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How to Make a Fiberglass Cowl

A cowl is the front section, or nose, of a model airplane that is commonly constructed using fiberglass. In order to have a surface to apply the fiberglass to, you must build a mold for the cowl. You can build a mold out of anything that can be formed into the shape you need, such as clay, wood and plastic. Another material that can be used for a cowl mold is a dense foam that can be found at all craft stores. This is the cheapest and easiest way to mold a fiberglass cowl for an remote control plane.

Things You'll Need

Dry foam brick
Marker
Compass
Coping saw
100-grit sandpaper
Masking tape
2 oz. fiberglass mat
Razor knife
Rubber gloves
Polyester resin
Catalyst (methyl ethyl ketone peroxide)
Small bucket
Paint stir
4-inch felt roller
Air roller

Instructions

- 1
  Determine the diameter you need the cowl to be. Using a dry foam block that is larger than the cowl will be, draw a circle to that diameter on the bottom or base of the foam block with a compass.
- 2
  Carve the foam block into the shape you want by using a coping saw and 100-grit sandpaper. Start by trimming the foam the long way into a bullet shape, staying on the outside of the mark you made for the diameter. When you get close to the final shape with the saw, begin sanding it smooth and rounding all edges off.
- 3
  Cover the entire foam mold in masking tape. Avoid any inconsistencies in the tape such as creases or bunched up areas.
- 4
  Cut a total of four layers of 2 oz. fiberglass mat that will cover the entire mold using a razor knife. Make relief cuts in the mat anywhere it might bunch up or not lay flat such as on the nose of the cowl mold.
- 5
  Fill a small bucket with polyester resin and add one to two percent catalyst. Thoroughly mix it in using a paint stir. Saturate the surface of the mold with the resin using a 4-inch felt roller.
- 6
  Cover the mold with the first complete layer of fiberglass mat and saturate it with resin using the felt roller. Work out all the wrinkles and air bubbles in the mat by going over it with an air roller. Apply the next layer and continue this same process until the four layers of mat are on the mold. Let the fiberglass harden for a couple hours or until it's hard and cool to the touch.
- 7
  Remove the foam from the inside of the fiberglass cowl. Sand the cowl smooth using sandpaper.

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