Manufacturer Lohner-Werke | ||
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The Lohner Type AA (a.k.a. Lohner 10.20, 10.20A, 10.20B, 111.03 and Lohner D.I) were a series of three prototype fighters built during World War I. The program would eventually be cancelled due to inherent instability concerns of the design.
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Design and development
In 1916 the manufacturing company Lohner-Werke of Vienna was given a contract from the Luftfahrttruppen to design and build a single seat fighter based around the 185 hp Austro-Daimler six-cylinder inline engine. Work was begun on the first airframe, serial number 111.01, and on 5 September 1916 the Lohner 10.20 was unveiled at Aspern. It was a single-bay biplane with equal-span wings and I-type struts. The empennage incorporated a conventional horizontal stabilizer with no vertical stabilizer and an abbreviated all-moving rudder. The fuselage was short and deep of laminated wood construction, armed with twin synchronized Schwarzlose machine guns.
During taxi trials, insufficient yaw control was reported with a tendency to "swap ends". A larger rudder was installed and the fuselage lengthened from 4.65m (15ft 3in) to 5.85m (19ft 2in). The Lohner 10.20 first flew on 29 December 1916 and exhibited poor stability. Further test flights followed and the prototype was severely damaged when it crashed in February 1917.
The fighter was sent back to the Lohner-Werke factory where repairs and extensive modification were completed. Now referred to as the Lohner 10.20A, the fuselage was again lengthened to 6.35m (20ft 10in), the I type struts were replaced with the more common twin struts with wire braces. The tail was completely redesigned with a fixed vertical fin and an even larger rudder. Flight testing of the 10.20A continued until 6 June 1917, when it was totally destroyed in another crash.
The second fighter prototype built was serial number 111.02, called the 10.20B. Tail surfaces were similar to the 10.20A and a deep dorsal fin was added. The I-type wing struts returned, reinforced by inclined V-struts. Its initial flight was at Aspern on 2 June 1917. In August 1917 the Luftfahrttruppen commandeered 10.02B and official trials continued through October when further development of this airframe ended.
The third and final airframe built was known only as 111.03. The I-type struts were again dropped in favor of the twin struts with wire braces and in an effort to gain directional stability the dorsal fin became even more pronounced. First flown on 28 June 1917, flight testing continued through October. Due to the lackluster performance, further development was halted and the Luftfahrttruppen assigned Lohner-Werke a licence to produce the Aviatik (Berg) D.I.
Specifications (Type AA 111.03)
Data from: Green and Swanborough