[recon]

How can I go about making my own fibreglass cowl? What weight of fibreglass would I use? What do I use for a resin? How do I get it to the shape I want? Thanks,

[Vulcan1]

Recon,
What size of cowl and type (AC) are you making : When I know more I could explain how to go about it. I have used a few different ways in the years past.
John

[recon]

It is for a .40 sized super sportster. I got the plane used and had to chop off the wooden 'cowl' to get the old motor off. I am going to recover the plane this winter and would like it to have a cowl again. Nothing to completly enclose the engine, but just to make it look more streamlined. Thanks.

[County C]

I'm right in the middle of making a set of cowls for the Comet I'm building. The way I've been going about it has so far been easy enough to accomplish but I've made a few basic mistakes which has slowed the progress but in the end I'll have an excellent set of cowls. This was my first try and by no means the best way.
First off I carved a plug using ping foam keep your center line reference and it will come out symmetrical. Trust me I have no artistic talent. I glued the 2 inch thick pieces together using Tightbond II. This was the first mistake. Tightbond doesn't sand as easily as other glues so I had a plug full of ridges where the glue lines were. Fixed that then waxed the plug up with Part-all 2 and started to cover it with fiberglass to make the one piece mold. I made one good choice by using a resin that has a working life of 2 hours so I had plenty of time. First two layers were .75 oz cloth only because that's what I had on hand and the next three layers were 6 oz glass cloth which when hardened made a real strong mold. Actually too strong I couldn't flex the damned thing to get the plug out so I just hacked the plug out. Thank the lord it was a foam plug!! Next one the mold was all waxed up again I stated by laying in a layer of epoxy and micro balloons and let that get tacky then laid in the first layer of .75 oz cloth. Careful because once that stuff touches the tacky resin she is stuck and if it didn't go where you wanted it too and you remove it the cloth strip is toast. The second cowl I pre-wetted the glass cloth strips. Right after that I added 2 layers of 6 oz and a bit extra at the mounting points. If I had to do it all over again then I would have made a two part mold to make it so much easier to get the cowl out. A couple of other mistakes I made:
1) Don’t vacuum bag the foam plug at max vacuum. The plug will get distorted.
2) Use less resin then you think you'll need. My first cowl was a heavy weight with all the extra resin I thought was needed.
3) Patience Patience Patience. My lack of it killed 1 cowl.
4) All you need to do to mark a cut out for say an intake is scribe it into the plug. Carving it into the plug is a lot of work and only makes it harder to the the cowl out.

Good luck and have fun.

Geoffrey

[Vulcan1]

Recon,
That is one way to make one. And it is probably the easiest since you are only doing one. A couple of tips also for removing just pour in a bit of acetone which will disolve the foam and then clean up. Don't leave it overnight or it will soften the resin.
Another way I like is basically the same except for the outer. Finish your mold and seal it with an acrylic clear coat. The water based type with about 3 coats. Sanding and fill between the coats. Then wax with a paste wax a couple of times and polish. I like to mount it on a small pedestal block to keep the ends clear of the table. Cover then with 2 layers of 6oz. cloth in strips and then a finer weave 2 or 4oz. for the outer. I then do something different here. I use a party balloon about the 10" type and blow it up then release some air to make it softer and push it over the layup. Make sure it covers the complete layup and then let harden. I think you will find the finish very good and not to much work after.
If you are going to make several I would go to the 2 piece mold and join them but for 1 this way is easier. Hope this helps
John