Hi Guys, first time playing with CF.
I am a designer and 3d printing enthusiast.

Im going to have a crack skinning the inside of these prototype velocity stacks that are going to live on a sprint car.
Obviously this is a fiddly curvature, I was thinking for layup I should approach it in 3 or 4 pie sections with the 2x2 twill I've got here. 
I was just assuming any less than 3 fabric sections per layer and it would start trashing the weave etc. 

Thoughts? (just one stack at a time not as a whole)

2" base dia  4.5" across the top.

Thanks in advance for any replies ! 

A antisphere (that's the mathematical term for this shape) is -in my opinion- the hardest continuous surface to get a good carbon finish on. Yours seem quite manageable, as the negative curvature is quite small till the outer "lip".
I guess they are used with full Range speakers? The efficiency should be very, very bad, but i guess it's more for the optics?
I didn't skin mine, but did a carbon infusion. They are 66cm in diameter. Skinning will be harder.
I did mine in 6 pieces, but I think you might get away with four. Make shure to take countermeasures against fraying,  or you will get very bad cut lines, especially down at the 2" end.

Hi oekmont,

thanks for the advice. 

These are for the air Intake on a race car (individual intake trumpets on each cylinder) 

Ill plan on doing extra sections, yours looks great by the way.
I can see an obvious benifit of doing an Infusion but due to just starting out I don't have the nessecary tooling just yet. 

FYI, I am not planning on skinning the entire thing, only trying to capture to top surface and outer lip. 

Ill get started in the next day or 3, just need to prep the mould a bit more as it's fresh off the 3d printer.

- Shaun

An alternative method, and the one I used for my single turbo trumpet, was to reverse the process. IE I made a male mould (out of wood on the lathe) and this made laying up the CF much easier IMO. Also meant that the visible surface was in contact with the mould, usually best in order to get the best finish.

Hi Steve, 
Ive got a spare one here to play with, the ones in the first pic are functional prototypes in polycarbonate that are being bolted on to test the profile, I will print another tomorrow of the negative and see if I can can get some Vac bags locally to have a go.

Or it just occurred to me to offset the negative surface of the second bit I'll make tomorrow and use the 2 mould halves as a sandwich...... 

Sometimes I see what I want to see... the mentioning of a sprint car should have make it obvious. High end audio is a very hot topic for me.
My experiences in this field should help you anyways.
If you are planning to use the prints as a mould, you should definitely use a negative. Because than you only have to deal with one clear cutted edge per cloth. And then, place them this way:

The first piece should be folded to the side, that you can place the last piece under it, and than fold it back. So every piece is positioned mould wise with the clear cutted edge, and the other side is wrapped over the clear cut edge of the next piece.
Is that a simulated shape? It seems far to coney to me. The mathematics behind intake trumpets are very closely related to that of audio horns.

thanks again oekmont, im feeling more confident now

this is the profile i kindly borrowed from a volvo penta engineers design study