So when you get all done, the endurance of the air car would be less than
ten minutes.  Sort of like the plastic toy cars with balloons on top that
you blow up and they shoot across the floor -- only bigger (and a lot more
expensive.)

>> Ok, I found a formula for the power in compressed air.
>> Pair [W] = Qv [m^3/sec] * Press [kgf/m^2]
>> 300bar is ~3x10^6 kgf/m^2
>
>Your calculations are probably approximately correct BUT they rely on a
>statement by the manufacturer that was accidentally misleading AND there is
>a need to alter your formula to account for the practical situation.
>
>Firstly, the stated tank volume of 90 m^3 was (probably) intended as the
>volume of gas at ambient after expansion (or before compression). The real
>tank volume is less than a cubic metre. (Note the size of the car itself is
>probably in the order of 5 cubic metres. They correct this error somewhere
>on their site (in the FAQ?). For the E=QP formula to apply the pressure
used
>must be maintained throughout the "work stroke" represented here by the
>Volume. (You use m^3/sec which is the instantaneous power but if you take
>total volume and remove the time term you get total available energy).

I know, I deliberately tried to calculate for the max. available energy,
with some shortcuts.

I missed the car volume (5m^3) vs tank volume (90m^3). The messages about
gas bags on top of cars suddenly make sense ;-)

Peter

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