Forces on sails: Difference between revisions

Revision as of 16:58, 13 March 2019

Revision as of 03:01, 4 June 2019

Line 2:

[[File:Points of sail--close-hauled (right) and down wind (left).jpg|thumb|right|300px|Aerodynamic force components for two points of sail. <br>''Left-hand boat'': Down wind with stalled airfow— predominant ''drag'' component propels the boat with little heeling moment. <br>''Right-hand boat'': Up wind (close-hauled) with attached airflow—predominant ''lift'' component both propels the boat and contributes

to heel.]]

[[File:Points of sail--English.jpg|thumb|right|300px|Points of sail (and ''predominant sail force component'' for a displacement sailboat).<br>A. Luffing (''no propulsive force'') &mdash; 0-30&deg;°<br>B. Close-Hauled (''lift'')&mdash; 30-50&deg;°<br>C. Beam Reach (''lift'')&mdash; 90&deg;°<br>D. Broad Reach (''lift–drag'')&mdash; ~135&deg;°<br>E. Running (''drag'')&mdash; 180&deg;°<br>True wind ('''V_T''') is the same everywhere in the diagram, whereas boat velocity ('''V_B''') and apparent wind ('''V_A''') vary with point of sail.]]

'''Forces on sails''' result from movement of air that interacts with [[sail]]s and gives them motive power for sailing craft, including [[sailing ship]]s, [[sailboat]]s, [[Windsurfing|windsurfers]], [[ice boat]]s, and [[Land sailing|sail-powered land vehicles]]. Similar principles in a rotating frame of reference apply to [[Windmill sail|wind mill sails]] and [[wind turbine]] blades, which are also wind-driven. They are differentiated from [[force]]s on [[wing]]s, and [[propeller]] blades, the actions of which are not adjusted to the wind. [[Kites]] also power [[Kite boarding (disambiguation)|certain sailing craft]], but do not employ a mast to support the airfoil and are beyond the scope of this article.