[RCSE] Stalling and speed of sound

2000-04-28 Thread Tord

The two limiting speeds for any subsonic aircraft
is the stalling speed, where flight is no longer
sustainable and the aircraft's top Mach speed, a
speed relative to the local speed of sound.

As you climb upward these two creep slowly close and closer,
to eventually meetm and making subsonic flight impossible.

But before it goes that bad you'll have a higher ground-speed
if you go higher, a fact the jetliners take advantage of, of course!

IC engines, like glow or ignition engines, fare badly as altitude
increases, as they eventually get starved of oxygen.

Those flying electric models at high altitude will notice faster
flights and higher propeller revs and possibly longer endurance,
but not much else to worry about. Any non turbo-charged engine will
have to be continiously monitored and the needles readjusted if you
plan to break any records :-)!

So higher stalling speeds, higher cruise speed, and higher tops speed,
if the model is a normal one. A very fast one might run into compressibilty
problems at the top of Mount Everest, had you planned to take your Vindicator
there :-)!

Tord,
Sweden

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Tord S. Eriksson, Ovralidsg.25:5, S-422 47 Hisings Backa, Sweden

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Re: [RCSE] Stalling and speed of sound

2000-04-28 Thread Sailplanes

  If I remember correctly, when the U-2 is at altitude, the difference
between its maximum design speed (VNE) and stall is only a few knots due to
the density altitude.  Kinda keeps it interesting for the pilot. :)

Jimmy

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