Brain teaser: wind power conundrum

[Arthur Smith]

New here, so I may have missed if this has come up before.

Is it possible to conceive of, design and construct a vehicle that, powered only by the wind, can sustain speed in excess of that wind while travelling in the direction of that wind?

 

[Beer w/Straw]

Are you asking if a windmill can move faster than the wind pushing it?

 

[Arthur Smith]

Are you asking if a windmill can move faster than the wind pushing it?

Not if you mean a building used for grinding grain.

 

[Arthur Smith]

Examples of vehicles powered only by the wind are yachts, sailboats, land-yachts, ice-yachts, hot air balloons etc.

 

[Michael 345]

Examples of vehicles powered only by the wind are yachts, sailboats, land-yachts, ice-yachts, hot air balloons etc.

Possible there is a YouTube video

Years ago MythBusters did something with a yacht driving it with a fan inside the yacht

Might help if the video exist

 

[Arthur Smith]

Possible there is a YouTube video

Years ago MythBusters did something with a yacht driving it with a fan inside the yacht

Might help if the video exist

But do you think the scenario is possible?

 

[Michael 345]

Not my area to even speculate even
But if a yacht can tack INTO the wind who knows?

 

[Arthur Smith]

Not my area to even speculate even
But if a yacht can tack INTO the wind who knows?

Well, one thing no yacht can do is sail directly downwind any faster than the wind.

 

[Michael 345]

Well, one thing no yacht can do is sail directly downwind any faster than the wind.

Ummmm try

https://www-sciencefocus-com.cdn.am...ts-sail-faster-than-the-wind-propelling-them/

Yes, although it sounds implausible.

With the wind blowing from behind and sails perpendicular to the wind, a boat accelerates. The wind speed on the sail is the difference between the vessel’s forward speed and that of the wind. Once the boat reaches the same speed as the wind it’s impossible to go any faster. But with the wind blowing from the front, the boat turns its sails into the wind by about 45°. The sails divert the wind slightly as it blows across them, which slows the wind and exerts a sideways force on the sail. The keel (the large fin that extends down beneath the hull) cancels out the sideways force. But, if the sail is angled correctly, some of that force also drives the boat forward. The vessel continues to accelerate until that force is matched by the drag of the water. So, with clever streamlined hull designs a boat can sail faster than the wind

As I said not my arena. But Mr Google ask nicely "can you sail faster than the wind" Bibiitty-Bop-Boo comes out with the above

 

[Arthur Smith]

So, with clever streamlined hull designs a boat can sail faster than the wind

Yes. Ice-yachts are even faster than hydroplane yachts, apparently capable of approaching 8-10 times wind speed. But not directly downwind.

 

[DaveC426913]

Yes. There are some quite popular Youtube videos about a successful attempt to do this.

Google Blackbird (along with dwfttw).

https://www.wired.com/2010/08/ddwfttw/

 

[Arthur Smith]

Yes. There are some quite popular Youtube videos about a successful attempt to do this.

Google Blackbird (along with dwfttw).

https://www.wired.com/2010/08/ddwfttw/

Rick Cavallaro originally built Blackbird in 2012 to demonstrate it could be done. Last year a physics professor disputed it was possible and agreed to bet $10,000 on the outcome. He lost.

https://www.google.com/amp/s/amp.if...er-won-a-10000-physics-bet-against-professor/

 

[Arthur Smith]

Here's a concise theoretical calculation.

https://www.rotaryforum.com/threads...r-than-the-wind-vehicle.1146527/#post-1182698

 

[RainbowSingularity]

Not if you mean a building used for grinding grain.

are you prejudice against grinders ?


your question is open ended

you have not defined your medium

land wheels caterpillar tracks water
muddy bog
alligator infested sewage pond
the moon
the moon on a low moon wind day
etc...

i know the new Americas cup boats can exceed wind speed
but that technology & medium is not wheels & moving around buildings might be hard
more soo if you need to parallel park beside a very expensive vehicle with no car insurance

hot air balloons etc.

being picky just for the sport of it
convection ? thermal ? when is wind not thermal or convection ?
etc...
is a hot air balloon powered by wind or thermals ?

pushed by wind
but lifted/powered by thermal exchange variance
no thermal exchange variance then its just a bouncy castle in a shit storm

 

[Arthur Smith]

@ Rainbow. Wind, in this instance can be construed as air in movement with respect to another medium.

 

[RainbowSingularity]

@ Rainbow. Wind, in this instance can be construed as air in movement with respect to another medium.

steam ?

steam has added heat energy

im being picky for conversation purposes

i guess there comes a point where friction becomes a compulsory element

 

[sideshowbob]

The misconception is that sailboats are propelled by air pushing against the sail. In fact, sailboats are propelled by air moving over the surface of the sail. So the movement of the sailboat is not directly related to the speed of the wind.

 

[RainbowSingularity]

The misconception is that sailboats are propelled by air pushing against the sail. In fact, sailboats are propelled by air moving over the surface of the sail. So the movement of the sailboat is not directly related to the speed of the wind.

negative force vector conveyance

discrepancy actuator

 

[Arthur Smith]

The misconception is that sailboats are propelled by air pushing against the sail. In fact, sailboats are propelled by air moving over the surface of the sail. So the movement of the sailboat is not directly related to the speed of the wind.

There has to be a transfer of kinetic energy. Air molecules are slowed by loss of momentum which is gained by the sail.

 

[billvon]

Is it possible to conceive of, design and construct a vehicle that, powered only by the wind, can sustain speed in excess of that wind while travelling in the direction of that wind?

Absolutely. Sailboats do that all the time. They "cheat" by generating lift between the water and air, both of which are moving at different velocities. In fact, boats can go INTO the wind at a speed faster than the wind.