On Sun, 25 Aug 2002, Roman Black wrote:

>Peter L. Peres wrote:
>
>> >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).
>
>>From memory it had pivoting weights similar to
>the system used for ignition advance weights in
>older cars. A slipring and cable (or similar) were
>used to "open" or "close" the wheel size when
>running so the vehicle could feed some energy back
>into movement for hills and soak it up on the
>downhills. It was only a tiny one-man thing.
>I suppose it's just a way of getting energy out
>of a flywheel without doing much. :o)

The only problem being that Wi = I * omega^2 where omega is the rpm
expressed in rads/sec afair. So changing I would be quadratic unless you
are tapping a very small amount of energy wrt the total. Then why bother ?

Peter

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