Kawanishi K-7 Transport Seaplane
The Kawanishi K-7 Transport Seaplane was a Japanese single-engined biplane floatplane of the 1920s. Eleven were built from 1924 to 1927, being used to carry passengers and airmail. Design and development. In December 1923, Eiji Sekiguchi, chief designer of the aircraft department of "Kawanishi Kikai Setsakuho" (Kawanishi Machinery Manufacturing Works), started design of a new high speed transport floatplane to equip "Nippon Koku KK" (Japan Aviation Co. Ltd.), an airline subsidiary of Kawanishi. Sekiguchi designed a single-engined sesquiplane (i.e. a biplane with the lower wing much smaller than the upper wing) of all-wooden  construction. Seating for four passengers was provided in an enclosed cabin, while the aircraft's two pilots sat in individual open tandem cockpits aft of the passenger cabin. The aircraft was powered by a single Maybach Mb.IVa water-cooled inline-engine providing 305 hp (228 kW), an engine type usually used to power Zeppelins or "Riesenflugzeug" like the Zeppelin-Staaken R.VI, received as part of Germany's reparations to Japan after the end of the First World War. The first example of the new aircraft, the K-7A Transport Seaplane was completed in November 1924, demonstrating both good performance and  handling. A further nine K-7As were built by the time production ended in 1927, together with a single example of the K-7B Mail-Carrying Aircraft, a modified version that could be operated either on floats or with a tailwheel undercarriage. Operational history. The K-7A entered service on "Nippon Koku"'s service between Osaka and Fukuoka in January 1925, mainly carrying airmail rather than passengers. The K-7A proved successful in service, one carrying mail from Fukuoka and Shanghai, China, a distance of over in May 1926, while the K-7B was used together with the Kawanishi K-10 Transport to operate an airmail  route between Osaka and the Japanese occupied city of Dalian in September 1926. The K-7A continued in use until 1929, when "Nippon Koku" was forced to be disbanded, with its routes transferred to the government owned "Nihon Koko Yuso KK" (Japan Air Transport).