George

I looked at the pictures you sent and you're right,  You desperately need to strengthen the cowling fore and aft.  I wouldn't necissarily use PVC pipe though.  It is heavy and non-structural.  I'd suggest a piece of 1/2" balsa core (since it has great temperature resistance).  If you want it hollow to blow some air through, tape some core down, and against the cowling, apply a little mold release wax and lay up a piece of 282 carbon fabric, about a 3mm coremat layer, then another 282 over that. When cured, pull off the part and tape then bond in place.  It will be light and have stiff side walls,  Also, always "sculpt" the pieces together.  In other words, no hard edges or corners.  This should apply to your new stiffeners, too.  Radius the point at which it butts against the plenum.

You should probably get some higher temp epoxy for the application, too.


Dan Newland