March 29, 2009 With a wind speed of just 30mph (48kmh), British engineer Richard Jenkins has set a new land speed record for a wind-powered vehicle at blistering 126.1mph. Driving the Ecotricity sponsored all carbon fiber land yacht Greenbird across the Ivanpah dry lake bed on the Nevada / California border Jenkins eclipsed the previous benchmark set a decade ago by American Bob Schumacher by almost 10 mph. It also continued a the rivalry between Britain and the United States for setting speed records that dates to the 1920s, when Sir Malcolm Campbell set several records on land and sea.
The Greenbird team were on stand-by in September 2008 at Lake Lefroy in Western Australia but were unable to run due to unseasonal rain. Jenkins has been chasing his dream of setting the record for 10 years and Greenbird is the fifth version of of the land yacht Jenkins originally called Windjet but renamed in a nod to Bluebird, the record-setting racers Britain's Donal Campbell drove in the 1950s and '60s.
The Greenbird is a 600 kg carbon fiber composite vehicle that uses wind (and nothing else) for power. The only steel in the vehicle is the wheel bearings and bearings used to make the vehicle steerable. The land yacht is a very high performance sailboat that uses a solid wing, rather than a sail, to generate movement. The aerodynamic design and light weight allows the vehicle to achieve speeds three to five times faster than the wind speed thanks to a phenomenon known as ‘apparent wind’.
For an example of apparent wind, imagine you are riding your bicycle on a completely calm day with no wind. You can feel wind on your face and it feels stronger as you pedal faster. That is because as you move forward, the motion creates its own wind. Now imagine you are riding your bicycle but there is a strong breeze coming at you from the right. This natural wind is called "true wind". When you add this side wind to the cycle ride, the wind the rider feels is now somewhere between the true wind (from the side) and the man made wind (from ahead). This resultant wind is know as the ‘apparent wind’ and will have a speed and apparent wind angle, measured from the direction of travel to the apparent wind angle.
Iron Duck, the previous record holder driven by American Bob Schumacher was a similar design and the record was set at the same location. The primary difference between the two is that where Greenbird is all carbon fiber the Iron Duck was steel framed with foam and fibreglass fairings.
Richard Jenkins also has an ice version of the Greenbird so the next challenge is to settle the debate about whether traveling on ice or land will be faster.
Paul Evans
Images via Greenbird.
