
Rick Cavallaro has sailed for over 30 years, and was well aware that sailboats could tack upwind, run directly downwind, and go significantly faster than the wind when sailing across the wind. He got to wondering whether it would be theoretically possible for a sailboat to sail downwind at an angle such that the boat's direct downwind progress would be greater than the wind speed. He did some basic vector arithmetic based on the concepts used in sailing and found that indeed it should be possible to do exactly this, given a boat of sufficiently high performance.
With just a bit of research Rick learned that ice-boats and land-yachts do this routinely. He realized this meant one could release a balloon and race it downwind by tacking downwind in a land-yacht - and the land yacht would win the race quite handily. Given his love for brain-teasers, and this new knowledge of something that seemed somewhat counterintuitive, he wondered if it would be possible to design a vehicle that could use the same principle to go DIRECTLY downwind faster than the wind. With a bit of thought it occurred that one could reproduce the aerodynamics and physical constraints of the land-yacht by simply having the sail follow a continuous downwind tack, but wind that tack into a spiral. Two such sails would simply form a propeller. By gearing this propeller to a set of wheels, you could constrain it to follow the same downwind path that the sail of the land-yacht follows on a steady downwind tack. So it seemed such a vehicle could in theory be constructed quite simply.
Sometime around 2004, Rick posted this brainteaser on an internet forum expecting to get some right answers, some wrong answers, and a few exclamations of "wow - that's pretty cool". What he got however was surprising. This problem raised a stink that ran across 1000's of pages over countless internet forums. Many people (including some aero and physics PhD's and professors) were absolutely certain it could not be done. Many were extremely insulting of Rick's intelligence and sanity.
In the course of these forum threads, it came out that Andrew Bauer had built such a vehicle in the 1960's - and it was designed to carry a driver. Unfortunately, there was no concrete evidence as to whether it had succeeded in its mission. Eventually, JB joined in on the fun, and convinced Rick that the skeptics would never be won over by Rick's analyses and analogies alone. JB was sure that the only way to convince the skeptics was to build a working model. Surely, if they saw compelling video evidence, it should quickly put the matter to rest.
So Rick and JB locked themselves in the Sportvision lab one rainy weekend and built such a model. Initial results with the model were marginal at best - but the effect was amazing. Within 2 days of posting the video on the internet, one of the greatest skeptics built his own version of the downwind cart. But his version was small and slick, and performed GREAT. In the true tradition of science, Rick and JB took that design, made slight improvements, and ran with it. The result - even greater controversy on the internet forums.
The project this group is now undertaking is to build a full scale model that will run outdoors and carry a driver, while witnessed by the public, is intended to put the matter to rest once and for all. No matter the outcome, we're reasonably certain it will not satisfy the most ardent of skeptics.