| 摘要 |
A windage brake for a fan descender comprises a rotatable spool connected by drive belts to a fan comprising a radial flow air impeller. A line is wound helically upon the spool. A user of the fan descender puts on a harness (not shown) at the free end of the line and jumps from an elevated position. The line is thereby drawn off the spool and rotates it. The rotating spool drives the fan and also winds a power spring formed by a resilient strip. The windage of the fan regulates the descent of the jumper, the fan being accelerated to a speed at which the braking force is such that the jumper descends at a rate safe for landing on the ground. When the jumper is on the ground, he removes the harness and releases the free end of the line. The line is then automatically retrieved by the power spring and rewound on the spool. |
