Because the powered Flyer was too large and heavy to be launched by hand, the Wrights spent $4 on four 4.5m (15ft) lengths of 50 x 100mm (2 x 4in) timber laid on edge, end to end, and sheathed with a thin strip of metal. After the pilot released a restraining line, the aircraft was carried along the 18m launch rail on a small dolly riding on a roller made from a modified bicycle hub, which was left behind on take-off. A second roller was attached to a cross-member at the front of the lower elevator supports. A helper at each wingtip steadied the aircraft until flying speed was attained.
After an abortive attempt on 14 December, the Flyer made four flights from level ground into a 17.4-23.5kt (32-43.4km/h) wind on 17 December. This was the first time in history that a piloted aircraft incorporating a proven three-axis control system had made unassisted take-offs from the level under its own power and achieved sustained and controlled flights.
Source: Flight International