NASA Defends Shuttle's Thermal Tiles / STS-107

Yahoo! News ^ | 2/5/03 | Paul Recer - AP

[NormsRevenge]

Investigators searching for clues to Columbia's loss are focusing on a 2 1/2-pound, 20-inch chunk of foam insulation that fell from the shuttle's external tank moments after liftoff and stuck the underside of the wing, possibly damaging the tiles. The shuttle was traveling at 2 1/2 times the speed of sound at the time, or just over 1,900 mph.

[Interesting Times]

He acknowledged, however, that there are key sites on the underside of the wing, such as the covers of the landing gear compartment, that make the craft vulnerable during re-entry into Earth's atmosphere.

The piece that was filmed coming off Columbia over northern Arizona seemed pretty big -- much brighter than you'd expect from a tile. I wonder if it could have been one of the landing gear covers.

[Bobby777]

2.5 lbs at 1,900 mph

a .223 travels at what, about 1300fps? ...

1900 mph is about 2786.66~ feet per second

somebody has probably already worked out the energy transfer on another thread, I'm sure ... and of course a lot depends upon the impact angle ...

[Capitalist Eric]

I wonder if the foam insulation was also applied with spit...

Un-friggin'-believable!

[Interesting Times]

As you suggest, this was discussed in detail on some other threads. The short version is that the chunk of insulation wasn't going at 1,900 mph relative to Columbia, but at whatever speed the 1,900 mph airsteam could accelerate it to in the distance between the point where it broke off and the point where it hit the wing.

[Bobby777]

(the impacting debris was decelerating from the same speed as the vehicle obviously, so the difference between the object and the impact area is the question ... not an easy answer I suppose) ...

[cinFLA]

2.5 lbs at 1,900 mph a .223 travels at what, about 1300fps? ... 1900 mph is about 2786.66~ feet per second somebody has probably already worked out the energy transfer on another thread, I'm sure ... and of course a lot depends upon the impact angle ...

About the only thing you have correct is that it depends on the impact angle.

[KellyAdmirer]

"We've had good success with the tile system."

Not now, we haven't.

[Bobby777]

yes, thank you ... I was just in the process of posting a reply to myself so that people would know I understood that ... appreciate your mentioning it, too ...

[cinFLA]

but at whatever speed the 1,900 mph airsteam could de-accelerate it to in the distance between the point where it broke off and the point where it hit the wing.

[Bobby777]

are the speeds wrong? ... please correct then ...

[bvw]

Yeah, well the foam that drops off is ALSO travelling at 1900 mph. In the dozen or so feet of falling, it wouldn't lose that much speed. You might be talking a relative impact speed ballparked 200 to 20 mph.

[freepersup]

I wonder... how does NASA know it was insulation and not a large chunk of ice ? In my lay mind a chunk of ice would have a much greater mass which would deliver far more energy into the wing's surface than something pliable like foam (which I have no clue, as to it's composition).

[Interesting Times]

I said 'accelerate' because I had just said 'relative to Columbia'...

[Bobby777]

About the only thing you have correct is that it depends on the impact angle.

again, what speed numbers are incorrect? ... I'm not talking impact speed ... I already referenced that ...

[Bobby777]

see my #6

[freepersup]

If you watch the video, the object (ice or foam ?) appears to stall in the burble, before exiting this turbulent space and then gets swept into the onrushing relative wind.

[Capitalist Eric]

You might be talking a relative impact speed ballparked 200 to 20 mph.

With respect, I must disagree. The effects of gravity will be negligible. What will make the difference, is the surface area exposed to the airstream. Considering the relatively low density of the foam, and a 1,900 MPH airstream hitting this piece of foam, it would decelerate the foam piece FAST, so that by the time it hit the wing, there would be a significant difference in speed at time of impact.

While no physics expert (only a few university classes), I would guess that the differential was significantly greater than your highest guess of 200 MPH...

Not trying to start an argument... JMHO.

FReegards,

[bvw]

If you know the frame rate of the video it is easy enough to calculate the relative speed. I don't know that frame rate.

[_Jim]

We've had good success with the tile system

So - that complicated structure making up the wing's leading edge HAS been cleared?

THAT'S news ...