ems@amdahl.UUCP (ems) (02/07/86)
In article <8602032227.AA10998@s1-b.arpa>, acourt@BBN-VAX.ARPA ("Anthony J. Courtemanche") writes: > (... long discussion of time delays in abort sequence omitted ...) > Now, even if all the above could be done in time and the Shuttle remain > intact, could the Shuttle obtain an aerodynamic trajectory before > hitting the ocean? I am not sure what you mean by 'aerodynamic trajectory'. At mach 3 (the speed I have seen mentioned on the net) you *are* flying. It doesn't matter much which way you are pointed with respect to the ground, only that the pointy end is facing into the mach 3 relative wind. > I don't remember the altitude that the Shuttle was > at when the explosion happened, but the Shuttle was on it's back and > this is not a graceful way to start gliding. As I remember it, the altitude was given as about 9 miles. As per graceful way to glide; see above comment about pointy end... The craft will take some gees in doing a turn/loop/whatever to get the bottom side pointed at the earth, but that doesn't matter much. One may also loose some altitude in doing this, but in an abort from an acending rocket package, this might be a good thing. Remember that the orbiter would be starting with an initial trajectory that has a considerable upward component and very high speed. > Also, correct me if I'm > wrong, but I don't think that any sort of engines are available to help > re-orient the orbiter during the abort (could the de-orbit engines be used?). > Hence, only the control surfaces on the Shuttle could be used to > establish a gliding (as opposed to plummeting) trajectory. At mach anything (or even sub-mach down to a few hundred mph ) the control surfaces should supply plenty of control force. I am somewhat unsure what you mean by 'plummeting'. The Websters says that this is to fall straight downward, but since the shuttle is going up, fast, this would not happen during an abort. The orbiter would glide (upward?) while performing some manuever to get away from the tank and srb's; eventually establishing an attitude suitable for getting the farthest with the minimum loss of altitude. (other attitudes might be useful, but I would expect first order of business to be preserving the energy at hand and directing it toward home...) > > To me, it seems doubtful that an abort could have succeeded in saving > the lives of 7 astronauts or the orbiter. > It seems that way to me, also; but mostly due to timing limitations. -- E. Michael Smith ...!{hplabs,ihnp4,amd,nsc}!amdahl!ems This is the obligatory disclaimer of everything.