Question...

[CTho9305]

Would a scaled-up heat pipe on the shuttle help in the event of losing multiple tiles? They move heat pretty fast... would it be possible to spread the heat out effectively enough that the shuttle makes it through the period of highest intensity heat? Or would having more than 1 or 2 tiles missing mean that so much heat would get in that even spreading it wouldn't help?

How much weight would such a system add?

 

[bmacd]

were the other dozen space shuttle threads not enough specific enough to post in?

-=bmacd=-

 

[CTho9305]

Originally posted by: bmacd
were the other dozen space shuttle threads not enough specific enough to post in?

-=bmacd=-

Do you read all 800 replies to threads that long?

 

[MacBaine]

Let me go call NASA and find out

 

[Heisenberg]

I'm sure if it was an effective solution the engineers would have included it.

 

[CTho9305]

Originally posted by: Heisenberg
I'm sure if it was an effective solution the engineers would have included it.

Presumably yes. My question is more of a "why isn't it effective" than "engineers are stupid" since I'm pretty sure they know more than I do . Maybe they didn't have reliable heatpipes 22 years ago, or they weigh a lot, or that situation isn't survivable anyway. Just wondering what the reason is

 

[her209]

Originally posted by: CTho9305

Originally posted by: Heisenberg
I'm sure if it was an effective solution the engineers would have included it.

Presumably yes. My question is more of a "why isn't it effective" than "engineers are stupid" since I'm pretty sure they know more than I do . Maybe they didn't have reliable heatpipes 22 years ago, or they weigh a lot, or that situation isn't survivable anyway. Just wondering what the reason is

We aren't all NASA engineers, FYI.

 

[Heisenberg]

Originally posted by: CTho9305

Originally posted by: Heisenberg
I'm sure if it was an effective solution the engineers would have included it.

Presumably yes. My question is more of a "why isn't it effective" than "engineers are stupid" since I'm pretty sure they know more than I do . Maybe they didn't have reliable heatpipes 22 years ago, or they weigh a lot, or that situation isn't survivable anyway. Just wondering what the reason is

In that case, I have no idea then since I'm not an engineer.

 

[CTho9305]

Originally posted by: her209

Originally posted by: CTho9305

Originally posted by: Heisenberg
I'm sure if it was an effective solution the engineers would have included it.

Presumably yes. My question is more of a "why isn't it effective" than "engineers are stupid" since I'm pretty sure they know more than I do . Maybe they didn't have reliable heatpipes 22 years ago, or they weigh a lot, or that situation isn't survivable anyway. Just wondering what the reason is

We aren't all NASA engineers, FYI.

I've seen some pretty knowledgeable people here. People who might be able to say "a heatpipe that could do the job would weight 10 tons" or "the heatpipe would melt" or something else useful.

 

[notfred]

Ok, you have 20,000 tiles on a shuttle. You're going to need 20,000 little heat pipes, ort bigger heat pipes that connect to multiple tiles.
Second, heat pipes do not get rid of heat, they simply move it somewhere else (typically in PCs, they'll move it fro mthe profcessor to a heatsink in front of a fan). Where do you suggest they move the heat too, from the bottom of the wings to the top of the wings?

Even if there were some benefit to heating the top of the wings instead of the bottom, they'd have to move the heat from the bottom, through the inside of the wing, to the top, thus completely removing the point of the tiles, which is to keep the heat from penetrating to the inside of the shuttle.

 

[CTho9305]

Originally posted by: notfred
Ok, you have 20,000 tiles on a shuttle. You're going to need 20,000 little heat pipes, ort bigger heat pipes that connect to multiple tiles.
Second, heat pipes do not get rid of heat, they simply move it somewhere else (typically in PCs, they'll move it fro mthe profcessor to a heatsink in front of a fan). Where do you suggest they move the heat too, from the bottom of the wings to the top of the wings?

Even if there were some benefit to heating the top of the wings instead of the bottom, they'd have to move the heat from the bottom, through the inside of the wing, to the top, thus completely removing the point of the tiles, which is to keep the heat from penetrating to the inside of the shuttle.

Of course you don't want heat inside the shuttle. But once it gets trhough the insulating tiles and into the shuttle, you had BETTER do something with it unless you want to fall apart. The idea is that in case of a problem with the tiles in one area, you might survive.

Obviously the heat is going inside the shuttle if you lose tiles. But... the way I understand it, if you lose multiple tiles in one spot, that spot gets so hot the structure in that location melts quickly. If you spread it out across the whole bottom of the shuttle (down the fuselage and both wings), then, would the WHOLE thing melt? Would it melt as fast? Would it stay together long enough to reach a slow speed so it no longer heats up?

Lets say it takes 1000 watts behind the insulatino to melt the metal above the missing tiles. If heat is coming in because of missing tiles at 5000 watts (insulation slows how fast the heat gets in), stuff melts right now. But if you can get the heat away, to other parts of the shuttle, then no given area will be heated too fast. Maybe nothing will melt, maybe everything will melt. I don't know.

 

[Heisenberg]

Originally posted by: CTho9305
Of course you don't want heat inside the shuttle. But once it gets trhough the insulating tiles and into the shuttle, you had BETTER do something with it unless you want to fall apart. The idea is that in case of a problem with the tiles in one area, you might survive.

Obviously the heat is going inside the shuttle if you lose tiles. But... the way I understand it, if you lose multiple tiles in one spot, that spot gets so hot the structure in that location melts quickly. If you spread it out across the whole bottom of the shuttle (down the fuselage and both wings), then, would the WHOLE thing melt? Would it melt as fast? Would it stay together long enough to reach a slow speed so it no longer heats up?

Lets say it takes 1000 watts behind the insulatino to melt the metal above the missing tiles. If heat is coming in because of missing tiles at 5000 watts (insulation slows how fast the heat gets in), stuff melts right now. But if you can get the heat away, to other parts of the shuttle, then no given area will be heated too fast. Maybe nothing will melt, maybe everything will melt. I don't know.

The main problem I see with that is the extreme temperatures on reentry. I don't think there's a heat pipe in existance that could handle that much heat and still fit the size/weight requirements to be on the shuttle. I would guess that the pipe would quickly lose it's ability to transfer the heat and you would only buy a few seconds.

 

[CTho9305]

Originally posted by: Heisenberg
The main problem I see with that is the extreme temperatures on reentry. I don't think there's a heat pipe in existance that could handle that much heat and still fit the size/weight requirements to be on the shuttle. I would guess that the pipe would quickly lose it's ability to transfer the heat and you would only buy a few seconds.

That may be true, but consider this: take a paper cup, put some water in it, and try to light the bottom on fire. It won't light until the water has boiled off. Assuming the heatpipe works, its evaporation/condensation might make it stay cooler longer.

 

[notfred]

Originally posted by: CTho9305
That may be true, but consider this: take a paper cup, put some water in it, and try to light the bottom on fire. It won't light until the water has boiled off. Assuming the heatpipe works, its evaporation/condensation might make it stay cooler longer.

it may not burn until the water boils off if you heat it w/ a cigarette lighter, but I bet it will if you use a welding torch.

 

[CTho9305]

Originally posted by: notfred

Originally posted by: CTho9305
That may be true, but consider this: take a paper cup, put some water in it, and try to light the bottom on fire. It won't light until the water has boiled off. Assuming the heatpipe works, its evaporation/condensation might make it stay cooler longer.

it may not burn until the water boils off if you heat it w/ a cigarette lighter, but I bet it will if you use a welding torch.

Right, because the cup doesn't get the heat to the water fast enough. How about thin copper/etc?

 

[Heisenberg]

Originally posted by: CTho9305

Originally posted by: Heisenberg
The main problem I see with that is the extreme temperatures on reentry. I don't think there's a heat pipe in existance that could handle that much heat and still fit the size/weight requirements to be on the shuttle. I would guess that the pipe would quickly lose it's ability to transfer the heat and you would only buy a few seconds.

That may be true, but consider this: take a paper cup, put some water in it, and try to light the bottom on fire. It won't light until the water has boiled off. Assuming the heatpipe works, its evaporation/condensation might make it stay cooler longer.

True, but try that same thing with a blowtorch. The water will evaporate nearly instantaneously and won't significantly delay the cup bursting into flames. The parameters involved in space flight are extreme. It's hard to have any comprehension of them in everyday life.

Edit: Even if the cup was copper, it wouldn't matter. The water would still evaporate too quickly to do any good.