Realising that the export potential for the
Tupolev Tu-104 was limited, the Council of Ministers issued directive No. 1511–846 on 12 August 1956, requiring the Tupolev Design Bureau to develop a four-engined version of the Tu-104, to enable the aircraft to safely cross large expanses of ocean, and improve safety on takeoff in case of engine failure. The Tu-110 was a major redesign of the Tu-104, powered by four
Lyulka AL-7 turbojets rated at 5,500
kgf (53.9
kN; 12,100
lbf) thrust each, with two staggered engines in the root of each extended centre-section. The first prototype was flown on 11 March 1957. Production of the Tu-110 was authorised at the
Kazan Aircraft Factory, with an initial order for ten aircraft, but only three aircraft were completed before the programme was terminated. The production aircraft featured extended-chord wings and enlarged baggage holds, as well as seating for up to 100 passengers in an all-tourist class seating arrangement. All four aircraft were converted to Tu-110Bs with
Soloviev D-20 turbofan engines, in an attempt to improve the performance of the aircraft, but to no avail. No further orders were forthcoming and the four Tu-110Bs were used for experimental work on avionics, missile systems and boundary layer control systems, remaining active into the 1970s. ==Variants==