A complex riddle that has baffled and enraged experienced engineers will be put to rest if a team of engineers, including Rick Cavallaro AE ’84, successfully ratify the record from a wind-powered vehicle that travels downwind faster than the propelling wind.
“[Many] thought I was a complete moron,” Cavallaro said of his original project plan, about which he expected interested and understandably skeptical responses.
The project began humbly as an experiment he posted on internet forums, intrigued by the concept of a Downwind Faster Than the Wind (DWFTTW) vehicle.
The ensuing discourse between Cavallaro and critics transformed a curious possibility into a raging debate spanning thousands of pages.
“It’s so counter intuitive to so many people. People on the internet are saying it can’t be done,” Cavallaro said in a press release.
Belittled by many scholars, including a Tech professor, but confident that his designs were mathematically correct, Cavallaro built a miniature model. This did little to assuage the doubts of internet posters, so he began to seek sponsors, including Joby Energy and Google. In collaboration with the San Jose State Aerospace Engineering Department, Cavallaro began a full-size vehicle to finally end the issue of the legitimacy of a DWFTTW vehicle.
After over a year of efforts, including design, fabrication, numerous trials and various redesigns, the vehicle dubbed ‘Blackbird’ was completed. The materials came from various sources, and some parts were even donated, ranging from highly accurate sensors to windsurfing masts. The vehicle itself is a highly aerodynamic 3-wheeled device with a 17 foot long propeller attached to a tower on the back. It is ultralight and seats one, and from this sparse construction arises much of the misconception about the vehicle. It is powered by neither battery nor motor, but instead the wheels turn the propeller that moves the vehicle, in turn spinning both wheels and the propeller faster.
Though suggestive of perpetual motion, the vehicle uses wind as an external power source. Cavallaro and his team made no new discoveries or inventions in building the vehicle, instead cleverly applying existing aerodynamic principles to create an incredible device.
Blackbird was put to official tests on July 2 and 3, in a dry lakebed in El Mirage, Ca., with the National American Land Speed Association (NALSA) to oversee the vehicle’s bid for the record for fastest DWFTTW vehicle. Cavallaro piloted the vehicle to unofficial top speeds of 53 mph, with a duration average of 2.5 times the wind speed. NALSA has been analyzing data from the vehicle’s sensors and verifying if the vehicle’s runs meets the NALSA’s guidelines to be approved as the record holder.
Given that Cavallaro’s team essentially created the category and built the first vehicle to ever qualify for it, Blackbird may hold the record for fastest DWFTTW vehicle by default.
“[It was] a brain teaser gone horribly wrong,” Cavallaro said of the machine.
However, Cavallaro has ideas about potential applications of the machine, even if they are purely theoretical and likely some time away from realization.
Modern windmills harness about 69 percent of the energy available from the wind, while a dynamic system using Cavallaro’s principles has “theoretically no limit” to how much energy can be harnessed from it. Although limitations stand in the way of creating such a system, there is incredible potential in some of the ideas and principles Cavallaro utilized to develop the next generation of hyper-efficient wind based energy.
“We don’t claim it’s perpetual motion. We’re not saying we’ve solved all the transportation problems. But these are interesting new applications involving harvesting wind power,” Cavallaro said in a press release.