Quote:
Originally Posted by NeilBlanchard
Please read the Riley page on 3 wheel dynamics that the OP linked to. (I first saw that page about 6 years ago.) The Cg is absolutely critical on a 3 wheel design - if it is too far back and/or too high up for all driving conditions, then they will be unstable.
As you mention in point #3, a reverse trike has the potential to greatly improve the aerodynamics, with the sides tapering in - which by the way would also improve the Cg as well as the Cd. But, a 4 wheeled design can also have a narrowing taper (see Dave Cloud's Dolphin) but avoid the stability challenge.
The Dolphin does weigh a lot - it carrying a ton (almost literally) of lead acid batteries and the structure to support it. But if you put a lithium pack in it with the same capacity, it would weigh about 1,500 less. The Dolphin chassis without the batteries is about 1,200 pounds, which is probably similar to the CR-X trike in this thread with it's engine in place.
The Dolphin is also one of the lowest aerodynamic drag cars I know of. It is also one of the most efficient cars that I know of; despite it's weight. If you build a trike, but do not take full advantage of the format, and/or you don't avoid the pitfalls of the layout, then why do it?
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Neil I am not bashing on the Dolphin in fact I think it was a great build albeit the cost figures were flawed a bit however I do agree with you on the aerodynamics of it as I stated in the first post. Yes also its a lead sled agreed, If Lithium was used weight would be reduced dramatically.
My original point was by going with 3 wheels you can have further weight reduction, Better natural Aero capability, reduced rolling resistance, and lower polar moment of inertia. There is no real big advantage to having the 4th wheel as I see it other than to have a bigger vehicle with more space for cargo.
There are plenty of 3 wheeled reverse trikes that do not take full advantage of the design. Many are designed as having high speed performance and sports car handling such as the T-Rex and its derivatives. They have wide front tracks and narrow wheelbases with low centers of gravity. This makes them extremely stable and quick in and out of turns.
There are not very many that I have seen that are even fully enclosed it is a shame. Zap Alias and Myers Motors to name a few has fully enclosed models which they are taking orders for now. I agree with you I would not do it unless I was taking full advantage of the 3 wheel design potential.
GreenHornet