Coandă 1911 Monoplane-Romanian Henri Coandă’s 1911 aircraft utilized wing warping and two 70 hp (52 kW) Gnome rotary engines coupled to a single propeller. It was one of the first twin-engine aircraft to fly.
Deperdussin-de Feure Model 2-The Deperdussin-de Feure Model 2 was designed by Georges de Feure and built in France in 1909. The unique aircraft featured a canard design, contra-rotating propellers, and movable wings to alter the center of pressure.
DuBois-Riout Ornithopter-Ornithopters are aircraft that use flapping wings to achieve flight. French engineer René Riout built his first full-size ornithopter in 1913. Although impressive, the machine was not a success.
Papin-Rouilly Gyroptere (Gyropter)-The French Papin-Rouilly Gyroptere was an early attempt at vertical flight. However, its design was deficient, and its unique power and control systems proved too advanced for 1915.
Petróczy-Kármán-Žurovec PKZ 2 Helicopter-Stephan Petróczy von Petrócz, Theodor von Kármán, and Wilhelm Žurovec combined their abilities to create a tethered helicopter that used three La Rhône rotary engines to power contra-rotating rotor blades.
Rumpler-Loutzkoy-Taube Aircraft-Boris Loutzkoy’s power system was the first to employ coaxial propellers that rotated in the same direction. Installed in a Rumpler-Loutzkoy-Taube aircraft in 1912, the system was not a success.