Originally posted by F4UDOA
Widewing,
I understand your point but your fuel loads are a bit off IMHO. The F4U-1 carried 361 gallons of fuel with a range of 1500 miles. It had a longer range than the P-51B on internal fuel and would never practically carry that load into combat.
Also according to the Navy's F-1 range formula the P-51B had approximately the same range as a F4U-1D (550 to 500miles) with only 237 gallons of fuel. When the F4U-1A vs P=51B test was flown they adjusted the weight by reducing the P-51B takeoff weight to 9100lbs to make the ranges equal.
Also the test was flown with the late model F4U-1A at combat power 2250HP. This was essentially our F4U-1D except without external stores pylons.
So to redefine the the test you should reduce the P-51B weight by approx 323LBS and use the F4U-1D at combat power. Also the Hog is carrying 705lbs (2350rounds) of 50cal as compared to 394lbs (1260rounds) of .50cal which was pointed out by the Navy in the test report.
The reduced weight P-51B is noted as "Loading condition #2". The climb chart I posted above is from the exact F4U-1A flown by the Navy in that test.
My numbers are spot on the money. In the TA, the AH2 F4U-1 has a max endurance of 44 minutes using 100% internal fuel (361 gallons). In the TA, the P-51B has an endurance of 41 minutes using 75% internal fuel (202 gallons). If I bump the P-51B up to 100% fuel (269 gallons), its endurance increases to 54 minutes. I believe that a 3 minute difference in endurance is close enough.
Now, I set fuel burn at 2.0 and I took a P-51B with 50% internal fuel, and an F4U-1D with 75% internal fuel. Climb was from 50 feet to 10,000 feet, beginning at 200 mph. The P-51B required 2:55.63 minutes and its climb rate actually increased from 3,100 fpm to 3,450 fpm over the course of the climb. For the F4U-1D, it required 3:06.78 minutes to attain 10k, and its climb rate was relatively steady between 3,000 and 3,100 fpm. The difference in endurance at these fuel loads was about 1.5 minutes in favor of the F4U.
Another factor not generally considered is that the P-51B climbs at a higher speed than the F4U-1D, while the Corsair climbs at a greater angle. This only amplifies the P-51's advantage as it covers a greater distance during the climb, while climbing faster to boot. So, not only does the P-51B get to altitude faster, it opens up a significant distance while doing so.
Unlike the AAF, the Navy calculated ideal range; meaning without considering start-up, warm-up, climbout, combat or reserve. On the other hand, the AAF calculated range, or more accurately, Combat Radius, while accounting for all of the above. They allow for start-up, warm-up, takeoff and climbout. They also factor in 20 minutes of combat time, broken down as 15 minutes at MIL power and 5 minutes at combat power. Finally, they also factor in a 30 minute reserve. Even with all that, the P-51B was conservatively rated for a 450 mile combat radius on internal fuel. I say conservative because with proper throttle, prop and mixture settings, the combat radius on 269 gallons could easily exceed 600 miles, or 1,200 miles round trip and still allow for ground ops, takeoff, climb, combat and reserve.
If we take the ideal 1,500 miles range for the F4U-1 and factor in fuel usage as does the AAF, we can safely reduce range to roughly 70 to 75% of ideal, or a max of 1125 miles. And that is with limiting its altitude to just 5,000 feet, while the P-51B numbers reflect climbing twice as high.
My regards,
Widewing
