|
The McDonnell XF-85 Goblin was an American prototype fighter aircraft conceived during World War II by McDonnell Aircraft. It was intended to be deployed from the bomb bay of the giant Convair B-36 bomber as a parasite fighter. The XF-85's intended role was to defend bombers from hostile interceptors, a need demonstrated during World War II. Two prototypes were constructed before the program was terminated. The XF-85 was a response to a United States Army Air Forces (USAAF) requirement for a fighter to be carried within the Northrop XB-35 and B-36, then under development. This was to address the limited range of existing interceptor aircraft compared to the greater range of new bomber designs. The XF-85 was a diminutive jet aircraft featuring a distinctive egg-shaped fuselage and a forked-tail stabilizer design. The prototypes were built and underwent testing and evaluation in 1948. Flight tests showed promise in the design, but the aircraft's performance was inferior to the jet fighters it would have been facing in combat, and there were difficulties in docking. The XF-85 was swiftly canceled, and the prototypes were thereafter relegated to museum exhibits. The 1947 successor to the USAAF, the United States Air Force (USAF), continued to examine the concept of parasite aircraft under Project MX-106 "Tip Tow", Project FICON and Project "Tom-Tom" following the cancellation. ==Design and development== During World War II, American bombers such as the Boeing B-17 Flying Fortress, Consolidated B-24 Liberator and Boeing B-29 Superfortress were protected by long-range escort fighters such as the Republic P-47 Thunderbolt and North American P-51 Mustang. These fighters could not match the range of the Northrop B-35 or Convair B-36, the next generation of bombers developed by the United States Army Air Forces (USAAF). The development cost for longer-ranged fighters was high, while aerial refueling was still considered risky and technologically difficult.〔O'Leary 1974, p. 37.〕 Pilot fatigue had also been a problem during long fighter escort missions in Europe and the Pacific, giving further impetus to innovative approaches.〔Gunston 1975, p. 483.〕 The USAAF considered a number of different options including the use of remotely piloted vehicles before choosing parasite fighters as the most viable B-36 defense.〔Sundey 1985, p. 10.〕 The concept of a parasite fighter had its origins in 1918, when the Royal Air Force examined the viability of Sopwith Camel parasite fighters operating from ''R23'' airships. In the 1930s, the U.S. Navy had a short-lived operational parasite fighter, the Curtiss F9C Sparrowhawk, aboard the airships and .〔Jenkins and Landis 2008, p. 81.〕 Starting in 1931, aircraft designer Vladimir Vakhmistrov conducted experiments in the Soviet Union as part of the Zveno project during which up to five fighters of various types were carried by Polikarpov TB-2 and Tupolev TB-3 bombers. In August 1941, these combinations flew the only combat missions ever undertaken by parasite fighters – TB-3s carrying Polikarpov I-16SPB dive bombers attacked the Cernavodă bridge and Constantsa docks, in Romania. After that attack, the squadron, based in the Crimea, carried out a tactical attack on a bridge over the river Dnieper at Zaporozhye, which had been captured by advancing German troops.〔Lesnitchenko 1999, pp. 4–21.〕 Later in World War II, the ''Luftwaffe'' experimented with the Messerschmitt Me 328 as a parasite fighter, but problems with its pulsejet engines could not be overcome.〔 Other late-war rocket-powered parasite fighter projects such as the Arado E.381 and Sombold So 344 were unrealized "paper projects".〔Lepage 2009, pp. 257, 258.〕 On 3 December 1942, the USAAF sent out a Request for Proposals (RfP) for a diminutive piston-engined fighter.〔Cowin 2011, p. 36.〕 By January 1944, the Air Technical Service Command refined the RfP and in January 1945, the specifications were further revised in MX-472 to specify a jet-powered aircraft.〔 Although a number of aerospace companies studied the feasibility of such aircraft, McDonnell was the only company to submit a proposal to the original 1942 request and later revised requirements.〔 The company's Model 27 proposal was completely reworked to meet the new specifications.〔 The initial concept for the Model 27 was for the fighter to be carried half-exposed under the B-29, B-35 or B-36. The USAAF rejected this proposal, citing increased drag, and hence reduced range for the composite bomber-fighter configuration.〔 On 19 March 1945, McDonnell's design team led by Herman D. Barkey,〔Pace 1991, p. 55.〕 submitted a revised proposal, the extensively redesigned Model 27D.〔Gunston 1975, p. 485.〕 The smaller aircraft had an egg-shaped fuselage, three fork-shaped vertical stabilizers, horizontal stabilizers with a significant dihedral, and 37° swept-back folding wings to allow it to fit in the confines of a bomb bay.〔Gunston 1975, p. 484.〕 The diminutive aircraft measured long; the folding wings spanned . Only a limited fuel supply of was deemed necessary for the specified 30-minute combat endurance.〔 A hook was installed along the aircraft's center of gravity; in flight, it retracted to lie flat in the upper part of the nose.〔 The aircraft had an empty weight just short of .〔Winchester 2005, p. 151.〕 To save weight, the fighter had no landing gear.〔 During the testing program, a fixed steel skid under the fuselage and spring-steel "runners" at the underside of the wingtips were installed in case of an emergency landing.〔〔("McDonnell XF-85 Goblin Parasite Fighter." ) ''Boeing''. Retrieved: 29 June 2011.〕 Despite the cramped quarters, a pilot was provided with a cordite ejection seat, bail-out oxygen bottle and high-speed ribbon parachute.〔 Four machine guns in the nose made up the aircraft's armament.〔Jenkins and Landis 2008, pp. 82–83.〕 In service, the parasite fighter would be launched and retrieved by a trapeze. With the trapeze fully extended, the engine would be airstarted and the release from the mother ship was accomplished by the pilot pulling the nose back to disengage from the hook.〔 In recovery, the aircraft would approach the mother ship from underneath and link up with the trapeze using the retractable hook in the aircraft's nose.〔O'Leary 1974, p. 38.〕 The anticipated production shift would see a mixed B-36 fleet with both "fighter carriers" and bombers〔 employed on missions.〔Jenkins and Landis 2008, pp. 80–81.〕 There were plans that, from the 24th B-36 onward, provisions would be made to accommodate one XF-85, with a maximum of four per bomber envisioned.〔 Up to 10 percent of the B-36s on order were to be converted to fighter carriers with three or four F-85s instead of a bomb load. On 9 October 1945, the USAAF signed a letter of intent covering the engineering development for two prototypes (US serial numbers ''46-523/4''), although the contract was not finalized until February 1947.〔Jenkins and Landis 2008, p. 82.〕 After the successful conclusion of two reviews of a wooden mock-up in 1946 and 1947 by USAAF engineering staff,〔 McDonnell constructed two prototypes in late 1947.〔 The Model 27D was re-designated XP-85, but by June 1948, it was changed to XF-85 and given the name "Goblin". There were plans to acquire 30 production P-85s, but the USAAF took the cautious approach – if test results from the two prototypes were positive, production orders for more than 100 Goblins would be finalized later.〔〔 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「McDonnell XF-85 Goblin」の詳細全文を読む スポンサード リンク
|