Print from Airliners.net discussion forum
http://www.airliners.net/aviation-forums/military/read.main/137435/

Topic: Changes In Shuttle Launch Stats And Reasons Why
Username: Thrust
Posted 2011-08-28 15:09:26 and read 3870 times.

Hi there. I've been observing videos of shuttle launches in the early 1980s, post-Challenger, and post-Columbia. I've noticed that earlier shuttle missions broke the speed of sound slightly later than the final shuttle missions, and also separated from the solid rocket boosters at lower speeds than the earlier shuttle missions. I know for a fact that the solid rocket boosters gained weight after the Challenger disaster due to the addition of a third o-ring, but I don't know how a much a difference that extra weight made. I also know the shuttle received numerous upgrades over the years, example, a glass cockpit over a traditional one, etc. I observed these changes by timing the clocks on the videos...obviously that is not the best way to do it, but I was hoping somebody on here could give me something that would tell me if my eyes are deceiving me or not. Thanks.

Topic: RE: Changes In Shuttle Launch Stats And Reasons Why
Username: ZANL188
Posted 2011-08-28 16:43:15 and read 3843 times.

By what means are you using the video to determine velocity?

Topic: RE: Changes In Shuttle Launch Stats And Reasons Why
Username: titanmiller
Posted 2011-08-28 19:32:44 and read 3784 times.

I don't have a definitive answer for you, but I can tell you that the weight and orbital parameters of each launch are different for every flight so that probably throws a lot of variability into it.

Topic: RE: Changes In Shuttle Launch Stats And Reasons Why
Username: BigSaabowski
Posted 2011-08-28 20:31:02 and read 3761 times.

You may be comparing apples to .....pears.
Many of the later missions were launched into high-inclination orbits (for the purpose of servicing the ISS), which have different energy requirements than a low-inclination orbit, and that alters the flight profile.

Topic: RE: Changes In Shuttle Launch Stats And Reasons Why
Username: HaveBlue
Posted 2011-08-28 21:27:18 and read 3745 times.

Quoting Thrust (Thread starter):
I've noticed that earlier shuttle missions broke the speed of sound slightly later than the final shuttle missions,
Quoting ZANL188 (Reply 1):
By what means are you using the video to determine velocity?

Good question, as to how are you determining that? What immediately came to my mind was are you using the visible 'shockwave' seen as it ascends? You can and do see that wave at speeds well below actual supersonic depending on conditions, and whether you see it at all or not is largely affected by humidity in the air, which is often abundant in FL and makes for exciting 'supersonic looking' airshow pictures  

Topic: RE: Changes In Shuttle Launch Stats And Reasons Why
Username: nomadd22
Posted 2011-08-29 11:56:46 and read 3568 times.

After Challenger they changed the flight profiles so the shuttle would enter the Maxq (maximum dynamic pressure) point at a higher altitude to reduce the peak stress on the system.


The messages in this discussion express the views of the author of the message, not necessarily the views of Airliners.net or any entity associated with Airliners.net.

Copyright © Lundgren Aerospace. All rights reserved.
http://www.airliners.net/