<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>does anyone know of a way to do away with heat tiles and to use a spray insulation type heat shield? i'm sure there is someone or somebody that's does? <br />Posted by wildbill1955</DIV></p><p>The shuttle main tank uses a sprayed insulator. That is the material implicated in the Columbia disaster, since there a tendency for chunks to break off. I'm not sure of the current material used since it was revised some time ago. The original material used quite a bit of cork and the mix that was sprayed had a very high content of methylene chloride -- and that is one reason for the update. I think the nose cone of the Pegasus also uses a sprayable material. </p><p>The most common material used to insulate rockets is cork. Yep, a sheet of cork derived from a tree. It is an astonishly effective ablative material, A good insulator. A good ablator. Light. And cheap. I once was looking into a sprayable replacement for cork, to reduce costs. But with just a little work the manufacturing guys made the cost of applying cork sufficiently effective that I could not make the cost reduction goals with a sprayable even if I could do it for free.</p><p>The problem with those materials for the orbiter is that they work via ablation. Basically they char and burn up and carry away heat by losing material. That works well for a rocket that is exposed to high velocities in the atmosphere for only a matter of minutes. It would not work so well for a vehicle with much longer exposure to aeroheating. Re-use would add more complication, but could probably be handled.</p><p>The shuttle tiles are ceramic and very effective. There is a pre-ceramic resin that was recently tested for use in tile repair. It is more a troweled-on application than a spray-on application, but might be closer to what you have in mind.<br /></p> <div class="Discussion_UserSignature"> </div>