Re-using vehicles which launch -hard-

Palomar · 2005-07-28 11:34:51

*If you look at slo-mo images of Saturn V launches, there's stuff falling off and all around it -- sometimes lots of stuff [edit -- ice, apparently, resulting from the upper-stages exhaust or whatever****See EDIT below].

Has the shuttle always been plagued with these sorts of problems (styrofoam, tiles, etc. falling off) or has the public only been notified since the Columbia disaster? I don't recall it being a *public* issue prior to Columbia. Could be my memory, of course.

Does it make sense to repeatedly launch really heavy vehicles under all that enormous pressure they're under and etc.? Or was the Saturn V ideal (expendable 1-time use) the smarter idea?

Maybe we should go back to the expendable 1-time-only use scenario...

--Cindy

::EDIT:: I remember asking about it in the old "Saturn V" thread in the Sci & Tech folder. This was Shaun's reply:

I believe that frothy looking white stuff is condensation of water vapour in the air.
The Saturn Vs ran on liquid hydrogen and liquid oxygen, which were kept in insulated tanks. But of course the insulation was imperfect and allowed some of the fuel to warm up and return to its gaseous form.
As I understand it, there were 'bleed-valves' which allowed for a release of these gradually warming cryogenic fuels before their expansion blew up the tanks! The still-very-cold-but-now-gaseous fuel leaking out of the bleed-valves came into contact with the surrounding air and caused the water vapour in it to condense into tiny droplets or even ice crystals.
I'm sure you must have seen slabs of ice vibrating loose from the outside of a Saturn V during films of their launch, too(?) All part of the same thing ... condensation of the humidity in the air on a cold surface.

How heavy were those slabs of ice on average, I wonder? Comparable to shuttle tiles or shuttle styrofoam? Anyway, you can definitely see them shaking and falling off in splinters during Saturn V launches. But then those ice slabs were merely byproducts of the machine and launch, and of course losing them didn't endanger lives...

GCNRevenger · 2005-07-28 12:16:37

The stuff falling off of the big Saturn-V was ice, since the LOX/LH2 tanks weren't insulated. (Kerosene was chilled too if memory serves)

For a fully reuseable space vehicle, it will be nessesarry just from a cost prespective to have thermal tiles and fuel tank insulation that doesn't need to have anything besides a minor inspection done for multiple flights (10-20 minimum). It isn't a question if a true RLV will need robust systems, they will have to have it.

As far as expendable rockets, so long as your payload rides on top of the thing, it really doesn't matter that much if foam falls off. Unless we build Shuttle-C or Bob Zubrin's Ares, which have fragile side-mounted componets. (Shuttle SRB nose cones are pretty strong).

PS: one of those ice slabs would be enough to obliterate Shuttle's fragile RCC pannels on the wings and nose, even if it just fell from the tank while it was sitting on the pad.

Fledi · 2005-07-28 20:03:28

Was just wondering if it would be possible to place the insulation on the inside of the Shuttle tank so it would have that lithium alloy (?) shell on the outside.

GCNRevenger · 2005-07-28 20:11:33

Not really, several inches of foam would reduce the tank volume alot, plus applying the foam would be really hard. Such a redesign isn't practical in any short timeframe anyway... NASA needs to quickly come up with a way to arrest foam shedding from the current design, and so something that will WORK this time around.

As far as a reuseable ship, I bet the insulation will be verrry carefully designed, not slapped on like the Shuttle tank.

RobertDyck · 2005-07-28 20:47:13

Tile loss problems started with the first launch of the Shuttle, mission STS-1. That was Columbia by the way. As I recall the military volunteered pictures from their telescope on a mountain in Hawaii. Those pictures were so good NASA engineers could determine which tiles were missing, and judge if the orbiter could return. The military was pissed-off when NASA released those images to the media. But NASA isn't about secrecy.

Yes, Saturn V had the same ice problems. Ice build-up was greater due to lack of foam insulation. But Saturn V is an axial configuration so there isn't anything delicate on the outside that would be damaged by falling ice.

Ares wouldn't be affected by foam or ice because the engine pod isn't reusable. The Ares engine pod is expendable so foam/ice would bounce off the engine pod's aluminum or composite skin.

It would be possible to re-design the tank to have some sort of skin over the foam. Paint it with an applied polymer film that would hold in any foam that breaks, and protect the foam from high speed air. Of course that film would add weight; over a surface as big as the ET that would significantly reduce cargo capacity. A reusable tank would require something more durable but an expendable tank wouldn't.

GCNRevenger · 2005-07-28 21:58:15

I disagree that Ares would be inherintly immune. Thin metal or particularly composites may not handle the impact that well. Even a few pounds of foam at supersonic velocity is nontrivial against thin housing pannels.

Some sort of covering over the tank is probobly the best way to go. What form it shoudl take, a fiber mesh or an elastomer coating or something is a good question.

RobS · 2005-07-29 01:20:44

Regarding putting the insulation inside the tanks: the problem there is that any foam that breaks off will run through the PUMPS and could damage them. Foam will be put under tensile stress from contact with the cryogenic liquid and launch vibration may break some loose.

This foam problem does not strike me as fixable. They've worried about it since the first launch. They can't develop a formula that doesn't break up or explode off. Punching little tiny vent holes in the foam didn't work. Apparently there's buildup of liquid nitrogen under the foam covering the liquid hydrogen tank and it vaporizes during ascent. It's a messy, complicated problem that results from side mounting the orbiter.

-- RobS

Palomar · 2005-07-29 05:48:19

Tile loss problems started with the first launch of the Shuttle, mission STS-1. That was Columbia by the way. As I recall the military volunteered pictures from their telescope on a mountain in Hawaii. Those pictures were so good NASA engineers could determine which tiles were missing, and judge if the orbiter could return. The military was pissed-off when NASA released those images to the media. But NASA isn't about secrecy.
Yes, Saturn V had the same ice problems. Ice build-up was greater due to lack of foam insulation. But Saturn V is an axial configuration so there isn't anything delicate on the outside that would be damaged by falling ice.

*Again, I didn't realize there was this sort of danger with the shuttle until the Columbia disaster...but then, as previously admitted, I've not followed shuttle launches and missions closely (ho-hum). I had heard of tiles falling off and potential risks involved, but falling foam being so potentially deadly? How much does that stuff weigh, anyway? I've always thought "light weight"...

As for Saturn V, its stages were basically huge pieces of mouldings welded together, right? I'll Google for it.

If the shuttle is truly this fragile, what was the purpose of going the "reused vehicle" route? I suppose nothing can be perfect or 100% fail-safe, but still...

This from spaceflightnow.com:

Timing of foam loss saved Discovery from big hit
The shuttle Discovery's crew might have dodged a bullet when a piece of foam debris broke away from an aerodynamic ramp on the side of the ship's external fuel tank during launch Tuesday. Had the foam broken away earlier, when the shuttle was deeper in Earth's atmosphere, the chunk could have hit the orbiter with potentially catastrophic results, engineers said Thursday.

::sigh::

--Cindy

BWhite · 2005-07-29 14:00:26

Regarding putting the insulation inside the tanks: the problem there is that any foam that breaks off will run through the PUMPS and could damage them. Foam will be put under tensile stress from contact with the cryogenic liquid and launch vibration may break some loose.
This foam problem does not strike me as fixable. They've worried about it since the first launch. They can't develop a formula that doesn't break up or explode off. Punching little tiny vent holes in the foam didn't work. Apparently there's buildup of liquid nitrogen under the foam covering the liquid hydrogen tank and it vaporizes during ascent. It's a messy, complicated problem that results from side mounting the orbiter.
-- RobS

I've read that if you clog a fuel pump in this manner, there is a good chance the thing will explode, spectacularly.

GCNRevenger · 2005-07-29 14:23:18

*Again, I didn't realize there was this sort of danger with the shuttle until the Columbia disaster...but then, as previously admitted, I've not followed shuttle launches and missions closely (ho-hum). I had heard of tiles falling off and potential risks involved, but falling foam being so potentially deadly? How much does that stuff weigh, anyway? I've always thought "light weight"...
As for Saturn V, its stages were basically huge pieces of mouldings welded together, right? I'll Google for it.
If the shuttle is truly this fragile, what was the purpose of going the "reused vehicle" route? I suppose nothing can be perfect or 100% fail-safe, but still...
This from spaceflightnow.com:
Timing of foam loss saved Discovery from big hit
The shuttle Discovery's crew might have dodged a bullet when a piece of foam debris broke away from an aerodynamic ramp on the side of the ship's external fuel tank during launch Tuesday. Had the foam broken away earlier, when the shuttle was deeper in Earth's atmosphere, the chunk could have hit the orbiter with potentially catastrophic results, engineers said Thursday.
::sigh::
--Cindy

The idea of a space shuttle was never a bad one, infact it will eventually be needed barring a breakthrough leading to a space elevator or a super fuel... but this thing that we dare feign to call a "Shuttle" was a compromise design between many interests and the final plan was decided by its political acceptability, not primarily its technical feasability.

One of these interests stretching the Shuttle plan beyond the practical break point were NASA brass that wanted to maximize Apollo engineer employment... to them, a labor hypra-intensive Shuttle was a good thing.

NASA can't ensure that Shuttle will ever be foam proof, so they just have to find a way to prevent signifigant foam shedding. Anything bigger then like a baseball anywhere near the orbiter is unacceptable. It drives me up a wall how the Michoud folks didn't seem to think much of applying large pieces of foam by hand the same way as the piece that killed Columbia.

Foam light weight? If I hit you with a styrafoam coffee cup moving at Mach-1, it'll knock you off your feet and the wind out of you but good... about like getting hit by a hammer or something.

Dook · 2005-07-30 12:15:40

The foam may be lightweight but it's also very cold, maybe even frozen, and more dense from being near the internal LOX and Hydrogen tanks.

GCNRevenger · 2005-07-30 13:52:20

It wouldnt' be any more DENSE, the foam doesn't contract much with temperature, but it would be a little more rigid.

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#1 2005-07-28 11:34:51

Re: Re-using vehicles which launch -hard-

#2 2005-07-28 12:16:37

Re: Re-using vehicles which launch -hard-

#3 2005-07-28 20:03:28

Re: Re-using vehicles which launch -hard-

#4 2005-07-28 20:11:33

Re: Re-using vehicles which launch -hard-

#5 2005-07-28 20:47:13

Re: Re-using vehicles which launch -hard-

#6 2005-07-28 21:58:15

Re: Re-using vehicles which launch -hard-

#7 2005-07-29 01:20:44

Re: Re-using vehicles which launch -hard-

#8 2005-07-29 05:48:19

Re: Re-using vehicles which launch -hard-

#9 2005-07-29 14:00:26

Re: Re-using vehicles which launch -hard-

#10 2005-07-29 14:23:18

Re: Re-using vehicles which launch -hard-

#11 2005-07-30 12:15:40

Re: Re-using vehicles which launch -hard-

#12 2005-07-30 13:52:20

Re: Re-using vehicles which launch -hard-

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