Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.3 4.3bsd-beta 6/6/85; site ucbvax.BERKELEY.EDU Path: utzoo!linus!decvax!decwrl!ucbvax!space From: hester@ICSE.UCI.EDU (Jim Hester) Newsgroups: net.space Subject: Re: Shuttle Ditching Message-ID: <8602121901.AA00467@s1-b.arpa> Date: Wed, 12-Feb-86 13:27:14 EST Article-I.D.: s1-b.8602121901.AA00467 Posted: Wed Feb 12 13:27:14 1986 Date-Received: Fri, 14-Feb-86 06:46:20 EST Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: hester@ICSE.UCI.EDU Organization: The ARPA Internet Lines: 69 Re time to abort: if the ground crew decides it should be done, they could do it themselves, while (perhaps) simultaneously advising the shuttle commander (he should be able to figure it out for himself pretty quickly, though). I'm not advocating stepping on his toes this way, but it is one possibility that could save a lot of the delays you mentioned. As for the physical problems of getting the shuttle far enough away to survive the explosion, that seems a more difficult problem. One thing to remember is that the shuttle is traveling with a fair speed relative to the air around it so it's manuevering flaps would have a reasonable effect. Assuming part of the abort program is to set everything the shuttle has on traveling "up" (relative to the shuttle; i.e., away from the booster), I would expect the shuttle to seperate quickly (recall, the separation speed is is better than linear, since the shuttle will continue to deviate it's course away). I don't know if it is good enough in this case, but consider that a bit academic. The point is, the shuttle should be ready for the fastest ditch it can make within the engineering and cost constraints it has. We cannot predict the time needed to escape in future mishaps; we can only be ready for the shortest time we can handle. Saying "It would have worked" or "it would not have worked" on this particular emergency is certainly of interest, but we must remember that a conclusion of "it would not have worked" on this mission is no reason to not prepare for it in the future. Re time needed after seperation for shuttle to attain aerodynamic trajectory: Same point: The shuttle already has velocity relative to the air around it, so the fact that it is "upside down" relative to the Earth is not major. As long as it is travelling "forward" through the air it can manuever, and thus can roll to orient with the earth. I would expect an abort operation to entail: Everything on the shuttle automatically set to make the shuttle go "up" relative to itself, to get away from the booster fastest. At some point, the shuttle will be traveling roughly perpendicular to the booster, parallel to Earth's surface, and upside-down relative to Earth. If it has enough velocity left, it can roll and end up gliding. If not, it can continue turning "up", or, towards the Earth in a dive to get back enough speed to roll and begin a glide. The altitude of ditching does not seem so important to me as the velocity when ditching (of course, they are directly related). Also remember that, while ditching, the shuttle will continue to gain altitude until it is traveling parallel to the surface. I'm not a pilot, but everything I've heard leads me to believe that the good ones don't care much what their orientation is relative to Earth, as long as they have control of their ship, which is dependant only on working controls and instruments, and forward motion relative to the air around them. Of course, the shuttle is no stunt plane, but then the pilot is presumably one of the best. There is always a time early enough in the liftoff where the shuttle would stall before being able to get into a controled dive, but I suspect this case was not in that category: the shuttle was moving relatively fast. As an afterthought, if the shuttle is equiped with a less efficient passenger ejection system, all the abort needs to do is get the shuttle away from the bomb to give time for the passengers to get out of the shuttle before it crashes. I have my doubts about this one, but it might be worth looking into if they determine that the shuttle can't be safely landed after an abort. Again, I am neither an engineer nor a pilot, but I would not rule out the possibility of mechanically quick aborts, and I tend to think that the shuttle could usually be adequately handled in the case of an abort, unless it was quite early in the liftoff. I am by no means sure of any of this, I am answering more because I am disturbed that you conclude the opposite on the basis of speculations and opinions which appear to be no better informed than mine, nor more complete. Neither of us has given arguments anywhere near conclusive, so why don't we just continue to point out this-and-that pro and con and leave asserting final conclusions to those who think they are qualified?