P-39 Expert
Non-Expert
Let me try and explain this again. In wwiiaircraftperformance, the gross weights listed on the test documents show "mean fuel" or average fuel available during the test. I'm not sure exactly which P-39 variant you are speaking of, but the 7300# weight is for the plane with half fuel. This weight number is for calculations of ratios (power/weight, wing loading etc) since there was a 720# weight difference (120 gal) between an empty P-39 and a full (of fuel) P-39. To get the correct published weight for the P-38, P-39 and P-47 in those tests you need to add back half of the fuel capacity. The planes were tested with full tanks but their weights differed drastically from the time they took off until the time they landed because they were expending their fuel during the test. Any calculation involving weight would need to specify which weight, the weight at takeoff or the weight at landing or the weight in the middle of the flight. So for calculations they used mean or average fuel giving a mean or average weight for the plane. So the figures are for a fully loaded (gross weight) plane at a weight after half the fuel has been burned, or the weight that the plane would likely be in actual combat. The planes tested took off with full tanks, the mean weight figure is for calculations. Nobody in combat took off with 60 gallons of fuel. Hope this helps.What month of 1943? P-38Hs were coming out of the Factory in May of 1943.
ANd what happens when you put enough fuel in the P-39 so it doesn't have the endurance of a bottle rocket?
You might want to check on what a light loaded P-38 could do since you are using the numbers from a light loaded P-39. That 7300lb or under figure is highly suspect.
That half fuel story is a bit bogus, Fine for figuring out what the plane can do for a few minutes in a fight, horrible for trying to figure out time needed to intercept as you claim the P-39s were doing in New Guinea. I have no doubt the P-39s that were there were trying their damndest to intercept but taking off with 50-60 gal of fuel and flogging the engine beyond recommended time limits just to reach altitude wasn't being done.
A P-39 at 7300lbs is lucky it has 62.5 gallons on board. Even if you start with around 70 and burn off the extra in warm up and taking off that doesn't leave whole lot. Charts for P-39K at 7400lbs shows 36 gallons needed to reach 25,000ft including warm up and take off using a "combat climb" of take-off power for the first five minutes and emergency maximum for 15 minutes. Now you are at 25,000ft in a combat situation with about 30-36 gallons on board? With an engine burning around 1.5 gallons a minute at full power at that altitude?
What happens after combat? you glide down 10-15,000ft and make a dead stick landing?
For the Spitfires. There were 4 squadrons of MK IXs at Dieppe. Aug 19th 1942, which rather predates the issue of P-39Ns regardless of Nov/Dec or transit times.