johnnyr@ihuxa.UUCP (John R. Rosenberg) (04/13/84)
This may be a naive question, but I thought I'd ask, just to
satisfy my curiosity...
Since they landed this morning out at Edwards instead of at the Cape, they
will be piggy-backing the shuttle on their 747. Has any thought ever been
given to refueling in CA. and flying it back under its own power? I
guess what my question really asks is... Does the shuttle have the
capability to fly under power (well throttled down) as a normal
airplane. Is there enough control, too much power ....???
Probably a stupid question, I know. But just a random thought that
stuck in my head this morning.
John Rosenberg AT&T Technologies
ihnp4!ihuxa!johnnyr Naperville Il.alb@alice.UUCP (Adam L. Buchsbaum) (04/15/84)
1) The main engines cannot be reused until they are refurbished, a process that takes a week or two. (Note, the countdown can be halted at any point up until the SRB's ignite; if it is halted AFTER the main engines ignite, the launch would be delayed for about two weeks until the ME's could be refurbished (basically cleaned up).) 2) There is no launch facility at Edwards, and the shuttle cannot take off horizontally. 3) Which do you think costs more? A jumbo jet ride across the country, using commercial airline fuel, or a shuttle ride, consuming half a million gallons of liquids hydrogen and oxygen (not to mention the cost of an external tank)?
dmmartindale@watcgl.UUCP (Dave Martindale) (04/16/84)
In addition to the cost considerations, a normal airplane is much better suited to manoevering in the atmosphere. It is designed to fly level, something which the shuttle is not. And it can abort a poor approach and go around again.
alb@alice.UUCP (Adam L. Buchsbaum) (04/16/84)
The shuttle does not use its main engines for the deorbit burn, a misconception you seem to hold. It uses its orbital maneuvering system.
inc@fluke.UUCP (Gary Benson) (04/18/84)
>In addition to the cost considerations, a normal airplane is much better >suited to manoevering in the atmosphere. It is designed to fly level, >something which the shuttle is not. And it can abort a poor approach >and go around again. -- From the ever smiling, .). ever happy fingers of: V Gary Benson + + John Fluke Mfg. Co. ILLEGITIMI NON CARBORUNDUM !fluke!inc + +
witters@fluke.UUCP (John Witters) (04/18/84)
There was a plan at one time to mount regular jet engines on the Shuttle for test flights. At some point, NASA decided to buy a used 747 and do drop tests instead. I'm not sure, but I think there may have been a plan to mount jet engines on the Shuttle after an orbital mission, and fly it back to the Cape. The engines would be removed before the next orbital flight. Are you out there NASA? Please give us the straight scoop on this.
lwe3207@acf4.UUCP (04/20/84)
Nf-From: acf4!lwe3207 Apr 15 19:43:00 1984 I think the point to be made, which I don't think the person asking the question realized, is that the Shuttle doesn't have an (or much of an?) internal fuel tank for the main engines -- enough I guess to do a de-orbit burn, but not enough to lift off horizontally. Since the thing is aerodynamic, however, I don't see why it shouldn't be able to take off horizontally. Clear the "rotation speed" would be rather high -- 275 knots? -- but you could do it, perhaps by putting a tank into the payload bay. The fact that burning the engines leaves lots of crud in them is a matter of technology, and presumably in the future, rocket engines will be designed so that you can burn them a couple of times in the low atmosphere before you have to wipe the gunk out. -- Lars Ericson cmcl2!acf4!lwe3207
lwe3207@acf4.UUCP (04/20/84)
Nf-From: acf4!lwe3207 Apr 15 19:45:00 1984 [<- Added RAID, same response -- sorry for duplicates.] I think the point to be made, which I don't think the person asking the question realized, is that the Shuttle doesn't have an (or much of an?) internal fuel tank for the main engines -- enough I guess to do a de-orbit burn, but not enough to lift off horizontally. Since the thing is aerodynamic, however, I don't see why it shouldn't be able to take off horizontally. Clearly the "rotation speed" would be rather high -- 275 knots? -- but you could do it, perhaps by putting a tank into the payload bay. The fact that burning the engines leaves lots of crud in them is a matter of technology, and presumably in the future, rocket engines will be designed so that you can burn them a couple of times in the low atmosphere before you have to wipe the gunk out. -- Lars Ericson cmcl2!acf4!lwe3207
lwe3207@acf4.UUCP (04/23/84)
Nf-From: acf4!lwe3207 Apr 15 22:52:00 1984 [] (More response.) I didn't consider the fact that the 747 is to the Shuttle as a glider is to an F-14: i.e., the glider has more lift. So clearly the 747 has a lot more appropriate lift for the lower atmosphere, and hence is more fuel- efficient a priori than a powered shuttle. The corollary being that if you tried to drop a 747 at 17K-knots out of orbit, it would melt while the wings were tearing off. (I guess the cabin pressurization in an airliner comes from the jet engines intake/compressors, so the passengers in said 747 would also have suffocated by that time. But it would be amusing to film such an event: you could ferry the parts of the 747 up into orbit, assemble it, and then "push it backwards" until it was below orbital velocity. Bugs Bunny could be inside, searching madly for the airbrakes, while robots with parachutes jumped out into the flaming void.) I guess this will always be a tradeoff in aero vs. space craft, until the materials technology for the skin (heat-reflective) and infrastructure (tough but light) are so good that you can make an orbiter capable of re-entry which also has a sufficiently good lift coefficient to be economical for self-powered flight in the lower atmosphere. Lars Ericson cmcl2!acf4!lwe3207