kjm@ut-ngp.UUCP (02/05/86)
[]
Several issues raised by recent net.columbia articles, plus a tidbit from
the newspapers:
The flight number in question is 51L.
There is no reserve fuel for the MPS (main propulsion system). Once the
tank is gone, they're useless (for the rest of that flight).
There is, I believe, in the _Space Shuttle Operators Manual_, a description
of a "manual thrust vector control" mode which can be used during ascent; I
got the impression this was for serious emergencies only. (Naturally this
is still a fly-by-wire system.)
The MPS engines are now run at 104% of their original rated power through
most of the ascent. The two exceptions are during maximum dynamic pressure
(i.e., going through Mach 1), and at the very end of the MPS burn (they are
throttled to hold acceleration to 3 gravities).
The MPS engines (Space Shuttle Main Engines) have a two-stage fuel and
oxidizer delivery system; i.e., there are both low- and high- pressure
turbopump stages in both the LH2 and LO2 subsystems. If I remember
correctly, the turbopumps are centrifugal.
One of the newspapers I get (I forget which one) claimed that the SRB
separation motors had *not* been fired, since those in the recovered
SRB nose cone had not been fired.
The OMS (Orbital Maneuvering System) engines are useless in low-altitude
aborts. The two OMS engines put out a total of 12000 pounds of thrust;
when applied to a 100 ton orbiter (this is a round number, probably low),
they produce an acceleration of not quite 2 feet/second**2, neglecting
air resistance.
The notion that the SRBs have to have ground guidance capability because
they were seen to appear to straighten up is probably bogus. I would
speculate that they are designed to be aerodynamically stable, if for
no other reason than that would decrease the chances of them hitting
the orbiter/ET combination during a normal separation. If they are in
fact aerodynamically stable, then the observed behavior would be expected.
--
The above viewpoints are mine. They are unrelated to
those of anyone else, including my cat and my employer.
Ken Montgomery "Shredder-of-hapless-smurfs"
...!{ihnp4,allegra,seismo!ut-sally}!ut-ngp!kjm [Usenet, when working]
kjm@ngp.{ARPA,UTEXAS.EDU} [Old/New Internet; depends on nameserver operation]