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
Scarlet Sails (film) Scarlet Sails (film) Scarlet Sails () is a 1961 Soviet film produced by Mosfilm and directed by Alexandr Ptushko. It is based on Alexander Grin's 1923 adventure novel of the same name and stars Vasily Lanovoy and Anastasiya Vertinskaya. The story is a romantic fantasy and is described as a "fairy tale", though it contains no overtly supernatural elements. The setting is a small fishing village. The former seaman Longren raises his daughter Assol alone after losing his beloved wife, making a meager living by selling the toy boats he carves from wood. As a child, Assol encounters an old