Is this Resin Starved?

General Composites Discussions Composites Talk
#1

Hi guys

I have recently started working on composites for RC planes. A friend of mine recently made a CF spar (rod) by vacuum bagging ( he rolled CF sheets over a rod, simultaneously applying resin over it).

The problem is that the outer most laminate (or the surface of the rod) does not seem to have enough resin. The CF cloth seems to be just about covered/coated with resin. If touched, one could feel the weave of the cloth on the finger tips. My friend says that’s how he has been making composites and it’s ideal for maintaining high vf (fibre to resin) ratio.

From what I have seen, composites are usually flat to touch, the resin covers up the fibres properly.

Which one of us is right? I still think his spars are resin starved.

#2

I can’t say whether or not your friend’s parts are resin starved but it sounds like a typical wet layup over a mandrel and I would guess it is alright. Smooth laminate surfaces come from one of two things - either you are feeling the surface that was against the mold during lamination or there was post finishing done to the part.