| 摘要 |
PROBLEM TO BE SOLVED: To give stability to an object towed by a flying airplane by shrinking the diameter of a circle against the force of an elastic means via a sleeve movable in the vertical direction to the plane of the circle as the drag is increased. SOLUTION: Blades 4, 5 are located at parallel locations where the angular moment caused by the air pressure applied to their free ends becomes equal to the angular moment in the opposite direction applied to the pivotal ends of the blades 4, 5 by the restoring force of a compressed spring 11 applied to the sleeve 6. When the speed of a towing airplane is increased, the cross sectional area generating drag is decreased. The blades 4, 5 have the minimum cross sectional area to generate the drag and form a substantially continued conical surface. The sleeve 6 is constrained not to be moved forward any more by lugs 9 colliding with the other ends of corresponding slots 10 respectively. |
