Wow, I don’t get to say that very often! But it’s true. In this post, Mark claims that it’s impossible to make a wind-powered vehicle that goes faster than the wind, while traveling in the exact same direction as the wind. He is wrong, and in his post, he gives us the empirical evidence why he is wrong.
Rather than fisk his entire argument, I think instead I’ll just show why he is wrong. Here’s the video that shows how faster-than-wind travel is possible:
The problem is, this video doesn’t do a very good job explaining the principle behind the engineering.
It’s hard to understand at first why it’s possible for a vehicle driven by the wind to move faster than the wind. Imagine a helium balloon being driven by the wind. There’s simply no way for it to move faster in a horizontal direction than the wind itself is blowing.
But think about this. There’s a tremendous amount of force in the wind. Drive a sturdy 10-foot stake into the ground. Now imagine a steady 20-MPH wind blowing across the stake. The stake’s not going to budge. Now attach a 10-foot-square sail to the stake, holding it with ropes so it stays perpendicular to the path of the wind. All the sudden a tremendous force is imparted. It may be difficult for you to hold the sail in place. Eventually the wind would rip the sail from your hands. Yet you could easily throw the same piece of cloth (bundled up in a wad) faster than 20 MPH. So that 20-MPH wind has enough energy to propel something faster than the speed of the wind. It’s stronger than you, and you can throw the object faster than the wind is moving.
Sailors know this, and there is no dispute that it’s possible to sail a boat across the wind at a speed faster than the wind speed. You can even sail into the wind. There’s plenty of energy in the wind to move a vehicle faster than the wind is blowing.
So how does the vehicle in the video work?
It’s mind-numbingly simple.
It’s just a little cart with a propeller driven by the wheels. The propeller is oriented so that when the wheels roll forward, it propels the air backwards, giving a little extra forward propulsion.
The wind pushes on the propeller, which starts by acting like a sail. This causes the car to roll forward, which makes the propeller spin. The spin of the propeller adds a little extra thrust. As long as the propeller is big enough, there’s plenty of energy to not just propel the car forward at wind speed, but a little faster as well.
In the video you can see that the treadmill is not only moving at a high rate of speed backwards, it’s also angled up. This craft can actually “sail” uphill, faster than the wind is blowing.
Mark argues that this isn’t a true perpetual motion machine, because the treadmill is constantly adding energy to the equation. That’s correct, but it’s only simulating a steady wind. Since the air in the room is still, the motion of the treadmill is equivalent to wind moving across the ground at the same speed. The vehicle is moving FASTER than the treadmill is spinning — faster than the “wind.” It’s not a perpetual motion machine, it’s converting the energy in the wind into forward motion. If there is no wind, the cart goes nowhere.
Mark also says that because the treadmill isn’t level, it’s not a fair experiment. But the treadmill is angled uphill. If it was angled downhill, he’d have a point. But it’s angled uphill. This simply adds to the force that the cart must overcome to move faster than the wind. The experiment would also work on a flat treadmill.
So now I get to truthfully say something I’ve never said before — and probably won’t ever say again. Mark Chu-Carroll is wrong, wrong, wrong. He’s a very smart guy, but he’s wrong on this one.