DC Motor Sizing Help For Electric Trike?
DC Motor Sizing Help For Electric Trike?
(OP)
Hey guys, I'm working on a little project building an electric recumbent trike, I'm designing for a maximum weight (including rider) of 300 lbs and I'm looking for a top speed of 30mph, the wheels are going to be standard bike wheels, 28", I can handle building a controller and all the accessory electronics, but, being a computer engineer, I'm a little out of water trying to figure out the physics and sizing a proper motor (or dual motors) for the job, can someone help me out with this?





RE: DC Motor Sizing Help For Electric Trike?
google for motor, speed and cc (50cc, 75cc, etc)
may give you a fair idea of what's being used by the industry.
saludos.
a.
RE: DC Motor Sizing Help For Electric Trike?
The equation is
power=v*(m*g*gradient+crr*m*g+1/2*rho*Cd*A*v^2)/efficiency
all in SI units
m is mass
g is gravity
crr is about .005-.007 for typical bike tyres
rho is 1.2
A is going to be about 0.5
Cd is probably 1 if you have no fairing, 0.5 for a reasonable looking nosecone, down to 0.2 for a beautifully made full enclosure with the right shape. If you get really good you might see <0.1
v is speed
You'll need a transmission to get the speed of the motor to match the speed of the wheels.
You may be dissapointed with the hill climbing performance if you don't have gears.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: DC Motor Sizing Help For Electric Trike?
Advnaced DC Motors
We used motors from advanced to power the golf carts shown at the top of the page here:
Planet Electric
We could actually get these close to 50 mph with the gear technology and battery technology we were developing. The golf carts load was about 600 pounds empty I believe.
RE: DC Motor Sizing Help For Electric Trike?