Hi Eric, Your design looks quite similar to my own carbon / kevlar trike (but prettier) so I might be able to help you avoid a few problems. Suspension, to make the rear end of the trike laterally (tortion about the long axis of the trike) stiff using your design, you would have to use quite thick chainstays which would make for a harsh ride. I made a seperate swingarm which worked extremely well (when locked out the ride is very bumpy but adding an elastomer spring makes for a plush ride with very little pedal induced bob). If you do this there are two things to consider.
1. The power side of the chain run should intersect the pivot axis, this minimises the effects of pedalling on the suspension. The pivot does not necessarily have to be a bearing, I am conidering using a composite 'hinge' constructed from a thin but wide section of kevlar that will flex vertically but be stiff tortionally for the next incarnation.
2. It may be necessary to go to a 20 inch rear wheel to maintain a good weight distribution (I have a 26 inch rear wheel and it is V easy to spin out in the wet).
I dispensed with the seperate seat and simply strengthened an existing design with two deep channels 3" either side of the centreline (which allows the chain to pass very close to the bottom of the seat, maximising ground clearance).
I would suggest that you consider using kevlar for the main body of the trike, it is as strong as carbon but has much better failure properties (it tends to start tearing itself out of the epoxy matrix before it breaks, giving a gentle failure). It's main disadvantage is that it is less stiff than carbon and harder to work. The stiffness can be compensated for in the design and although it is harder to work with, it doesn't form the horible sharp splinters that carbon is prone to whe you use a wet layup. It's also half the price!
Thursday, 29 January 2009