The Tupolev Tu-28 (NATO reporting name Fiddler) was a long-range interceptor aircraft introduced by the Soviet Union in the 1960s. The official designation was Tu-128, but this designation was less commonly used in the West. It was the largest and heaviest fighter ever in service. Iosif Nezval, of Tupolev Design Bureau. led development of the new interceptor aircraft. The work began in 1958, based on an existing single prototype of the unsuccessful Tu-98 supersonic bomber. The military designation of the interceptor was at first Tu-28, but it was changed in 1963 to Tu-128, identical to the designation used by the OKB. The Tu-128 had a broad, low/mid-mounted swept wing carrying the main landing gear in wing-mounted pods, and slab tailplanes. Two Lyulka AL-7F-2 turbojet engines were mounted in the fuselage. The two-man crew of pilot and navigator were seated in tandem. The Tu-128, with its maximum weight of 43 tonnes, was the heaviest fighter to enter service. It was an interceptor with high wing loading, unsophisticated but reliable avionics and poor visibility. It was not an agile aircraft, intended only to combat NATO bombers like the B-52 not engage in dogfights with smaller aircraft. The interceptor made its initial public appearance in the 1961 Tushino air parade. Western experts, unaware that the bulge on the belly carried testing instruments, mistook it for a large ventral radar for a mixed interceptor/AWACS role.[3] The production version lacked the bulge and had a large nose radome housing a radar, known as RP-S[nb 4] Smerch, having a detection range of about 50 km (31 mi) and a lock-on range of about 40 km (25 mi). Armament of the Tu-128 was four Bisnovat R-4 air-to-air missiles (known as K-80 during development; NATO reporting name AA-5 'Ash'). Usually two of them were R-4Rs with semi-active radar homing and two were R-4T infrared-homing missiles, with the former on the outer pylons and the latter on the inner underwing pylons. There was no internal weapons bay. Production of the Tu-128 ended in 1970 with a total of 198 aircraft having been built. Development of various projects designated Tu-28A, Tu-28-80, Tu-28-100, Tu-138, and Tu-148 were proposed by the Tupolev Design Bureau but all were abandoned. For background, operational history and variants, click here.