Léon Levavasseur (8 January 1863 – 26 February 1922)[2] was a French powerplant engineer, aircraft designer and inventor.

[9] Blériot tried to dissuade the directors of Antoinette from becoming aircraft manufacturers, fearing that they would begin competing against their own customers.

[11] This convinced Levavasseur that Latham could cross the English Channel in an Antoinette aircraft and win the Daily Mail prize for doing so.

Between Latham's attempts, former Antoinette vice-president Blériot successfully crossed the Channel in his own aircraft.

[15] Latham's efforts to promote Levavasseur's Antoinette products were more successful at the Grande Semaine d'Aviation de la Champagne on 22–29 August 1909 at Reims, France, where he won the altitude prize, finished second in the speed competition, took third place in the Gordon Bennett Cup for aeroplanes, and, in the Grand Prix event, trying to fly the longest distance around the circuit in a single uninterrupted flight, he won second prize in one aircraft (an Antoinette IV) and fifth prize in another (an Antoinette VII).

[23] The variable area wing design[24][25] won Levavasseur a "Safety in Aeroplanes" prize[26] and was later acquired by the French government.