摘要 |
<p>The flat frame (1-5) of the toy kite etc., has a central longitudinal rod (1-3) and two oblique rods (4,5) joined to the central rod near the front end and diverging to the rear. The flying surface is formed by a single plastics sheet, divided into four zones by the frame members. The two rear zones (21,22) have an arrangement of slits (23,24) which form valves. The slits are open only to a negligible degree in normal flight, but open fully when the flying surface deforms due to irregular or excessive aerodynamic pressure.</p> |