|
Mark,
I beg to differ on the TAS vs IAS
effect on Vne. A good example is the ES. It has a Vne of 220
KIAS. However many turbocharged ES's (as well as the Columbia 400) can
fly up in the mid 20's at a TAS of around 225 all
day. I'm guessing that at that speed, the IAS is somewhere in
the vicinity of 150-160. Until you reach a critical mach number (I
don't even know what that is for my ES), IAS is the number you need to
worry about with regard to flutter.
As for the military guys punching out
at high speed, you're mistaken. I have a few thousand hours in ejection
seats and TAS has nothing to do with opening shock - it's IAS we worried
about. In the Navy jets I flew, our chutes had a limiting IAS beyond which
you could rip out the parachute panels if you deployed them. The
other issue was flailing injuries to your body from wind blast at high
speeds. I know of at least two Viet Nam ERA POW's who had
serious knee damage when they punched
out of their A-4's at high speed (›400
KIAS) after being hit by SAM's (John McCain was one of them).
I seem to recall max speed to punch out
in my plane was 450 knots IAS. Most seats employ a small drogue
chute that deploys after ejection to stabilize and slow you down a bit before
pulling out the main chute. In the McDonnell Douglas Escapac seats I
flew, the seat had an altitude sensor that wouldn't release you from the
seat until you descended below a preset altitude. My memory is a bit
scratchy here, but I believe it was somewhere around 20,000'. You could
always manually release yourself too. At low altitudes, you separated
immediately. Martin Baker seats worked differently, but still had a
max IAS for ejection. In F-14's you wore leg restraints
that held your legs to the seat until separation to prevent
flailing. I know of at least one F-14 RIO who punched himself out over the
water in excess of 600 knots and was never found. Bottom line though, TAS
was never a limitation in any ejection seat I rode in.
Skip Slater
|