"The Natural Philosopher" wrote in message
...
Andy Champ wrote:
On 18/09/2012 19:27, The Natural Philosopher wrote:

Motors in hub are an extremely bad thing. Adds to unsprung weight.
http://en.wikipedia.org/wiki/Unsprung_weight

Not if the motors weigh less than the axles they replace.

I'm more likely to believe you than some. Is this really possible?


yes.

Not cheap - Neodymium magnets and enough silicon iron in the stator..

http://www.hobbyking.com/hobbycity/s...ner_Motor.html

is running at about 5bhp per kg.you probably need about 20bhp per wheel
for a small car (80bhp AWD). Which is 4kg per wheel. That's probably about
the same as an axle hub and CV joint.

Its definitely better weight wise to use a motor per wheel and dump the
differential as well.

The problem with an inboard motor is you need the CV joints (or a dreadful
swinging axle) as well. Those add weight and cost.

Plus you get better packaging with in wheel motors.

Biggest problem is you probably can't gear it - except with more in wheel
weight like an epicylic box. So it needs a LOT of poles to get the actual
torque you need. AND you need flexible and pretty substantial cables as
well

Have 4 motor-in-hub's, one in each wheel, will give the torque and power all
around.

But overall I think that the best way to package a leccy car from a 'blank
sheet' is battery under the floor to keep weight down low and extending
right into the axle regions, and a motor on each wheel.
The battery is far and away the heaviest thing so you want it low and in
the car model. The means you probably don't want transmission there at
all.

Spot on.

Bernie Ecclestone has announce a 'Formula E' series for all electric
racing. It will be fascinating to follow. And see what they end up with by
way of battery swapping and getting performance out of the cars.

http://www.bbc.co.uk/news/business-19402383

About time. They will **** all over IC F1 cars once they settle down the
layouts.