"Faster than the wind," impossible they say but the Blackbird settles the debate

[RedDevil]

Mind blown 2!
Veritasum at 13:55 comes up with the same concept of my simple car 3 posts back! Or rather, I unknowingly came up with his same concept...

[aerohead]

Originally Posted by RedDevil

The misconception some people have is that if you have two bodies that are moving relative to one another, that any object that is in touch with both and nothing else cannot move beyond the speed of either.

So we have the ground at standstill, and the wind at a steady pace, and nothing can move against the wind or faster than the wind.

Now if we substitute the wind for a wooden plank, that would mean if you put something in between the ground and the wooden plank and you pusth the plank over that object, it would not move faster than the plank.
Right?

Behold my super simple car:



Note it has a double set of wheels; one in touch with the ground, one in touch with the plank. But the upper set also rests on a disk that is attached to the lower set of wheels, but half its size.

Now if you move the car then the upper wheels will turn at half the speed of the lower wheels and in the opposite direction. As the plank rests on those wheels, it will move in the same direction as the car but at half the speed.
That should be obvious.

Now what happens if you don't push the car, but rather the plank?
Of course the car will shoot away at twice the speed of the plank! Because the plank and car will still move relative to each other with the same ratio as when you push the car.

The wind does not provide as much grip as a wooden plank does, but if your propeller is big enough and other sources of friction are low then it would work just the same.

1) If the car moves from left to right, the upper wheels will rotate counterclockwise, and the plank will move at half speed in the opposite direction of the car.
2) The video said that the aerodynamic drag of the cars body pushed the car to speed, while momentum of the moving car powered the propeller via the wheel-geared powertrain.
3) Under the law of conservation of energy and the second law of thermodynamics, the propeller can never see as much energy as is contained in the wind.
4) When ground speed and air speed are equal, there is no more momentum impulse acting on the non-propeller parts of the car.
5) There's no additional energy being added to the system.
6) For the car to continue acceleration, would require extracting energy from a negative wind speed to overcome the equilibrium velocity.
7) Perhaps you guys are in possession of an airfoil section that has such a specific lift-to-drag ratio, that it can impart enough thrust to 'tack' on its shaft, lifting beyond some threshold.
8) I'd for one, would still like to see 'proof' that the car did what was said.

[California98Civic]

It is worth noting how intelligently, reasonably, and humbly they all pursued their disagreement. Some folks have a little egg on their face, and it is alright. That is one helluva youtube channel.

[California98Civic]

AEROHEAD... watch the video in post #69. It is really good. You'll see things worth seeing, given you last post (#72).

[some_other_dave]

Here's the part with the wheeled device that RedDevil proposed. It does exactly what he says.

EDIT: shoot, the forum doesn't seem to want to post time-stamped links correctly.

Anyway, it's at 13min 15sec, or just add "&t=825s" onto the end of the URL in your browser.

https://www.youtube.com/watch?v=yCsgoLc_fzI&t=825s

Derek won his bet. You can pause his video to see the equations. You can also see some of the earlier runs with more-complete instrumentation.

Watch through it with an open mind, aerohead. It's not a perpetual-motion device, it merely finds a neat way to take advantage of a body moving while in contact with two media that are moving at different velocities. Much like a modern sailboat does.

-soD

[RedDevil]

Originally Posted by aerohead

1) If the car moves from left to right, the upper wheels will rotate counterclockwise, and the plank will move at half speed in the opposite direction of the car.

related to THE CAR. the plank will move in the same direction as the car related to THE GROUND at half the speed of the car. Just like in Veritasum's video.

The whole point of that demo is to prove that you can make an object move faster than the speed of the two media it interacts with.

Originally Posted by aerohead

2) The video said that the aerodynamic drag of the cars body pushed the car to speed, while momentum of the moving car powered the propeller via the wheel-geared powertrain.

I don't know where it says that, but I would agree to it if you replace 'body' with 'propeller'. Als long as the car moves slower than the wind the minimal drag on the body helps a bit though.

Originally Posted by aerohead

3) Under the law of conservation of energy and the second law of thermodynamics, the propeller can never see as much energy as is contained in the wind.

Exactly! The car does not break the law of conservation of energy (thermodynamics are not relevant here, but not violated either).

If anything, it makes clever use of it.
There are two media at work here: the wind and the ground.
The wind pushes against the propeller, the ground pushes against the wheels.

The forward force on the propeller and the wheels are roughly equal.
But the distance the wheels move over the ground is larger than the distance the propeller moves the air relative to the car. And energy is force times distance.

So the energy needed to spin the propeller to withstand that force is less than the energy obtained by pushing the wheels over the ground with that same force. No broken laws, just a well used one.

Originally Posted by aerohead

4) When ground speed and air speed are equal, there is no more momentum impulse acting on the non-propeller parts of the car.

Ground speed and air speed are equal in a windstill. The car obviously has no power source then. I think you meant to say something else, but I'm not guessing.

Originally Posted by aerohead

5) There's no additional energy being added to the system.

Indeed.

Originally Posted by aerohead

6) For the car to continue acceleration, would require extracting energy from a negative wind speed to overcome the equilibrium velocity.

Negative to the car you mean? Because that is exactly what we try to achieve.
There's no such thing as negative wind speed compared to the ground.
There's no such thing as negative wind speed compared to the surface of the propeller blades.
Obviously the wind needs to keep pushing against the propeller. It has to turn to allow for that.

Again, energy is force times distance. And as the propeller is forcing the air backwards slower than the wheels move over the ground, it needs less energy to do so than the wheels provide from the same force.

Originally Posted by aerohead

7) Perhaps you guys are in possession of an airfoil section that has such a specific lift-to-drag ratio, that it can impart enough thrust to 'tack' on its shaft, lifting beyond some threshold.

No need for tacking if you rotate around an axle for an 'infinite tack'. The propeller is nothing but two sails on an axle.
As for lift to drag ratio, that can go all the way to 60:1. Seems adequate.

Originally Posted by aerohead

8) I'd for one, would still like to see 'proof' that the car did what was said.

Ha! What would anyone have to do to convince you?
When building the damn thing, having sceptics inspect it, having an official registration of a record 2.8 times wind speed and all, and winning a 10,000 dollar bet with an UCLA professor does not even convince you?

No proof will ever be good enough for you, because the only thing you'd do with it is trying to debunk it.

Because deep in your heart you KNOW it cannot work.

Because you make a mistake in interpreting its physics, but you cannot admit that somehow.

[freebeard]

https://youtu.be/yCsgoLc_fzI?t=285

He claims that an unconscious bias on the part of the observer affects the outcome of the experiment. It's systemic? This is a professor of physics?

7) Perhaps you guys are in possession of an airfoil section that has such a specific lift-to-drag ratio, that it can impart enough thrust to 'tack' on its shaft, lifting beyond some threshold.

That was Xyla Foxlin's fourth model.

He has a very good stage presence.

Off-by-one error?

[jakobnev]

1) If the car moves from left to right, the upper wheels will rotate counterclockwise, and the plank will move at half speed in the opposite direction of the car.

The plank will move half speed in the same direction as the car.

The upper wheels turn half as fast as the bottom wheels.

[AeroMcAeroFace]

Originally Posted by freebeard

https://youtu.be/yCsgoLc_fzI?t=285

He claims that an unconscious bias on the part of the observer affects the outcome of the experiment. It's systemic? This is a professor of physics?
?

I think it is his conscious bias that is causing the accusation of unconscious bias.

[California98Civic]

Originally Posted by AeroMcAeroFace

I think it is his conscious bias that is causing the accusation of unconscious bias.

Yes, but to the professor's credit, he admitted he was wrong and conceded the bet. That's integrity. An interest in learning. We can't be right all the time.