Rating is available when the video has been rented.
This feature is not available right now. Please try again later.
Uploaded on Dec 1, 2008
Demonstration of a concept that comes into play in one of the DDWFTTW (directly down wind faster than the wind) designs. The spool is propelled by the tension in the wire, yet it moves faster than the wire is moving. If the spool had vanes on the lower surface of its core that could be feathered during the trip around the top, it would be able to move DDWFTTW. The key is that the lower surface of the core is moving forward more slowly than the hub, so it can feel a tailwind even when the hub (and thus the spool as a whole) is outrunning the wind and feeling a net headwind.