Aviation Historian 17
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J.Forsgren - The Imperfect 10
Gerhard Fieseler beside Raab-Katzenstein Kl.1c Schwalbe D-1212 during the 1928 German aerobatic championships.
An Sk 10 taxies in after a solo training flight. An attractive, well-proportioned biplane, the type nevertheless required a much higher level of skill to fly than other contemporary trainers, particularly the de Havilland Moth, which some Flygvapnet officers felt was a more suitable training machine.
One of the first production Sk 10s was photographed on January 25, 1934, probably just before its delivery to Flygvapnet. The Walter Castor IA seven-cylinder radial engine was of Czechoslovakian origin, the Walter company being a specialist in small three-, five-, seven- and nine-cylinder radials throughout the 1920s.
The cockpit of Sk 10 c/n 19, serial 535, wearing the number of its unit, F 5, ahead of the national tri-crown marking, and individual code number “41” aft of it, as per standard in 1936. The controls were duplicated front and rear, and the type was intended to provide the requisite skills to convert to Flygvapnet’s Bristol Bulldogs.
The original RK-26 SE-ACO was re-registered as SE-ADK in 1932, before being sold in 1934 to the first of a number of new owners, including the Norrkoping Automobile Flying Club and Lennart Hemminger, who donated the aircraft for use by F 19, Sweden’s volunteer unit in Finland, in early 1940.
A report on the “Tiger-Swallow” in the June 1933 issue of American magazine Popular Flying explained that “the great strength of the machine is due to the use of tubes and sheets of Swedish nickel-chrome steel. This steel has a tensile strength almost triple that of the tubing and sheet used in most aircraft”. But it was also heavier.
German aerobatic champion Gerhard Fieseler with one of the Raab-Katzenstein biplanes he helped to design in the late 1920s. Fieseler would go on to win a German design competition for a STOL liaison aircraft in 1936 with his famous Storch.
A rare head-on view of the first RK-26 to be imported into Sweden, SE-ACO, which was fitted with a 200 h.p. Armstrong Siddeley Lynx, replaced on production Sk 10s with the heavier Walter Castor IA.
Retaining the Tigerschwalbe’s purposeful lines, the Sk 10 was nevertheless an entirely different animal, being considerably heavier - with a consequently higher wing loading - than its forerunner. In total, 25 examples were built, nearly three-quarters of which had been written off by the time the last example was retired in 1945.
A line-up of Sk 10s at Rinkaby airfield in southern Sweden in September 1936, by which time five of the 25 had been written off in accidents, although all of the mishaps that befell the type were ascribed to pilot error, rather than an inherent design flaw in the aircraft. Despite the high attrition rate, only two people were killed in Sk 10s.
The original RK-26 SE-ACO was re-registered as SE-ADK in 1932, before being sold in 1934 to the first of a number of new owners, including the Norrkoping Automobile Flying Club and Lennart Hemminger, who donated the aircraft for use by F 19, Sweden’s volunteer unit in Finland, in early 1940.