Americas Cup 2010: BMW Oracle Wing-Sail

The 33rd 2010 Americas Cup was won 2-0 by  the challenger BMW ORACLE trimaran powered by main rigid wing-sail, which showed to be far superior to the soft sail catamaran ALINGHI.

VPLP who designed BMW ORACLE reports that:

• The primary advantage of the wing over a soft sail is that it is easier to control and does not distort. This makes it easier for the trimmers on board to maintain an optimum aerofoil shape in a wide range of conditions.
• The wing-sail trimaran sails upwind and downwind at apparent wind angles of 20 - 30 degrees (monohulls typically sail at 30 - 40) 
• The trimaran can sail up to 3 times the wind speed. 

This fits with the computational results presented in The Mathematical Secret of Flight and  Why It Is Possible to Fly and Why It Is Possible to Sail: With an apparent angle of 30 degrees and a speed of 2 times the wind speed, the effective angle of attack is about 10 degrees, which is an efficient regime for a wing but not for a soft sail. At a wind of 5m/s the BMW ORACLE could beat upwind at 10 m/s about 20 knots.  See the 68 m wing-sail!  See the performance. Extreme engineering!

The lift at 10 degrees angle of attack is mainly coming from the leading edge, which favours 

a high narrow wing-sail, just as seen. Compare with Omer Wing-Sail.