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transparency. The Gyropter would have four ballast tanks located around the rim of the disc for controlling trim and an upper fin and rudder. Wibault also expected the rotor to provide a degree of gyroscopic stability. No details of dimensions or weights were pro- vided, but an initial prototype would have been similar in both respects to the Avro Canada Project Y2 research craft and fitted with a fully retractable three- or four-strut undercarriage. The first design in this series was completed in mid-1953 along with larger versions of the Gyropter using multiple enclosed rotors. Wibault also evolved the air- craft’s disc planform into more of a spade- shaped delta and the final concept from this series showed a sleek VTOL transport aircraft that still looks very contemporary with three lift rotors and two jet engines at the rear, fed with air from all three rotors. Michel Henri Wibault was a well-known Paris-based designer with a number of air- craft to his credit and a strong interest in VTOL technology. In 1950 Wibault began working on a disc-shaped aircraft that he called the Gyropter. It utilised an enclosed rotor system that would provide a full VTOL and hover capability while also allowing high-speed level flight. Air would be drawn in around the upper stator and driven downwards, while the enclosed rotor was protected from the influences of airflow during horizontal flight. The rotor would be driven by several tip- mounted jet engines or ramjets protruding from the fuselage, with fuel (and possibly air) fed along the hollow rotor arm. This might seem rather a complicated arrangement, but tip-driven rotors eliminate problems associ- ated with torque. Forward flight would be achieved by adjustment of the airflow from the rotor and supplementary jet engines seemed a certainty. The initial design was for a one-man vehi- cle, with the cockpit located in the centre of the main hub and covered by a dome-shaped An early design by Michel Wibault for a blower unit capable of providing aircraft with VTOL performance. via Bill Rose 99 Above: Cross-section of the Wibault tip-driven rotor design for his VTOL aircraft concepts. via Bill Rose Right: Michel Wibault’s design for a three-rotor VTOL transport aircraft. via Bill Rose Postwar Discplane Development