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bobw
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http://uplink.space.com/showthreaded.php?Cat=&Board=sciastro&Number=439735&page=&view=&sb=&o=&vc=1<br /><br />Shuttle_guy wrote something very interesting, in the thread above, and I have a few questions... sort of spawned. I have been wondering about it for ten days now; it's burning a hole in my brain. Please, anyone, feel free to reply. This post isn't specifically aimed at shuttle_guy. <br /><blockquote><font class="small">In reply to:</font><hr /><p>One side note: The APU exhaust (all 3) are near the vertical stabilizer (rudder) pointing in the same direction thus they are propulsive. This propulsive force is used to pitch the Orbiter around after the de-orbit OMS burn rather than using the RCS thrusters. Some engineers are clever.<p><hr /></p></p></blockquote><br />I have always thought that as the shuttle orbiter travels doors-down it must be rotating, about it's long axis, at the rate of 1 rev/orbit. Does it take a lot of correction burns to keep it that way or is it the rotation pretty stable once the astronauts get it going?<br /><br />The de-orbit burn is conducted doors-down, engines forward but sort-of pointed up. I figgured that the one rev/orbit rotation would automatically carry the orbiter to a bottom-down, nose forward attitude for re-entry after half an orbit. I guess it is more complicated than that. How much of a rotation does the APU exhaust thrust actually cause? 1/4? 1/2? Do they actually have to correct for overshoot? Just a general figgure would be great.<br /><br />Clever, indeed! Those rocket scientists think of everything.<br /><br />Thanks, all.<br /> <div class="Discussion_UserSignature"> </div>