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From: kwan@smeagol.UUCP (Richard Kwan)
Newsgroups: net.columbia
Subject: Re: Ejection Seats
Message-ID: <603@smeagol.UUCP>
Date: Thu, 13-Feb-86 21:02:43 EST
Article-I.D.: smeagol.603
Posted: Thu Feb 13 21:02:43 1986
Date-Received: Sun, 16-Feb-86 04:47:00 EST
References: <2911@ut-ngp.UUCP> <3046@umcp-cs.UUCP> <2755@amdahl.UUCP>, <516@oliven.UUCP> <139@bucsb.UUCP>
Organization: Spacecraft Data Systems, JPL, Pasadena, CA
Lines: 41

In <139@bucsb.UUCP>, Dino writes:
> Some ejection seats are modules...
> ... This, I would imagine,
> would take care of the problem of the ouside air killing the pilot/
> passengers on contact and the problem of ejection through the roof of
> the craft.
> 
> Ofcource the module would be fried by the exhaust.....

CAVEAT: On this subject, I must rely on very old neurons, and I don't
have access to the sources any longer, so if you come upon them and can
show otherwise, feel free to correct me.

I believe A. Scott Crossfield tells in his autobiography "Always
Another Dawn" that ejection capsules/modules had been mandated by the
Air Force in the 1950s.  The X-15 design team, faced with this
constraint, decided that it would impose too much weight on the craft.
They obtained an exemption from the Air Force on the basis of their
alternative.  The pilot wore a fairly bulky pressure suit, and a boom
would protrude sufficiently far in front of the seat so that the shock
wave would not intersect pilot or seat.  The seat would be propelled out
and away from the craft by a solid rocket motor, out of the way of tail
and engine exhaust.

(BTW, the fleet of three X-15s made 199 flights with only one pilot
fatality late in the program.  On one other flight, the pilot had to
crash land and was seriously injured; following surjury and recuper-
ation, he returned to flight duty.)

Of course, as mentioned elsewhere in this news group, this depends on
being able to blow the canopy or a small exit in your craft.  If the
diagrams I've seen are correct, the shuttle crew seems to be spread on
two decks at launch.  An ejection option would require an easy access
path from seats on the lower deck, thru the upper deck, and out thru
the skin of the craft.

	Rick Kwan
	JPL Spacecraft Data Systems

Disclaimer:  this is not to express an opinion for or against ejection
seats.  That, to me, is an engineering decision.