lulue@nosc.NOSC.MIL (D L ) (09/30/88)
While listening to the launch broadcast this morning I noticed that as the shuttle's velocity increased, its altitude seemed to decrease. At some where around 15000fps the altitide was 65 nautical miles and then a few seconds later around 19Kfps it sounded like the controller called out the altitude as 61 n.m. Did I mis-hear this? Also, how far does the shuttle coast after main engine shut down? If the final altitude is around 100 miles, does it coast the last 30 or so? A speed/downrange distance/altitude table would be very helpful, and very interesting. Thanks in advance. Dan.
pritch@tut.cis.ohio-state.edu (Norm Pritchett) (09/30/88)
In article <790@nosc.NOSC.MIL> lulue@nosc.NOSC.MIL (D L ) writes: > >While listening to the launch broadcast this morning I noticed that as >the shuttle's velocity increased, its altitude seemed to decrease. >At some where around 15000fps the altitide was 65 nautical miles >and then a few seconds later around 19Kfps it sounded like the >controller called out the altitude as 61 n.m. Did I mis-hear this? No, you didn't mis-hear that. That is part of the normal profile of every shuttle launch. Depending on whose TV coverage you watched they probably whould have made some mention of it. I am pretty certain I have heard an explanation for this but I can't find the reason in any of my references - they only state it occurs. However, if memory serves me right, I heard it mentioned that this was done to insure proper ditching of the external tank into the ocean rather than having it go into orbit. -- Norm Pritchett, The Ohio State University College of Engineering Internet: pritchett@eng.ohio-state.edu BITNET: TS1703 at OHSTVMA UUCP: pritch@cis.ohio-state.edu
adolph@ssc-vax.UUCP (Mark C. Adolph) (09/30/88)
In article <790@nosc.NOSC.MIL>, lulue@nosc.NOSC.MIL (D L ) writes: > > While listening to the launch broadcast this morning I noticed that as > the shuttle's velocity increased, its altitude seemed to decrease. > At some where around 15000fps the altitide was 65 nautical miles > and then a few seconds later around 19Kfps it sounded like the > controller called out the altitude as 61 n.m. Did I mis-hear this? According to sources I've read, the shuttle actually does a shallow *dive* to pick up speed on its way to orbit. I thought that it was done about twenty miles higher, but it's been a long time since I read that stuff. -- -- Mark A. ...uw-beaver!ssc-vax!adolph
henry@utzoo.uucp (Henry Spencer) (10/02/88)
In article <23004@tut.cis.ohio-state.edu> pritch@tut.cis.ohio-state.edu (Norm Pritchett) writes: >>While listening to the launch broadcast this morning I noticed that as >>the shuttle's velocity increased, its altitude seemed to decrease. >>At some where around 15000fps the altitide was 65 nautical miles >>and then a few seconds later around 19Kfps it sounded like the >>controller called out the altitude as 61 n.m. Did I mis-hear this? > >... I heard it mentioned that this was done to insure >proper ditching of the external tank into the ocean rather than having >it go into orbit. The early shuttle missions flew a dip maneuver to put the ET into the Indian Ocean. The later ones used a direct-ascent trajectory which did away with the dip and put the ET into the Pacific. I don't know which trajectory this flight is using, offhand. Another possible reason for the dip is simply that the shuttle is accelerating horizontally and the small loss in altitude is unimportant. *Velocity* is the main requirement for getting into orbit; any fuel spent on maintaining altitude is unproductive overhead. Some such overhead is necessary, since the shuttle has to get out of the atmosphere to do its accelerating, but the less fuel spent on it, the better. The shuttle may simply have been starting to fall back to Earth, with no attempt made to stop it since orbital velocity was not far away anyhow. -- The meek can have the Earth; | Henry Spencer at U of Toronto Zoology the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu