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Safety concerning heat shielding

Posted by: Ekkehard Augustin - Wed Jul 27, 2005 10:36 am
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Safety concerning heat shielding 
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Post Safety concerning heat shielding   Posted on: Wed Jul 27, 2005 10:36 am
At the lauch of the Space Shuttle yesterday once more the heat shield of the Shuttle has been damaged and it isn't clear yet if it means and acute thread of catastrohy for Discovery and its crew.

1. Doesn't this mean that the heat shield should be protected during launch? Which way could this be done?

What about - for example - covering the tile-side of the wings by a light-weight plate that has the only purpose to keep off any mechanical impacts from the tiles and that could be removed when the Shuttle is in space?

2. What about extending or equipping the ISS or future stations by inspection and repair modules? Each port and harbour for ships and each airport has such equipments and provides such services.

I suppose that new technologies are required for this purpose because they have to be optimized for weightlessness, temperatures in space, vacuum of space and so on.

Recently an article under www-space.com reported the problems and challenges of that alternatice/idea - so it seems to be an interesting topic to think about and to work on and for innovation.

3. t/Space's CXV will have a cooling for reentry and behave like SSO has been made behaving by the feather-technique - so in principle a reasonable alternative to the shiled of the Shuttle has been developed. What else can you imagine? And what about combining several technologies? The cooling can be the main technology while a heat shield or the Shuttle's tiles could be a backup.

...




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Post Re: Safety concerning heat shielding   Posted on: Wed Jul 27, 2005 1:17 pm
Ekkehard Augustin wrote:
thread of catastrohy

Didn't we kill off the thread of catastrophesome months ago?

:wink:

DKH

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Post    Posted on: Wed Jul 27, 2005 1:40 pm
Hello, Dr_Keith_H,

Thank You Very Much for pointing to misspelling threat as thread :D . I often recognize that I randomly did spelling-errors by pressing the wrong key(s) in several posts - long after submitting those posts.



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Post    Posted on: Wed Jul 27, 2005 1:59 pm
Here are some close up pictures of the damage done to the heatshield and also a bird strike on the ET. NASA isn't saying to much at the moment about the damage, they are still waiting for more data from the inspection being carried out in orbit now.

I think that maybe to much is being made of the whole issue of debris strikes to tiles at the moment, lots of tiles have to be replaced after each mission due to damaged sustained during take off. Having extra cameras on the ET has allowed NASA to see tiles being chipped by debris and in all probability such minor strikes occur with every launch so there is probably nothing to be concerned about. Over stressing the whole issue in the media creates unnecessary extra worry for family and friends of the crew, lets wait to hear what NASA has to say after their investigation.

http://www.spaceflightnow.com/shuttle/s ... 726images/

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Post    Posted on: Wed Jul 27, 2005 2:13 pm
I agree to what you say. I took the news simply as an opportunity to look for ideas to solve the problem. Perhaps something reasonable or interesting not found before can be triggered this way or some of my thoughts can serve as catalysts for new ideas which could work. To provide inspections and repairs at a space station could be service or business for privates - could Bigelow's inflatables be modified or extended for this perhaps?

The plate covering the tiles at launch could include springs/clips to press the tiles onto the wings or increased air-pressure could be provided between the plate and the tiles to keep them from being damged, falling of and the like - would that work?



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Post    Posted on: Wed Jul 27, 2005 2:48 pm
The trouble with protecting the heatshield is its size, the weight of any protecting material clipped over it would be significant and the amount of fixtures needed would mean a lot of modifications. Even having a few small covers over critical areas would be a problem and the damaged caused if one came off during launch would be horendous. If air travelling at hypersonic speeds got between the orbiter and cover it would tear off.

I think that it might have been worth having a maintence bay at the ISS if the shuttle was just starting service but at this late stage with so few missions left NASA's approach of patch it up and send it home is probably best. NASA hasn't got the money or resources to have an orbiter repair yard attached to the ISS and the private sector would not see it as an investment opportunity with the timescales involved in developing and launching it would be ready as the shuttle retired.

Sending a Bigelow inflatable to the ISS to act as extra crew space for a marooned shuttle crew might be a good idea, Bigelow might even supply the module free of charge if he was allowed to use it for tourists and got a free launch from NASA. The Russians might buy space in it for their proposed lunar tourism business, see link.

http://today.reuters.com/news/newsArtic ... ACE-DC.XML

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Post    Posted on: Thu Jul 28, 2005 3:05 am
Hi Andy Hill,
I think you're quite correct in your analysis of the heat shield issue however you haven't gone far enough. Wiith your permission I'll carry it a bit further.
The heatshield idea is not exactly new and neither are the shuttle tiles. In fact that's the whole problem. The tiles are ok but they have real disadvantages in practice. For example, there are lots of them; they have to be manually glued in place, they are relatively fragile in that they can't withstand what could be considered even minor impact damage, and they are high maintenance on return of the shuttle to Earth - but then again, that isn't saying much as the whole shuttle is high maintenance. :(
So having said that, what is really required is a total rethink on methods of protecting spacecraft from the friction effects on reentry.
Now unfortunately I don't have the solution however others have obviously been thinking about this issue ie. Rutan, and I'm sure that he can't be the only one.

Perhaps a thread could be started to discuss such a topic?

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Post    Posted on: Thu Jul 28, 2005 7:46 am
A talk to Andy Hill via PM has clarified what caused the misunderstanding which occurred from my point of view:

I am talking about the tiles but not about the shuttle. In principle such tiles or really these kind of tiles can be going to be used at other space vehicles too. If this would occur really then the experience that tiles are damaged at take-off of the shuttle should have the consequence that they should be protected during take-off, inspected and repaired in orbit and best after docking to a repair facility at a space station and anything more.

If the tiles are used no longer then the alternatively used technology, technique or method has to be considered regarding all this.

I am talking about future designs as reaction to the problems with the current design.

Obviously there is a difference or a chasm between the thinking of engineers and the thinking of non-engineers which I should try to handle some way. I asked Andy Hill what caused the misunderstanding and he explained to me the thinking of Engineers - that thinking is some way off the thinking of Economists and others and this is valid reverse too.

I'll expalin my thinking and try to initiate a synopsis using what Andy Hill and other engineers told me or - more precisely - how I understand it.



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Post    Posted on: Sat Jul 30, 2005 8:26 am
An article of www.welt.de is reporting an improvement of the technology of the tiles used by the Space Shuttle today.

Scientists have developed a method to produce a built-to-dimesion/customised heat-shiled made of carbon-fiber inforced silicon-carbide-ceramics.

According to the article iot is posible to produce larger parts as a whole - no tiles are needed any longer. It's pressure- and chemical resistent and relativly light. Their size makes the parts more robust and firm, the danger of catastrophic dmages is significantly less and the new material has been tests already by unmanned flights launched from Baikonur

In the laboratory the parts were 80 centimeters long.

Nasa already has shoiwn interest. A nose made of that material has been ordered by NASA fpr the X-38 and in March this year a group of NASA-people has visited the scientists to get informations.

The article is quoting the DLR and Herrmann Hald, who is working on the material etc.

The DLR is the "Deutsches Zentrum für Luft- und Raumfahrt" in Stuttgart.- www.dlr.de.



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Post    Posted on: Wed Aug 03, 2005 5:16 pm
Discovery is very clean. The fibers sticking out were never that much of a problem, and the RCC composed WLE looks good. Discovery is in good shape--and outside of that one small bit of the tile near the nose wheel--very much within margin--is spotless.

Still--Griffin could have takern this opportunity to call it quits with Orbiter--and go on with HLLV--but politics dictate that he must go on so as to not lose support.


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Post    Posted on: Fri Aug 05, 2005 7:02 am
To the improved heat shield technology the DLR developed a second idea can be added:

www.welt.online has published today an interview with the german astronaut and physicist Ulrich Walter. Walter during that interview proposed to keep foam falling off the external tank by a supporting stocking.

This proposal is meant to enable a launch in March 2006 but there is no sign that Walter considers this to be a long-run solution.



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Post    Posted on: Mon Aug 08, 2005 7:09 am
There is an additional way to handle the danger of damages possibly.

The heat shield is required for safe reentry - not at lift off. May be that a vehicle has to protected at lift off too but such a shield has done its task once the vehicle is in space.

So it would be sufficient if the heat shield required for reentry is going to be installed/mounted in orbit and not on Earth. The parts of the heat shield could be lifted as cargo then and stored there - the amount should be sufficient for more than one departing vehicle, 10 for example.

Parts like those developed by the DLR should be used then to reduce the amount. They should be put together in space - automatically perhaps - to have the heat shields ready.

If they should be available to each vehicle either all vehicles have to be able to move to a few spacedocks where the shields would be stored or at the objects to be visited by vehicles shields have to be stored at.

This means that a real infrastructure should be considered or thought of - comparable to some infrastructures on Earth - those of air traffic for example. A future orbital tourism would be assisted by this too.



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Post    Posted on: Sun Mar 02, 2008 11:13 am
More Tile-Talk:-

http://www.orlandosentinel.com/news/spa ... 2843.story

Looks like NASA will be using the tiles on Orion, I think this should be OK as it is a much smaller area to cover and are far less likely to be damaged during launch as the craft sits on top of the stack.

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Post    Posted on: Fri Nov 28, 2008 7:13 pm
Only extending the thoughts begun in 2005:

In principle it should be possible to apply a thin flexible material that can suffer impacts and withstand high tensile strength.

It should be removable automatically and mechanically via wires or tethers, small wheels...



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Post    Posted on: Fri Nov 28, 2008 8:34 pm
Far easier to move the shuttle to the top of the stack.

Trying to solve simple problems with intense engineering gimmicks is what has kept Nasa in LEO for 30 years.

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