Another way to build prototype pieces fast and cheap, is to use pre made Styrofoam shapes from craft stores. A huge selection of shapes are available. It can be white clued together and also connected with lengths of sharpened welding wire shoved through the length of several pieces. Like real long nails. You can also use the water based contact cement on most styrene. The radius for anything may be built up from child's modeling clay. On smaller items the entire buck may be modeling clay. For Styrofoam bucks only epoxy may be used. The styrene resin in bondo and fiberglass kits will melt styrene based foam.

 

Port runners, brackets, air horns and similar are easy in clay. If the surface finish is not a factor, very complex pieces can be produced. The clay buck can be removed with any hydrocarbon solvent.

 

Surfaces against the clay will be smooth and shiny.  Larger volume pieces such as fuel tanks also are easy to build. You pin some Styrofoam sheets together and even fit it into the proposed space, before you glass anything together. You can screw AN fittings right into the foam and glass them in place, or any threaded boss you might need. The styrene based foam is melted out after the epoxy has set up. Drain sumps and fuel filler areas may be built from clay as above. The shapes are limited only by your imagination.

 

Large flat panels made of glass cloth or more exotic materials can be produced by waxing a sheet of Formica counter top material. For larger areas. Wax up a strips of half round wood trim, or a bit wider cap trim. Can be wood or cheap foam trim. Grind the ends to a nice boat bow shape and hold them short of the edges of the work. Lay them on the Formica in a few places to add stiffness before you lay down the first piece of cloth. Rotate the next piece 45 degrees for added stiffness. You don't have to fasten the strips down. Just don't push on them when wetting the cloth. 

 

The wing skins for the Dyke Delta is manufactured this way. The side against the Formica will be the outside, and will be like a sheet of glass.They can be as smooth as any plastic airplane out there.

 

The preferred shape for intake plenum is round or at the worst oval because of the possibility of a back fire. There will be a rapid expansion, (sounds safer than explosion) and that may be a substantial amount of pressure. As I discovered with flat sided mufflers on rotaries, you start by adding through bolts through the flat sides to keep them in the area of the muffler.  

 

I like the idea of using food grade tubing for buck runners. That will be slick inside and easy to build.  Once you succeed at a few complex pieces, The new radiator duct is just a day away. Or a new cowl? Or wheel pants with retracting doors? Faring's? Wing tips?

 

Styrene based products will continue to change shape for about a week after being molded. So leave it in the mold. This can be a plus, in some cases, where you want to reverse part of a convex shape or fit a piece into a spot where it will not fit if allowed to become rigid. Epoxy will become totally rigid in just a few hours in most systems. Check with the supplier on this feature. Most Epoxy systems will adhere to styrene systems. Most styrene systems will not adhere to an epoxy system.

 

Lynn E. Hanover 

 

 

Kelly Troyer wrote:
> Ernest,
>    Unusual direction for what I presume to be your secondary
> injectors to be aimed...........I am sure you will educate me
> about your reasoning !!.............<:)
>