On Sun, 25 Aug 2002, Roman Black wrote:

>Russell McMahon wrote:
>
>> Now start expansion.
>> At zero stroke you have 300 bar. At 1/300th of the stroke you are down to
>> 150 bar (already) as volume has doubled. At 2/300 of stroke it's 100 bar. At
>> 3/300 or 1% of stroke its 75 bar. And so it goes on. At 50% of stroke
>> pressure is about 2 bar ! You need a very special expansion engine to handle
>> such wide expansion ratios efficiently.

>Which is why turbines etc have rotors of differing
>sizes as the gas reaches lower pressures and higher
>velocities. Did they specifically say that the car
>was piston powered?

Yes. Go read at their webpage.

>A properly designed turbine may have other advantages,
>ie; flywheel effect, which has already been considered
>for electric vehicle use as it can give a bit of
>"oomph" to a paltry 6kW average vehicle.

>Slightly OT, but I once saw an "economy marathon" type
>vehicle with variable-diameter flywheel, so energy could
>be fed into it (or drawn out like a spinning ballerina)

You mean the wheel had constant rpm and changed the interial moment by
physically changing the diameter of the moving part ? Clever but I suspect
'some' mechanical troubles. It could be done with liquid, pumping it in
and out at the hub to change Mi. The centrifugal force would keep it glued
to the circumference (on the inside of a hollow wheel). There would be
interesting things happening if the wheel would not be horzontal. Even a
h. wheel would do interesting things. Imagine driving into a pothole on
the right front and the car tilting left instead of falling in ...

You'd need two wheels mounted rigidly and counter-rotating to cancel these
effects. Double trouble.

Peter

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