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The Beechcraft Model 18 (or "Twin Beech", as it is also known) is a six to 11-seat,〔 twin-engined, low-wing, tailwheel light aircraft manufactured by the Beech Aircraft Corporation of Wichita, Kansas. Continuously produced from 1937 to November 1969, (over 32 years, the world record at the time), over 9,000 were produced, making it one of the world's most widely used light aircraft. Sold worldwide as a civilian executive, utility, cargo aircraft, and passenger airliner on tailwheels, nosewheels, skis or floats, it was also used as a military aircraft.〔("Long Description: Beechcraft D18S Twin Beech." ) ''National Air and Space Museum'' of the Smithsonian Institution, Washington, D.C. Retrieved: December 17, 2014.〕〔("Factsheets: Beech C-45H Expeditor." ) ''National Museum of the U.S. Air Force'', Wright-Patterson Air Force Base, Dayton, Ohio. Retrieved: December 17, 2014.〕〔("Twin Beech: The 1930's airplane that set Beech Aircraft Corporation on a course towards 50 years of success" ), in ''Flying Magazine'', Feb. 1982, pp.26-30, Retrieved: Dec. 17, 2014 from Google Books.〕 During and after World War II, over 4,500 Beech 18s saw military service—as light transport, light bomber (for China), aircrew trainer (for bombing, navigation and gunnery), photo-reconnaisance, and "mother ship" for target drones—including United States Army Air Forces (USAAF) C-45 Expeditor, AT-7 Navigator, AT-11 Kansan; and United States Navy (USN) UC-45J Navigator, SNB-1 Kansan, and others. In World War II, over 90% of USAAF bombardiers and navigators trained in these aircraft.〔〔〔("Factsheets: Beech AT-11 Kansan." ) ''National Museum of the U.S. Air Force'', Wright-Patterson Air Force Base, Dayton, Ohio. Retrieved: December 17, 2014.〕 In the early postwar era, the Beech 18 was the pre-eminent "business aircraft" and "feeder airliner." Besides carrying passengers, its civilian uses have included aerial spraying, sterile insect release, fish seeding, dry ice cloud seeding, aerial firefighting, air mail delivery, ambulance service, numerous movie productions, skydiving, freight, weapon- and drug-smuggling, engine testbed, skywriting, banner towing, and stunt aircraft. Many are now privately owned, around the world, with over 300 in the U.S. still on the FAA Aircraft Registry in December 2014.〔〔〔Bauschspies, James S. and William E. Simpson, ("Research and Technology Program Perspectives for General Aviation and Commuter Aircraft" ), NASA Contract NASW-3554 for NASA, Sept. 1982, N83-17454#. Retrieved: Dec. 18, 2014. (In particular, see: Table 2.4 "COMMUTER CARGO FLEET IN 1981 - TOP TEN AIRCRAFT MODELS - NUMBER IN FLEET," which notes Beech 18 units are more than the next two aircraft ''combined'' (Convair 500/680 and Douglas DC-3), and more than the next three general aviation aircraft combined.〕〔("Beech 18" search results, FAA Aircraft Registry. ) '' Federal Aviation Administration''. Retrieved: December 17, 2014.〕 ==Design and development== By the late 1930s, Beechcraft management speculated that a demand would exist for a new design dubbed the Model 18, which would have a military application, and increased the main production facilities. The design was mainly conventional for the time, including twin radial engines, all-metal semimonocoque construction with fabric-covered control surfaces and tailwheel undercarriage. Less conventional was the twin-tailfin configuration. The Model 18 can be mistaken for the larger Lockheed Electra series of airliners which closely resemble it. Early production aircraft were powered either by two 330-hp (250-kW) Jacobs L-6s or 350-hp (260-kW) Wright R-760Es. The 450-hp (336-kW) Pratt & Whitney R-985 became the definitive engine from the prewar C18S onwards. The Beech 18 prototype first flew on January 15, 1937. Prior to the Pearl Harbor attack, the Beech 18 was outsold by the Lockheed 12 by two-to-one. However, war priorities forced Lockheed to concentrate on its heavier aircraft, and Beechcraft received a major boost through wartime contracts. The aircraft has used a variety of engines and has had a number of airframe modifications to increase gross weight and speed. At least one aircraft was modified to a 600-hp (447-kW) Pratt & Whitney R-1340 powerplant configuration. With the added weight of about 200 lb (91 kg) per engine, the concept of a Model 18 fitted with R-1340 engines was deemed unsatisfactory due to the weakest structural area of the aircraft being the engine mounts. Nearly every airframe component has been modified. In 1955, deliveries of the Model E18S commenced; the E18S featured a fuselage that was extended higher for more headroom in the passenger cabin. All later Beech 18s (sometimes called Super 18s) featured this taller fuselage, and some earlier models (including one AT-11) have been modified to this larger fuselage. The Model H18, introduced in 1963, featured optional tricycle undercarriage. Unusually, the undercarriage was developed for earlier-model aircraft under an STC by Volpar, and installed in H18s at the factory during manufacture. A total of 109 H18s were built with tricycle undercarriage, and another 240 earlier-model aircraft were modified with this.〔("Model 18 Specifications." ) ''Beechcraft Heritage Museum''. Retrieved: August 24, 2008.〕〔Young, Shad. ("The Beechcraft Model 18 & Volpar Tri-Gear – A Brief History". ) ''ascendant-online.net.'' Retrieved: August 8, 2008.〕 Construction of the Beechcraft Model 18 ended in 1970 with a final Model H18 going to Japan Airlines. Through the years, 32 variations of the basic design had flown, over 200 improvement modification kits were developed, and almost 8,000 aircraft were built. In one case, the aircraft was modified to a triple tail, trigear, humpbacked configuration and appeared similar to a miniature Lockheed Constellation. Another distinctive conversion was carried out by PacAero as the Tradewind. This featured a lengthened nose to accommodate the tricycle nosewheel, and the Model 18's twin tailfins were replaced by a single fin.〔("Expeditor." ) ''Canadian Museum of Flight.'' Retrieved: August 13, 2012.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Beechcraft Model 18」の詳細全文を読む スポンサード リンク
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