Sailing directly downwind faster than the wind.

[loic2003]

Since the level of physics in here is so high (mmm.... conveyor) I put this to you.

Check out this video and see what you think. Some people think it's a trick: it's going downhill or something. What do you think: Text

 

[MrPickins]

That's not sailing. It has a propeller.

 

[loic2003]

ok.... *moving* faster than the speed if wind going directly downwind....

 

[Ramma2]

There's a reason they don't show a close up of the vehicle...

 

[halik]

Eh doesn't the prop just build up kinetic energy, so when the wind dies down some it keeps going forward?

 

[darkswordsman17]

It could just be tethered to something pulling for all we know. It went awfully straight on considering it only has one wheel in front. That or its radio controlled (at the beginning, the guy says, whoops had the brake on whenever it had kinda stalled and again at the end he says he turned the brake on and it slowed down). There's too many unknowns to be able to determine what is going on or even what exactly the guy is trying to accomplish and its not like the poor quality of the video helps out any.

Now this is cool.

 

[Fern]

I don't know what to make of that contraption etc.

But as a person with some experience in sailing (boats) you cannot sail downwind (or otherwise) faster than the wind. Period.

Fern

 

[rivan]

Originally posted by: darkswordsman17
It could just be tethered to something pulling for all we know. It went awfully straight on considering it only has one wheel in front. That or its radio controlled (at the beginning, the guy says, whoops had the brake on whenever it had kinda stalled and again at the end he says he turned the brake on and it slowed down). There's too many unknowns to be able to determine what is going on or even what exactly the guy is trying to accomplish and its not like the poor quality of the video helps out any.

Now this is cool.

Those walker things are sweet.

 

[James Bond]

Originally posted by: rivan

Originally posted by: darkswordsman17
It could just be tethered to something pulling for all we know. It went awfully straight on considering it only has one wheel in front. That or its radio controlled (at the beginning, the guy says, whoops had the brake on whenever it had kinda stalled and again at the end he says he turned the brake on and it slowed down). There's too many unknowns to be able to determine what is going on or even what exactly the guy is trying to accomplish and its not like the poor quality of the video helps out any.

Now this is cool.

Those walker things are sweet.

Wow, seriously..

 

[JulesMaximus]

Originally posted by: Fern
I don't know what to make of that contraption etc.

But as a person with some experience in sailing (boats) you cannot sail downwind (or otherwise) faster than the wind. Period.

Fern

Agreed. You have resistance from the hull of the boat moving through the water.

<--Has quite a bit of experience sailing boats.

 

[HomeBrewerDude]

Originally posted by: darkswordsman17
It could just be tethered to something pulling for all we know. It went awfully straight on considering it only has one wheel in front. That or its radio controlled (at the beginning, the guy says, whoops had the brake on whenever it had kinda stalled and again at the end he says he turned the brake on and it slowed down). There's too many unknowns to be able to determine what is going on or even what exactly the guy is trying to accomplish and its not like the poor quality of the video helps out any.

Now this is cool.

:thumbsup:

 

[smack Down]

 

[MrPickins]

Originally posted by: darkswordsman17
It could just be tethered to something pulling for all we know. It went awfully straight on considering it only has one wheel in front. That or its radio controlled (at the beginning, the guy says, whoops had the brake on whenever it had kinda stalled and again at the end he says he turned the brake on and it slowed down). There's too many unknowns to be able to determine what is going on or even what exactly the guy is trying to accomplish and its not like the poor quality of the video helps out any.

Now this is cool.

Amazing :thumbsup:

 

[joecool]

Originally posted by: JulesMaximus

Originally posted by: Fern
I don't know what to make of that contraption etc.

But as a person with some experience in sailing (boats) you cannot sail downwind (or otherwise) faster than the wind. Period.

Fern

Agreed. You have resistance from the hull of the boat moving through the water.

<--Has quite a bit of experience sailing boats.

what they said. anything that can generate more energy then it receives from its energy source (wind, gravity, gas, sunlight, etc), is by definition a perpetual motion machine == IMPOSSIBLE!

<-- also has extensive sailing (and physics!) experience

 

[Toastedlightly]

well.. I did stay at a holiday inn last night.

 

[Eeezee]

How is it moving faster than the wind? I don't even understand what is trying to be claimed here.

 

[SagaLore]

The propeller is turning a belt which is turning the wheels.

The reason it is staying so straight is because he has a remote control - you can hear him saying he's putting on the brakes.

 

[loic2003]

Originally posted by: joecool

Originally posted by: JulesMaximus

Originally posted by: Fern
I don't know what to make of that contraption etc.

But as a person with some experience in sailing (boats) you cannot sail downwind (or otherwise) faster than the wind. Period.

Fern

Agreed. You have resistance from the hull of the boat moving through the water.

<--Has quite a bit of experience sailing boats.

what they said. anything that can generate more energy then it receives from its energy source (wind, gravity, gas, sunlight, etc), is by definition a perpetual motion machine == IMPOSSIBLE!

<-- also has extensive sailing (and physics!) experience

for this we really need to negate resistance from water, and imagine perhaps a contraption in a frictionless environment, such as on ice.

A sail doesn't capture *all* the wind, so it must be possible to use a mechanical method to capture more of this energy and propel you faster than the wind. What if you had a wind turbine instead, and then an electric motor powering the vehicle. Is it still totally impossible to go faster than the wind in this scenario? Does changing the engery form from mechanical to electrical make it suddenly possible?

This is the way I see it: the prop as it turns creates an area of pressure (like any prop), but instead of it pulling itself through the air, the wind pushes against the pressure from the prop. In this way the prop acts as a sail, rather than your traditional powered propellor. The prop is driven by the forward motion of the vehicle (it's linked to the wheels), which is why it would always need an initial push to establish an area of pressure for the wind to push against.

How to go faster than the wind speed? Lets take a look at your regular down wind sail, like a spinnaker. Imagine the force (pressure) of the wind is 10 units. A sail offers 0, so the sail is pushed along at force 10 max. However, the propellor can actually push *back* a little, so the wind pushes at force 10, but the prop is pushing back at say 1 or 2, so you get overall force = 11 or 12. Faster than the wind.

The vehicle has a remote control in this video. I don't think it's fake.

 

[mugs]

Originally posted by: SagaLore
The propeller is turning a belt which is turning the wheels.

What strikes me as odd about the video (and the PDF document that it links to) is that the way the propeller is facing it would blow air backwards, which of course would be necessary for the thing to move faster than the wind. So how is the wind powering it? If the wind was moving the propeller, wouldn't it move it in the direction that would push air toward the front of the car? The same direction the wind is moving?

The PDF says it is self-starting.

 

[loic2003]

Originally posted by: mugs

Originally posted by: SagaLore
The propeller is turning a belt which is turning the wheels.

What strikes me as odd about the video (and the PDF document that it links to) is that the way the propeller is facing it would blow air backwards, which of course would be necessary for the thing to move faster than the wind. So how is the wind powering it? If the wind was moving the propeller, wouldn't it move it in the direction that would push air toward the front of the car? The same direction the wind is moving?

The PDF says it is self-starting.

yeah I read that. You can actually see it self start in the vid. Guess I was wrong on that one.

The wind is pushing against the pressure created by the prop!

 

[AeroEngy]

It is possible for a sailboat to travel faster than the wind and they do it all the time. It is just impossible to do it exactly downwind. However, a sailboat can travel faster than the wind speed if it is moving at an angle with respect to the wind direction.

Here is a Link to back it up.

Here is another link

If this is really traveling faster than the wind speed then it is probably just using the same principle. Replace sail with propeller, replace keel with wheels.

 

[loic2003]

Originally posted by: AeroEngy
It is possible for a sailboat to travel faster than the wind and they do it all the time. It is just impossible to do it exactly downwind. However, a sailboat can travel faster than the wind speed if it is moving at an angle with respect to the wind direction.

Here is a Link to back it up.

Here is another link

If this is really traveling faster than the wind speed then it is probably just using the same principle. Replace sail with propeller, replace keel with wheels.

This is a given. I imagine it as squeezing a bar of soap in your hands. This is all about directly downwind, though...

 

[loic2003]

sly bump an other people discussing it.

 

[alkemyst]

you don't really sail with the wind directly behind you though.