Hi.

I have designed  and built a UAV which is operating quite successfully. The prototype fuselage was made using a ‘lost foam’ technique which is neither repeatable or pretty. I am considering making a mould for further units. It is a ‘twin boom’ type design so the fuselage is fairly stubby, about 50cm long.

It would be a split mould and I would like to use a pressure/ bladder system.

Clearly the mould would have to not distort under the internal pressure. Im guessing at least 20mm thick.

Question.

Could I layup the first layers of the mould using epoxy,then build up some thickness with cheaper poly/CSM?

Could I laminate in steel box sections/ribs or might this cause internal stresses/distortion?

I couldn’t find much advice on getting a good surface finish on the plug. Can you point me in the right direction?

Also any info on bladder materials welcome.

Thanks.

Vince

EDIT...................................

‘Lost Foam’ vacuum bagged prototype fuselage. The insidefinish is better than the outside! Need to make a mould now.