In the 1950s, military aircraft designers were becoming increasingly interested in developing VTOL (vertical take-off and landing) aircraft. In these early stages there were many unusual designs – perhaps most notable were the “tail-sitter” aircraft like the Convair XFY-1 “Pogo” and the Lockheed XFV-1 “Salmon”. In the mid ’50s the first jet-powered tail-sitter arrived in the form of the Ryan X-13 Vertijet. Then in the late ’50s the French unveiled the mother of all weird tail-sitters, the SNECMA C.450-01 Coleoptere.
SNECMA, or the Societe nationale d’etudes et de construction de moteurs d’aviation – which in English translates as the “National Company for the Design and Construction of Aviation Engines” – developed the aircraft based on experiences learnt from a previous VTOL aircraft, the SNECMA Atar Volant.
The SNECMA Coleoptere was a completley unorthodox aircraft from top to bottom. Whereas the Convair and Lockheed prototypes had more or less conventional wings and enlarged vertical stabilizers, the Coleoptere had an annular wing which wrapped around the aircraft’s fuselage like a giant barrel. Four small stabilizers at the rear of the wing provided directional control.
The cockpit of the aircraft featured a specially designed tilting mechanism for the pilot’s seat which allowed them to sit in a more upright position when the aircraft was vertical. However it didn’t help with rear visibility – which was virtually non-existent. And clearly that’s not a good thing when you’ve got to land the thing in reverse, with no visible cues, and no second chances.
Powering the aircraft was a SNECMA ATAR 101E.V turbojet engine which provided 8,157 lbs of thrust. To control the aircraft during take off and landing the engine was fitted with a jet deflection nozzle.
The SNECMA Coleoptere made several tethered flights in 1959 before attempting free flight. Several non-tethered flights of the aircraft in hover mode were successfully completed. It was reported that the aircraft was difficult to fly and unstable. Nonetheless, it flew.
However on July 25th 1959, during the Coleoptere’s ninth free flight, an attempted conversion from vertical to horizontal flight resulted in loss of control. The pilot, Auguste Morel, was forced to eject at an altitude of just 160 feet (50 metres). He was badly injured in the accident but survived. Unlike the Coleoptere was completely destroyed on impact. Following the destruction of the only prototype the program ended.
In the end the SNECMA Coleoptere was killed off not just by its catastrophic accident, but also by its own overly ambitious design. The annular wing worked, but the trade-off was unpredictable handling, poor rearward vision, a tiny payload capacity, short operational range and vulnerability to damage.
To put it bluntly, even if it had gone into production, it would have been virtually unusable as a military aircraft.