The Tupolev Tu-14 (prototype 73′ )was a three-engined allmetal monoplane with unswept shoulder-mounted wings, an unswept vertical tail, swept-back stabilisers and a tricycle undercarriage. In the course of the project work and prototype construction many issues relating to the further development of heavy aircraft were resolved. For instance, the optimum high-altitude flight profile necessitated pressurised cabins for the crew.
Special interest was centred on the housing of the third engine in the fuselage. The engine air intake was situated on the upper fuselage where its contours smoothly blended into the fin. A similar solution was later applied to the Hawker Siddeley HS.121 Trident, Boeing 727 and Tu-154 three-turbofan airliners. In cruise mode the air intake for the third engine was closed by a faired shutter. Another feature of interest in the layout was the housing of the engines in underwing nacelles which also housed the main landing gear units. The nacelles were ‘tadpoleshaped’ (the largest cross-section was in front of the wings, tapering gradually so that the smallest cross-section was in the area of the greatest wing thickness); this anticipated the ‘area rule’ concept which only became practice in world aircraft design in the 1950s. For the first time the OKB introduced powerassisted controls. As on the Tu-12, the pilot sat on an ejection seat; escape hatches were provided in the lower fuselage for the other crew members.
In October 1947 the first prototype ’73′ was completed, apart from its armament, and underwent manufacturer’s tests between 29th October 1947 and 14th June 1948 at the hands of F. F. Opadchiy with chief engineer B. M. Grozdov. The first flight was made on 20th December. The results of the tests were good enough to recommend state trials with the armament fitted. The first phase of the trials was held at N11 WS between 18th August and 1st October 1948 when M. A. Nyukhtikov made six test flights. Then the trials were suspended due to engine malfunctions and the OKB spent the rest of the year making modifications to the aircraft. The trials were resumed on 6th January
1949, continuing until 31st May. At their conclusion Nil WS reported that the aircraft’s performance more or less met the terms of the government directive apart from its range which fell 190 km short. Apart from that, the lack of radar and radio-navigation blind bombing aids were a serious failing, there was insufficient protection for the crew, especially from below, there was no de-icing equipment on the edges of the wings or tail surfaces, the engines were of different types and the tyre pressures were too high.
Even before the manufacturer’s tests had ended, the question of placing the ’73′ in series production (with the designation 73S’) had been decided. MAP Order No. 194 of 9th April 1948 stated that Factory No.23 was to build an experimental batch of ten machines with RD-45 and RD-500 engines. To speed up production of the batch, fifty OKB members under Deputy Chief Designer N. I. Bazenkov were seconded to Factory No.23 which was preparing components for building the first batch.
Then, on 14th May 1949, came the government directive based on the state trials results of the IL-28 and the Tu-14 which cancelled series production of the latter. Later, the components manufactured at Factory No.23 were sent to Factory No.39 at Irkutsk for use in series production of the ’81S’ (Tu-14).
The experimental ’73′ continued to fly on various research programmes, in particular as a weapons testbed for missile testing.