Nevertheless, Lilienthal's contributions to the development of heavier-than-air flight remain significant. He made over 2000 flights in gliders of his design between 1891 and his death five years later. Lilienthal helped to prove that heavier-than-air flight was practical without flapping wings, laying the groundwork for the Wright brothers a few years later to build the first successful powered airplane.
Lilienthal suffered a number of crashes in his experiments, but his aircraft could only reach low speeds and altitudes. On 9 August 1896, a gust of wind fractured his wing and he fell from a height of 17 m, breaking his spine. He died the next day, saying, "Opfer müssen gebracht werden!" ("Sacrifices must be made!")