One of the most extraordinary of the 1950s and 60s VTOL projects was the French Coleoptere annular wing. Early trials were made with an Atar turbojet mounted in a special test rig, fitted with a four-wheeled undercarriage. After unmanned trials, a piloted version, the "Atar Volant", made its first tethered hovering flight on April 8, 1957 , followed by a free flight on May 14. The next step was to enclose the Atar in a fuselage, surrounded by an annular wing to allow the machine to transition from vertical to horizontal flight.
So it was on only the Coleoptere's 7th flight, when it failed to complete its first transition. The pilot ejected and the Coleoptere shot off at about 50 degrees before crashing, bringing an end to the program.