'e could if 'e was Chuck Norris, mate.
It would be somthing like one of the variable pitch windmills they had on farms a hundred years ago. They didn’t rip apart in severe wind, so were used more in an open prarie type setting like Kansas. They’re not exactly what I discribed, but would give you an idea of the spring setup.
My response:
A propeller doesn’t make it slower. It moves the bike forward less efficiently. You then must provide more leg energy into pedaling to go the same speed you did when all the forward motion was provided by the tire.
Was to this:
However, I don’t agree that mounting a rider driven propeller to the back of a bicycle will make it slower.
It would have to be quite a considerable wind, otherwise, what’s actually going to be happening is that some of the work done by the rider is expended byt the fan blades in driving the air through the fan.
The correct variable pitch fan blades should fix it. There are drawbacks, and if this was all hashed out, it wouldn’t be something to experiment with. I didn’t say it was always going to be practical in aiding the rider, just sometimes.
While I can see that windmill wheels would, in principle, work, wouldn’t it be easier to just stick a mast and sail on the bike, and tack it like a sailboat?
Because of Newton’s second (?) law. Every action provides an equal and opposite reaction. The water “pushes back” harder than air does, because it’s more dense and more viscous.
Unless you were joking, in which case I was whooshed…
Balancing a 2-wheel vehicle with a sail would be tricky. But it’s pretty simple to do with a tricycle.
The sail would make balancing a bitch even on a windless day. You’ld have to deal with rigging, and tack back and forth, becuse the sail would hinder movement against the wind. You would have to counter balance by leaning way out like on a windglider. in even a small wind so pedaling is out completely. The blades in the wheel don’t have the problems of the sail. It would look silly.
Many literaries have dreamed of a sailing covered wagon or a ship on wheels.
No I was not entirely joking, an Everglades Fan Boat is pretty much the same as a push bike with a fan on the back.
In this case, though, the method of propulsion is chosen because a conventional screw propeller (which I think would still be more efficient) would foul with weeds or be damaged in very shallow water.
Exactly !
Ooo! And then you could land airplanes on it!
As I noted before the (single person, flying start) human powered boat record is a fanboat:
pic:
http://www.humanpoweredboats.com/Photos/HydrofoilHPBs/Decavitator.gif
YouTube video:
The main page is gone, but you can do search on decavitator for info.
Brian
Unless it’s on a treadmill, of course…
Why not?
In fact, the spoke-sails have the problem that they’re constantly changing their forward speed relative to the ground [a point on the rim of the wheel is at rest once per revolution, and is going at twice the overall bike speed once per revolution]. This means that the effective wind direction the spoke-sails see is constantly changing, so they would have to be constantly changing angle to be maximally effective.
People, you’re forgetting the primary benefit - using the spinning blades to mow down pedestrians.
You’d need much wider bikeways, though. Or at least known, predictable wind directions.