Quote:
Originally Posted by Jyden
You forget he's making a sandwhich construction. And the fiberglas should NOT be sanded down. Wowen cloth should be used, and filled with epoxy, and then the epoxy sanded smooth.
You can NOT compare a sandwhich to a monoshell. Sandwich is MUCH stronger.
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Yes, the sandwich construction should not have to be sanded much at all after layup and such.
I found on the tail, and a motorcycle fairing made 20 years ago, that the foam should be as smooth as needed for a "show car". That is the secret to light-weight fabrication. Get the foam smooth first.
Then start the lay-up. Use any technique to keep overlapping layers of cloth very flat with hardly any finish sanding required.
Use epoxy/micro mixes to fill in low areas. Do not sand away at the glass lay-up, as that is where all the strength is.
Use multiple layers of glass at any mounting points to the frame, as this is where higher stresses are.
Look closely at the many pictures of my tail construction project.
Neil is correct, in the fact that he is maintaining the foam as a composite structure in the overall body construction. Removing the foam would result in a much weaker and heavier structure if reinforced with more glass, due to the absence of the foam.
Note: there are airplane designs out there that make use of fiberglass composite techniques. These airplane structures are found to out-perform the old aluminum skin/riveted/ribbed structures similar to the Cessna series planes built many years ago. A properly executed foam composite structure is actually stronger and more resistant to buckling than the aluminum structures.
I have a DVD video of a Burt Rutan designed wing shape being placed on two blocks and being stood on by a full size male and the fiberglass out-performs the aluminum in this case.
Jim.