Guardian

Hey guys I had an Idea to build a heli, I was thinking of using the cross sections and setting up the ply wood formers so that they are appropriately spaced, then insert blue foam in between, hot wire the shape, sand smooth then apply fiberglass, is that a good idea ? how many layers of fiber glass cloth should i use ? what oz ? I can give tech spec's later( need to find'em )I was thinking of using kevlar instead, would that be better ?

Mike

Ollie

If you use the formers in pairs to guide the hot wire, the shape will be fasceted. The foam has to stand proud of the formers between the formers to allow for contouring. Kevlar will be lighter, stronger, stiffer, more vibration resistant, more difficult to cut and much more expensive than fiberglass. Kevlar fuzzes up uncontrollably if you try to sand it. The number of layers and weight of kevlar depends on how much foam and formers are removed after molding. It also depends on the curvature. Compound curves of small radius require fewer layers than flat panels for a given stiffness so it depends on the size and shape of the shell and how it is supported. Kevlar with a crowsfoot weave will drape better and lay down to the form better than plain weave. You will probably want to use somewhere between two and six layers of 1.7 ounce kevlar depending on the factors mentioned above. Plan on making one shell to check your layup schedule and a final piece to incorporate the necessary changes.


BTW, some people prefer Bow-Flex for body building.