M.Simons The World's Vintage Sailplanes 1908-45
THE RS-1 ZANONIA
In 1936 Harvey Stephens, an actor, commissioned Harland Ross to design him a high performance sailplane. It was ready in the following year. The Ross-Stephens 1, Zanonia, was wooden with a single-spar, ‘gull’-form wing, an
oval, plywood-covered fuselage, pendulum elevator and contoured cockpit canopy. It had a relatively small wingspan but quite a good aspect ratio with a high wing loading by contemporary standards. Ross chose the latest American aerofoils from the NACA four-digit series, the 2418 for the wing root, tapering to 2412, a thinner version of the same basic profile, for the tip, with 3.5 degrees washout to prevent tip stalling. Spoilers were fitted on the upper surface of the wing. These were of unconventional type operated by heel pressure on the base of the rudder pedals. They could be operated both at once for landing but to start a turn one could be opened to drop one wing without the ailerons and rudder, whilst the other remained shut. This produced a very quick turn. There was a small landing wheel, rather well buried in the fuselage belly, leaving only minimum ground clearance.
Competing in the 1937 US Nationals. Ross finished fifth, making one very good cross-country flight of 194 km, during which he flew between thermals at what was thought to be very high speed, over 130 km/h. Unfortunately, before the contest was over another glider, stalling on the approach, crashed on top of three other sailplanes on the ground and the RS-1 was badly damaged.
Stephens was not an experienced pilot at that time and probably found the aircraft too fast for him. He damaged it later in the year of delivery and it required extensive repairs. Probably the all-moving tailplane was redesigned at this time, Ross having recognised the need for greater stability. Henceforth the Zanonia flew with a tailplane mounted on top of the fuselage in front of the fin, with a hinged elevator. The modification also reduced the risk of damage on take-off or landing.
Stephens later struck a hidden obstruction when landing in an otherwise good field, and further extensive repair work was necessary. Soon after this the Zanonia was bought by John Robinson and its contest-winning and record-breaking career began. Robinson did a great deal of careful filling, sealing and polishing. The wheel was removed and a drop-off dolly was substituted for take off. The results were astonishing. The stalling speed was reduced from 80 to 61 km/h and then the best glide ratio was found to be 1 : 29.7 at 76 km/h. He often flew at wing loadings of 26.8 kg/sq m (5.5 Ibs/sq ft) and between thermals usually flew at 120 km/h. On very strong days, 145-160 km/h inter-thermal speeds were used in competition flying. He won the US Nationals three times, in 1940, 1941 and 1946, placed 3rd in 1947 and 2nd in 1948.
Robinson in the Zanonia set national distance records of 466 km in 1940 and in 1947, 523 km. He also made a great altitude flight from Bishop in California on New Year’s Day, 1949, when he broke the World Altitude record with an ascent to 10210 metres (33,500 ft), surpassing Paul MacCready’s flight of the previous day in the Orlik. In 1950, Robinson became the first pilot in the world to win all three diamonds for his gold badge. The record distance and altitude flights of 1947 and 1949 counted for two diamonds, the third came with a 355 km goal flight from El Mirage, California, to Overton, Nevada.
Robinson owned the Zanonia for 13 years, selling it at last in 1952. After being damaged in 1958 by its then-owners, the Zanonia was repaired but not flown much until, in 1974, it was again restored by Paul Gibson in Seattle, who finally sold it in turn to a vintage glider enthusiast in Connecticut.
RS-1 Zanonia: Span, 14.02 m. Wing area, 11.29 sq m. Aspect ratio, 16.93. Empty weight, 168 kg. Flying weight, 272 kg. Wing loading, 24.1 kg/sq m. Aerofoils, NACA 2418 at root, tapering to 2412 at the tips. Best glide, 1 : 29.7 (after 'clean up’ by Robinson).