Hello,
Can you please tell me which technique is used to build the carbon fiber hull on this picture? Is it prepreg, RTM…?
I have tried various techniques to create 90 degree (and more) complex shapes but failed to create them perfect without air pockets.
Thank you
I’d bet prepreg. With all the sharp corners in the picture, would be hard to do a dry layup. Couldn’t find their web page, I thought maybe they’d talk about the construction some.
With pre preg this would be pretty standard stuff. We do these sorts of corners all the time. Piece o’ cake. 
Resin Infusion:D
Would appreciate a picture from further away to see what it is.
It’s a Green Samba, electric jet ski: http://www.tomsguide.com/us/green-samba-electric-jetski,news-6885.html
So there is no way to create these sharp corners without prepreg, right?
There is no way to know for sure just from looking at a pic.
I have created details like that with small sharp corners using compression molding. It is the only method I have ever been able to get to work for small corners like that with woven carbon fiber. That absolutely does not mean that other methods couldn’t work.
I could see it working with a vacuum bagging method along with some rigid inserts too (but that is similar to compression molding. Either way, it needs something to hold the material in place while it cures.
It doesn’t matter if it is made with prepreg or a wet lay up if there isn’t a viable method of holding the fabric in place in the fine details of the mold. I think it would be easier to do it with prepreg without damaging the weave though.
I make freestyle jetskis that have a very similar jet pump tunnel area and I use infusion for creating mine.
I think that particular intake looks like pre preg only since all the weave is so neat and straight.
A wet lay up or infusion would have a bit more of a weave wave to see.
I have been repairing the petrol jet surf boards recently and these were made by vacuum infusion process.
Infusion will get all the corners good and full even if it is full of resin.
It’s possible to do a wet lay-up without disturbing the weave. It’s just technique. Regardless of whether they used prepreg or not, it looks like professional work to me. The guys that made it knew what they were doing…
Btw, I recommend checking out the Weblock cf fabric sold my composite envisions if you haven’t already. It looks like regular 2x2 twill weave except that the weave doesn’t break apart when you cut it or handle it.
Those guys at Composite Envisions have made a really excellent product imo. I just started using it for a particularly difficult project I am working on and it’s so much better than regular cf. It takes all the effort out of moving cf fabric without damage and really reduces wastage.
It’s a little more expensive but you only need it for the surface layer of cosmetic parts.
Of course it is possible to make wet laid parts that look great but it is of course easier with small or simple part shapes.
This guys problem is doing these sharp corners, just not really possible with a wet hand laid technique.
If I am right you can see a bigger airbubble in one corner what looks typically for an infusion failure. It does not look like that in prepreg. Thats why I thought it is made by infusion.
The rest looks more like a prepreg part.
It is if you have good insert to hold the fabric in place.
That would apply regardless of whether they used prepreg or a wet lay-up. For a small sharp corner like that, you need something to hold the fabric against the mold surface or it will come away and leave a void during curing. That could be a vacuum, an insert or a male mold but it needs something.
Even if a person was able to make some prepreg stick to the sharp corners of the mold before putting it in the oven, the fabric would come away from the mold when the resin reliquified with the heat… unless it was held firmly in place.
Either way, making details like that is a real PITA. I have a corner just like it on a rifle stock pattern I am making in cf and it drives me nuts. I prefer to remove details like that from the pattern if I have a choice. Making cf parts is so much easier if corners are rounded off.