Directorly Downwind Faster than the Wind

[quarktoo]

What?  Forget about the torque.  You are converting the speed of the wind into energy going into the cart.

Make that propeller and way you want just don't exceed the diameter of the wheel. You just invented REVERSE.

Of course you need higher wind speed otherwise it would also be impossible . It takes both - I just saying don't ignore traction and torque aspects.

[blueweaver]

I just got this, watching these videos:
At start-up the prop is acting like a sail - its resistance to the tail wind, pushes the cart in the direction of the wind. This reaction occurs entirely thru the thrust-bearing on the prop, the prop-shaft is pushing the cart.

The prop never turns the wheels, it is always vica-versa - the wheels drag on the ground , and turn the prop.

At start-up speeds, the prop does not spin fast enough to have a propeller effect - it is as though it is a stationary sail and the wind is "pushing" it.

However, as it speeds up, and matches wind speed, something changes, maybe even before "hitting neutral" (this may not even be an important moment). The propeller now, driven by the wheels, is literally pulling the cart, by thrust created by the spinning blades. Now the "apparent wind" the blades are experiencing is much faster than the relative wind - the blades, by spinning, are creating their own wind (and most likely a significant low-pessure field on front faces of propeller airfoils that is pulling it all forward), and therefore a significant thrusts. This thrust is transferred by the shaft , thru the thrust-bearing into the body of the car and thereby rubbing the wheels on the desert surface making them turn and they in turn, by the chain, drive the prop. There are 3 elements here, in kind of circle.

It looks to me like the same principle as tacking across the wind - on a windsurfer or good sail boat: one creates a higher "apparent wind" speed by going at this angle. This propeller-car does it by spinning the propeller - that creates the higher the wind-speed that the propeller sees - literally a spinning sail.

Gotta think about it a while to see if it can go cross or upwind and use similar principles. It would be cool to design a wind-generator that could use these too....

[onthecuttingedge2005]

I can see it now, trying to avoid all those mobile wind sails in motion. what a horror.

[Cloxxki]

I just got this, watching these videos:
At start-up the prop is acting like a sail - its resistance to the tail wind, pushes the cart in the direction of the wind. This reaction occurs entirely thru the thrust-bearing on the prop, the prop-shaft is pushing the cart.

The prop never turns the wheels, it is always vica-versa - the wheels drag on the ground , and turn the prop.

At start-up speeds, the prop does not spin fast enough to have a propeller effect - it is as though it is a stationary sail and the wind is "pushing" it.

However, as it speeds up, and matches wind speed, something changes, maybe even before "hitting neutral" (this may not even be an important moment). The propeller now, driven by the wheels, is literally pulling the cart, by thrust created by the spinning blades. Now the "apparent wind" the blades are experiencing is much faster than the relative wind - the blades, by spinning, are creating their own wind (and most likely a significant low-pessure field on front faces of propeller airfoils that is pulling it all forward), and therefore a significant thrusts. This thrust is transferred by the shaft , thru the thrust-bearing into the body of the car and thereby rubbing the wheels on the desert surface making them turn and they in turn, by the chain, drive the prop. There are 3 elements here, in kind of circle.

It looks to me like the same principle as tacking across the wind - on a windsurfer or good sail boat: one creates a higher "apparent wind" speed by going at this angle. This propeller-car does it by spinning the propeller - that creates the higher the wind-speed that the propeller sees - literally a spinning sail.

Gotta think about it a while to see if it can go cross or upwind and use similar principles. It would be cool to design a wind-generator that could use these too....

Nice first post, welcome!

Great isn't it? I suppose when the baldes are just slicing the wind, like a neutral, the cart has similar speed as when it would have had stationary blades. Of course there it more to the cart than just the blades creating air drag towards propulsion. The non-blades part though, is the part that resists it to go beyond wind speed. That's why it's such an aero vehicle, while it in fact travels straight downwind. Stick such a prop on a regular car and it won't do as well. It will still bring a great fuel saving of course, the full prop's worth.

I am thinking more and more about vehicles which have a huge part, or all of their frontal surface, taking up by an air intake. the air is funneled into a much narrower channel, where it's sped and/or compressed up to fit. The opposite would happen on the back. Adjacent to the narrow air duct, and where the turbine engine is placed, there will be room for payload. Effectively the vehicle will eternally resemble a simple cilinder. Open front and rear, like a tube. It's airodynamics properties would be such also. The thrust of the engine will not be used to drag an attached vehicle, as the vehicle is inside the "engine".
Stick this thing on specially designed maglev tracks and crazy speeds can be attained with limited engine power. The compress/decompress effect of the airflow should be more or less neutral. And more on topic, a DDWFTTW vehicle of this shape could be greatly efficient when going directly downwind. Little overhead air friction. With sidewinds, retractable sails would unfold. Thin permanently opened vertical fins could even be hinged and damper-centered, to immediately kick in for tacking with the first gust of side wind.
The maglev type vehicle would be great as an alternative to vacume tube capsules. If vacume is too cumbersom, then just fill up the tunnel with a verhicle, and suck all air right through. Couple this to tracks where boarding stations are at sea level and tracks dive hundreds of meters below it to build up speed, and you have a very efficient system. Acceleration to 500-600kph takes up no energy at all, cruising is efficient as heck, and decelleration is done by gravity again. No brakes necessary, just back-up systems. The maglev tracks could be used for propulsion as well, the prop duct merely reducing effective air drag to zero. I wonder how much energy it would take to channel air through a 3.5m across tube of long length with a 1m bottleneck in it, at say 500kph. Just to keep it at 500kph. Preferably an off-center bottleneck to create some living space aboard.
if an aerodynamicist is interested to work with me on this, write me on hotmail please.