Hi, Matt.

Thanks for responding.  Leonard also.  No time here for a full response,
but will attampt a quickie - -

Hey, when I posted that, I didn't realize NASA was about to do another
test, this time, with some of those real carbon type panels.  I heard
briefly on radio this afternoon, but haven't read anywhere, that the
insulation projectile did cause significant damage to the carbon
reinforced panels in today's test article, which used some of the
"real", but hideously espensive, panels.

It is late now, and I now read that today's tests provide the
"smoking gun" evidence as to how the insulation impact could have done
the damage to Columbia's wings which resulted in the catastrophe.


 MM> That is the only test that I have read about also, and I share the same
 MM> question.  I _think_ I can rationalize that the shuttle was at max
 MM> acceleration on a trajectory from 0 MPH to 17,000 MPH, and with NASA
 MM> knowing the split second timing from the breakaway to impact, they
 MM> probably calculated the change-of-speed of the shuttle itself during
 MM> that approximate three seconds from breakaway of the foam until impact
 MM> time.

Impact time was just before 82 seconds after liftoff, right?  But - -
Hey, where did you get that "approx three seconds" from?  That has just
got to be _way_ wrong.  Think about it.  My little calculator shows that
even down here at terra firma, a free-falling object would fall about
145 ft in 3 seconds, and reach a velocity of about 66 mph.

 MM> They might not have even needed to calculate for air resistance.  If at
 MM> that point in time the shuttle was accelerating at ~200MPH per second,
 MM> that 2.8 seconds to impact would give about 530 MPH increase in shuttle
 MM> speed relative to the speed of the piece of foam.

OK switching to 2.8 seconds - (that still has to be _way_ wrong) - -

Your assumed acceleration of 200 MPH per second works out to 293.3 ft
/sec**2 (approx 9G's). Does the shuttle accelerate that strongly just
under 82 seconds after liftoff?

But your assumptions break down -  neglecting the (32.2) gravity
deceleration component on the loose piece of insulation, at shuttle
acceleration of 293.3,  S = 1/2 a t**2 (and assuming shuttle initial
velocity of _zero_ during those 2.8 seconds, another gross error)

S = .5 * 293.3 * 2.8 *2.8 = 1150 ft.

So the shuttle launch vehicle moved forward well over 1000 feet during
your cited 2.8 seconds.  But the whole launch vehicle is only about 200
ft tall, Matt. Think about it. Your 2.8 seconds and other assumptions
seem to be way off the mark.

So lets think about -  two objects going at the same speed, maybe 120
feet apart, and they separate, and impact one another shortly thereafter
at a velocity of over 500 MPH. -  there will have to be some drastic
relative acceleration + decelleration differential between them to get
up to the 500+ mph impact range,

I dunno what the Shuttle speeds may be at about 82 seconds after
liftoff, but just guessing, and making these up  (a SWAG scenerio -
don't beat me up about this) - -

Instant 1 - launch vehicle going 2250 mph - insulation falls off
Instant 2 - vehicle going 2260 mph - insulation slowed down by air
friction and now going 1750 mph - Impact of insulation with vehicle at
510 MPH.

Please feel free to tell me where I'm wrong.

- - -  JimH.

... Inquiring minds want to know. - Bubba
--- MultiMail/MS-DOS v0.32