n for all tests), and same test conditions for all trials. The parameter being tested is rate of climb at 18,000 feet. The hub is a C-532D, which, in a version with a cannon channel, is also used on some P39s.None of these differences matter. No minor propeller change, minute changes to the airframe (moving the .30s from the nose to the wings), a fin fillet, an extra inch of length, a symmetrical airfoil or the weather will make up 1000fpm climb. Only 836lbs of weight will do that.
Amen, mister - but that was a reference stolen from the "Lancaster as a potential nuclear bomber" thread, which seems to parallel this thread quite closely.Hot fueling avgas with a gravity nozzle? Not me, friend!
Amen, mister - but that was a reference stolen from the "Lancaster as a potential nuclear bomber" thread, which seems to parallel this thread quite closely.
Don't worry, we'll wrap you in asbestos and you'll be fine...Hot fueling avgas with a gravity nozzle? Not me, friend!
Hello Ivan,Hello GregP,
The extra .30 cal nose guns on the P-39C were actually between the two .50 cal MG.
See attached photographs.
I have been looking through my copy of Aerodynamics for Naval Aviators and can't seem to find that formula though there is a lot of coverage about Jets in my copy.
Edit: Found it. The "Power" that is specified IS Horsepower but not nearly as simple as first thought and is based on thrust and angle of climb..... So it does take into account the factors, I was asking about and the calculations are a bit more complicated.
- Ivan.View attachment 601269View attachment 601270