Quote:
Originally Posted by jakobnev
aerohead -
Watch from 9:15 to 9:45, inside the craft energy always travels from the wheels to the propeller, there is no wind turbine!
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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.
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).