Physics brainteaser

[Turok]

Quote from Haroki:

1-Yes I know that. It was a trick question to see if you could explain why the streamer, at times, was blowing towards the front of cart, and why the video was cut part way in, right when the streamer was like that.

*Our* video cut Jacks video up to fit our dialog. Jacks video is uncut:

http://www.youtube.com/watch?v=aJpdWHFqHm0

The at the start of the video, the streamer blows to the front because is a tailwind. The streamer starts to hang and wander as the cart approaches and passes through the actual wind speed. The latter part of the video shows an extended period of time with the streamer towards the rear, demonstrating a headwind to the cart, while there is a tailwind to the road.

Look, I understand that a breeze passing through the prop will cause it to spin, which will in turn power the drive wheels, and if the gearing is correct, the cart will briefly be able to go faster than the wind when the wind dips briefly in velocity,since the spinning prop will store a lot of kinetic energy, giving the illusion that it can go DWFTTW, steady state, with a little creative video editing.

The editing of Jacks video was done by us to fit our needs. Jacks video is unedited. Watch it and then come back with your new reasons.

At the end there is near 2 minutes of streamer strongly back with about 2 seconds of streamer barely front -- surely you're not claiming that the whisper over the back propels that cart that far. I mean there are lots of things that could be propelling that cart -- many of which we mention in the video (downhill, string, etc), but I hardly see how you can claim that one whisper can keep the thing going for a full minute.

The wind is your power source. There MUST be wind blowing through the prop in order to supply power to the drive wheels.

Just as wind does not "blow through" a sail, wind is not blowing through the prop sail -- in both cases, it merely needs to blow *across* it to generate lift.

When an ice-boat or a sail-boat reaches a VMG (velocity made good) of the wind speed, the sails on their craft do not hang limp. No, the apparent wind across the sail continues to accelerate the craft to an even greater speed (ice-boats, regularly achieve VMGs of 3x+ the wind speed).

As the cart nears wind velocity, there will be no more power source, since the net flow through the prop is zero.

Tell that to the sailor who achieve it regularly

This is what is seen in that video. That is why the streamer can be seen, at times, to be blowing towards the front of the cart. The cart is VERY efficient at going down wind, but it cannot go faster than the wind - STEADY STATE - it can only do this for brief periods when the breeze slackens and kinetic energy is powering the cart.

Nope -- if what you were saying were true, traditional sailing craft would not achieve VMGs of even 1.0, let alone 3-4x.

(I'll address your further comments next post)

----- But since you claim to understand the physics, explain exactly HOW the physics work that enable this. Videos don't cut it.

As to your your bolded comment: you and I couldn't agree more.

JB

 

[Turok]

You would need a wind tunnel still, but you'd need to let it roll, which means you'd need a very long wind tunnel. So that's out.

Haroki, I know this may sound silly on something so simple -- but you're pretty sharp to catch that above.

Of the hundreds I have discussed this with, many say "windtunnel, windtunnel, windtunnel" without realizing that you would have to turn this device *around* and run it the 'wrong way' in the wind tunnel. Only a few have been bright enough to catch what you caught.

Gotta run, but I'm enjoying the exchange and hope we can continue.

So that makes it a free energy device.........

We'll check back with you on that one after some more back and forth.

See Ya'

JB

 

[Smart Money]

Quote from Turok:

I have built, and can demonstrate on demand a vehicle which can travel directly downwind, faster than the wind, powered only by the wind, steady state.

http://www.youtube.com/watch?v=Vjt6G8D4x0k

Huh? Ok, so if you build a big one, and it is going faster than the wind, how can the tail wind get to it? If it goes as fast as the wind, it would be like it was sitting in still air to the person riding aboard it...and at that point...what would be powering it?

SM

 

[Turok]

Quote from Smart Money:

Huh? Ok, so if you build a big one, and it is going faster than the wind, how can the tail wind get to it?

Well, first off a little one works just like a big one.

If it goes as fast as the wind, it would be like it was sitting in still air to the person riding aboard it.

That's exactly right if you are sitting on the cart chassis. However if you were sitting on the propsail you would feel lots of wind as the propsail is moving relative to the cart chassis.

..and at that point...what would be powering it?

At any speed, the power comes not from wind relative to the cart, but wind relative to the ground. When the cart is moving the same speed as the wind, said wind is *still* moving relative to the ground. Since the have a 'hook' into each medium, we can extract energy from their relative motion.

JB

 

[Turok]

Well, in the above exchange (all posted months ago), I don't believe I managed to convince a single person that it's possible to build a wind powered device that can go directly downwind, faster than the wind, powered only by the wind, steady state.

Fair enough, but it IS possible and rather simple -- just unintuitive.

In the ensuing period since the above posts, we have demonstrated this device many, many times for skads of skeptics (including many university professors, physicists, aero engineers, etc.).

Tomorrow will be a fun day as we were invited by Stanford University to address the graduate student program from the Aero and ME departments, discussing and demonstrating the device to the Masters and Doctorate students and Professors.

I got permission to video tape the presentation and the rights to distribute it -- I'll post it on youtube later today or tomorrow.

After anyone who is interested views the presentation, perhaps you'll have a re-look at my position. Both the device and the testing methods have proven valid and are accepted by very bright minds in the field.

Later.

JB

 

[Turok]

http://www.fasterthanthewind.org/2010/03/sweet-success.html

On Monday, March 22, 2010 our project with San Jose State University overwhelmingly succeeded in demonstrating 'direct downwind faster than the wind' on the Ivanpah dry lakebed south of Las Vegas, Nevada.

There were numerous NALSA (North American Land Sailing Association) officials in attendance, and one NALSA BOD member (Bob Dill) was there for each of these runs, and collected some of his own rough wind and ground speed data. All collected video and data corroborate the personal witnesses.

To be clear, this was NOT a NALSA sanctioned event but was presented as a demonstration to the NALSA BOD that the vehicle was capable of ddwfttw. Post demonstration, the team is working out the details with NALSA for rules and instrumentation related to any upcoming official NALSA ratified tests and records.

Pending NALSA BOD approval, we expect to be able to certify a record according to these upcoming rules in the range of 3 times the speed of the wind.

http://www.youtube.com/watch?v=7SYvg40NHtc

http://www.youtube.com/watch?v=aDzWh9J1dk4

Entire San Jose State University project blog at www.fasterthanthewind.org

 

[Wayne Gibbous]

Pretty cool. Okay, I think I'm getting it. In the same way that a simple sail-powered device cannot move directly up wind, a propeller cart actually can move directly up wind. The prop-shaft-wheel arrangement can easily overcome the wind resistance.

So when we move down wind, due to the curvature of the prop, the wind is tangent to the blade surfaces. With each rotation essentially 1/2 of its blade surfaces are up wind, and 1/2 are down wind. This allows the cart to "cheat" the wind and go faster than it down wind.

At least, I think that's how it works!

 

[Turok]

Quote from Wayne Gibbous:

Hi Wayne

Okay, I think I'm getting it. In the same way that a simple sail-powered device cannot move directly up wind, a propeller cart actually can move directly up wind.

Actually, it's a *turbine* cart that can move directly upwind, rather than a propeller cart.

Conversely a turbine cart can't exceed the speed of the wind while going dead downwind while a propeller cart can - different applications, different tools.

So when we move down wind, due to the curvature of the prop, the wind is tangent to the blade surfaces. With each rotation essentially 1/2 of its blade surfaces are up wind, and 1/2 are down wind. This allows the cart to "cheat" the wind and go faster than it down wind.

It is true that because of it's spiral path, different stations of the propeller blades see a different apparent wind, but I don't think it's quite as you are imagining it.

The prop is twisted so that at design speed, each station of the prop airfoil sees the same angle of attack even though the apparent wind comes from a different angle to each station. Thus the entire prop is attacking the apparent wind at the same angle.

Once above windspeed, all portions of the propeller are seeing an apparent wind from in front quadrant of the vehicle.

The part that catches most folks off guard is that the spinning airfoils are not acting as turbines and powering the wheels, but rather are acting as propeller blades and are *powered by* the wheels.

It's a mind fuck because it looks so different, but actually is using the exact same principle that the BMW Oracle America's Cup boat uses to go faster than the wind.

JB

 

[Turok]

Here's a recent write up in Sail Magazine (the issue will be on newstands in the next few weeks).

http://sailmagazine.com/racing/running_faster_than_the_wind/

JB

 

[Son of a Gann]

What if tread mill will move very slow? Power generated by tread mill should be stronger than weight of your devise. If tread mill will not generate enough power device will not move faster so is it powered by the wind or tread mill?

Try this take a bottle of your favorite drink close yourself in room. You can spend hours in the same room and nothing will change until you take a drink. But once you empty the bottle will it stay same? Still same amount of fluid in the same room. You can blow the air or pass the air either before or after taking a drink I can guaranty there will be difference.

You are trying to prove that pull and push are same.