The Greenbird ice craft assembled on Canyon Ferry Lake, Montana USA, January 2009.


How It works

Part aeroplane, part sailboat , part Formula One car

The most basic principle of wind-powered vehicles is harnessing and optimising airflow. Just as airflow over an aircraft's horizontal wing pushes the aircraft up, the flow of air over The Greenbird's vertical sail pushes the vehicle forward.

The Greenbird utilises a combination of technology, usually found on aircraft and Formula One, to achieve staggering efficiency. Made from carbon composites, the vehicle takes huge forces at top speed, being able to transfer up to one ton of side force into the ground.

Wind powered speed records are unlike any normal speed records where more power will almost always equal more speed. With land sailing speed records, more wind does not always equal more speed - instead a technical solution is required, where lift is maximised, but more importantly, drag is minimised.

How can it travel faster than the wind?

The Greenbird can travel faster than the wind thanks to a phenomenon known as ‘apparent wind’.

For example, you are riding your bicycle on a completely calm day with no wind. However, 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.

The Greenbird is so efficient that it can travel at up to 3 to 5 times the true wind speed on land.

An image showing apparent and true wind.

Here’s a more technical explanation of apparent wind


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