>From John Fields, ...
> Note that with the wind pushing the cart and the pitch of > the propeller as shown, the wind would, intuitively, be > forcing the propeller to rotate counter-clockwise as > viewed from the rear of the cart. > > However, such is not the case. > > What's really happening is that the wind is pushing on > the prop, forcing the cart to move forward, and the torque > generated by the wheels is coupled to the prop in such a > way as to cause the prop to rotate clockwise when viewed > from the rear. > > This direction of rotation makes the prop a "pusher", > and will increase the apparent force of the wind. > > As long as the wind is blowing from the rear, the cart > will accelerate until it reaches wind speed, when the > wind speed will effectively be zero. > > However, because of the prop's action as a pusher, the > cart will be going a little faster than wind speed, at > wind speed. Then, as soon as the prop feels the > headwind it'll stop being a propeller and will become > a turbine, driving the wheels and accelerating into the > headwind until, eventually, everything settles out and > the cart reaches its speed limit. Well, I'll be keelhauled! Thanks for the clarification John. My previous suggestion of using a "control" vehicle fitted with a Viking-like sale is woefully inappropriate. It would be more accurate to describe this vehicle's prop as TACKING through the wind. As most sailors know, a sailboat tends to sail the fastest when sailing at an angle of around 45 degrees INTO THE WIND. (I think maximum dynamics is approx 45 degrees into the wind. Feel free to correct me on that point, maitees.) The point being: Sailing closer into the wind seems counter intuitive but it's the truth - insofar as sailboats are concerned. I can see it now. Sailors take note! This opens up a whole new dimension to regatta races. You heard it here first! Where's my parrot. Regards Steven Vincent Johnson www.OrionWorks.com www.zazzle.com/orionworks
