The Nakajima AT27 was a pure concept fighter aircraft originating in the early part of World War 2 (1941-1945). The aircraft was spotted in a Japanese publication (of April 1941) under the article heading "Dreams of Future Designers" and appeared as a streamlined single-seat, twin-engine design of extremely slim profile - making for both a low-drag product and a small target at range. The design was later covered in the American publication "Flight" (of December 1941) which led American intelligence - which lacked credible sources on Japanese air power at the start of the war - to assume the AT27 was a very real fighter/interceptor now in service with the Imperial Japanese air branches. As such, and in keeping with other Japanese aircraft of the period, the Americans assigned it a nickname - in this case "Gus".
Beyond its super-slim appearance, one of the more interesting design qualities of the AT27 was in its planned propulsion scheme: power was to stem from 2 x Vee-type 12-cylinder, liquid-cooled engines developing 1,250 horsepower each, for a grand output total of 2,500 horsepower, to drive a pair of three-bladed propeller units centered at the nose. The blades would spin in contra-rotating fashion, generating considerable pull ability, giving the AT27 exceptional straight-line performance. Estimated maximum speed was to reach 410 miles-per-hour while range would have topped at 1,250 miles. Compared to contemporaries, it can assumed that the AT27's service ceiling would have teased near 40,000 feet - requiring some sort of cockpit pressurization and oxygen supply for operating at such altitudes.
The AT27 exuded sleek styling and clean lines, keeping aerodynamic efficiency at the forefront of its design. The single-seat cockpit was positioned slightly ahead of midships under a low-profile, framed canopy. The pilot's placement was bookended by the engine pairing, one fore with the other aft, and shafts were used to drive the propeller units at the nose. Tapering aft, the fuselage grew evermore slim until terminating at the conventional, single-finned tail unit. A tail-dragger undercarriage, though not detailed, is assumed for the aircraft. The low-mounted mainplanes were to be set ahead of midships and were drawn up as straight appendages with rounded tips and tapering edges. Operating weights were estimated with an empty rating of 8,000lb and a loaded weight near 11,600lb. No structural dimensions were given.
While armament was unknown, the AT27 would most likely have fallen in line with other fighter-interceptors of the mid-war period: perhaps 4 x 20mm automatic cannons or a mix of 2 x 20mm automatic cannons and 12.7mm Heavy Machine Guns (HMGs) - installed within the cowling and/or wing mainplanes.
It was only later that American intelligence realized their mistake in believing the AT27 was a real design, as the Japanese shown their hand with each passing month, and the Gus name fell from intelligence reports for the duration of the war- leaving the AT27 as nothing more than a fantasy IJA/IJN design.