In a non-pressurized aircraft, the breathing of pure oxygen
is not adequate for sustained pilot survival much above
37,000 feet. They can use oxygen delivered under pressure
to the mask, but only about 1/4 psi of "boost" to the pilot
or it will rupture the lungs.
Engines used mechanical air pumps, large turbochargers and
later they had turbo-compound engines.


"Peter Duniho" wrote in
message ...
| "G. Sylvester" wrote in
message
| . com...
| 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?
|
| Lots of power, big constant speed props (it's been
explained to me that you
| don't need to "supercharge" a prop...as long as the blade
angle can be
| adjusted for the conditions, the prop can deliver whatever
power the engine
| is generating, just as the wing can generate the same lift
equal to airplane
| weight regardless of altitude).
|
| It's true that supercharging eventually drops off, but
since it makes "sea
| level" for the engine start much higher, you can still get
pretty high
| before you don't have enough power to fly. Keep in mind
that while your
| true airspeed does need to be higher to keep from stalling
the wing, drag is
| reduced so the power requirement is lower.
|
| Frankly, I don't find it all that surprising. I own a
turbocharged
| airplane, essentially turbonormalized (the turbo version
is only 20hp more
| than the normally aspirated version). Critical altitude
for the
| turbocharger is about 16000', the airplane is certified
for 20000', and I've
| spoken with one of the manufacturer's test pilots who says
they took the
| airplane over 25000' during certification tests.
|
| This is an airplane that's only 270hp, has a boost of only
about 4". The
| WWII piston airplanes had what, an order of magnitude (at
least) greater
| power, with boosts of anywhere from 15" to 30"? I'm no
expert and I might
| have some of those numbers a bit off, but still...if my
little recreational
| 4-seater can get up to 25000', I don't have a hard time at
all believing
| that one could get a powerhouse piston fighter or bomber
up to 37000'.
|
| And yes...the engines do "lost most of their performance
that high". That's
| why 37000' is the *ceiling*.
|
| Pete
|
|