| 摘要 |
In an aerodynamically stable body 1 travelling along a path, the direction of travel 2 of the body may be changed by a certain angular amountχ1 by acting on the body 1 with forces Fa, Fb of a certain strength and duration. The duration must be short relative to the period of the natural oscillation of the body 1, and the forces must be directed such that their resultant F1 extends via the centre of gravity 6 in a plane 5 fixed in space and comprising the axis of symmetry 3, in which a change of direction is desired. Such an action of force will entail in said plane 5 a velocity contribution having a component Vt directed crosswise to the axis of symmetry 3. This velocity component Vt is added to the velocity of the body in the direction of travel 2 and gives the body 1 a new direction of travel 7, but entails also an angular difference between the new direction of travel 7 and the axis of symmetry 3. This angular difference is equalised during a course of settling, during which the axis of symmetry 3 will oscillate around the new direction of travel at gradually diminishing amplitude of the oscillation motion for eventually converging into the new direction of travel. By dividing the action of force into two parts which are released at two different, accurately controlled, points of time t1, t4, and the strength and duration of which are related to each other, respectively, at a fixed ratio, it may be obtained that the axis of symmetry 3 will swing smoothly into the new direction of travel 7 without any pendulous action. <IMAGE> |
