Sailing faster than the wind

Sailing boats ( sailboats, ice sailing and land sailer) can reach speeds greater than the speed of the true wind. This requires a slight resistance in the movement over the surface, and a sail having a sufficiently high glide ratio.

Physics

The apparent wind produced on the bearing surface ( Sail) a force (according to the slip ratio of the airfoil ) can have an angle of almost 90 ° relative to the apparent wind. So until not come directly to the apparent wind on the wing from the front, this force can have a forward component that drives the sailors. A sailor can say, speeding or keep his driving, even when the apparent wind is inclined from the start, as is the case when you go quicker than the wind.

On space Wind courses can sailors there is a parallel from the true wind -speed - component ( downwind VMG) develop, which is greater than the true wind speed. So that they can overtake the air mass in Wind direction through Kreuzen from the wind. This somewhat counterproductive - intuitive fact can one is best illustrate with reference to an vector - diagram.

A classic sailors can, however, following in not:

• Direct sail against the wind
• Sail directly downwind faster than the wind

In both cases, the apparent wind comes directly to the wing from the front. If the construction is, however, allowing the wings to move relative to the vehicle, so the above limitation for the courses to the wind no longer apply. This is the case with the rotor sailors.

Classic sailors

Sailboats

Sailing boats with a displacement hull make it because of the high water resistance hardly to sail faster than the wind. Glider, however, reach significantly higher speeds. In 2009, the trimaran Hydroptère a world speed record of 95 km / h with a wind of 55 km / h.

Although kitesurfers and windsurfers achieve similar top speeds, but mostly a lower multiple of wind speed. Rob Douglas in 2010 was at about 80 km / h Wind on a record with a kiteboard of 103 km / h.

The most efficient sailboats achieve a downwind VMG, which is more than double the wind speed. In 2010 America's Cup winning yacht sailed the 37 km with the wind in 1 hour 3 min. This was their downwind VMG 2.5 times the wind speed.

Ice yachts

Ice yachts routinely reach a multiple of wind speed due to the low friction between sled and ice. It has been reported of speeds over 200 km / h reliable but 135 km / h are confirmed by measurements with GPS.

Country sailors

The country sailors Green Bird Established 2009 set a world record for wind-powered land vehicles of 203 km / h with the wind speed 50-65 km / h, respectively.

Rotor sailors

In the rotor sailors the wings rotate about a horizontal axis, so they learn a different apparent wind than the vehicle. Its rotation is linked to the movement of the vehicle, for example, via wheels on land, or a second rotor in the water. In contrast to the classic sailor rotor sailors can go faster than the wind directly into the wind, both theoretically as well as directly from the wind. While the rotor braking is applied in both cases the true wind, the direction of the power flow to and from the different wheels (or propeller ):

• Directly opposite the Wind: The air - rotor acts as a turbine, which drives the wheels (or the water propeller).
• Directly in front of the wind faster than the wind: air - rotor acts as a propeller that is driven by the wheels (or of the water turbine).

The maximum speed in both directions is not, however, limited by the efficiency of the wind speed. In practice, however, although boats can go directly into the wind, so far in any of the two directions faster than the wind. Land vehicles, however, have demonstrated practically faster than the wind, both directly before the wind faster than the wind, as well as directly into the wind.

Built in 1969, Dr. Andrew Bauer a rotor - car, which reached 1.2 times the wind speed directly from the wind. This result was significantly exceeded on 2 July 2010, when the propeller - Cart Black Bird 2.8 times faster than the direct tailwind drove and thus the first certified world record in this category aufstellte .. On June 16, 2012 represented a turbine version of the Blackbird on another world record with 2.1 times the wind speed directly against the wind.