NickS wrote:If the tub were of larger frontal X-section, would it be possible to increase its stiffness with no weight penalty? Or would the larger panels be too flexible? (i.e. Would it be possible to increase stiffness but only with a weight penalty by simply making the thing bigger?) Obviously there'd be a serious aero penalty....
Yeah that would work for stiffness. If you consider the chassis as looking like a tube of certain radius (r) and thickness (t) from the front, the second moment of area is approximately equal to I=2*pi*t*r^3. So increasing the distance from the centre to the material, the higher the stiffness.
Like you said though, the aero loss (and also the shorter allowable a-arm length) kills any stiffness advantage.
With composites, the stiffness when used in a chassis mostly comes down to how you join them together. If you have ever got a chunk of aliminium honeycomb and tried to twist it, you will see even with big lengths, they are still bloody stiff. Its more important to work on bonding procedures to increase joint stiffness and reduce weight.