kenjiMR said:
Any materials engineers here? What negative properties does CF have compared to aluminum and steal? I have heard that high heat weakens or deteriorates it. Would CF deform within a couple years if it were to be used for body paneling on a production car?
(Dont quote me, Im not a ME.)
CF doesnt fail progressively like steel or aluminum. When you approach the limits of a metal part, it will usually stretch or deform and give you a visible indication that the part is failing. CF is far less forgiving and will just break when its limits are exceeded.
As per heat resistance, I think the matrix (epoxy, etc) determines the heat resistance. Some CF plate Ive used are ok up to 450F. From what Ive read, the space shuttle carbon/carbon panels are CF in some sort of carbon matrix. They basically heat it until the glue turns to carbon -- hence carbon/carbon, so its already "pre-burned"
Unfortunately, its quite brittle as NASA is finding out.
The mclaren f1 and F50 are both largely CF and I havent heard any complaints about the body panels sagging.
Interestingly, structural aluminum is less heat resistant than CF though since heating it over ~300F starts to ruin its temper and it turns to mush (ok, its not quite mushy, but its properties decline quickly).
Small airplanes use CF for their wings and fuselage these days no?
Burt Rutan is notorious for creating record breaking airplanes using CF. As ChrisK pointed out, the B2 bomber uses CF -- as does the F117, F22, JSF, Commanche, etc.
... wait... I do not know anybody who has them! 
