Author Topic: SpaceX: Advanced Launch Abort System (LAS)  (Read 222487 times)

Offline R7

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Re: SpaceX: Advanced Launch Abort System (LAS)
« Reply #520 on: 07/15/2013 11:28 am »
what g forces is the MPCV tower LAS expected to pull and is it more or less that the SDs?

Max 15g.

http://www.nasa.gov/pdf/450266main_PA-1_Team_FS.pdf
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Offline Garrett

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Re: SpaceX: Advanced Launch Abort System (LAS)
« Reply #521 on: 07/15/2013 11:45 am »

Which direction are you firing relative to ground? Suspect you need to do a vector addition of 1g downwards for gravity. If you start out horizontally, the fall adds slightly to your net speed.
But, for instance, 0.999g whilst sitting on the ground - never. Not enough thrust to lift off the ground.
cheers, Martin
Am firing directly upwards, as I presume that's a decent approximation to the Dragon LAS profile. Was calculationg g-forces as an addition to gravity, but after your comment and a quick search online, I see that I misused the term. So yes, I need to add 1g so that an acceleration of 1g would mean sitting still on the ground.
avg acceleration     
time to sound barrier
5g
8.7 s
6g6.9 s
7g5.8 s
8g5.0 s
9g4.3 s
9.7g4.0 s
10g3.9 s

Note that the "4 seconds" number mentioned earlier could have come from somebody mistakenly subtracting the 1g.
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