I tried doing it all using cad programs, but not only was this taking quite a while, I wasn't very sure how acurately I could simulate things like center-of-gravity.
To make things easier I decided to make some wooden mockups using some junk lumber I had. The following pictures don't show it, but the measurements were made with me sitting on the mockup.
For several reasons I wanted to keep the maximum width of the trike less than 1 meter (about 39.5 inches), to de sure I decided on a maximum width of 39 inches which makes a front wheel track of 34 inches. The front legs are set at 34 inches wide, length of the mockup is variable.
This first mockup was to test weight distribution. Notice the bathroom scale under the back end, you can also see the wooden blocks under the front legs. The wooden blocks are approximately the same thickness as the scale to keep the trike level.
The wood clamp on the front end allowed me to move the front beam forward and back to get the desired weight distribution of 70% front vs 30% rear.
Note: weight distribution of the actual trike is 71% vs 29% without the fairing/motors/batteries.
The next mockup was to check lean angle. More important than how steep of a hill I can sit on, this tells me something about how the trike will handle in a corner.
A 45 degree slope simulates 1g of lateral acceleration. If the trike can handle this then I know it can handle 1G before tipping up on the outside wheel (assuming it didn't loose traction first).
Unfortunately this design could only handle a little less than 40 degrees. Still I'm pretty sure the tires will slide before I get that much lateral acceleration, so I decided to procede. The other options are lower the ground clearance (approx 6 inches) or widen the track, neither option was acceptable.
Note: On road testing shows that the trike does indeed slide before tipping
Next I needed to figure out how long to make the boom and what angle to bend it at. Crank height was set by the following fixed parameters:
Crank axle to pedal axle = 7 inches (175 mm)
Pedal axle to back of shoe = 8 inches
Minimum ground clearance = 6 inches
Fairing to heel clearance = .5 inches
For a total of 21.5 inches. There is also one variable to add, I wanted some extra height to allow the fairing to slope down from the pedals to the front of the seat. I chose 2 inches for a total of 23.5 inches.
That's all I have for now. As soon as I can get some of my notes converted to digital data I will add them in here.
