Tupolev Tu-144 - Development

Development

The Soviet government published the concept of the Tu-144 in an article in the January 1962 issue of the magazine Technology of Air Transport. The air ministry started development of the Tu-144 on 26 July 1963, 10 days after the design was approved by the Council of Ministers. The plan called for five flying prototypes to be built in four years, with the first aircraft to be ready in 1966.

Despite the close similarity in appearance of the Tu-144 to the Anglo-French supersonic aircraft, there were significant differences in the control, navigation and engine systems. In areas such as range, braking and engine control, the Tu-144 lagged behind Concorde, but the aerodynamics of the Soviet aircraft were better. While Concorde utilized an electronic engine control package from Lucas, Tupolev was not permitted to purchase it for the Tu-144 as it could also be used on military aircraft. Concorde's designers used the fuel of the airliner as the coolant for air conditioning the cabin and the hydraulic system (see Concorde for details). Tupolev installed additional equipment on the Tu-144 to accomplish this, increasing the weight of the airliner.

Alexei A. Tupolev continued to work to improve the Tu-144 with upgrades and changes were made on the Tu-144 prototype. While both Concorde and the Tu-144 prototype had ogival delta wings, the Tu-144's wing lacked Concorde's conical camber. Production Tu-144s replaced this wing with a double-delta wing including conical camber, and they added a simple but practical device: two small retractable canard surfaces, one on either side of the forward section on the aircraft, to increase lift at low speeds.

Moving the elevons downward in a delta-wing aircraft increases the lift, but also pitches its nose downward. The canard cancels out this nose-downwards moment, thus reducing the landing speed of the production Tu-144s to 315–333 km/h (196–207 mph; 170–180 kn), still faster than that of Concorde. The NASA study lists final approach speeds during Tu-144LL test flights as 315–335 km/h (196–208 mph; 170–181 kn), however these were approach speeds exercised during test flights specifically intended to study landing effects at maximum possible range of speeds, regardless of how hard and stable the landing can be. As to regular landings, FAA circular lists Tu-144S approach speed as 329 km/h (204 mph; 178 kn), as opposed to Concorde's approach speed of 300 km/h (190 mph; 160 kn) 162 kn (300 km/h), based on the characteristics declared by the manufacturers to Western regulatory bodies. It is open to argument how stable the Tu-144S was at the listed airspeed. In any event, when NASA subcontracted Tupolev bureau in the 1990s to convert one of the remaining Tu-144D to a Tu-144LL standard, the procedure set by Tupolev for landing defined the Tu-144LL "final approach speed... on the order of 360 km/hr depending on fuel weight." Brian Calvert, Concorde's technical flight manager and its first commercial pilot in command for several inaugural flights, cites final approach speed of a typical Concorde landing to be 287–296 km/h (178–184 mph; 155–160 kn). The lower landing speed compared to Tu-144 is due to Concorde's more refined design of the wing profile that provides higher lift at low speeds without degrading supersonic cruise performance – a feature often mentioned in Western publications on Concorde and acknowledged by Tupolev designers as well.