The Santos-Dumont No. 6 was an airship designed and built by the Brazilian pioneer aviator Alberto Santos-Dumont. In 1901 it was used by him to win the Deutsch de la Meurthe prize for a flight from Parc Saint Cloud to the Eiffel Tower and back within thirty minutes. Background In April 1900 Henri Deutsch de la Meurthe offered the Deutsch de la Meurthe prize, also simply known as the "Deutsch prize", of 100,000 francs to the first machine capable of flying from the Aéro-Club de France's flying field at Parc Saint Cloud to the Eiffel Tower in Paris and back in less than thirty minutes. The winner of the prize needed to maintain an average ground speed of at least to cover the round trip distance of in the allotted time. The prize was to be available from May 1, 1900 to November 1, 1901. To win the prize, Alberto Santos-Dumont decided to build dirigible No. 5, a larger craft than his earlier designs. On August 8, 1901 during one of his attempts, the airship began to lose gas, causing the envelope to lose shape and making it necessary to shut down the engine, which also powered the ventilator which inflated the internal ballonet. It started to descend and was unable to clear the roof of the Trocadero Hotel. Santos-Dumont was left hanging in a basket from the side of the hotel. With the help of firemen he escaped without injury, but the airship was a write-off, only the engine being salvaged. Design After the wreck of No.5 Santos Dumont immediately started work on a replacement, which was finished by September 1. Similar to the No.5 but slightly larger, it had an envelope of varnished silk from which an elongated uncovered gondola was suspended by steel wires. The envelope was fitted with a single manoeuvering valve and two automatic pressure-relief valves: in addition there were two ripping panels to enable hydrogen to be rapidly vented in an emergency. The triangular section gondola was constructed of lengths of pine connected with aluminium sockets and braced with piano wire. The 12 hp (9 kW) engine was mounted in the centre of the gondola and drove a two-bladed pusher propeller at the rear via a long driveshaft. The pilot stood in a small balloon basket at the front. The triangular rudder was carried between the rear of the gondola and the envelope. Operational