freeman@argosy.UUCP (Jay R. Freeman) (10/26/89)
If memory serves, the return to launch site abort involves a
push-forward from the Shuttle's inverted attitude, with engines
running. However, it is *not* like the last half of an outside loop,
because the push-forward is merely an attitude change, not a reversal
of course. The Shuttle ends up somewhat above its normal trajectory,
pointed nose-high back toward KSC, but still traveling down-range at
several thousand miles per hour. I have forgotten whether the
maneuver commences before or after solid burnout (I suspect after),
but in any case the main engines are still producing thrust, so the
Shuttle's downrange speed slowly dwindles. Presently it is
momentarily hanging motionless, miles downrange, then it begins to
acquire velocity back toward KSC. When it is going fast enough to
make it back, there is main-engine cutoff and tank jettison.
A "split-s" style course reversal would bring the Shuttle into denser
atmosphere sooner; I suspect thermal and aerodynamic loads would
destroy it.
Funny, even after more than a generation of spaceflight, lots of
people still think that a winged or finned vehicle ought to be "going
the way it is pointing". I guess we've all watched _Star_Wars_ too
many times ...
-- Jay Freeman
<canonical disclaimer -- all opinions are mine>