🚀 go-pugleaf

In article 4021@phred.UUCP, petej@phred.UUCP (Peter Jarvis) writes:
>In article <17270@mindlink.bc.ca> Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes:
>>
>>        I believe that the RCS thrusters also have the capability of
>>performing a de-orbit burn if the OMS system is non-functional.
>>
>This is true. The aft RCS thrusters can be used for de-orbit burn. Just
>takes several minutes, 3.5 times longer than an OMS burn, to do it. OMS
>fuel can also be cross-fed to the RCS thrusters.
>
As strange as it may sound, a procedure exists to partially complete
a deorbit burn with the Forward RCS thrusters. It is called a 'Fast Flip'.
If the Aft RCS/OMS Prop level is too low to complete a D/O burn, the
shuttle will start its D/O burn in a 'nose first' attitude (Velocity
vector pointing straight out of the nose); then the 'fast flip' procedure
is executed by firing the +Z thrusters in the FRCS, while simultaneously
firing the -Z thrusters in the ARCS. The D/O burn is then completed with
the +X ARCS thrusters.

If the doo doo is really hitting the turbine that day (i.e. dreadfully
low on gas), OMS/RCS fuel can be conserved via a 'prebank' maneuver.
For example, deorbiting head-first with a roll angle of 90~180 degrees.

These procedures have been successfully accomplished by every crew of
every flight (at least after STS-26) during their pre-mission
simulations at JSC in Houston. 

--
Phil Forrest - Ascent FDO wanna be
Auburn University Mechanical Engineering
Auburn, AL