Best Composite to Use

[Dook]

I am trying to find the best composite (light weight/low cost/high strength) to use for the structure of a Manned Mars Exploration Vehicle and I was hoping someone here could help me. The configuration is a 8' wide cylinder, 17' long, and 3/4" thick (thickness is just a guess). The cylinder must support itself as well as two occupants and @ 4,000 lbs (earth weight) of equipment at temperatures ranging from -80 F to 75 degrees F. There will also be a floor and two rear pressure bulkheads. The internal pressure is not much, 15 psi or less. I need an overall weight and cost estimate. I realize the intended use is much different than you are used to but hopefully someone here can help.

If you wish to see the post on the entire design:
http://www.newmars.com/cgi-bin/ikonboard/ikonboard.cgi?;act=ST;f=23;t=33

[Not A Guest]

I believe the moon landers had reasonable bodies. You might investigate why the materials used were chosen.

Don't forget to check the launching/landing forces.

[Dook]

I believe the moon landers had reasonable bodies. You might investigate why the materials used were chosen.

Don't forget to check the launching/landing forces.

The moon vehicles had thin aluminum skin and likely chosen because kevlar hadn't been invented yet. Aluminum will work but it has too much heat transfer for extended use where temperatures get as low as -80 F. I was thinking more along the lines of a kevlar skin but I need to know how much it is going to weigh. I am already over the allowable weight limit which is 2.2 tons.