At 04:35 PM 2/2/2003 -0500, Andrew Case wrote:
On Sunday, February 2, 2003, at 04:23 PM, Pierce Nichols wrote:One of the other proposals from the heyday of paper SSTOs had a metallic water cooled TPS (Sorry, don't remember the name of the ship). This has always seemed to me like a good idea. A bit heavier than ablative, but refurb simply consists of refilling the water tanks. I assume you'd exhaust steam across the surface of the TPS to get the most use out of it.
The Chrysler SERV proposal used a system of large, bolt-on ablative panels. Something similar would work well for a DC-X style future vehicle.
Water cooling would be most effective as a sort of transpiration cooling. I.e. make the TPS skin porous so that pressurized water behind it transpires through it over the whole surface to be cooled. I don't think the mass penalty over ablative would be as bad as it first appears. In both cases you are carrying a certain amount of material purely for cooling purposes. Water is an excellent material due to its large latent heat of vaporization and heat capacity -- better than most ablatives, so the mass penalty will be entirely in the support structure. However, getting it spread evenly and reliably over the surface of the TPS during re-entry seem to me to be a tricky problem. It's a really sweet operational model, but the complexity and failure modes are daunting.
-p
Mars or Bust!
www.marssociety.com
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