Art Medcalf
Airman
- 32
- Jul 11, 2024
Just an aside, I used to be in contact with the P&W engineer that ran R-2800 test stand during WW II. His in-house goal was to stay ahead of the test stand team developing the R-4360 in absolute performance. A 100 hour test was run on the R-2800 at 3000 HP out put. The peak HP attained on the test stand was 3800HP and the engineer felt 4000 HP was attainable , but meaningless in real world conditions. However, what that meant in actual service is the engine was able to take all kinds of overboost, misuse, and extreme operating conditions while staying together and getting the job done. If I had been a pilot during WW II and could have chosen what to fly and survive the war, would have chosen an R-2800 powered type. As a flight line worker in the early 1950s, I will say you have not lived until you watch a overloaded radial engine transport screaming past you on the ground a few hundred feet from the end of the runway with blue flame shooting out 50 feet behind. The gear gets pulled and the a/c sinks a few feet and disappears from sight, finally you see it two or three miles from the end of the runway, now at an altitude of maybe a hundred feet finally beginning to slowly climb away. I can only guess what the overspeed was in low pitch or what manifold pressure might have been. Certainly something well beyond what was the design maximums. These were the engines that saved many pilots and planes during WW II. In that area of technology, the USA was ahead of everybody else, why is a complex story but with rational reasons.One could argue that with lower octane gas than the Allies (C3 was what, roughly equivalent to 100/130, whereas late in the war R-2800 ran on 115/145?), and poorer valves, bearings etc., the Germans could get away with slightly more volume per cylinder before running into cooling limits due to the surface area vs volume issues you described.
ArtieBob