[ExI] Electric cars without batteries

[spike]

> ...On Behalf Of Mike Dougherty
> ...
> >> Since when?
> >
> > Since always.  The turbines aren't necessarily noisy but the gear 
> > trains are.  For a gas turbine to be efficient it must spin like all 
> > hell, which makes them inherently challenging for mechanical 
> > engineers.  If you know a practical way to quiet those gear trains and 
> > deal with the lubrication and wear problems, do share, so we can be 
> > rich and famous (you famous, me rich.)
> 
> Sorry for the confusion - I was commenting on John's 
> statement that he didn't want to discourage anybody.  :)

OK cool.  I have been thinking of this and reviewing my mechanical
engineering textbooks from college, the ones which give off the distinctive
odor of age-decaying paper when opened.  {8-[

BOTECs show that the small turbines (20-ish kw) that would be appropriate
for use in our detroits need to spin in the thirty to eighty thousand RPM
range.  That limits the diameter of a generator because the enormous
centrifugal force.  A very small diameter generator introduces heat transfer
challenges.  

Assuming the class of generator in which the copper windings are stationary
(in the stator) and the rotor is a permanent magnet, the engineering
challenges would be in material strength and heat dissipation capacity.  I
could either calculate or I could just google and find the fastest-spinning
generator on the market and the slowest spinning small gas generator, and
see if the speeds will even wave at each other.

I have also been trying to imagine a planetary gear train in order to gear
that turbine speed down without big side loads on the turbine shaft
bearings.  So far this looks like a damn hard problem.

spike