Directorly Downwind Faster than the Wind

[BEP]

I'm with Chet on this.

I can't say I'm much of a sailor. I had a 21' sloop and spent a lot of summers alone on it. If the tell-tales are slack there is no wind seen by the vehicle.
This thing's function seems natural but I still can't explain it.

At least, the armchair debunkers will stay busy.

[Cloxxki]

It's all about the positive feedback loop. No energy is being created. It's sucked out of the wind better.
If 5m² of sail can extract x amount of energy from the wind at wind=ground speed V, it can power a 1m² car by more than V.
The propellor, in contrast to a sail, had no negative drag. It's (geared to be) scooping up air faster than it hits the prop at. So, it only offers positive thrust, on top of the speed of the cart.
Only when the losses of the cart (cockpit air drag, rolling resistance) equal the maximum energy input of the wind multiplied by prop efficiency, is equilibrium speed reached. I am not engineer, but that's how I understand it at this point.

Another thought expirent, before testing it in reality:
We have a sloping road, and no wind.
We mark a start and finish line.
We let the cart go at start line, from standstill
We let a cart with freely spinning prop go down it, and time it.
We let the cart, less prop, but with compensating ballast do the same. We likely find a quicker descend time.

Next, we gear the prop to always spin faster than the cart is rolling.

Does the latter cart beat the propless cart? This time there is no difference in cart speed and apparent wind speed to exploit.

It's not meant as a trick question, I haven't thought about it long enough to come to a hypothesis yet.

In stead of the wind (which is proven to work DDW) we'd be trying to exploit the pull of gravity. Gravity has a pulling potential related only to mass and angle, but it doesn't push back when you decide to move "down" quicker than 9.8m/s².

[BEP]

Except for the need of drag on the wheels and atmospheric pressure, I doubt gravity has much to do with it.

It seems to just be a difference of potential. The driving wheels create a greater difference of potential between the air in front and behind of the prop. This difference creates more acceleration. More acceleration creates more difference in potential, etc.

This seems more like the air pressure equivalent to a static charge, except a static charge can't continuously increase its own charge.

Maybe reverse of common logic? Perhaps it is a motionless object tends to stay motionless. Maybe they can only travel from East to West?

Enough. Off to work....

[Cloxxki]

Except for the need of drag on the wheels and atmospheric pressure, I doubt gravity has much to do with it.

Perhaps the term "traction" fits better than "drag". A perfect cog/rail system will create zero drag for unlimited traction. Actually, a large bicycle wheel offer greater traction for the total load on it, while at the same time reducing rolling resistance compared to the smaller wheel.

It can't be overstated, in case of the DDWFTTW cart, it's all about the speed difference between the ground and the wind. One could also see the prop driven by the wheels as a the cart creating a smaller surface area at its front, compared to its big butt being pushed by the wind. A solid shape can't do that to the same effect. And with DDW, the wind from head is always weaker and slower than from behind. This strength difference is being exploited to get teh wind to push a "second, and third time", if you will.

Any takers for the wind still downhill rolling prop cart's performance vs. a textbook V=1/2 G*T²?
Eternal respect is to be won! I have not asked Spork or other prop cart owners to test this, but it would be equally controversial, if anomolies were to be found...

[AlanA]

Hi folks,

for all out there who think that this is a joke see the work in progress:
http://www.fasterthanthewind.org/2009_10_01_archive.html


the idea bases on the project of Dr. Andrew Bauer:
http://projects.m-qp-m.us/donkeypuss/
scoll down to:
DWFTTW Update, Saturday, May 2, 2009
there you can download the paper from Andrew Bauer

You will see that this is not only an idea, it is a reality