wind machine that goes faster than the wind!

[jimshaw]

For all of you wind loving brainiacs, here is a concept to wrap our heads around. Ken, Kendall, or anyone else, can you help me wrap my head around this:

http://watch.discoverychannel.ca/clip298008#clip298008

[OP]

When I first heard of this I was "bull." Thinking it violated energy. But it does work. Easiest way to imagine it:

Starts around :55
[youtube]http://www.youtube.com/watch?v=E7vcQcIaWSQ[/youtube]

[Tom C]

This one can take some effort to get your head around. But if you carefully work out the forces acting on the cart you can see that it does work. The cart is taking advantage of the speed difference between the ground and the wind. It must be coupled to both media in order to work its magic. It requires some clever engineering to determine the proper gear ratios and overall design that will allow it to overcome the friction and mechanical losses. If you could find some of that frictionless hardware that they always talked about in my physics books the top speed would be limited by the aerodynamic drag as the cart pushes through the slower moving air.

Here's another video by the same guy. This one's one step closer to the wind powered cart. https://www.youtube.com/watch?v=k-trDF8Yldc The top surface of the large wheel (pushing against the ruller) is analogous to the surface of the propeller pushing against the wind.

This topic stirred up quite a debate on several internet forums a while back. If you want to waste a few days, here's an example http://forums.randi.org/showthread.php?t=171585. This one went on for about 260 pages before it finally fizzled. It can be an entertaining and frustrating read.

I once worked out a simplified derivation of the net force acting on the cart, but I can't seem to find it at the moment. I guess you lucked out on that one.

[dhmartens]

Scientific Method would allow their peers to reproduce the results.
Or if you had $43 Billion Dollars, you could prove the concept.

Larry Ellison's Sail Boat Is Literally Faster than the Wind
http://gizmodo.com/5848153/larry-elliso ... n-the-wind

[AlC]

Too late, it's been proven and Guinness Record granted. Really long thread here: http://www.hanggliding.org/viewtopic.ph ... &start=520 Jump to the last page.

I thought I saw somewhere that they are selling the vehicle...

- Alan

[TerryH]

Sail boats routinely go faster than the wind. The cool thing here is that this system can do it going directly down-wind.

[dhmartens]

They demonstrated upwind at 2x wind speed.
[youtube]http://www.youtube.com/watch?v=b8MWCvKIi7E[/youtube]

Now they are selling the prototype on ebay, $5,220 current bid.
http://www.ebay.com/itm/Blackbird-Faste ... 4173ba917c

Now its being adapted to boats to go directly upwind:


Soon we may see a hang glider prototype that can fly upwind?

[dhmartens]

Faster than wind Hang Glider

[OP]

Doug's brief time as an air freight handler:

[youtube]http://www.youtube.com/watch?v=tPzRPga6uDg[/youtube]

Just teasing.

[chadness]

and also in every day low tech occurrence - visit Supine Jim at Lake El Mirage and he will take you on his land yacht (small sail boat on a carts with wheels instead of a hull). he routinely hits speeds much faster than the wind (like double). ok now with this design, this is not done directly downwind but the apparent wind (a sailing term) will pull around almost to a headwind.

[OP]

OFN (old news) chadness;

sailboats avoid stright down wind. The jibe with wiscars to speed the downwind legs.

[chadness]

true but what is neat about a sail boat with wheels (land yacht - very efficient) is that you can be sailing about 30 degrees from downwind (true) and your "apparent wind" direction will be about 30 degrees off the nose (apparent). and your ground speed is a multiple of the wind speed. pretty cool. and *feels* pretty close to the rigs that employ a specialized setup that takes ground speed energy and uses it to drive a propeller.

[dhmartens]

Op, I had an even shorter career as a Porta-potty placement selection specialist.
[youtube]http://www.youtube.com/watch?v=LGq-NYjueXw[/youtube]



Edit:
A Picture is worth 100 words.


Notice in the faster than wind hang glider photo in an earlier post, the upper prop is above the boundary layer.


This land yacht broke the speed record at 126mph.
[youtube]http://www.youtube.com/watch?v=TRFRQXPtXTs[/youtube]