Félix du Temple de la Croix

[5] Félix du Temple patented the designs for his aerial machine in 1857,[5][6] which incorporated a retractable wheel landing gear, a propeller, a 6 hp engine and a dihedral wing design, under the title "Locomotion aérienne par imitation du vol des oiseaux" ("Aerial locomotion by imitation of the flight of birds").

[1] As they tried to build a machine capable of carrying a man, they realized that steam engines lacked power and were too heavy.

They also experimented with the new internal combustion gas engine design developed by Lenoir, but this also lacked the necessary power.

Du Temple continued his research and finally succeeded in creating a very compact high-speed circulation steam engine, for which he applied for a patent on 28 April 1876.

The engine used very small pipes packed together "to obtain the highest possible contact surface for the smallest possible volume" [7] In 1874, the two brothers built the Monoplane, a large plane made of aluminium in Brest, France, with a wingspan of 13 meters and a weight of only 80 kilograms (without the pilot).