Genuine question but what would using a small fan prove? Surely its just the amount of "Wind" it can produce? They used a big fan as thats what is required to match the power of the wind. If there was very little wind then the boat wouldn't move forward the way that a small fan wouldn't be able to push it forward..
Blowing your own sail
- Thread starter Liquidfox
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Genuine question but what would using a small fan prove? Surely its just the amount of "Wind" it can produce? They used a big fan as thats what is required to match the power of the wind. If there was very little wind then the boat wouldn't move forward the way that a small fan wouldn't be able to push it forward..
No, the boat would still move forward with less wind, that fan is chucking out far more air than a normal breeze.
As grant says in the video it is working on a different principle than under normal circumstances, and is purly caused by the excess volume of air being blasted at it.
And even with all that excess wind, it hardly moves forward. If it worked like a normal sail, it would be moving forward many times the speed it is.
Again watch the video I posted with the helicopters, a much better experiment based on identical newtons laws and has the same principles.
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So to answer the OP's question of "Can a fan attached to a boat power a sail boat on a windless day?" Yes if a person was to put a powerful enough fan and point it on there sail they would indeed be able to move forward, However it does not break newtons law and its far more efficient to point the fan the oposite way.
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It doesn't matter if it was flawed it still moved forward. Im not arguing about newtons law.. im saying that if some person was to put a big enough fan and point it at the sail it would go forward as demonstrated by the mythbusters.
Those Mythbuster guys aren't very clever IMO. The other day they were trying to test if a muzzle flash on a gun can ignite a gas and they didn't even place the gun INSIDE the same container as the gas. They were shooting the container from outside and wondering why nothing was happening
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Yes, but thats not really the point of the question or myth.
It had nothing to do with the sail.
You could have removed the sail and it would have still gone the same way (just faster)
It was purely the thrust of the fan moving the boat
Probably not but i didn't say it was. After you told me how it works i was corrected and accepted it did not break newtons law. So i specifically quoted a line of the question for which it did prove it could do. I was then sent a shipment of fail.
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Your question was incorrect that is why I sent you a shipment of fail,
It had nothing to do with turning the fan round to blow the other way and it had nothing to do with powering it by sail.
The fan blew into the sail but the sail couldn't catch all the thrust created by the fan therefore some of it went round the sail and allowed the boat to move in the same direction as it would have done with no sail what-so-ever.
So NO you cannot power a SAIL boat with wind (acting on the sail) to move the boat. from a fan that is mounted on the same boat.
You are using a FAN to power the boat. Nothing more, nothing less.
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that isn't what happened.the fan is facing forward and the boat is moving forward. Without a sail, the thrust is moving forawrd and thus the boat is moving backwards, so without the sail, you would get a different direction of travel.
Theres a guy in a lake whos driving his fan powered boat. A screw comes unloose and the fan spins around and gets stuck facing the oposite direction ( He can not move it ). If he powers the fan with nothing infront of it he will go backwards further out into the lake. He looks around and all he has is some old sail. Are you saying he should not put that sail up infront of the fan to go forward?
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Assuming you are commenting on the full sized boat experiment and not the desktop experiment then they are not using the force on the sail to move forward but simply using the sail a a vector.
The mass of air from the fan has hit the sail and returned from it.
Again it is purely the thrust from the fan being vectored from the sail in a backwards direction making the sail boat go forward. The sail is not the motive force which is the crux of the whole thread
The reason this is working on mythbusters full scale is something like this (someone correct me if i am horrifically wrong)!
The sail is not 100% efficient at catching the bombardment of air, and due to its shape - it is redirecting the air around its curve and roughly toward the back of the boat .
If the sail could catch all of the force of the fan effectively the boat would not move.
As Above
This is a case of "In a perfect world where everything was efficient to 100%, the boat would not move, but in the real world where the sail distorts with pressure, other effects conspire to forge the appearance that the scenario is functioning" .
The sail is not 100% efficient at catching the bombardment of air, and due to its shape - it is redirecting the air around its curve and roughly toward the back of the boat .
If the sail could catch all of the force of the fan effectively the boat would not move.
As Above
This is a case of "In a perfect world where everything was efficient to 100%, the boat would not move, but in the real world where the sail distorts with pressure, other effects conspire to forge the appearance that the scenario is functioning" .
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If the sail was removed the boat would have gone in the opposite direction, the thrust from the fan is going towards the sail which propels the boat in the opposite direction, like an aircraft as acidhell says.