From: George Murphy (firstname.lastname@example.org)
Date: Sat Jun 07 2003 - 06:16:00 EDT
D. F. Siemens, Jr. wrote:
> On Fri, 06 Jun 2003 22:31:06 -0400 George Murphy <email@example.com>
> > I don't have the exact parameters for the space shuttle but news
> > reports of the
> > tests to determine the cause of the Columbia break up-puzzle me. A
> > piece of foam like
> > that which broke loose from one of the fuel tanks and struck the
> > shuttle's wing was
> > fired at a wing at a reported speed of 530 mph = 777 ft/s. I don't
> > know the shuttle's
> > acceleration but am pretty sure its maximum must be less than 10 g =
> > 320 ft/s^2 , so the
> > acceleration of the foam relative to the wing was less than 11 g =
> > 352 ft/s^2. To reach
> > a speed of 777 ft/s at this acceleration it would then have to
> > travel a distance
> > d = v^2/2g = (777)^2/2*352 ~ 860 ft.
> > & I think this is a good deal longer than the total length of the
> > shuttle plus fuel
> > tanks.
> > I'm just guessing at numbers here but it seems to me that
> > the speed they're
> > using is too high. Does anyone have the right values?
> > Shalom,
> > George
> I don't have explicit data, but I've got a guess. Shuttle and booster
> were obviously flying at the same speed and acceleration when the piece
> broke off. But the piece was quickly decelerated by the air through which
> they were flying, so the relative velocity on striking the shuttle wing
> was close to the velocity of the craft.
This would require that air resistance quickly kill off the _upward_ velocity
the foam would have had on breaking away. That would take some time, & again one needs
to know some numbers to estimate whether there would have been enough time.
George L. Murphy
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