Forces on sails to stay within the limitations of a craft's stability and power requirements, which are functions of hull (for boats) or chassis (for land craft) design. Sails derive power from wind that varies in time and with height above the surface. In order to do so, they are designed to adjust to the wind force for various points of sail. Both their design and method for control include means to match their lift and drag capabilities to the available apparent wind, by changing surface area, angle of attack, and curvature. Wind speed increases with height above the surface; at the same
Black Sails EP Black Sails EP Black Sails EP is an extended play by the American rock band AFI. It was released on April 27, 1999, through Nitro Records. Only 5,000 copies were pressed. It is a sampler of the band's fourth studio album "Black Sails in the Sunset". The first three tracks can be found on the album "Black Sails in the Sunset", with several minor changes. On the full-length album, "Porphyria" is re-titled "Porphyria Cutanea Tarda" and contains a crossfade into the next track, "Exsanguination". "Who Knew?" is a B-Side from the full-length album, and appears on the Japanese edition of