Tupolev Tu-144

Tu-144
The Tu-144LL used by NASA to carry out research for the High Speed Civil Transport
Role	Supersonic airliner
Manufacturer	Tupolev OKB
Designer	Alexey A. Tupolev
First flight	31 December 1968
Introduction	26 December 1975
Retired	1 June 1978 (1999 in operation with NASA)
Primary user	Aeroflot, Ministry of Aviation Production
Number built	16

The Tupolev Tu-144 (NATO reporting name: "Charger") was one of the world's only two supersonic transport aircraft (SST) to enter civilian service, along with the Concorde, and was constructed under the direction of the Soviet Tupolev design bureau headed by Alexei Tupolev. McDonnell Douglas, Lockheed and Boeing were three other manufacturers who attempted to design SST airliners for the US market during the 1960s, but without success.

A prototype (OKB: izdeliye 044 - article 044) first flew on 31 December 1968 near Moscow, two months before the similar Aérospatiale / British Aircraft Corporation Concorde. The Tu-144 first broke the speed of sound on 5 June 1969, and on 15 July 1969 it became the first commercial transport to exceed Mach two. The Tu-144 was introduced into passenger service on 1 November 1977, almost two years after the Concorde, but was soon withdrawn after just 55 scheduled passenger flights due to potentially severe problems with aircraft safety and was not re-introduced to service.

The Tu-144 was Tupolev's only supersonic commercial airliner venture. Tupolev's other large supersonic aircraft were designed and built to military specifications. All these aircraft benefited from technical and scientific input from TsAGI, the Central Aerohydrodynamic Institute.

Although the Tu-144 was technically broadly comparable to the Concorde, it lacked a passenger market within the Soviet Union and service was halted after only about 100 scheduled flights. The Concorde remained in service until 2003, being withdrawn three years after a catastrophic crash near Paris (25 July 2000), the only loss of an SST in civilian service.

Design and development

Tu-144 Prototype in June 1971, Berlin-Schönefeld

The Soviets published the concept of the Tu-144 in an article in the January 1962 issue of the magazine Technology of the Air Transport. The air ministry started development of the Tu-144 on 26 July 1963, following approval by the Council of Ministers 10 days earlier. The project started two years later than Concorde. The plan called for five flying prototypes to be built in four years. The first aircraft was 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, aerodynamic sophistication, braking and engine control, the Tu-144 lagged behind Concorde. 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 this airliner as the coolant for air conditioning the cabin and the hydraulic system (see Concorde#Heating issues for details). Tupolev installed additional equipment on the Tu-144 to accomplish this, increasing the weight of that airliner.

Tupolev continued to work to improve the Tu-144. Many substantial upgrades and changes were made on the Tu-144 prototype (serial number 68001). 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 an extra 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 speed.

Moving the elevons downward in a delta-wing aircraft increases the lift, but that 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 (170-180 kn, 196-207 mph) - however, still faster than that of Concorde. The NASA study lists final approach speed during performed Tu-144LL test flights as 170 to 181 knots (315 to 335 km/h), 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 178 knots (330 km/h), as opposed to BAC/Aerospatiale Concord(e) approach speed of 162 knots (300 km/h), based obviously on the characteristics declared by the manufacturers to Western regulatory bodies. However it is open to an argument how stable was Tu-144S 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 executing several inaugural flights, cites final approach speed of a typical Concorde landing to be 155 to 160 knots, i.e. 287 to 296 km/h. Lower Concorde 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 the Concorde and acknowledged by Tupolev designers as well.

Paris Air Show crash

At the Paris Air Show on 3 June 1973, the development program of the Tu-144 suffered severely when the first Tu-144S production airliner (reg 77102) crashed.

While in the air, the Tu-144 underwent a violent downwards maneuver. Trying to pull out of the subsequent dive, the Tu-144 broke up and crashed, destroying 15 houses and killing all six people on board the Tu-144 and eight more on the ground.

The causes of this incident remain controversial to this day. A popular theory was that the Tu-144 was forced to avoid a French Mirage chase plane which was attempting to photograph its canards, which were very advanced for the time, and that the French and Soviet governments colluded with each other to cover up such details. The flight of the Mirage was denied in the original French report of the incident, perhaps because it was engaged in industrial espionage. More recent reports have admitted the existence of the Mirage (and the fact that the Russian crew were not told about the Mirage's flight) though not its role in the crash. However, the official press release did state: "though the inquiry established that there was no real risk of collision between the two aircraft, the Soviet pilot was likely to have been surprised." Howard Moon also stresses that last-minute changes to the flight schedule would have disoriented the pilots in a cockpit with notable poor vision. He also cites an eyewitness who claims the co-pilot had agreed to take a camera with him, which he may have been operating at the time of the evasive maneuver.

Another theory claims that the black box was actually recovered by the Soviets and decoded. The cause of this accident is now thought to be due to changes made by the ground engineering team to the auto-stabilisation input controls prior to the second day of display flights. These changes were intended to allow the Tu-144 to outperform Concorde in the display circuit. Unfortunately, the changes also inadvertently connected some factory-test wiring which resulted in an excessive rate of climb, leading to the stall and subsequent crash.

A third theory relates to deliberate misinformation on the part of the Anglo-French team. The main thrust of this theory was that the Anglo-French team knew that the Soviet team were planning to steal the design plans of Concorde, and the Soviets were allegedly passed false blueprints with a flawed design. The case, it is claimed, contributed to the imprisonment by the Soviets of Greville Wynne in 1963 for spying. Wynne was imprisoned on 11 May 1963 and the development of the Tu-144 was not sanctioned until 16 July. In any case, it seems unlikely that a man imprisoned in 1963 could have caused a crash in 1973.

Operational service

Tu-144 with distinctive Droop-nose at the MAKS-2007 exhibition

The Tu-144S went into service on 26 December 1975, flying mail and freight between Moscow and Alma-Ata in preparation for passenger services, which commenced in November 1977 and ran a semi-scheduled service until the first Tu-144D experienced an in-flight failure during a pre-delivery test flight, and crash-landed with crew fatalities on 23 May 1978. The Aeroflot flight on 1 June 1978 was the Tu-144's 55th and last scheduled passenger service.

A scheduled Aeroflot freight-only service recommenced using the new production variant Tu-144D (Dal'nyaya - long range) aircraft on 23 June 1979, including longer routes from Moscow to Khabarovsk made possible by the more efficient Kolesov RD-36-51 turbojet engines used in the Tu-144D version, which increased the maximum cruising speed to Mach 2.15. Including the 55 passenger flights, there were 102 scheduled Aeroflot flights before the cessation of commercial service.

It is known that Aeroflot still continued to fly the Tu-144D after the official end of service, with some additional non-scheduled flights through the 1980s. One report showed that it was used on a flight from the Crimea to Kiev in 1987.

Production

A total of 16 airworthy Tu-144s were built: the prototype Tu-144 reg 68001, a pre-production Tu-144S reg 77101, nine production Tu-144S reg 77102 – 110, and five Tu-144D reg 77111 – 115. A 17th Tu-144 (reg 77116) was never completed. There was also at least one ground test airframe for static testing in parallel with the prototype 68001 development.

Along with early Tu-134s, the Tu-144 was one of the last commercial aircraft with a braking parachute.

Engines

Although studies showed that turbojet engines are highly desirable for supersonic airliners, none were available. Therefore, originally the Tu-144 prototype was fitted with the inefficient Kuznetsov NK-144 turbofan engines and additionally gave much greater nacelle drag. While this permitted early test flights, unfortunately this did not permit cruise at Mach 2 without the afterburner on: a maximum cruising speed of 2,430kph/1,510 mph (Mach 2.29) was obtained but required the afterburner to be engaged. One important offshoot of this was that while Concorde could supercruise (maintain supersonic flight without using its afterburners), the Tu-144 could not. Later work on the Tu-144S did resolve this shortcoming. The turbofan engines suffered from heavy fuel consumption, and this limited range to about 2,500 km/1,600 miles, thus giving the Tu-144 far less range than the Rolls-Royce/Snecma Olympus 593 turbojet powered Concorde.

The Tu-144S model of which nine were produced featured the Kuznetsov NK-144F turbofan engines that offered better fuel efficiency over the original engines. The 4 engines had a maximum afterburning thrust of 196.2 kN (20,000 kgp / 44,100 lbf) each and each had separate inlet ducts in each nacelle and variable ramps in the inlets. It gave it a cruising speed of 2,000kph/1,240 mph (Mach 1.88). This also gave it a longer range of 3,080 km/1,914 miles, but still under half the range of Concorde.

The final Tu-144D model of which six were produced was powered by the Kolesov RD-36-51 turbojet. This gave the Tu-144D the ability to cruise at a comparable speed to Concorde at 2,124 kph/1,319 mph (Mach 2.0). The new engines also gave the Tu144D a much larger range- more than double the original model at 6,500 km/4,039 miles. Plans for an aircraft with 7,000+ km (3,780 nmi, 4,350 mi) range were never implemented.

Post-production use

Tu-144D #77112 on display at Sinsheim Auto & Technik Museum, Germany

Although its last commercial passenger flight was in 1978, production of the Tu-144 did not cease until six years later, in 1984, when construction of the partially complete Tu-144D reg 77116 airframe was stopped. During the 1980s the last two production aircraft to fly were used for airborne laboratory testing, including research into ozone depletion at high altitudes.

Tu-144LL in flight

In the early 1990s, a wealthy businesswoman, Judith DePaul, and her company IBP Aerospace negotiated an agreement with Tupolev and NASA, (also Rockwell and later Boeing). They offered a Tu-144 as a testbed for its High Speed Commercial Research program, intended to design a second-generation supersonic jetliner called the High Speed Civil Transport. In 1995, Tu-144D [reg 77114] built in 1981 (but with only 82 hours and 40 minutes total flight time) was taken out of storage and after extensive modification at a total cost of US$350 million was designated the Tu-144LL (Template:Lang-ru — where LL is an abbreviation for Flying Laboratory). It made a total of 27 flights in 1996 and 1997. In 1999, though regarded as a technical success, the project was cancelled for lack of funding.

The Tu-144LL was reportedly sold in June 2001 for $11 million via online auction, but the aircraft sale did not proceed after all — Tejavia Systems, the company handling the transaction, reported in September 2003 that the deal was not signed. The replacement Kuznetsov NK-321 engines (from the Tupolev Tu-160 bomber) are military hardware and the Russian government did not allow them to be exported.

At the 2005 Moscow Air & Space Show, Tejavia founder Randall Stephens found the Kuznetsov NK-321 engine on display, and the Tu-144LL rusting on Tupolev's test base at the Gromov Flight Test Center. In late 2003, with the retirement of Concorde, there was renewed interest from several wealthy individuals who wanted to use the Tu-144LL for a transatlantic record attempt; but Stephens advised them of the high cost of a flight readiness overhaul even if military authorities would authorize the use of NK-321 engines outside Russian Federation airspace.

The last two production aircraft remain at the Tupolev production plant in Zhukovsky, reg 77114 and 77115. In March 2006, it was announced that these airframes had been sold for scrap. Later that year, however, it was reported that both aircraft would instead be preserved. One of them could be erected to a pedestal near Zhukovsky City Council and TsAGI or above the LII entrance from the Tupolev avenue.

Civil operators

Soviet Union

• Ministry of Aviation Production
• Aeroflot Soviet Airlines

While several Tu-144s were donated to museums in Moscow Monino, Samara and Ulyanovsk, at least two Tu-144D remained in open storage in Moscow Zhukovsky.

Currently, one aircraft is located outdoors at LII aircraft testing facility, Zhukovsky (at coordinates 55.569738°N 38.156161°E / 55.569738; 38.156161), the other no longer appears to be present in aerial photographs. Previously, they were constantly on display at MAKS Airshows.

The only Tu-144 on display outside the former Soviet Union was acquired by the Auto & Technikmuseum Sinsheim in Germany, where it was shipped — not flown — in 2001 and where it now stands, in its original Aeroflot livery, on display next to an Air France Concorde.

Reasons for failure and cancellation

Due to political pressures resulting from the Concorde launch into regular commercial service, the Tu-144S was prematurely launched into passenger service before proper testing and tuning of the aircraft were completed.

Early flights in scheduled service indicated the Tu-144S was extremely unreliable. During 102 flights and 181 hours of scheduled freight and passenger flight time, the Tu-144S suffered at least 226 failures, 80 of them in flight (this list is likely to be incomplete. The list was included in the Tu-144 service record provided by the USSR to BAC-Aérospatiale in late 1978, when requesting Western technological aid with the Tu-144, and is probably incomplete.). A total of 80 of these failures were serious enough to cancel or delay the flight.

After the inaugural flight, two subsequent flights, during the next two weeks, were cancelled and the third flight rescheduled for several days later. The official reason given by Aeroflot for cancellation was bad weather at Alma-Ata, however when the journalist called Aeroflot office in Alma-Ata about local weather, Alma-Ata office said that the weather there was perfect and one aircraft had already arrived in fine condition that morning. Subsequently, outright flight cancellations might have become less common, as several Tu-144s were docked at Moscow Domodedovo airport (travelers at Domodedovo during the years of Tu-144 passenger service noted up to four Tu-144s parked in the airport and presumably several Tu-144s were also available at all times in Alma-Ata as standby replacements).

Some of the failures included decompression of the cabin in flight on 27 December 1977, and overheating of an engine exhaust duct causing the flight to be aborted and returned to the takeoff airport on 14 March 1978.

Alexei Tupolev, Tu-144 chief designer, and two USSR vice-ministers (of aviation industry and of civil aviation) had to be personally present in Domodedovo airport before each scheduled Tu-144 departure to review the condition of the aircraft and make a joint decision on whether it could be released into flight.

Tu-144 pilot Aleksandr Larin remembers a particularly troublesome flight on or around 25 January 1978 that he piloted. The flight with passengers aboard suffered the failure of 22 to 24 on-board systems. Seven to eight systems failed even before the takeoff; however given the large number of foreign TV and radio journalists aboard the flight, and also some other foreign notables aboard, it was decided to proceed with the flight in order to avoid the embarrassment of cancellation. After the takeoff, failures continued to multiply. While the aircraft was supersonic en route to the destination airport, Tupolev bureau's crisis center predicted that front and right landing gear would not extend and that the aircraft would have to land on left gear alone – at the aircraft landing speed of over 300 km/h. Due to expected political fallout, Soviet leader Leonid Brezhnev was personally notified of what was going on in the air. With the accumulated failures, an alarm siren went off immediately after the takeoff with sound and loudness similar to that of a civil defense warning. The crew could figure no way to switch it off and the siren stayed on throughout the remaining 75 minutes of the flight. Eventually the captain ordered the navigator to borrow a pillow from the passengers and stuff it inside the siren's horn. Luckily, all landing gears extended and aircraft was able to land.

The last passenger flight of Tu-144 on around May 30, 1978 involved valve failure on one of the fuel tanks.

Suggesting low confidence of the Soviet decision-makers in Tu-144 is also the fact that despite having eight Tu-144S certified aircraft by the time passenger service commenced in 1977 and a number of routes suitable for supersonic flights, only one route was ever used, with flights limited to once a week. Furthermore, booking was limited to 70–80 passengers a flight or less, well below the Tu-144's seating capacity, despite waiting lists. Over its 55 scheduled flights, Tu144s transported 3194 passengers, an average of 58 passengers per flight. With officials being acutely aware of the aircraft's poor reliability and fearful of possible crashes, Soviet decision-makers were purposefully limiting flight frequency to the absolute minimum possible that still allowed them to claim regular service, and also were constraining passenger load to minimize the impact and political fallout of a possible crash.

Yet the most serious problem with the aircraft was discovered when two Tu-144S airframes suffered catastrophic destruction during lab testing soon before the Tu-144 was allowed to enter passenger service. This data is also included as a chapter in Firdlyander's memoirs. The destruction of two airframes during stress testing is also mentioned in Bliznyuk et al. The problem so acutely discovered in 1976 may not have been exactly unknown even before then: reports of the large crack in the airframe of the Tu-144 prototype (aircraft 68001) discovered in Warsaw during the prototype return flight in June 1971 after the tour to Salon Aeronautique coming back to Moscow via East Berlin and Warsaw might have manifested the same problem.

In retrospect, the most fatal design decision for Tu-144 was the decision to assemble the Tu-144 from large machined blocks and panels, many over 19 meters long and 0.64 to 1.27 m wide. While at the time this approach was heralded as an advanced feature of the Tu-144 design program, it turned out that large whole-moulded and machined parts were bound to contain non-uniformities in alloy structure that cracked at stress levels well below what the part was supposed to withstand. Furthermore, once a crack started to develop, it spread very quickly across the entire large part, for many meters, with nothing to stop it. The same kind of catastrophic cracks were to develop from fatigue too. In 1976 during repeat-load and static testing in TsAGI, a Tu-144S airframe cracked at 70% of expected flight stress with cracks running many meters in both directions from the spot of their origin.

Later the same year, a Tu-144 was subject to a test simulating heat and pressure conditions during actual flight. The Tu-144 was placed into a hyperbaric chamber heated to 130–150 degrees Celsius to make it contract and expand just as it would during flight. Contraction and expansion happens because of the cooling during ascent and descent, heating during supersonic acceleration and cruise, and because of the pressure change from high altitude (low outside pressure causing the airframe to expand) to ground-level pressure (causing it subsequently to contract). The airframe creaked heavily and eventually cracked in a similar way as during the TsAGI load testing.

While fatigue cracks are normal in aircraft, the normal occurrence is that a crack develops slowly and stops once it reaches the end of the panel of which larger parts are assembled. Thus an aircraft could fly with a minor crack for a sufficiently long time, before it could be fixed. The Tu-144 design was the opposite of standard practice, not only fostering a higher incidence of non-uniformities in alloy structure leading to crack formation, but also allowing the crack to develop very fast and for many meters. Academician Fridlyander, leading Soviet metallurgist and long-term collaborator of Tupolev and his bureau for virtually all of the bureau's civil and military aircraft since mid-1940s and through the 1990s, including Fridlyander's participation in Tu-144 development and testing, concludes his account of the Tu-144 program: "Airplane (the Tu-144) was doomed as soon as the decision was made to compose it of large monolithic fragments machined of large metal panels. Instead of safely damageable design, this created its antipode — unsafely damageable design".

Fridlyander's account also stresses safety considerations during the design of the Concorde airframe, as opposed to the Tu-144 airframe design. Bliznyuk et al. mention an attempt to counter the problem by requesting the redesign of the alloy to slow down the development of the cracks and to tighten uniformity controls; however it is left unreported to what extent it was possible to deliver on these requests, and in any event these attempts were directed at limiting the scope of the problem rather than resolving it. Noteworthy, when requesting Western technological aid with the development of the Tu-144 in 1977-1978 (see below), one of the technological items requested by the Soviet Union in the late 1978 was the ways to reinforce airframe strength to withstand damage.

It is also noteworthy that the Soviet leadership made a political decision to enter the Tu-144 into passenger service in November 1977 despite receiving testing reports indicating that the Tu-144 airframe was unsafe and basically not airworthy for regular service. Curiously, Aeroflot appears to have thought so little of the aircraft that it didn't even mention it in its five-year plan for 1976–1980. However, it was not the airline executives' decision and Aeroflot reluctantly put the Tu-144 into passenger service on 1 November 1977.

Though the decision to cancel the Tu-144S passenger service came a few days after the Tu-144D crashed during the test flight on 23 May 1978, this crash was only the last drop to an already full cup of fears and concerns about the reliability of the Tu-144. Even the fact that the technical reason for the crash was specific to the Tu-144D fuel pump system and did not apply to the Tu-144S did not help. The decision to pull the Tu-144S out of passenger service after merely 55 flights is thus more likely to be attributable to high incidence of failures during and before the scheduled flights. Coupled with already existing concerns about the airframe reliability, and underscored by recent Tu-144D crash, it must have incited Soviet leadership to satisfy themselves with the symbolic status already achieved by token flights, rather than keep risking the embarrassment of a crash with passengers on board.

The problem most noticeable for passengers during flights was very high discomforting level of noise inside the cabin. The noise was partially coming from the engines, but the chief source of the noise was air conditioning and the aircraft skin cooling system. Unlike conventional subsonic aircraft, a cooling system is absolutely vital for supersonic cruise to cool off the aircraft skin and prevent it from overheating and losing structural integrity. Heat generated by intense air-to-surface friction in supersonic flight is passed to the coolant (cabin air, in case of both the Tu-144 and the Concorde) and subsequently discharged via heat exchangers to the fuel stream right before it is pumped to the engines. Unlike the Concorde, the Tu-144 cooling system was very noisy. Passengers seated next to each other could have a conversation only with difficulty, and those seated two seats apart could not hear each other even when screaming and had to pass hand-written notes instead. Noise in the back of the aircraft was unbearable. Alexei Tupolev, who was aboard the flight, acknowledged the problem to foreign passengers and promised to fix it. Available publications do not provide any clues that might suggest what was the exact technical reason for the aircraft being this noisy. It is also not known whether the problem was eventually fixed or not. The fact that publications based in Tupolev sources (Gordon, Bliznyuk) that go into some detail describing the cooling system design avoid mentioning this well-publicized problem that was major passengers' complaint at all, suggests that it had likely stayed unresolved. It was rumored that Aeroflot eventually resorted to issuing earplugs to Tu-144 passengers, but it is unclear whether these rumors are accurate.

As to the component of the cabin noise originating from the engines, it was stronger in the Tu-144 than in the Concorde in part because Tu-144's engines were located much closer to the cabin. (This also increased the potential for contagious engine failure, where the shock wave from one stalled engine disrupts the others.)

A redesign of the Tu-144 to resolve the issues mentioned would have required a substantial time before it would be possible to re-enter the Tu-144 in passenger service as an aircraft trying to compete, if only symbolically and politically, with the Concorde.

A degree of desperation of Tu-144 proponents among the Soviet policy makers over the USSR ability to deliver the Tu-144 as operationally capable aircraft with decent characteristics is apparent in the unprecedented Soviet request for Western technological aid with the development of the Tu-144 – a request that was made despite it obviously not helping to foster Soviet technological prestige, which was one of the key purposes of the whole Tu-144 programme. In 1977 the USSR approached Lucas Industries plc, a designer of the engine control system for the Concorde, requesting help with the design of the electronic management system of the Tu-144 engines, and also asked BAC-Aérospatiale for assistance in improving the Tu-144 air intakes. (The design of air intakes' variable geometry and their control system was one of the most intricate features of the Concorde, contributing to its fuel efficiency. Over half of the wind-tunnel time during the Concorde development was spent on the design of air intakes and their control system.) In late 1978 the USSR requested a wide range of Concorde technologies, obviously reflecting a broad spectrum of unresolved Tu-144 technical problems. The list included de-icing equipment for the leading edge of the air intakes, fuel-system pipes and devices to improve durability of these pipes, drain valves for fuel tanks, fireproof paints, navigation and piloting equipment, systems and techniques for acoustical loading of airframe and controls (to test against acoustic fatigue caused by high jet-noise environment), ways to reinforce airframe strength to withstand damage, firefighting equipment, including warning devices and lightning protection, emergency power supply, landing gear spray guards (aka water deflectors or "mud flaps" that increase engine efficiency when taking off wet airstrip). These requests were denied after the British government vetoed them on the ground that the same technologies, if transferred, could be also employed in Soviet bombers. Soviet approaches were also reported in British mainstream press of the time, such as London Times.

A particularly deadly blow to Tu-144 development was stricken by the crash of the Tu-144D during a test flight on 23 May 1978 caused by a fire in the fuel supply system, however the history of Tu-144 development failures does not end at that.

On 31 August 1980, Tu-144D (77113) suffered a compressor disc failure in supersonic flight leading to further destruction of airframe structural elements and onboard systems. The crew was able to perform an emergency landing at Engels-2 strategic bomber base. On 12 November 1981, a Tu-144D's RD-36-51 engine was destroyed during bench tests, leading to a temporary suspension of all Tu-144D flights. One of the Tu-144Ds (77114, aka aircraft 101) suffered a crack across the bottom panel of its wing. In all likelihood, the list of problems was more extensive.

Finally, the 1970s hikes in oil prices were starting to catch up with the Soviet Union. Much later than in the West, but since the late 1970s, commercial efficiency was starting to become a factor in aviation development decision-making even in the USSR. The Tu-144 disappeared from Aeroflot published prospects, replaced by the wide-body jet IL-86 as the new coming flagship Soviet aircraft.

In the late 1970s Soviet insiders were intensely hopeful in conversations with their Western counterparts to reintroduce Tu-144 passenger service for the 1980 Moscow Olympic games, even perhaps for flights to Western Europe, giving the aircraft high visibility, but apparently the technical condition of the aircraft weighed against such re-introduction even for token flights.

As discussed by Moon, economic efficiency alone would not have doomed the Tu-144 altogether: continuation of token flights for reasons of political prestige would have been possible, if only the aircraft itself would have allowed for it, but it did not. The Tu-144 was to a large extent intended to be and trumped as a symbol of Soviet technological prestige and superiority. With a Soviet aircraft that could counterpose the Concorde nowhere near in sight for at least years to come, the Tu-144 programme was becoming more of a political embarrassment rather than pride to the Soviet Union, a symbol of technological race lost to the West, and was quietly rolled down.

The decision to cease Tu-144D production was issued on 7 January 1982, followed by a USSR government decree dated 1 July 1983 to cease the whole Tu-144 programme and hereafter to use produced Tu-144 aircraft only as flying laboratories. A formal decision to cease the Tu-144 programme was also in all likelihood related, to an extent, to the generational change in the Soviet leadership and departure of those officials who had strong individual commitment to the Tu-144 and stakes in the project, and corresponding change in the bureaucratic balance. The Tu-144 luck fared worse after the death of Minister Petr Dementiev on 14 May 1977, but the last bureaucratic straw must have been the death of Brezhnev on 10 November 1982.

In retrospect it is apparent that the Tu-144 suffered from a rush in the design process to the detriment of thoroughness and quality, and this rush to get airborne exacted a heavy penalty later. The rush is apparent even in outward timing: the 1963 government decree launching the Tu-144 programme defined that the Tu-144 should fly on 1968, so it did indeed fly on the last days of 1968 to fulfill government goals arbitrarily set five years earlier. (By the way of comparison, the Concorde's first flight was originally scheduled for February 1968, but was pushed back several times until March 1969 in order to iron out problems and test components better. ) Unlike the Concorde development, the Tu-144 project was also strongly driven by ideologically and politically motivated haste of Soviet self-imposed racing against the Concorde; Aleksei Poukhov, one of Tupolev's designers, reminiscences: "For the Soviet Union to allow the West to get ahead and leave it behind at that time was quite unthinkable. We not only had to prevent the West from getting ahead, but had to compete and leapfrog them, if necessary. This was the task Khruschev set us... We knew that when Concorde's maiden flight had been set for February or March, 1969, we would have to get our plane up and flying by the end of 1968."

The introduction of the Tu-144 into passenger service was timed to the 60th anniversary of the Communist revolution, as was duly noted in Soviet officials' speeches delivered at the airport before the inaugural flight – whether the aircraft was actually ready for introduction into passenger service was deemed of secondary importance. Even the outward details of the inaugural Tu-144 flight betrayed the haste of its introduction into service: several ceiling panels were ajar, service trays stuck, window shades dropped without being pulled, reading lights did not work, not all toilets worked and a broken ramp delayed departure half an hour. On arrival to Alma-Ata, the Tu-144 was towed back and forth for 25 minutes before it could be aligned with the exit ramp. Equally telling is the number of hours spent on flight testing. Whereas the Concorde had been subjected to 5,000 hours of testing by the time it was certified for passenger flight, making it the most tested aircraft ever,, total flight testing time of the Tu-144 by the time of its introduction into passenger service was less than 800 hours — over six times less than for the Concorde. Flight testing time logged on the prototype (68001) was 180 hours flight testing time for the Tu-144S till the completion of state acceptance tests was 408 hours; service tests till the commencement of passenger service were 96 hours of flight time; altogether totalling 756 hours. It is unclear why the Minister of Aviation Industry and the Minister of Civil Aviation did not endorse the protocols of state acceptance tests for four months after the tests completion. One reason could be the change of the guard — Minister Dementiev, who was one of the chief backers of Tu-144, died a day before the tests completed (something Gordon fails to notice) — but it might also had something to do with aircraft reliability record uncovered during the tests that was in all likelihood not better than subsequent dismal service record in 1977–1978.

Flight profil of Tu-144 and Mirage IIIR

Perhaps one of the most tragic manifestations of ideologically driven haste during the Tu-144 programme was the 1973 crash of the Tu-144 during the Paris Air Show. A picture of the events and causes is well-emerged by now after the revelations in recent years. The details are briefly as follows. The day before the Tu-144 crash the Concorde performed an impressive lively display at Le Bourget; landing on the airstrip, engaging thrust reversors and stopping, then accelerating and taking off again from the middle of the airstrip. The Tu-144S could not match this performance; it did not have thrust reversers and was braked, like a bomber, by the braking parachute, so it could not take off immediately after landing without packing the chute first. The Tu-144S also had poorer general landing characteristics, such as higher landing speed, compared to the Concorde. After heated discussion in the hotel that evening, key members of the Soviet delegation and the Tu-144 crew decided to try beating the Concorde show by performing the next day some impromptu designed air manoeuvres with the Tu-144, including the steep "hump" manoeuvre that ended in the crash. Their impromptu decision was approved by the higher leadership, apparently by Soviet Aircraft Industry Minister Petr Dementiev. This decision was a flagrant violation of safety and general basic rules and multiple air regulations. The intended manoeuvres were not included in the flight plan, but more than that, they had never ever been tried on the Tu-144 before. Experimental parts of the aircraft control system were engaged, apparently in an attempt to improve the aircraft manoeuvrability for performing the intended air "tricks". The cockpit panel that controlled experimental parts of the flight control system had a cover specifically placed over it before the departure from Moscow, and the cover was sealed off in Moscow. In Paris, the seal and the cover were removed and switches were engaged to activate experimental parts of the aircraft control system. Pilots tried to perform the steep manoeuvre that had never been tried or thought through, driving the Tu-144 into a regime relying on the aircraft stability characteristics that the crew did not fully account for, and with pilots engaging new elements of the control system that had not been well tested yet, the effects of which which the crew did not fully understand and that proved to work differently than the crew expected – all in a hasty attempt to rival the Concorde.

Fridlyander also points out that in addition to the Tu-144, Tupolev's bureau had to work in parallel on other projects, including the Tu-154 passenger aircraft and the Tu-22M bomber. Despite large and high-priority resource investment in the Tu-144 development programme and the fact that a large part of the whole Soviet R&D infrastructure was subordinated to the Tu-144 project, parallel project development overwhelmed the bureau and caused it to lose focus and make design errors. (Design errors affected not only the Tu-144, but the Tu-154 as well. The first batch of 120 Tu-154s suffered from wing destruction due to excessive structural load and had to be withdrawn.)

The rush and introduction in service of poorly tested aircraft also happened previously with another Tupolev project that had high political visibility and prestige: the Tu-104 passenger jet liner that was the first successful passenger jet airliner in service (the Comet 1 was not considered successful because four of the original nine aircraft crashed). In a decision-making similar to the Tu-144 story, the Soviet government introduced the Tu-104 into passenger service before satisfactory stability and controllability of the aircraft could have been achieved, despite the fact that during high-altitude and high-speed flights the aircraft was prone to longitudinal instability, and also that at high echelons, it had a narrow range of attack angle separating the aircraft from stalls. These problems created the preconditions for spin dives, that happened twice before the Tu-104 was eventually properly tested and the problem was resolved.

This politically motivated rush, coupled with the fact that the project was essentially ideologically motivated rather than driven by intrinsic needs of the Soviet society, coupled with general technological backwardness and backwardness of Soviet industrial base, contributed to the final undoing of the Tu-144 project. (Alexadner Poukhov, one of the Tu-144 design engineers who subsequently rose to be one of the bureau's senior designers, subsequently was estimating in 1998 that the Tu-144 project was 10–15 years beyond the current USSR's capabilities.)

Moon suggests that subordination of available Soviet R&D resource allocation to the Tu-144 programme significantly slowed down the development of other Soviet aircraft projects, including more sound ones such as the IL-86 wide-body jet, and stagnated Soviet aviation development for almost a decade.

After project cancellation

The Tu-144 programme was ceased by Soviet government decree dated 1 July 1983 that also provided for future use of the remaining Tu-144 airplanes as airborne laboratories.

The Tu-144 was indeed used as a flying research laboratory. Starting in 1985, Tu-144D was used for training of pilots for the Soviet "Buran" space shuttle. In 1986–1988 the Tu-144D №77114 was used for medical and biological research of high-altitude atmosphere radiological conditions. Further research was planned but ceased due to lack of funding.

In 1996-1999 the Tu-144D №77114 was used as a testbed by NASA teaming with Russian and U.S. airspace industries to develop technologies for a proposed second-generation supersonic airliner.

Right after ceasing the Tu-144 programme, Tu-144D №77114 (aka aircraft 101 or 08-2) performed a number of flights on 13-20 July 1983 to establish 13 world records registered with FAI. The list of the records can be retrieved from the FAI online database. In a nutshell, these records establish a top altitude of 18,200 meters with range of loads up to 30 tons, and sustained speed over a closed circuit up to 2,000 km of 2,032 km/h under similar loads.

The clause about loads probably does not have much significance, as loads were almost certainly compensated by the reduction of fuel load to maintain the same total aircraft takeoff weight. Indeed, it would be hard to imagine the aircraft suddenly carrying the load thrice what it was designed to carry, with the maximum fuel load at the same time. Furthermore, submitted records cover a range of closed circuit lengths up to 2,000 km, but go no further: the fact that the USSR did not attempt to submit flight records for longer circuit lengths suggests that the aircraft was carrying only a partial fuel load.

Still, these record numbers are surprisingly low and it is doubtful whether they indeed represent the aircraft's maximum achievable performance. To put the numbers in prospect, Concorde's service ceiling during routine flight under typical trans-Atlantic load of about 10 tons is set to 60,000 ft (18,290 meters), higher than the record set by the Tu-144D, but Concorde could surely climb further above the regular service ceiling if the goal were to set the record altitude. According to unverified sources, during a 26 March 1974 test flight a Concorde reached its maximum speed ever of 2,370 km/h (1,480 mph, Mach 2.23) at an altitude of 63,700 ft (19.4 km) and during subsequent test flights reached maximum altitude of 68,000 ft (20.7 km). It is unclear why Tu-144D’s maximum achievable altitude would be lower than the Concorde's even regular flight altitude given that Tupolev's data claim better lift-to-drag ratio for the Tu-144 compared to the Concorde (over 8.0 for Tu-144D vs Concorde's 7.3-7.7 at M2.x) and the thrust of the Tu-144D's RD-36-51 engines is higher than the Concorde's Olympus 593 engines.

While the Concorde set over 170 world records since its first flight in 1969, it apparently did not log records in flying over a closed circuit category, but it is nevertheless unclear why the sustained airspeed of 2,032 km/h claimed in Tu-144D's records would be lower than even the Concorde's typical commercial cruising speed of M2.02 to 2.05.

While the Concorde was originally designed for cruising speeds up to M2.2, its regular service speed was limited to M2.02 to reduce fuel consumption and extend airframe longevity, and also apparently to provide a safety margin. One of Tupolev's web site pages concurs that "TU-144 and TU-160 aircraft operation has demonstrated expediency of limitation of cruise supersonic speed of M=2,0 to provide structure service life and to limit cruising altitude". The Concorde's maximum design cruise speed was M2.2 and maximum tested speed was M2.23.

Neither the Concorde nor the Tu-144 are limited in their maximum speed by the airframe drag, nor by the engines thrust, they are limited by the airframe heating and structural integrity of their aluminium alloys, with alloys used in both aircraft being very similar in their properties. The Tu-144 prototype (airplane №68001) might have had a slight edge since about 15-20% of its parts were built of titanium. Indeed, the Tu-144 №68001 shortly achieved maximum speed of 2,443 km/h (M 2.26) during one of the test flights on 17 May 1968. However the use of titanium for production Tu-144's was radically cut down and the Tu-144S/Tu-144D were built almost entirely of aluminium alloys; titanium and stainless steel were used only for the leading edges, elevons, rudder and under-surface of the rear fuselage (that was heated by the engines exhaust, since Tu-144 engines were located closedly to the fusalage). Given that the alloys used for both airplanes are almost identical, as well as the thermodynamics of their critical edges is very similar, one should expect that the speeds achievable by both aircraft while maintaining the same level of structural safety should also be about the same. The Tu-144S might have had an edge due to its much higher fuel expenditure per km, that also doubled as a heat discharge medium, and thus potentially might have been able of stronger heat discharge, but the Tu-144D moved closer to the Concorde in its fuel consumption.

Proposed military versions

Earliest project configurations of the Tu-144 were based on the unbuilt Tu-135 bomber, retaining the latter aircraft canard layout, wings and engine nacelles. Deriving from the Tu-135 bomber, early Tupolev’s design for supersonic passenger airplane was code-named Tu-135P before acquiring the Tu-144 project code.

Over the course of the Tu-144 project, the Tupolev bureau performed early designs of a number of military versions of Tu-144. Neither of these versions were ever built. In the early 1970s Tupolev was developing the Tu-144R intended to carry and air-launch up to three solid-fueled ICBMs. The launch was to be performed from within the Soviet air space, with the aircraft accelerating to its maximum speed before releasing the missiles. The original design was based on the Tu-144S, but later changed to be derived from the Tu-144D. Another version of the design was to carry air-launched long-range cruise missiles similar to the Kh-55. The study of this version envisioned the use of liquid hydrogen for the afterburners. The NK-144 engines with cryogenic afterburning passed bench test.

In the late 1970s Tupolev contemplated the development of a long-range heavy interceptor (DP-2) based on the Tu-144D that was also to be able to escort bombers on long-range missions. Later this project evolved into an aircraft for deployment of electronic countermeasures (ECM) to suppress enemy radars and facilitate bomber's penetration through enemy air defenses (Tu-144PP). In the early 1980s this functionality was supplanted with theatre and strategic reconnaissance (Tu-144PR). The dimmer civil prospects for Tu-144 were becoming, the more Tupolev was trying to "sell" the aircraft to the military. One of the last attempts to "sell" the Tu-144 to the military was a project for a long-range reconnaissance aircraft for the Soviet Navy (Tu-144MR) intended to provide targeting information to the Navy's ships and submarines on sea and oceanic theaters of operations; another proposed navy version was to have a strike capability (two Kh-45 air-to-surface cruise missiles) along with reconnaissance function.

The military were unreceptive to Tupolev's approaches. Vasily Reshetnikov, then commander of Soviet strategic aviation, and subsequently a vice-commander of the Soviet Air Force remembers how in 1972 he was dismayed by Tupolev's attempts to offer for military use the aircraft that "fell short of its performance target, was beset by reliability problems, fuel-thirsty and difficult to operate.

Reshetnikov goes on to remember:

The development and construction of the supersonic airliner, the future Tu-144, was included in the five-year plan and was under the auspices of the influential D.F. Ustinov (then Soviet minister of defence and confidant of Brezhnev, who represented interests of defence industries lobby in opposition to the military) who regarded this mission as a personal responsibility — not so much to his country and people as to "dear Leonid Il'ych" (Brezhnev) whom he literally worshipped, sometimes to the point of shamelesness... Yet the supersonic passenger jet was apparently not making headway and, to the dismay of its curator, it looked like Brezhnev might be disappointed. It was then that Dmitry Fedorovich (Ustinov) jumped at someone's bright idea to foist Aeroflot's "bright in search of a wedding" on the military. After it had been rejected in bomber guise, Ustinov used the Military Industrial Commission (one of the most influential Soviet government bodies) to promote the aircraft to the Strategic Aviation as a reconnaissance or ECM platform, or both. It was clear to me that these aircraft could not possibly work in concert with any bomber or missile carrier formation; likewise I could not imagine them operating solo as "Flying Dutchmen" in a war scenario, therefore I resolutely turned down the offer.

Naval Aviation Commander Aleksandr Alekseyevich Mironenko, followed suit.

But nothing worked! Ustinov could not be put off that easily. He managed to persuade the Navy C-in-C (admiral) S.G. Gorshkov who agreed to accept the Tu-144 for Naval Aviation service as a long-range reconnaisance aircraft without consulting anyone on the matter. Mironenko rebeled against this decision, but the commander-in-chief would not hear of heed — the issue is decided, period. On learning of this I was extremely alarmed: if Mironenko had been pressured into taking the Tu-144, this meant I was going to be next. I made a phone call to Aleksandr Alekseyevich, urging him to take radical measures; I needn't have called because even without my urging Mironenko was giving his C-in-C a hard time. Finally Ustinov got wind of the mutiny and summoned Mironenko to his office. They had a long and heated discussion but eventually Mironenko succeeded in proving that Ustinov's ideas were unfounded. That was the last time we heard of Tu-144.

Espionage against the Concorde and influence by the Concorde

The development of the Tu-144 is said to be closely related to industrial espionage against the French company Aérospatiale, which was developing the Concorde, although the TU-144 flew two months before. When Sergei Pavlov —officially acting as Aeroflot’s representative in Paris—was arrested in 1965, he was in possession of detailed plans of the braking system, the landing gear and the airframe of the Concorde. Another agent named Sergei Fabiew, who was arrested in 1977, was believed to have obtained the entire plans of the prototype Concorde back in the mid-60s. However, these were early development plans, and would not have permitted the USSR engineers to come up with their own aircraft; they could only serve as a general indication of the work of the Concorde design team. An espionage theory purportedly involved the Anglo/French Concorde team that knew that the Soviets were planning to steal the plans. For this reason, a set of dummy blueprints were put into circulation by the Anglo/French team with deliberate design flaws.

Noticeable appearances in media

The Tupolev Tu-144 was featured in the 1987 Phoenix Force adventure book series Weep, Moscow, Weep.

Variants

• Tu-144 - (izdeliye 044 - article 044) The sole prototype Tu-144 aircraft
• Tu-144 - (izdeliye 004 - article 004) Six re-designed production aircraft powered by Kuznetsov NK-144 engines in widely spaced nacelles, and re-designed undercarriage
• Tu-144S - (S - Sereeynyy - series) Alternative designation of production aircraft
• Tu-144D - (izdeliye 004D - article 004D)(D-Dahl'neye - long-range) Production Tu-144 aircraft powered by Koliesov RD36-51 non after-burning engines. One aircraft converted from Tu-144 CCCP-77105(c/n10031) and five production aircraft (CCCP-77111 [c/n10062] to CCCP-77115 [c/n 10091]) plus one (CCCP-77116) uncompleted
• Tu-144DA - Projected improved version of the Tu-144D with greater fuel capacity and therefore longer range
• 'Tu-144LL - One Tu-144D aircraft (CCCP-77114 [c/n10082]) converted to a flying laboratory with four Kuznetsov NK-321 afterburning turbofan engines and re-registered RA-77114. The first flight took place on 19 November 1996 with the 27th and last flight on 28 February 1998

Specifications

These are the specification for the later experimental version the Tu-144D which employs the more efficient turbojet engines.

Orthographically projected diagram of the Tu-144LL.

General characteristics

• Crew: 3
• Capacity: 120-140 passengers, but normally 70~80 passengersFuel capacity: 70,000 kg (154,000 lb)

Performance

• Thrust/weight: 0.44

Image gallery

• 
  Engines RD-36-51A of a Tu-144D
• 
  Nose of the Tu-144
• 
  Fuselage of the Tu-144
• 
  Cockpit of the Tu-144
• 
  Cockpit of the Tu-144
• 
  Cabin of the Tu-144 in Sinsheim Auto & Technik Museum
• 
  empennage

See also

• Supersonic transport

Related development

• Tupolev Tu-244
• Tupolev Tu-444

Aircraft of comparable role, configuration, and era

• Concorde
• Boeing 2707
• Lockheed L-2000

References

Notes

Bibliography

• Bliznyuk, Valentin et al. Reality of supersonic passenger airplanes (in Russian: Близнюк В., Васильев Л., Вуль В. и др., Правда о сверхзвуковых пассажирских самолетах). Moskva, 2000. ISBN 5-239-02044-2.
• Gordon, Yefim. Tupolev Tu-144. London: Midland, 2006. ISBN 1-85780-216-0.
• Calvert, Brian. Flying Concorde: The Full Story. London: Airlife, 2002. ISBN 1-84037-352-0.
• Gordon Yefim, Tupolev Tu-160 Blackjack: The Russian Answer to the B-1 (Red Star 9). London: Midland Publishing, 2003. ISBN 978-1-85780-147-7.
• Kandalov, Andrei and Paul Duffy. Tupolev: The Man and His Aircraft: The Man and His Aircraft. Warrendale, PA: Society of Automotive Engineers, 1996. ISBN 1-56091-899-3.
• Melik-Karimov, Vitaly, Life and death of the Tu-144 (in Russian: В. Мелик-Каримов, Жизнь и смерть самолёта Ту-144, Огонёк, № 3, январь 2000.
• Moon, Howard. Soviet SST: The Technopolitics of the Tupolev-144. London: Orion Books, 1989. ISBN 0-517-56601-X.
• Wright, Peter and Paul Greengrass. Spycatcher: The Candid Autobiography of a Senior Intelligence Officer. London: Viking, 1987. ISBN 0-670-82055-5.
• Taylor, John W.R. Jane's Pocket Book of Commercial Transport Aircraft New York: Macmillan, 1974. ISBN 0-12-080480-6.
• Wynne, Greville. The Man from Odessa. Dublin: Warnock Books, 1983. ISBN 0-586-05709-9.
• Gordon,Yefim & Rigmant, Vladimir. Tupolev Tu-144. Midland. Hinkley. 2005. ISBN(10) 1 85780 216 0 ISBN(13) 978 185780 216 0

External links

• Tupolev TU-144 page
• Auto + Technik Museum Sinsheim
• TU-144 SST - Flying Forever on the Internet
• List of Tu-144s with eventual fate
• NASA video clip
• Stats
• Transcript of PBS NOVA episode "Supersonic Spies", aired 27 January 1998
• The Tu-144: the future that never was