Hi Guys,

First posting here so HELLO.

I play spanner monkey on local 24 hour endurance racing team. A recent locking pin “incident” resulted in the bonnet flipping back going down the pit lane. As a result some GRP work was required. But as part of this one of the jobs that also needed doing on the bonnet was the NACA scoop, at the moment there is a horrid ABS plastic unit bolted with nutserts to the bonnet and sitting proud.

Well I thought I could do a lot better, so here we go.

This is the original scoop, it sits about 10mm proud at the front, hardly the streamlined and aerodynamic venturie it is supposed to be.




First was to make a wooden buck, cover with bondo, multiple coats of paint, release wax and release agent.



Then lay on the carbon fibre. I used the 200g 2-2 twil, four layers (pro Finish for first layer) on the main part but only two on the flange to give the flange some flex to contour the bonnet properly.




Did I mention mould release ! hmm, yes I did use lots. I think the sides were too vertical for good part release, never mind.



A quick clean up (more finishing work still to do) and here we are.



Not a bad finish.



Some balsa cross bracing on the back side.
The balsa increases the effective thickness of the carbon fiber with very minimal weight.

[imghttp://3.bp.blogspot.com/-Vpuf5d8hNcY/T73UmKgAA-I/AAAAAAAABRU/B7Ui7msHa7M/s1600/g.jpg[/img]

190g and its strong enough to stand on !



All I've got to do now is sand it, lacquer it and then fit it into the bonnet.

Any comments, hints tips etc always appreciated.

I'm temped by vacuum infusion but will see how much work I end up doing in the end.

Cheers,
Richard B.


 

did you use rattle cans paint? if so thats what it came away with the buck instead of releasing as the chemicals in the paint slowly release and destroy the release agents.

spot on with the rattle cans !

proper 2 pack paints that are then baked off. 2 pack paints are a bit like resins in such that the paint needs the catalyst mixed with it to cause the chemical reaction that makes it cure.  The advantage is once its cured, it is cured.

aerosol paints generally tend to use a solvent to keep them liquid which them evaporates off to dry the paint.  The problem being they release solvants for a long time and in situations like this it can cause all sorts of problems.

There are some good filler primers that can be 2 pack sprayed, then sanded and polished to a shiney finish.

You could try using both chemical release agent AND wax. Do several layers of release agent, then wax on top of the release agent.