Debris mass and impact velocity

From: Matson, Robert (
Date: Fri Feb 07 2003 - 22:32:22 EST

  • Next message: Robert Oler: "Re: Root Cause Analysis"

    Hi Don,
    > I believe however that NASA has set a weight of about 3 
    > kilograms- or about 7 pounds-for the weight of the piece that
    > flaked off the ET.
    I thought it was 2.7 lbs?
    > If that same piece hit the leading edge of the wing of a B-747 
    > at the wing root at Mach .89, well it's a good chance the
    > stressed leading edge would lose it's effectiveness ...
    Is Mach .89 the velocity that they came up with for the impact?
    Seems high, but maybe it's right.  The velocity can be estimated
    by taking the distance from the flake-off point to the left wing
    leading edge and dividing it by the time it took to get from one
    to the other.  I don't know what the frame resolution of the
    tracking video was -- perhaps the standard 30 fps?  In how
    many frames does the debris appear?  I remember it being
    something like 3 or 4.  So we're talking about a distance
    in the ballpark of 80 feet (?) being covered in 3 frame
    durations (0.1 seconds?):  800 feet-per-second.  ~550 mph.
    So not exactly a trivial impact... --Rob
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