| 摘要 |
<p>A new boomerang consists of a planar annular body of stream-lined cross section with three wings extending radially from its outer perimeter. The wings are twisted to produce aerodynamic lift when the boomerang is spinning and the plan form area of the body central opening is greater than the total plan form area of the wings. The device can be moulded from plastic and preferably has on the perimeter of the central annulus a cushion layer of softer elastomeric material. The relatively large central opening gives improved performance as a boomerang, and also facilitates catching of the device by the thrower when it returns.</p> |
