DWFTTW | Down Wind Faster Than The Wind

[Cloxxki]

Thanks for this Cloxxki. I get it. WELL. ROLL ON WIND POWERED VEHICLES. There seems to be so many, many preferable alternatives to oil. Hopefully we'll get these into operation.

You're most welcome witsend.

If you get this, you're on the "quick" end of the academic world.
After elaborate explanations from the builders (and the Blackbird team is not the first in its kind), the academic physics world has gone on any available record that beating the wind would be violation conservation of energy, and thus impossible.
Sometimes it seems an obstacle for minds when their knowledge came from books and large classrooms.

While it's surely not a practical form of propulsion (large sails/props, small vehicle, violently moving parts, huge torques), it does pack a whole lot of punch, and "FREE".
As the prop needs to move along the ground to extract more energy, it's not easy to boost turbine efficiency with similar technology, although there's some really promising build out there exploiting the 3rd dimension of wind. Turbines are typically roughly 2D, after all. This DDWFTTW prop is 3D, and it catches up with the wind, and extracts the surplus speed the wond holds relative to the ground.
I can't get enough of imagining the wind's general push (making the vehicle roll) be turned back at it via that spinning prop. Like the vehicle is always slipping out of the grips of the wind. Like a boxer or wrestler uses the power of his/her opponent.

When looking to apply on-board propellors for propulsion, you get into the building style of recumbent speed record bikes, high-end sail boats, and solar vehicles. All could be combined what I'm concerned. Imagine a solar car racer (up to and over 100mph on flat windless roads), fitted with collapsible prop as well as airfoil, to exploit significant wind from any direction.

I may have stated this on this forum already, but my end goal with wind energy is the same as I have had for human powered vehicles :
A ground effect (low altitude) flying craft. If a sheet of paper can glide on a air cushing, then the wind CAN be harnessed to propel and keep airborne such a vehicle. My general idea is a uniwing craft, smaller than the huge man-pedaled biplanes that crossed the Channel. Getting lift from speed rather than from large wind surface. I always wanted a prop on the back, and the DDWFTTW ideas make me want a high-end substitution for the cart's wheels to drive the prop. Throw in lightweight solar panels boosting the prop and you have the greenest air scooter imaginable with current day's proven physics.

[witsend]

You're most welcome witsend.

If you get this, you're on the "quick" end of the academic world.

LOL. I'm not anywhere near the academic world. Gross amateur Cloxxki. I get it that this is a passion of yours. It strikes me that you'll always need some wind which is possibly a downside. But you're right. If you can generate the initial velocity then - the sky's the limit. Also. There must be some level of our atmosphere where wind 'prevails'. It seems to ring a bell. Perhaps one just needs to concentrate on getting craft high enough and then this super wind driven number will be more than feasible. Great improvement on the jet plane.

It's just so nice when one sees this kind of passion. Hope to hear much more about your work here.

[Cloxxki]

LOL. I'm not anywhere near the academic world. Gross amateur Cloxxki. I get it that this is a passion of yours. It strikes me that you'll always need some wind which is possibly a downside. But you're right. If you can generate the initial velocity then - the sky's the limit. Also. There must be some level of our atmosphere where wind 'prevails'. It seems to ring a bell. Perhaps one just needs to concentrate on getting craft high enough and then this super wind driven number will be more than feasible. Great improvement on the jet plane.

It's just so nice when one sees this kind of passion. Hope to hear much more about your work here.

It's hard to not be passionate about a principle adacemics deem impossible, which seems to lend itself for the betterment of mankind.

A serious downside to the DDWFTTW principle is the need for a prop which with an rpm in fixed relation to ground speed. This is easy on a car (wheel are very sturdy, and have near unlimited traction), much harder on water (scoop wheel like a Missisippi boat?), let alone in the air. Even if the drive works, there will be significant drag losses. Hang a waterwheel overboard, even without a load, and see how it drags. One doesn't need to test to know it will. Engineering can improve performance of course, and I have my (wild) ideas for that.

One needs a sort of lever between the air and something solid (earth is a prime choice), to get the most out of the wind. If an airplane would be horizontally tethered to a huge mast (unwinding a coil onboard, axle connected to prop), it would work, yet obviously impratical. There used to be torpedo's (Brennan designed I think)operating by this principle.
I *think* a ground effect plane, low altitude, could be made to work wind-powered and prop-thrusted. Exploiting wind speed differential between ground and higher up in part. Just, it's going to take top engineering, and the wind is less than a constant.

I have an idea for railway track lined with vanes, always directing any wind to enhance performance of a prop cart riding it. A multiple of wind could be made available, and efficiency boosted. When no cart is on-track, track lined turbines would make use of the channeled air to send power to the grid. Railways are great for energy collection, due to the infrastructure available, and lack of open transport. Just trains and personnel get close to it.

[witsend]

I have an idea for railway track lined with vanes, always directing any wind to enhance performance of a prop cart riding it. A multiple of wind could be made available, and efficiency boosted. When no cart is on-track, track lined turbines would make use of the channeled air to send power to the grid. Railways are great for energy collection, due to the infrastructure available, and lack of open transport. Just trains and personnel get close to it.

Hi Cloxxki. I missed this entirely. Indeed. It makes REALLY GOOD SENSE. But surely the same principle could be applied to motor cars - in fact to anything to moves? I can see that Rail service providers have got a kind of 'geographic' edge - but what about our motor ways? Some careful redesigning of their camber and we'd be able to make better use of all the backwind. In fact the possibilities are endless. A car at a given velocity can let some turbo blades assist in the general 'push' - and on and on. I really think you're onto something. To my mind it's definitely exploitable. Anything that helps in the reduction of oil use has got to be good. If you've got the skills why not start designing on these lines? Some really futuristic vehicles. It deserves its own thread. Frankly I'm inspired. I see turbo assisted hybrids running on HHO. SO NICE.

[distilling1]

Great find Peter! Very cool that Google is actually sponsoring them.

This pump I posted:

http://www.energeticforum.com/97309-post91.html

The output is WAY faster than the air leaving the diesel or electric
pump blowing air at the front of the pipe inlet. And everything goes
thru the pipe without touching the sides.

This kind of thing is definitely more than possible

Does anyone have info on how this pump functions?

[Aaron]

proprietary pump

The pump is proprietary.

[mbrownn]

The mind boggles!

This is the first time I have read this thread and I just can’t get my head around this one.

We have one vector potential, driving a second that opposes the first, the net result is 2x the input in a 100% efficient system. I can understand that but how can it go faster than that?

With a sail boat you have two vector potentials just the same. The sail cutting wind speed is the first and the keel cutting water speed is the second. The resultant speed is the sum of both less any losses. It’s a bit like squeezing a bar of soap in your hand, the soap flies out in a third direction with the combined input of two directions squeezing it.

I think it has something to do with the sail area of a prop, stationary it is only the size of the prop blades but when the prop is turning it is the size of the swept area I think.

HELP this one has my brain in knots or is it nuts. Can anyone help me understand?

[Harvey]

It is a matter of directed energy.

The wind represents an energy store and that energy absorbed in one direction is put to work in another.

Don't forget to include the ground and lateral friction forces in your force diagrams should you choose to work them out.

Imagine that you have a large squirrel cage fan mounted on a vertical axis which will spin regardless of which direction the wind is blowing from.

Now imagine you have that geared for high torque to drive wheels on a cart and you direct the cart into the wind. Driving into the wind actually improves the operation because it increases the air velocity relative to the fan.

As long as the drag coefficient and other losses of the system are less than the energy being scavenged from the air flow, the cart will have no problem moving into the wind.

[mbrownn]

I think I understand the sail concept, assuming no losses, wind on a sail can propel a boat up to the speed of the wind when travelling with the wind, but as the boat approaches wind speed the energy available to the boat diminishes as the sail is no longer able to capture as much force. Sort of a law of diminishing returns therefore the boat cannot travel with the wind, faster than the wind.

Moving tangentially to the wind, the force will remain constant so that a boat will continue to accelerate until a balance is reached, thus the speed of the boat can exceed the wind. If that boat then turns in the direction of the wind it will begin to slow as there is no pressure available to power the sail but there is momentum so that for a short period the downwind speed may exceed wind speed.

Similarly the same must be true for sailing into the wind.

Again assuming no losses, if we use the wind to power a propeller we should be able to push as much air at the same speed with this propeller as it took to power it. Now if that air was pushed in the opposite or the same direction as the wind the effect would be either to cancel out the wind providing double the force or add to the wind, doubling the speed.

What I don’t see is how 2 x wind speed can be exceeded when travelling downwind without a sideways component and how this speed was maintained.

If the cart was moving tangentially to the wind and the prop…………..

The penny just dropped, the speed has to be tangential. The speed attained is directly proportional to prop speed and prop speed is directly proportional to the cart speed, therefore any additional speed given by the wind will result in acceleration until a balance is reached.

Theoretically infinite speed can be attained in a tangential direction assuming no losses.

I have written this and my brain just crashed, need to reboot, I cant grasp this one.

[Harvey]

Ok, let us look at this from an energy perspective.

Let us say that our cart requires 10 units of energy to move it 10 units of speed on a level surface.

Now let us suppose that we have a sail capable of capturing 40 units of energy from a wind moving 10 units of speed. This means we can now 'load' our cart with 30 units of generators on the wheels to store or convert that extra energy even though the sail will still move our cart at 10 units of speed equal to the wind speed.

Now we can use those extra 30 units to accelerate to a higher downwind speed. One way is to push against the tail wind with a prop. Another way would be to compress incoming air (making a forward vacuum) and jet forward. And still another way would be to have other drive wheels and apply the generated energy to them.

Naturally, there will be a point at which we develop a head wind. And at that point it may be nice to also have a turbine like the picture I linked to in my prior post. That way it will convert the energy regardless of the direction of differential. So the sail would work where no differential occurs (cart velocity = wind velocity) and the turbine would work where a differential exists.

[Roland]

I read about this on Boing Boing on the 1'st. I didn't think it was as significant as everyone else seems to.

I like this one video that uses a gear ratio analogy.
YouTube - Under the ruler faster than the ruler

Great thread,
These 4 videos where a real eye opener for me. It took all 4 videos of coolaun's, and some repeat viewings to finally get my head wrapped around it. It was time well spent. I must thank you guys.
It is a great feeling to get to the point where i can understand this kind of stuff.