Jester ([info]jester_uk) wrote,
2005-08-10 09:16:00
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  • Mood: contemplative

Blindingly obvious time

NASA are still wondering how to stop large chunks of insulating foam falling off the shuttle's external fuel tank during lift-off.

I assume they /have/ considered putting some sort of mesh over the whole thing so that if anything comes loose it can't actually go anywhere.

This is probably where somebody who understands aerodynamics points out that the airflow over a mesh would be horrendous, which, unfortunately, leads me to envision the external tank with a thin rubber coating.

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  • 12 comments

[info]geekling

August 10 2005, 08:24:07 UTC 6 years ago

Nononononooo!

the obvious question is....

Have they considered gaffa tape?

With the obvious follow-up question of....

For space shuttle applications, black of silver?

[info]ahruman

August 10 2005, 13:35:20 UTC 6 years ago

Duck tape is part of the standard Space Shuttle Emergency Repair Kit. No, really. (Strictly speaking, gaffer tape is less sticky.)

[info]korenwolf

August 10 2005, 14:53:05 UTC 6 years ago

Well of course it is, it has a dark side, a light side and holds the universe together.

[info]songster

August 10 2005, 08:47:31 UTC 6 years ago

I suspect the tensile strength of the foam they use is considerably higher than standard mesh or rubber. Problem is, moving at several times the speed of sound, pretty much any conventional material's going to rip.

Another point is that rubber's firstly going to get chilled and brittle while on the launch pad (the foam's there to insulate the cryogenic fuel tank, and often ices up), and then is going to get heated to ignition point during the launch.

[info]jester_uk

August 10 2005, 08:55:47 UTC 6 years ago

Surely a mesh is going to be more able to cope with vibrations than the virtually solid object that is the foam layer?

Obviously it's time for some unconventional materials. The carbon tiles on the shuttle itself manage to stay in place, although they're horribly brittle. Possibly that's because they're smaller units (with packing material to stop them knocking together because of the lift-off vibrations.

I suppose the other question is whether any billions of dollars put into this would be better used developing the shuttle's replacement anyway.

Wonder how Rutan's getting on with the next stage of development from SpaceShip One.

[info]artela

August 10 2005, 09:02:30 UTC 6 years ago

Now that things have moved on so much since the time they built the fleet, I wonder if they've considered removing the wretched tiles and instead using a spray on coating to do the same job instead? There are plenty of new materials that could be used - they just need to "think outside the box" (argh. horrid phrase, but I couldn't think of a better way of saying it!)

[info]jester_uk

August 10 2005, 09:35:44 UTC 6 years ago

Well, at the moment the tiles are more reliable than the spray-on stuff on the tank. Whether that's because they're still using exactly the same stuff as when the shuttle was designed, I don't know.

[info]korenwolf

August 10 2005, 09:39:20 UTC 6 years ago

Though they'd need something different on the orbiter anyway as the tank only needs to be good enough to get into low orbit at which point it's dropped off. The stuff on the orbiter needs to handle re-entry.

[info]korenwolf

August 10 2005, 09:38:19 UTC 6 years ago

Such as sticking the orbiter on top of the stack rather than on the side. Bits fall off the firecracker? Who cares they're not going to hit the important it because it's on the top.

[info]ahruman

August 10 2005, 13:38:17 UTC 6 years ago

If something damages the solid rocket boosters you’re in serious trouble either way, though.

Anyhow, the shuttle’s only going to do a handful more missions. Significant redesign at this point would be a tad silly.

[info]korenwolf

August 10 2005, 14:52:30 UTC 6 years ago

Though the only failure on the shuttle of the SRBs was down to faulty design of a component not something hitting them. The point about putting the orbiter on top (in future designs) is that the most fragile part of the whole machine is put above the point at which it can be damaged by stuff falling onto it. The actual design of the existing system isn't going to change significantly and from at least one report it looks like they had the problem licked right until they did repair on part of the foam on the big tank. It looks like it's the repair which failed not the foam as originally applied.

[info]korenwolf

August 10 2005, 09:37:26 UTC 6 years ago

Another problem is that they've moved from an ozone unfriendly based process to a friendly one. This results in larger bubbles being able to form inside the foam which weakens it.
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