G. Sylvester wrote:
I was just at the Museum of Flight which is an *amazing* museum. Many
of the WWII a/c have ceilings of upwards FL370. How do piston and prop
a/c have ceilings that high? Even supercharged engines I presume lose
most of their performance that high. Even more so I'd expect the prop
which can't be 'supercharged,' also must lose most of their performance.
Any background on how they operate so high?

Like others have mentioned, a large displacement engine with a
multi-stage blower makes it possible. Of course, at 37,000 feet the
prop is not very effective as the air is so thin so its efficiency
stinks. That extreme altitude is not an effective operational altitude,
as the wing's stall margin is tiny and you wouldn't want to get into a
turning fight. IIRC most air-to-air engagements happened below 20,000
feet. A quick Google search shows the B-29's ceiling at 40,000 ft.