Re: Columbia

From: George Murphy (gmurphy@raex.com)
Date: Sat Jun 07 2003 - 06:16:00 EDT

  • Next message: George Murphy: "Nahin"

    D. F. Siemens, Jr. wrote:
    >
    > On Fri, 06 Jun 2003 22:31:06 -0400 George Murphy <gmurphy@raex.com>
    > writes:
    > > 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
    >
    > 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.
                                            Shalom,
                                            George
                                                            

                                                               
            

    George L. Murphy
    gmurphy@raex.com
    http://web.raex.com/~gmurphy/



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