Buoyancy center of gravity

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For air and water transport is a center of lift ( English Center of lift ) denotes the point at which the dynamic lift forces that rise the vehicle against gravity attack. The distance between the center of mass of the body and the center of buoyancy influences its dynamic behavior in general and the basic construction methods differ in this aspect.

Examples

  • In the case of a watercraft, the stability during the transition to planing (see displacer and glider ) is relevant: the boat must not be lifted on one side at the front due to the ground effect and a center of buoyancy that is far forward, as otherwise it can overturn backwards.
Center of mass and lift with compensation by the elevator in an airplane .
  • In an aircraft , the center of gravity is in slow flight important: By ahead of the center of lift of gravity it tilts a stall forward and thus, accelerated again at a sufficient altitude and thus controllable. Gliders, for example, are designed in such a way that they are slightly top-heavy as long as the pilot has an average body weight - lighter pilots have to compensate for this with trim weights in the cockpit. For cargo aircraft, the permissible position of the center of gravity must be planned by the load master. The disadvantage of this design is that the center of mass lying in front of the center of lift must be compensated by a downforce on the horizontal stabilizer , which in turn is compensated for by a higher lift on the wing. This results in higher air resistance and thus fuel consumption.
  • Vertical take-off aircraft: In rotary wing aircraft such as helicopters , the center of mass is always below the rotor plane, which forms the center of lift. With stern starters this ratio is reversed, which makes maneuvering in hover more difficult. In quadrocopters, on the other hand, the two points are close to each other or at the same height, which requires rotation rate damping.

See also

Individual evidence

  1. ^ David F. Anderson, Scott Eberhardt: Understanding flight . McGraw-Hill Professional, 2001, ISBN 978-0-07-136377-8 , pp. 100- (accessed December 16, 2011). , P. 99.