| 摘要 |
A plastic shell, shaped in the form of a football contains a pair of internal brackets. A gyroscope is rotatably attached to these brackets with its axis of rotation coincident with the axis of rotation of the football. A flexible plastic gear rack engages a pinion gear on the gyroscope, and when pulled through the football, sets the gyroscope in motion. When thrown, the football assumes a nearly perfect spiral rotation during flight.
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