Structural resin systems

There are minimum specifications required for the type of epoxy system used in structural applications for aircraft. The original testing and spec was done in the 1970's by Burt Rutan for the VariEze, and airplanes built since that time have used similar products.

RAES and RAEF as designated in the Quickie plans no longer exist, and nor does Saf-T-Poxy which was Rutan Aircraft Factory's first choice.

These days formal materials testing is done to a standard defined by the American Society for Testing and Materials, or ASTM. If you have another resin system available and you wish to use it - perhaps because the usual products are not readily available in your area - then be sure to compare all characteristics of the epoxy carefully with these standards before going ahead, particularly ATSM D638 and D790.

Systems which have been identified as "equivalent" to the original resins are:

System 2000
Saf-T-Poxy 2410
Epolite 2427
E-Z-Poxy EZ10
RAE 2426
West ProSet 125

A comparison chart can be found here:

www.fibreglast.com/contentpages-System+2...rison+Chart-319.html

If you are considering any other resin system, compare carefully to the above chart first. Significant variation in the results for D638 or D790 suggests that the resin is not suitable.

Information from the RAF Canard Pusher newsletters suggests that certain resin systems of lower structural strength, but with easier working properties, may be used for finishing the aircraft. West Systems 205 is specifically mentioned for this application.

Resins systems used for boats, car parts, surfboards, skateboards and the like are not usually suitable in structural applications, and nor is West System 205. If you need to do any structural repair always use a suitable structural resin.