Composites

Material Selection

Google's cache of the now-defunct www.pe.net/~rpm/about2.htm mentions:

• All gas tanks are made of vinyl ester resin for chemical resistance to gasoline.
• Fenders and side plates are made of iso-flex or DCPD resins, no low grade ortho resins are used.
• All parts are made with iso-flex gel coats to reduce cracking.

Epoxy Resin vs. Vinylesters and Polyesters at Red Rock Store. This is an excellent layman's explanation of the different chemical properties of resins.

• Epoxy resin
  • Strongest molecular bond
  • Will crack along a single line rather than splintering
  • Minimal shrinkage
  • Thin resin, easier to thoroughly wet-out fabric
  • Excellent repairability
• Vinylester resin
  • Essentially polyester resin toughened with epoxy molecules
  • Weaker molecular bond than epoxy
  • Difficult to repair/patch
• Polyester resin
  • Cheapest resin available
  • Highest water absorption
  • Highest shrinkage
  • Spider cracks when stressed
  • Difficult to repair/patch

Vacuum Bagging

• Vacuum Bagging On $50
  • Glad ForceFlex trash bags are polyethylene and are suitable for vacuum bagging with epoxy.

• Vacuum Bagging Basics is a good overview from a boating perspective.

• Simple Vacuum Bagging Systems recommends using a cheap hand-pump vacuum pump from an auto parts store. They have a built-in vacuum gauge.

• JoeWoodWorker.com has some excellent guides intended for applying veneers to woods.
  • Project EVS is a how-to guide for building a very advanced vacuum system for a relatively low cost.
    • Uses two vacuum reservoirs made of Schedule 40 or 80, solid-core PVC pipe. Just as an air tank prevents an air compressor from having to run continuously, a vacuum reservoir reduces the strain on a vacuum pump.
    • Uses a vacuum controller to switch the vacuum pump on only when additional vacuum is needed.
    • Uses a "3-way Mac Valve" to relieve vacuum from the vacuum pump, which otherwise might prevent it from re-starting after cycling off.