Thrust
Topic Author
Posts: 2586
Joined: Wed Sep 17, 2003 12:17 pm

Changes In Shuttle Launch Stats And Reasons Why

Sun Aug 28, 2011 10:09 pm

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.
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zanl188
Posts: 3454
Joined: Sat Oct 21, 2006 9:05 pm

RE: Changes In Shuttle Launch Stats And Reasons Why

Sun Aug 28, 2011 11:43 pm

By what means are you using the video to determine velocity?
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titanmiller
Posts: 86
Joined: Thu May 25, 2006 2:57 pm

RE: Changes In Shuttle Launch Stats And Reasons Why

Mon Aug 29, 2011 2:32 am

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.
 
BigSaabowski
Posts: 130
Joined: Fri Jul 04, 2008 1:33 pm

RE: Changes In Shuttle Launch Stats And Reasons Why

Mon Aug 29, 2011 3:31 am

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.
 
HaveBlue
Posts: 2111
Joined: Fri Jan 30, 2004 3:01 pm

RE: Changes In Shuttle Launch Stats And Reasons Why

Mon Aug 29, 2011 4:27 am

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  
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nomadd22
Posts: 1566
Joined: Fri Feb 22, 2008 7:42 pm

RE: Changes In Shuttle Launch Stats And Reasons Why

Mon Aug 29, 2011 6:56 pm

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.
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