|
The Blackbird is an experimental land yacht, built by Rick Cavallaro and John Borton of ''Sportvision'', sponsored by Google and Joby Energy in association with the San Jose State University aeronautics department to demonstrate that it is possible to sail directly downwind faster than the wind. In a test supervised and recognized by the North American Land Sailing Association in July 2010, Cavallaro achieved a speed of in winds: almost three times the speed of the wind.〔 - Explanation of the Blackbird workings and its physics.〕 == History == In 2006, following a viral internet debate started by Rick Cavallaro as a brain teaser,〔(boat design ) lengthy discussion, linking to many other discussions on this topic.〕 a propeller-driven land yacht was built and filmed, demonstrating that it is possible to sail 'dead' downwind faster than the wind by the power of the available wind only. In 2009, professor Drela of MIT worked out the equations for such a device and concluded that one could be built "without too much difficulty". Other researchers arrived at similar conclusions.〔, (A lecture about upwind-carts & DDWFTTW-carts at the Technical University of Denmark )〕 In the same year, after being challenged that the video was a hoax, team members Rick Cavallaro and John Borton of ''Sportvision'', sponsored by Google and in association with the San Jose State University aeronautics department, built a test vehicle nicknamed Blackbird. A year later, in 2010, Cavallaro successfully tested the vehicle, achieving more than 2 times the speed of wind,〔 - Explanation of the Blackbird workings and its physics.〕 definitively demonstrating that it is possible to build a vehicle which can achieve the claim. A second test with an improved vehicle in 2011 reached close to 3 times the speed of wind. After proposing the vehicle's design, and presenting the analysis to demonstrate its viability, the Blackbird team learned that others had previously conceived and built similar designs - most notably Andrew Bauer of Douglas Aircraft built and demonstrated such a vehicle in 1969, based on an analysis presented in a student's paper from some 20 years earlier.〔, (Picture of Bauer with his cart )〕〔.〕 Bauer observed "a rearward deflection of a foot-long tuft located about 12 feet forward of the propeller plane" thus conclusively demonstrating that his vehicle went faster than the wind (that is, Bauer observed that a streamer located well forward of the propeller was deflected backwards by the apparent wind, meaning that the vehicle was going faster than the real wind). There are no known independent verification to Bauer's claims, although there are several sources of engineering and scientific articles, explaining the theory and physics of such a device.〔〔〔 〕〔 (【引用サイトリンク】title=A lecture about upwind-carts & DDWFTTW-carts at the Technical University of Denmark )〕〔A similar device was built and tested in 2006, see 〕 Besides still photography, a film has been found showing it in operation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Blackbird (land yacht)」の詳細全文を読む スポンサード リンク
|
