Randall wrote:

RC> I heard it broke loose about a minute into the launch.  At that point,
RC> they're still in the stratosphere, but supersonic.  A piece of
RC> ice-coated insulation would be very draggy, and would pull several
RC> hundred g.  It would have been essentially stopped by the time the
RC> wing hit it at Mach 1+.  Ouch.

Travelling at Mach 1+ would probably not lead to substantial melting
of a compact ice layer. In our few experiments at SPL with LOX
lines, that were lightly insulated (20 to 30 mm) we noticed, that the
formation of ice depended heavily on the temperature and the humidity
and whatnot. In some cases the frozen water had a fluffy snow like
structure and sometimes virtually compact ice was formed. What kind
of conditions prevailed when she sat on the pad I do not know. But
I am sure there should be people that know.

RC> I never took the insulation strike hypothesis very seriously before,
RC> but ice at Mach 1+ would do enough damage to make that scenario
RC> credible.  Ouch again, and damn.

Assuming Mach 1+ to be 400m/s a chunk of 2kg would represent an energy
of 160kJoule. Further assuming that the impact was not oblique but
at a shallow angle there remained eventually some 50kJoule.
To produce 50kJoule by an objet dropped from a height of 10m under
1G would take a mass of roughly 500kg. Ouch. If damage depended more on
the impulse rather than kinetic energy, then the impact would compare
to a mass of only 50kg falling from 10m. Still ouch. And who says the
chunk was only 2kg as it was visible from a rather big distance?

Hans



Hans Ulrich Ammann
mailto:[EMAIL PROTECTED]
http://www.spl.ch

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