Why does the shuttle throttle on ascent?

Yes, and it is also why the shedding foam can only do serious damage within
the lower atmosphere, as the drag cannot decelerate the chunks enough to
strike with enough force to do harm at that altitude.

Brian

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Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
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"Dudley Henriques" wrote in message
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"Danny Deger" wrote in message
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Why does the shuttle throttle to 3 Gs on ascent?

Danny Deger

As the shuttle ascends, the dynamic pressure (in slugs/sq.in) increases as
the square of the velocity. The shuttle is throttled back to 65% thrust to
avoid over stress at a speed computed under what is called critical q.
As the shuttle ascends, it is ascending into lower air density (which of
course transfers into a lowering dynamic pressure). The throttling back
takes the shuttle through a transition area during the ascent that ends as
the lowering air density meets the parameters that allow throttle up. This
I believe occurs at about 35 to 37K.
The point where lowering air density meets the ability to throttle up
again is the max q for the shuttle. (Max q meaning maximum dynamic
pressure)
After reaching max q, the shuttle is go for throttle up as the increasing
velocity past max q will never exceed the structural limitations of the
shuttle due to it's entrance into lower air density that doesn't have the
ability to overstress the structure.
Hope this helps a bit.
Dudley Henriques