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Aviation History
1962
1962 - 3071.PDF
FLIGHT International supplement, 20 December 1962 Air-Cushion Vehicles The third experiment (191 J), with a propeller for propulsion Although free flights had not been attempted, Robertson Porter felt that both devices had performed well enough in their tests to vindicate his theory and to justify further investigations on similar but much more ambitious lines. His third machine was constructed in 1911 and completed during August of that year. In general layout it was a modification of the second, the lack of rigidity of which dictated a reduction in external diameter to 8ft. The design constituted the integration of the results obtained with the previous types and was a considerably refined and advanced concept. As improved lift had been derived by covering in the area below the turbine disc, this feature was incorporated and the airflow was supplemented by the provision of a bell-shaped intake struc ture mounted above the annular deflec tor. The sides of the intake were formed to impart a gentle initial curvature to the air flow so that it was drawn at a less acute angle into the turbine, now equipped with four blades to maintain as steady a pressure of air as possible into the deflectors. As an added inducement to increased pressure, the angle of curva ture in the deflectors had been reduced to avoid losses occasioned in earlier trials by too sharp a deflection of the airstream. In addition to the principle of rising vertically by providing a continuous curtain of air surrounding the pilot and engine, provision was made in the third machine for forward motion by extend ing the turbine overhead-drive shaft to turn a normal pusher propeller at the rear. Greatly increased power was now provided by a Gnome rotary engine and, as the workshop lacked sufficient room, the inventor intended to test the machine at Brooklands during the summer of 1911. Recorded results of further trials, however, do not appear to have survived. Robertson Porter's activities in the field of the vertical riser extended for at least a further eighteen months, as he exhibited his "Gyropachute" at the 1913 Olympia Aero Show. This was larger than any of his earlier machines, having a diameter of 14ft, and was about 11ft in height. The 50 h.p. Gnome drove the centrifugal fan inside the annular shroud and was equipped with a reverse gear. Forward motion was expected to be imparted by the controllable flaps fitted in the path of the airstream inside the deflectors. In the light of the successes of the past few years, Robertson Porter's experi ments in direct lift reveal him to have been yet another of those visionaries with a mind containing ideas well ahead of their time. He had sufficient motive power at his disposal, and the main reason for the apparent failure of his machines would appear to be that the gap between the annular outlet and the ground surface allowed the almost com plete dispersal of the air cushion. In the centre of this photograph, at the 1913 Olympia Aero Show, is Robertson Porter's fourth machine, the "Gyropachute" (50 h.p."Gnome) fOLSEtr ,J» es, & w>f..... • .-...•• • • pj2j£fc ?- f-*JJ-JT 116
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