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The overall concept of the boat involves providing the skipper with a degree of active control which compares to that provided to a pilot of a glider or sailplane. At speed, the boat hulls rise free from the water surface through aerodynamic lift generated by a wing in ground effect. Once the hulls are free from the surface, the skipper is able to actively control the boat in roll, height and yaw. The high degree of active control enables the skipper to maintain the hulls free from the water surface for prolonged periods of time.
In this configuration, only a single keel and rudder with 'T' hydrofoil is penetrating the surface of the water. The maximum speed of the boat is restricted by the cavitation speed of the keel and rudder foils. Since the skipper is able to actively control the height of the boat above the water surface, he is in effect controlling the depth of penetration of the keel and rudder foils. These foils form the largest contributors to the overall drag of the boat, therefore actively controlling the height of the boat is an active form of speed control. This process enables the skipper to maintain a boat speed close to the incipient cavitation speed of the underwater foils for prolonged periods when the boat is subjected to a range of conditions.
The v-44 can sail on both port and starboard tack; the wing-sails and keels roll
through 90 degrees as she turns through the wind. The vertical sail becomes the horizontal wing and the horizontal wing becomes the vertical sail. As the boat tacks, transposing of keels takes place, enabling the use of a cambered foil. The use of camber increases the performance and cavitation speed of the keel.
Each rigid wing-sail of v-44 is split into an inner and outer plank (four planks in total). Each plank is free to rotate or ‘weathervane’ about its longitudinal axis, aligning itself into the air stream. Similarly, each wing-sail outrigger is free to rotate about the same axis described above. When an outrigger is not in contact with the water, it simply 'weathervanes' or aligns into the air stream. With a given plank, the angle of attack relative to the air stream is determined by the degree of flap deflection at the trailing edge. Referring to the cross-section through the wing-sail, with zero flap deflection, a plank produces zero lift. Increasing upward deflection of a given flap induces increasing lift from the plank.
The adopted aerodynamic design makes it necessary for each plank to mimic the behavior of a tubular or axisymmetric structure centered at the axis of rotation. A tubular structure, or one which behaves as such, which is free to rotate about its longitudinal axis, has no motive to rotate under bending loads. This requirement is essential to preserve the close coupled aerodynamic balance of the wing-sails.
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