According to flight crew the aircraft proved to be flexible and easily piloted. A.N.Tupolev, A.A.Tupolev and many others attended the first take-off. The first flight became the vent of world-wide importance and main milestone in history of Russian and International aviation. It was the first flight of Soviet supersonic passenger aircraft – the first “Concord” will lift-off only on 2 March, 1969. 5 June, 1969 the prototype exceeded sonic speed for the first time at the altitude of 11 000 m. By May, 1970 the machine performed flights at speeds of M1.25-1.6 at the altitudes up to 15 000 m. 12 November, 1970 the aircraft “044” performed half-hour flight at speed more than 2000 km/h; at the altitude of 16960 m maximal speed of 2430 km/h. In the course of the tests the aircraft flown beyond USSR boarder several times. In May-June, 1971 “044” aircraft participated Le-Bourget Airshow where it met “Concord” for the first time. The “044” a/c was provided with prototype NK-144 engines with SFC at cruising supersonic mode equal to 2.23 kg/kgf hour. At such SFC during tests TU-144 a/c reached supersonic flight range of 2920 km which was significantly less than required range. Furthermore in the course of tests some design defects: during flight they observed enhanced vibration level and tail fuselage heating from the package of four engines, even titanic structures could not help. Upon completion of test flight program (totally about 150 flights) the “044” machine remained in one copy. Nobody expected more form it. It fulfilled its task to demonstrate that USSR was capable to built supersonic passenger aircraft. It was necessary to move ahead improving the aircraft structure and engines.

Activities on development of “044” a/c 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 a/c. 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 a/c with RD-36-51 engines. In parallel it was proposed by Ministry of Aircraft Industry to manufacture six TU-144 a/c provided wit NK-144A with reduced SFC. The TU-144 a/c structure with NK-144A engines was supposed to be significantly upgraded, to change aerodynamics seriously to obtain Kmax more than 8 at supersonic cruising flight. Said 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-q44 a/c 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 76o while the basic one was increased to 57o), the wing shape became close to “ogee”. 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. Fuselage length was increased intending for 150 passengers, nose portion was improved which also made positive effects on aerodynamics of he aircraft. Opposite to “044” each couple of engines installed in double nacelles with air intakes were spaced. 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” a/c. 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” form “044” became introduction of nose multisectional winglet extendable from fuselage at take-off and landing modes which provides required balancing of the aircraft at deflected elevons-flaps. Design improvement, increase of payload and fuel resource resulted in increase of take-off weight of the aircraft which was more than 190 tones (for “044” – 150 tones).

Building of pre-production TU-144 No. 01-1 (side number 77101) was finished in early 1971. I June, 1971 the aircraft performed its maiden flight. According factory tests program the aircraft made 231 flight, duration 338 hours, 55 hours off them – fall on supersonic flights. On this machine aspects of interaction between powerplant and aircraft under various conditions were tried out. 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. Pre-production machine served as a basis for serial production at Voronezh Aircraft Plant.

The first flight of TU-144 a/c No.01-2 (side number 77102) with NK_144A engines was performed 20 March, 1972. According to results of pre-production machine wing aerodynamics was improved and its area was slightly changed. Take-off reached 195 tones. SFC of NK-144A by the moment of operational tests was supposed to reach 1.65-1.67 kg/kgf hour and further – to 1.57 kg/kgf hour. In this case flight range should be increased to 3855-4260 km and 4550 km respectively. In reality in 1977 during TU-144 a/c tests and development with NK-144A Cp=1.81 kg/kgf h was reached at supersonic thrust of 5000 kgf, Cp=1.65 kg/kgf h at take-off afterburning thrust 20000 kgf, Cp=0.92 kg/kgf h at cruising subsonic thrust 3000 kgf and at maximal afterburning transonic thrust 1 1800 kgf.

3 June, 1973 during demonstration flight at Le-Bourget the first production aircraft 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 a/c 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”.

Production of TU-144 a/c with NK-144A was continued in Voronezh up to 1977. Large amount of flight tests were made on this aircraft and flights with passengers were started. The first flight of TU-144 No.02-1 (side number 77103) was performed 13 December, 1973. Flight and navigation complex NPK-144, power supply system were tried out, the aircraft was tested aborted takeoff, technical flights were performed to various cities of the USSR.

On TU-144 No.02-2 (side number 77104) – the first flight was made 14 June, 1974 – aerodynamics, strength, large angles of attack tests were performed. Aircraft systems and equipment was checked under nonstandard conditions. In 1975 the aircraft flown to Le-Bourget.

TU-144 No.03-1 (side number 77105) was built in 1973 and was modified streight away to TU-144D with RD-36-51A engines.

TU-144 No.04-1 (side number 77106) – the first flight was performed 4 March, 1975 – was used to assess effectiveness of air-conditioning sytem/ Some problems on fuel system were solved on this aircraft. 26 December, 1975 this machine performed the first operational flight on the route Moscow-Alma-Ata. The aircraft carried goods, mail. The flights were made at the altitude of 18000 m at the speed of 2200 km/h. Currently TU-144 No. 04-1 is demonstrated in Monino Museum.

On TU-144 No.04-2 (side No. 77108) – the first flight was performed 12 December, 1975 – development works were made on navigation system, flight-director approach, sub-autothrottle. TU-144 No.05-1 (side number 77107) – the first flight was performed 20 August, 1975 – after factory tests and special tests in 1977 was submitted as complex subject for joint government testing. According results of said tests it was noted that flight performance data of the aircraft except to operational range of fight with prescribed passenger number and takeoff weight complied with requirements to TU-144 a/c (when testing operational flight range reached 3080 km at takeoff weight of 195 tones and payload equal to 15 tone and at payload of 7 tone – flight rage was3600 km. It was highlighted that the range of 4000-4500 km at payload of 14-15 tones could not be realize on TU-144 with NK-144A and it was noted that such range could be reached with RD-36-51A engines.

Upon joint tests completion the decision was taken on beginning of passenger transportation on TU-144 a/c with NK-144A engines. TU-144 No. 05-2 (side number 77109) and TU-144 No. 06-1 (side number 77110) were used for regular passenger transportation on Moscow-Alma-Ata route. TU-144 a/c made his first passenger flight 1 November, 1977. Flights for range of 3260 km at the altitude of 16000-17000 m at the speed of 2000 km/h were performed once a week; number of passengers did not exceed 80 persons. Before the moment of termination of regular operation with passengers inn May, 1978 Aeroflot crews made 55 flights on TU-144 a/c totally carried 3284 passengers. TU-144 with NK-144A became the first USSR passenger a/c which was granted with national airworthiness certificate for safety of passenger transportation.

As it was previously noted activities on alternative RD-36-51 engines for TU-144 a/c started in 1964. Flight range at takeoff weight of 150 tones with 150 passengers on board was stipulated as 4500 km, while with 120 passengers and at takeoff weight of 180 tones – 6500 km. Modification of TU-144 /c with new engines was designated as TU-144D (“004D”). By the middle of the 70-s the RD-36-51 engine became real. The first RD-36-51A engines had takeoff weight of 20000 kgf, cruising thrust of 5100 kgf and SFC at cruising supersonic flight equal to 1.26 kg/kgf h. Lter it was supposed to have takeoff weight of 2 1000 kgf and cruising SFC not more than 1.23 kg/kgf h (in future it could be 23000 – 24000 kgf at takeoff and 5400 kgf at cruising flight).

The first TU-144 a/c provided with RD-36-51 engines was the aircraft No.03-1. Before mid-1976 a new powerplant was developed on this machine. 5 June, 1976 the aircraft performed its large range flight for the distance of 6200 km at payload of 5 tones. This flight confirmed realizability and perspecrtiveness of continuation of works on TU-144D a/c.

In late 70-s Voronezh plant began serial production of TU-144D. The Tu-144 No.06-2 (side number 77111) was the first production aircraft. The first flight was performed 27 April, 1978. The aircraft started joint testing but 23 May, 1978 it crashed near Yegorievsk. The reason for the crash was breakage of fuel line in engine compartment. The aircraft was piloted by test pilot Popov, co-pilot was Yelyan. The flight crew managed to performed forced landing with retracted landing gear. During the landing Yelyan was wounded and two test engineers were killed. This crash was a direct reason to suspend TU-144 operation with passenger and later on to complete termination of such flights. Four machines more were produced and developed – TU-144 №/№ 07-1, 08-1, 08-2 and 09-1. The first two machines were subject to joint government tests which were finalized in mid-80s. Basing on results of said tests TU-144D was recommended to be operated with passengers as well as TU-144 a/c with NK-144A. The aircraft was given airworthiness certificate but was not operated. The program was cut down. The last production machine TU-144 D No.09-2 was not demanded and stood for a long time on Voronezh airfield. Apart those mentioned machines several TU-144 airframes were built to be used in structural tests. TU-144D a/c takeoff weight exceeded 200 tones, during joint government tests supersonic range was reached equal to 5330 km at payload of 15 tones, and with 11-13 tones – the range if 5500-5700 km, and with payload of 7 tones – the range of 6200 km all these with fuel reserve of 10 tones. In the 80-s some of built TU-144 aircraft were used as flying laboratories for various test programs to build advanced supersonic heavy aircraft including the programs of further SST development. In July, 1983 on one of TU-144Ds the flight crew headed by test pilot S.Agapov (co-pilot B.Veremey) established 13 world records of flight speed flight altitude with different cargo ( the machine was designated as “101”). In the 70-s there were projects for further modernization of TU-144 a/c. Practice of development, test and initial operation of TU-144 a/c with NK-144A engines showed that only minimum program could be provided – operation on airlines as long as 4000 km. The beginning of works on TU-144 with RD-36-51 engines showed that TU-144 a/c is capable to reach demanded range and has further margins for modernization. First of all they refused from unification of the structure regarding powerplant. By review of airframe structure, aircraft systems and equipment fuel load ratio was supposed to be increased. The new project was assigned as TU-144DA. Initial study have revealed that there were possibility to increase fuel reserve up to 125 tones (instead of 90-95 tones on TU-144D) at takeoff weight of 235 tones, in this case wing area should be increased up to 544 sq.m (instead of 507 sq.m on TU-144D). Powerplant was moved to “61” type engines with thrust reverser (development of RD-36-51 A engine) with SFC=1.23 kgf/kg h at cruising flight and maximal takeoff thrust of 21 000 kgf. Amount of passengers reached to 130-160 persons, designed operational flight range with normal payload was increased up to 7000-7500 km. Works on TU-144DA were not further developed because of cutting down of entire TU-144 program. However works done on the project were used in investigations for SST-2 (TU-244) which started.

It is interesting to compare destinies of TU-144 and “Concord” – the machines that are close by purposes, design approaches and time of building. First of all it should be noted that “Concord” was designed mainly for supersonic flights over uninhabited ocean spaces (main purpose – flights between Europe and America overseas). It was the reason for selecting maller altitudes of crusing supersonic flight which resulted in smaller wing area, smaller takeoff weight, smaller demanded cruising thrust of the powerplant and SFC. TU-144 had to flight mainly over land which lead to large flight altitudes and respectively increase of parameters and demanded thrust of the powerplant. It should be added that the engines were less perfect (by specific parameters the engines of TU-144 a/c were brought close to “Olympus” only in their last modification). All these negative initial data were compensated in the course of development of the project by high aerodynamic cleanness of TU-144 which was achieved by making the design more complicated and by lowering maintainability of the aircraft. Quantity of production TU-144s and “Concord” was approximately the same. But opposite to TU-144 a/c the English-French SST were in operation substantially till early 90-s. In 1986 ticket price for London-New-York flight made 2745 USD. It is affordable only for very prosperous people for whom formulae “times is money” is the main credo. There are such people in West and for them flights by “Concord” are natural saving of time and money. It is confirmed by total flying time of “Concord” in 1989 equal to 325 000 hours. Thus we can consider “Concord” program more commercial and prestigious to some extent in comparison with Americans. In the USSR there were no people for whom time could turn to money therefore the natural market of services which could be satisfied by TU-144s just did not exist. So the aircraft was notoriously unprofitable. Thus from one hand – heroic efforts of Tupolev DB and other aviation organizations on TU-144 a/c development and from the other hand – initial non-professional enthusiasm followed by hamper from Aeroflot side. Therefore in early 80-s when future economic and political crisis became evident in the USSR and Soviet government started money saving policy the TU-144 a/c Program was one of the forst which was affected. Tu-144 a/c building and development became the largest and the most complicated program in history of Soviet aircraft industry. As a result of long term activities it was possible to build aerial vehicle of world level class not being inferior to any western production aircraft of such class.

While active works on Tu-144 were substantially closed in the middle of the 80-s te direction of activities was realized in our DB in creation of SST-2 – TU-244 a/c. Within SST-2 activities one of TU-144D a/c was re-equipped into flying laboratory TU-144LL “Moscow” (4xNK-321) which made several tens of experimental flights within joint program on building in future economically and ecologically perfect supersonic passenger aircraft of the 21 century.