Leduc 010, Musée de l'Air et de l'Espace, Le Bourget, 20 June 2007. The flight of the Leduc 010 on 21 April 1949 with its ramjet operating represents the first flight of an aircraft solely propelled by a ramjet engine. One of the ramjet's main problems is its absence of thrust when it is motionless. To obtain an initial speed necessary for the startup of the engine, Rene Leduc thought of releasing his apparatus at altitude from a transporter aircraft. The selected aircraft was a four-engine transport SE-161 "Languedoc" especially modified.