Snecma C.450 Coleoptere

The Sencma C.450 Coleptere was a French VATOL research aircraft.

Development
Undoubtedly one of the two most interesting research aircraft to be produced during 1958 (the other being the North American X-15), the SNECMA C-450 Coléoptére consists of an annular wing mounted coaxially about a fuselage incorporating an Atar EV turbojet and cockpit. The power plant provides a thrust/Weight ratio of 1.4:1 which is sufficient to enable the Coléoptére to perform the thrust-versus-gravity manoeuvre demanded for vertical take-off. Technical considerations inﬂuencing the choice of an annular wing include the possibility of reducing structural weight and using the wing as the outer wall of an integral ramjet power plant.

The sole prototype was destroyed on its ninth flight on 25 July 1959. While there were intentions at one stage for a second prototype to be produced, financing was never sourced.

Design
The Coléoptère featured a central core akin to the Atar Volant, but differed in that the fuselage was surrounded by an annular wing greatly resembling the proposals made by von Zborowski. Aerodynamic control and stability was regulated by a series of four triangular winglets, which were installed upon the outwards side of the annual wing; however, these were only effective during conventional horizontal flight. Instead, control while hovering was provided by a series of deflecting vanes within the engine exhaust. The undercarriage of the Coléoptère consisted of four relatively compact castored wheels.

The pilot controlled the aircraft from within an enclosed cockpit; however, the pilot's position was somewhat unorthodox. To accommodate the changing orientation of the aircraft between vertical and horizon flight, the pilot was seated upon an ejector seat that would tilt appropriately to match the flight mode of the aircraft, moving so that they would be seated nearly-upwards during the vertical phase of flight, such as landing and taking-off. The intakes for the powerplant, a single SNECMA Atar axial-flow turbojet engine were positioned on either side of the cockpit. While the aircraft had been designed by SNECMA, the majority of the manufacturing process was performed by another French aircraft company, Nord Aviation.