Foil Building

This section is going to be about building the Geko hydrofoils. Check back soon for more information and some photos. I've included a couple of photos of the control rod and hinge detail.

  

Foil Mould

The hydrofoils are manufactured in female moulds. This is for a couple of reasons:

  • Producing multiple sets is less work - ie front and rear foils
  • The foil section is more controlable

The moulds were constructd by routing out a rough foil section from a setion of plywood, then using a template to apply filler to form a good surface.

I assembled the mould in a n shape so the top of the hydrofoil and half the vertical foil is moulded in one piece and the mould for the vertical mould is shared between each half. While this means multiple foils cann't be molded at the same time less time is spent making the moulds. The photos below shows a close up of the mould with half a foil section in it and the complete mould with a vacuum bag round it.

  

 

Foil Moulding

Moulding the foils is fairly simple. I used 2 layers of 200gms square weve carbon on the outside to provide hoop strength to the foil, then 3 layers of 400 gms unidirectional carbon fibre for the main structual strength. The unidirectional layers are 80mm wide.

The rear 25mm of the foil forms the flap. I had a change of design in respect to the hinge design.