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VACUUM FORMING – Project 008

 

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Project 008 – Cowl for Slick 360 Plane

The engine cowl on my Slick 360 plane was damaged in a crash and a replacement was not available. I used the damaged cowl to make a mould so I could make my own. Then I could crash as often as I liked.

 

The crash was caused by a low speed stall on a landing approach because the battery ran out of charge. I did one more circuit than I should have after the flight timer alarm told me to land. The flight timer time has since been reduced.

Making The Moulds

This is the original cowl made from fibreglass. I cut it in half so I could make two moulds from plaster.

 

 

Before I poured plaster into each half, I made a T shaped former ‘B’ from timber to prevent the plaster from running out the back of the cowl. I also made some plates from HIPS ‘C” to block plaster from running out the front of the cowl. These plates became part of the mould. I poured about 10mm of plaster into the bottom of the mould. After that had dried, I then put the mould on its side and put in some more plaster. I did this to the other side too.

 

When it was dry, I filled the central gaps left with polystyrene foam blocks. This made the plaster casts lighter than they would have been using all plaster. I topped the last 10mm with more plaster to make a flat surface.

 

 

I filled in defects where there was damage to the original cowl. The inside surface of the original cowl had a fibreglass texture on it which transferred to the surface of the moulds so I sanded the moulds until they were smooth.

Here are the two finished moulds.

 

Making The Cowl

The two parts of the cowl were vacuum formed from 0.75mm thick HIPS sheet. The outlines on the mould were transferred to the formed parts which were then trimmed. A large joining strip was glued with Revell liquid glue for plastics inside the two sides of the bottom half first. The top half was then glued to the joining strip. A full circular joining strip was glued behind the motor opening and a few other small joining strips were put on the inside of the front left and front right corners. Once the two halves are glued together, the assembly becomes very strong. The cowl is 160mm wide and 185mm long.

 

 

The top part of the cowl to be painted was masked off and a couple of coats of plastics primer was sprayed on (Motorspray ‘Flexi Prime’ spray can). The final two coats came from a spray can of orange enamel. HIPS has a glossy smooth white surface so the rest of the cowl is unpainted. To cover up the joins along the sides, a decal for each side was made. They were made from white ‘Contact’ which is available from stationery retailers and used to cover books. They were painted orange and black before taking their place partially on the fuselage and partially along the cowl join. Enamel paint sticks to ‘Contact’ without the need for primer.

 

 

 

The finished cowl installed on the plane. Good as new!

 

 

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