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Virginia Tech assigned the design to a class of 8 engineering students who calculated the stress points and potential power development. With 3 pistons and a piston surface area of 1 square inch, operating at 3000 PSI, they calculated the power at 35 HP per wheel at the wheel itself. The really interesting thing is the torque, 380 pounds feet at the first revolution! Similar to electric motors but with highest efficiency at the instant you start to move.
Calculated losses were in the range of 5%. With accumulator and line flow friction it should still be higher than 90% total. Hopefully a full regeneration cycle will exceed 82%.
As Vekke noticed, separating the engine (or motor if electric) operation from the actual vehicle propulsion function means the engine can operate completely independently from the speed of the vehicle, always within a few percentage of best BSFC.
The engine-motor only acts to replenish accumulator pressure, unless you are climbing one heck of a grade. Larger displacement engines run for a lower percentage of the total time the vehicle is moving, while smaller engines would operate for a higher percentage of time. The accumulator acts as a load leveler, allowing for complete elimination of any idling or light load operation that is inefficient. You could even have two small engines, with one available for significant grade climbing.
Since the engine is only connected to a fuel supply, as well as two hydraulic lines and a couple of electrical connections, changing the engine would take about 30 minutes.
In an electric configuration you would only need to have the battery power on or off to accomplish pressure regeneration so there would be no need for any power controller.
The vehicle could initially be propelled by a motorcycle engine. I'm thinking of the Honda CBR 250 since it already has fuel injection and a catalytic converter, as well as a feedback fuel system almost identical to current automobiles.
Once the drive is finished and with an accumulator acceleration would be regulated to the maximum traction of the single drive wheel. It would be better to have all wheels driven since that would allow regeneration to occur down to 0 wheel speed regardless of the accumulator pressure level. Even with no engine in the vehicle acceleration with accumulator pressure alone would be very rapid. Ideally 0-60 times would be in the range of 30 revolutions of the single rear wheel. From a dead stop that is around 200 feet!
regards
Mech
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