Quote:
Originally Posted by AeroMcAeroFace
sorry, that isn't true, the energy doesn't always flow from the wheels to the propeller, the energy can flow from the propeller to the wheels.
in the beginning, the car isn't moving, but has a tail wind, the rotor spins, which in turn drives the wheels. the car accelerates partly due to the drag of the vehicle, and partly due to the propeller driving the wheels.
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at wind speed. so when there is no air resistance on the craft (essentially in still air in a reference frame), the wheels are driving the propeller. The propeller is driven through gearing faster and produces a small amount of thrust, This accelerates the craft slightly, at which point the craft is in a headwind, the propeller can then propel the craft upwind.
You would agree, that given the right gearing, a car could travel upwind?
you would agree, that given the right gearing, a car could travel downwind?
The hard bit to understand, is the changeover from the car going downwind to the car going upwind(or more technically downwind faster than the wind). |
1) we know that a 'propeller' is a lousy 'turbine.'
2) I didn't see a 'thrust-reverser' as found on a Lockheed C-130 Hercules, which allows the aircraft to back itself out of an airport terminal without a tug.
3) whatever energy is extracted from the 'lousy turbine' to accelerate and build kinetic, there are energy losses at every step of power transfer between blades and wheels, regardless of direction.
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4) at wind speed, there is no net force acting anywhere on the vehicle, it's at terminal velocity.
5) if the tattle is 'WRONG', and the car is actually going slower than the actual airspeed ( which is what I believe), then it's just air drag propelling the car.
6) for the blades to be producing net thrust requires over-unity, which is impossible given the already stated mechanical efficiencies between blades and wheels.
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A trip to Palo Alto, California, and NASA's largest wind tunnel would provide for a laboratory-quality test, where all parameters can be accounted for.
Until something like that, it's a 'stunt.' A parlor trick.