Tu-144 Charger Pre-Production Aircraft
Activities on development of "044" aircraft basic structure were performed in two directions: creation of an advanced and efficient non-atferburning turbojet engine of RD-36-51 type and significant improvement of aerodynamics and structure of Tu-144 aircraft. It had to result in compliance with requirements to flight range of supersonic flight. In 1969 Committee of Council of Ministers of the USSR took a decision about the version of Tu-144 aircraft with RD-36-51 engines.
In parallel it was proposed by Ministry of Aircraft Industry to manufacture six Tu-144 aircraft provided with NK-144A with reduced Specific Fuel Consumption. The Tu-144 aircraft structure with NK-144A engines was supposed to be significantly upgraded, to change aerodynamics seriously to obtain K-max more than 8 at supersonic cruising flight. This upgrading had to ensure fulfillment of the first step requirements to flight range (4000-4500 km). Further the production Tu-144 airplanes were supposed to be switched to RD-36-51 engines.
Preproduction upgraded Tu-144 aircraft building started at "Opyt" plant in 1968. Estimated supersonic flight range (Cp=2.01) with NK-144 engines had to make 3275 km while with NK-144A engines (Cp=1.91) to exceed 3500 km.
Aiming at improvement of the aircraft aerodynamic characteristics at cruising flight M=2.2 wing planform was modified (wing leading edge extension sweep was reduced to 76° while the basic one was increased to 57°), the wing shape became close to the "ogive" seen on the Concorde. In comparison with "044" wing area was increased and more intensive conic twist was introduced for end wing. The most important novelty introduced into wing aerodynamics became modification of mid-section of the wing which provided self-balancing at cruising flight with minimal quality losses in view optimization of flight-load deformation under said condition.
The fuselage length was increased so as to accomodate up to 150 passengers, and the nose portion was improved, which also made positive effects on aerodynamics of he aircraft. In contrast to "044", each pair of engines was installed in double nacelles with spaced air intakes. They were removed from lower fuselage and unloaded it from increased heat and vibration loads; modifying lower wing surface at the point of estimated location of air flow pressurization, gap between lower wing surface and upper surface of air intake. All this made it possible to use air flow pressurization before air intake at Kmax more efficiently than in "044" aircraft. New arrangement of engine nacelles required landing gear modification: main landing gear legs were disposed under nacelles, they were retracted into the space between air ducts of engines, switched to 8-wheels bogie, nose landing gear retraction arrangement was also modified.
The main distinguishing feature of "004" from "044" became the introduction of nose multisectional extendable winglet from the fuselage at take-off and landing modes which provides required balancing of the aircraft at deflected elevons-flaps. Design improvements, increase of payload and fuel resource resulted in an increase of take-off weight of the aircraft, which was more than 190 tons ("044" had been 150 ton).
Building of pre-production Tu-144 No. 01-1 (side number 77101) was finished in early 1971. In June 1971 the aircraft performed its maiden flight. According to the factory tests program, the aircraft made 231 flight, with a duration 338 hours, 55 hours of them in supersonic flights. On this machine aspects of the interaction between powerplant and aircraft under various conditions were tried out. On 20 September 1972 the aircraft performed a flight on route Moscow-Tashkent. In this case the route was passed during 1 hour and 50 minutes. Cruising flight speed reached 2500 km/h. The pre-production machine served as a basis for serial production at Voronezh Aircraft Plant.
The first flight of Tu-144 aircraft No.01-2 (side number 77102) with NK_144A engines was performed 20 March, 1972. According to the results of the pre-production machine, wing aerodynamics was improved and its area was slightly changed. Take-off weight reached 195 ton. The specific Fuel Consumption of the NK-144A by the time of operational tests was supposed to reach 1.65-1.67 kg/kg thrust hour and later to 1.57 kg/kg thrust hour. In this case the flight range should be increased to 3,855-4,260 km and 4,550 km respectively. In reality in 1977 during Tu-144 aircraft tests and development with NK-144A Cp=1.81 kg/kg thrust hour was reached at supersonic thrust of 5000 kg thrust, Cp=1.65 kg/kg thrust h at take-off afterburning thrust 20,000 kg thrust, Cp=0.92 kg/kg thrust hour at cruising subsonic thrust 3000 kg thrust and at maximal afterburning transonic thrust of 11,800 kg thrust.
On 03 June 1973 during demonstration flight at Le-Bourget the second pre-production aircraft 01-2 CCCP-77102 crashed. The whole flight crew died (test pilot M.V.Kozlov, co-pilot V.M.Molchnov, Deputy Chief Designer V.Benderov, flight engineer A.I.Dralin, navigator G.N.Bazhenov, engineer B .A.Pervukhin. To investigate the crash special Commission was established involving USSR and French experts. According to the investigation French side highlighted that there were no technical failures. The crash was provoked by unfastened crew members, unexpected appearance of "Mirage" aircraft within field of view Tu-144 aircraft crew, video-camera available in hands of one of the crew members which could jam control stick when it fell. To all appearances at that time this explanation satisfied everybody. Perhaps the most expressive remark was made by E.Yelyan: "This crash was sad example showing how coincidence of minor negligence also from French air traffic control services resulted in tragedy".
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