had been assembled. In order to simulate flight conditions, Santos-Dumont attached the aircraft under his latest non-rigid airship, the Number 14, which is why the aircraft came to be known as the "14-bis". The aircraft was then transported to the grounds of the Château de Bagatelle in the Bois de Boulogne, where there was more space. The forces imposed by the aircraft pulled dangerously at the airship's envelope, nearly tearing it and only allowing limited control. The danger of these tests caused Santos-Dumont and his team to quickly abandon them, although some useful information was obtained that led to adjustments in the balance and weight distribution of the aircraft. Further trials were made with the aircraft hung from a rope attached to pulleys running along a long steel cable slung between two posts, one high and the other high, much like a zip-line or tyrolienne of today. The first free-flight trials of the 14-bis took place at the Polo Ground in the Bois de Boulogne on 21 August, but were halted by damage to the newly fitted aluminium-bladed propeller, which replaced one with silk-covered wooden blades. After repairs another trial took place the following day; although the nosewheel left the ground, the aircraft had insufficient power to take off, and Santos-Dumont decided to replace the engine with a Antoinette. Trials resumed on 4 September without great success, and on 7 September, after the propeller was damaged, a new slightly larger one was fitted. On 13 September 1906 Aéro-Club de France observers gathered to witness an attempt to make a prize-winning flight. The aircraft failed to take off during a first attempt, but during the second it lifted and flew between at an altitude of about . The aircraft then landed in a nose-up attitude, breaking the propeller and bringing an end to the day's experiments. This brief flight did not qualify for any prize, but earned Santos-Dumont an ovation from the crowd. On 23 October, after a series of engine tests and high-speed ground runs (one of which ended as one wheel came loose, but this was quickly fixed), Santos-Dumont made a flight of over at an altitude of . This earned Santos-Dumont the first of the aviation prizes, 3,000 francs for a flight of or more. This landing damaged the aircraft slightly, but Santos-Dumont announced that he should be ready to attempt the 100 meters prize on 12 November