Even though I’ve experienced the evidence firsthand I’ve never quite been able to totally accept that the treadmill and turntable tests accurately represent a cart being powered solely by wind (like many others). So I’ve built a circular wind tunnel to test DDWFTTW in a “real” wind and the cart is only powered by moving air. It’s not high-tech but it works. Things move around quite quickly so you need to use slow motion or frame by frame to see what’s happening. This video was taken during construction to show and explain the workings . . . http://www.youtube.com/watch?v=simRdTslucs&feature=channel_page This video is the wind tunnel and cart in action (the uploaded quality is very poor compared to the original) . . . The cart not only beats the wind it also beats the vanes that create the wind! The series of images below show the flap each time it comes around and you can clearly see that the cart has advanced from vane 4 to vane 1. There is an image missing between the last two because the flap was in the reflection on the plastic and couldn’t be seen. The sequence represents eight revolutions of the cart. It wasn’t taken from the video posted but the same thing can be seen in that video as well. http://www.accommodationz.co.nz/images/sequence.bmp The vanes are turned by hand and it’s very easy to keep a constant speed. When the air is up to speed there is very little energy required to retain that speed so the vanes aren’t travelling much faster than the wind. The tunnel is totally enclosed and the air moves essentially as a single mass. The wind created would be at least as constant and stable as an outdoor wind.