The Tupolev Tu-144

Of course, during the 1960s the Soviets and the West were in competition, and anything spectacular the West wanted to do, the Soviets wanted to do as well. That included an SST.

The Soviet Tupolev design bureau developed the USSR's answer to the Concorde , the Tupolev "Tu-144", also known by the NATO codename "Charger". The Tu-144 prototype performed its first flight on 31 December 1968, with test pilot Eduard Elyan at the controls, beating the Concorde by three months. 17 Tu-144s were built, the last one coming off the production line in 1981. This sum includes one prototype; two "Tu-144C" preproduction aircraft; and 14 full production machines, including nine initial-production "Tu-144S" aircraft, and five final production "Tu-144Ds" with improved engines.

Tupolev Tu-144 crash at Goussainville

The Tu-144 got off to a terrible start, the second Tu-144C preproduction machine breaking up in midair during a demonstration at the Paris Air Show on 9 June 1973 and the debris falling into the village of Goussainville. All six crew in the aircraft and eight French citizens on the ground were killed, 15 houses were destroyed, and 60 people were injured. Since the initial reaction of the crowd watching the accident was that hundreds of people were likely to have been killed, there was some small relief that the casualties were relatively light. The entire ghastly accident was captured on film.

The details of the incident remain murky. The Concorde had put on a flight display just before the takeoff of the Tu-144, and a French air force Dassault Mirage fighter was in the air, observing the two aircraft. The Concorde crew had been alerted that the fighter was in the area, but the Tu-144 crew had not. The speculation is that Elyan, who was piloting the Tu-144, saw the Mirage shadowing him. Although the Mirage was keeping a safe distance, Elyan might have been surprised and nosed the Tu-144 down sharply to avoid a collision. Whatever the reason for the nosedive, it flamed out all of the engines. Elyan put the aircraft into a dive so he could get a relight and overstressed the airframe when he tried to pull out.

This scenario remains speculation. Other scenarios suggest that Elyan was trying too hard to outperform the Concorde and took the machine out of its envelope. After a year's investigation, the French and Soviet governments issued a brief statement saying that the cause of the accident could not be determined. Some suspect a cover-up, but it is impossible to make a credible judgement given the muddy trail, particularly since the people who could have told exactly what had happened weren't among the living any more.

The Tu-144 resembled the Concorde , sometimes being called the "Concordski", and there were accusations that it was a copy. Many Western observers pointed out that there were also similarities between the Concorde and American SST proposals, and there was no reason to believe the resemblances between the Concorde and the Tu-144 were much more than a matter of the normal influence of published design concepts on organizations, as well as "convergent evolution", or the simple fact that two machines designed separately to do the same task may out of simple necessity look alike.

The truth was muddier. Building an SST was an enormous design challenge for the Soviet Union. As a matter of national prestige, it had to be done, with the Soviet aircraft doing it first, and since the USSR was behind the West's learning curve the logical thing to do was steal. An organization was established to collect and analyze open-source material on SSTs from the West, and Soviet intelligence targeted the Concorde effort for penetration.

In 1964, French counterintelligence got wise to this game and sent out an alert to relevant organizations to beware of snoops and to be careful about releases of information. They began to keep tabs on Sergei Pavlov, the head of the Paris office of Aeroflot, whose official job gave him legitimate reasons for obtaining information from the French aviation industry and put him in an excellent position to spy on the Concorde effort. Pavlov was not aware that French counterintelligence was on to him, and so the French fed him misinformation to send Soviet research efforts down dead ends. Eventually, on 1 February 1965, the French arrested him while he was going to a lunch date with a contact, and found that he had plans for the Concorde's landing gear in his briefcase. Pavlov was thrown out of the country.

However, the Soviets had another agent, Sergei Fabiew, collecting intelligence on the Concorde effort, and French counterintelligence knew nothing about him. His cover was finally blown in 1977 by a Soviet defector, leading to Fabiew's arrest. Fabiew had been highly productive up to that time. In the documents they seized from him, they found a congratulations from Moscow for passing on a complete set of Concorde blueprints.

Although the Soviets did obtain considerable useful intelligence on the Concorde, they were traditionally willing to use their own ideas or stolen ideas on the basis of which seemed the best. They could make good use of fundamental research obtained from the Concorde program to avoid dead ends and get a leg up, and they could leverage designs of Concorde subsystems to cut the time needed to build subsystems for the Tu-144.

In other words, the Tu-144 was still by no means a straight copy of the Concorde. The general configuration of the two aircraft was similar, both being dartlike delta-type aircraft with four afterburning engines paired in two nacelles; a drooping nose to permit better view on takeoff and landing; and a flight crew of three. Both were mostly built of conventional aircraft alloys. However, there were many differences in detail:

Tu-144 / Concorde comparison

• The Tu-144 was slightly longer and larger, with five-abreast seating compared to the four-abreast layout of the Concorde , giving the Soviet machine a capacity of 140 passengers.
• The Tu-144 was somewhat faster than the Concorde , with a cruise speed of up to Mach 2.4, and incorporated steel and titanium assemblies on wing leading edges and other high-temperature elements of the airframe.
• While the Concorde wing outline was an elegant ogival curve, the Tu-144's wing was a more straightforward double delta, with a sweep of 76 degrees on the forward part of the wing and a sweep of 57 degrees on the rear part of the wing.
• The Tu-144's engine nacelles were spaced closer together, with four elevons outboard of the engines on each wing and, unlike the Concorde , no elevons inboard of the engines. The Tu-144 did have a two-part rudder like the Concorde's.
• The Tu-144's main landing gear was also much "busier" than that of the Concorde , featuring eight-wheel bogies in a four-across arrangement retracting forward into the engine nacelles. The prototypes had featured twelve-wheel bogies. It is unclear why so many tires were used. It seems unlikely, though not impossible, that the Soviets wanted to fly an SST from a rough airstrip. It is possible that there wasn't enough space in the engine nacelles for a landing gear assembly with bigger tires. The gear doors were insulated to protect the landing gear from heat in flight. The two-wheel nose gear was steerable and retracted forward.
• The most significant visible difference between the Concorde and the Tu-144 was that the Tu-144 had a set of canard "winglets" behind the cockpit that were extended for takeoffs and landings. Apparently the French were very interested in the canards and the Mirage fighter that may have led to the accident at the Paris Air Show in 1973 was trying to obtain imagery of them in operation.

The Tu-144 was powered by four Kuznetsov NK-144 afterburning turbofans with 196.2 kN (20,000 kgp / 44,100 lbf) afterburning thrust each. The engines had separate ducts in each nacelle and variable ramps in the inlets. The Tu-144D, which performed its first flight in 1978, was fitted with Kolesov RD-36-51 engines that featured much improved fuel economy and apparently uprated thrust. Production machines seem to have had thrust reversers, but some sources claim early machines used drag parachutes instead.

The Tu-144 prototype was a bit shorter and had ejection seats, though production aircraft did not, and also lacked the retractable canards. The engines fitted to the prototype had a lower thrust rating and were fitted into a single engine box, not a split box as in the production machines. Pictures of the preproduction machines show them to have had a production configuration, though no doubt they differed in details.

The Tu-144 was not put into service until 26 December 1976, and then only for cargo and mail transport by Aeroflot between Moscow and Alma Ata, Kazakhstan, for operational evaluation. The Tu-144 didn't begin passenger service until 1 November 1977, and then apparently it was a cramped and uncomfortably noisy ride. Operating costs were unsurprisingly high and apparently the aircraft's reliability left something to be desired, which would not be surprising given its "bleeding edge" nature and particularly the haste in which it was developed.

The next year, on 23 May 1978, the first Tu-144D caught fire, had to perform an emergency landing, and was destroyed with some fatalities. The program never recovered. The Tu-144 only performed a total of 102 passenger-carrying flights. Some flight research was performed on two of the aircraft up to 1990, when the Tu-144 was finally grounded.

That was not quite the end of the story. As discussed in the next section, even though the Concorde and Tu-144 were clearly not money-making propositions, interest in building improved SSTs lingered on through the 1980s and 1990s. The US National Aeronautics & Space Administration (NASA) conducted studies on such aircraft, and in June 1993 officials the Tupolev organization met with NASA officials at the Paris Air Show to discuss pulling one of the Tu-144s out of mothballs to be used as an experimental platform for improved SST design. The meeting had been arranged by British intermediaries.

In October 1993, the Russians and Americans announced that they would conduct a joint advanced SST research effort. The program was formalized in an agreement signed by American Vice-President Al Gore and Russian Prime Minister Viktor Chernomyrdin at Vancouver, Canada, in June 1994. This agreement also formalized NASA shuttle flights to the Russian Mir space station.

The final production Tu-144D was selected for the tests, as it had only 83 flight hours when it was mothballed. Tupolev performed a major refurbishment on it, providing new uprated engines; strengthening the wing to handle the new engines; updating the fuel, hydraulic, electrical, and avionics systems; and adding about 500 sensors feeding a French-designed digital data-acquisition system. The modified Tu-144D was redesignated the "Tu-144LL", where "LL" stood for "Letnoya Laboritoya (Flying Laboratory)", a common Russian suffix for testbeds.

The new engines were Kuznetsov NK-321 turbofans, used on the huge Tupolev Tu-160 "Blackjack" bomber, replacing the Tu-144's Kolesov RD-36 engines. The NK-321 provided about 20% more power than the RD-36-51 and still better fuel economy. Each NK-321 had a max dry thrust of 137.3 kN (14,000 kgp / 31,000 lbf) and an afterburning thrust of 245.2 kN (25,000 kgp / 55,000 lbf). The details of the NK-321s were secret, and the Western partners in the venture were not allowed to inspect them.

A sequence of about 26 test flights was conducted in Russia with officials from the NASA Langley center at the Zhukovsky Flight Test Center from 1996 into 1999. Two NASA pilots, including NASA space shuttle pilot C. Gordon Fullerton, flew the machine during the course of the trials. As also discussed in the next section, the whole exercise came to nothing, but it was at least nice to get the machine back in the air one last time.

Future SST aircraft

Although the US had given up on the Boeing 2707-300 in 1971, NASA continued to conduct paper studies on SSTs, and in 1985 US President Ronald Reagan announced that the US was going to develop a high-speed transport named the "Orient Express". The announcement was a bit confusing because it blended an attempt to develop a hypersonic spaceplane, which emerged as the dead-end "National Aerospace Plane (NASP)" effort, with NASA studies for an improved commercial SST.

By the early 1990s, NASA's SST studies had emerged as the "High Speed Research (HSR)" effort, a collaboration with US aircraft industries to develop a "High Speed Civil Transport (HSCT)" that would carry up to 300 passengers at speeds from Mach 2 to 3 over a distance of 10,500 kilometers (6,500 miles), with a ticket price only 20% more than that of a conventional subsonic airliner. The fact that an SST could move more people in a shorter period of time was seen as a possible economic advantage. The NASA studies focused heavily on finding solutions to the concerns over high-altitude air pollution, airport vicinity noise levels, and sonic boom that had killed the 2707-300.

Other nations also conducted SST studies, with Japan flying large rocket-boosted scale models in the Australian outback, and there was an interest in international collaborative development efforts. The biggest non-environmental obstacle was simple development cost. While it might have been possible to develop an SST with reasonable operating costs, given the high development costs it was hard to see how such a machine could be offered at a competitive price and achieve the sales volumes needed to make it worthwhile to build.

Some aerospace firms took a different approach on the matter, proposing small "supersonic business jets (SSBJs)". The idea was that there was a small market of people for whom time is money and who would be willing to pay a high premium to shave a few hours for a trip across the ocean. Firms such as Dassault in France, Gulfstream in the US, and Sukhoi in Russia came up with concepts in the early 1990s, but the idea didn't go anywhere at the time.

Although the NASA HSR program did put the Tu-144LL back in the air, the study was finally axed in 1999. NASA, in good bureaucratic form, kept the program's cancellation very quiet, in contrast to the grand press releases that had accompanied the effort. This was understandable since NASA has to be wary of politicians out to grab headlines by publicly attacking government boondoggles, but in a sense the agency had nothing to hide: NASA studied the matter front to back, and one official stated off the record that in the end nobody could figure out how to make any money on the HSCT. From an engineering point of view, a conclusive negative answer is as useful as a conclusive positive answer, but few politicians have an engineering background and understand such things.

Some aircraft manufacturers didn't give up on SST research after the fall of the HSCT program. One of the major obstacles to selling an SST was the fact that sonic booms prevented it from being operated at high speed over land, limiting its appeal, and of course an SST that didn't produce a sonic boom would overcome that obstacle. Studies showed that sonic boom decreased with aircraft length and with reduction in aircraft size. There was absolutely no way the big HSCT, which was on a scale comparable to that of the Boeing 2707-300, could fly without generating a sonic boom, and so current industry notional configurations envision an SSBJ or small supersonic airliner.

Gulfstream has released a notional configuration of a "Quiet Supersonic Jet (QSJ)" that would seat 24 passengers, have a gross takeoff weight of 68,000 kilograms (150,000 pounds), a length of 49 meters (160 feet), and swing wings. Gulfstream officials project a market of from 180 to 400 machines over ten years, and add that the company has made a good profit building machines in productions runs as small as 200 aircraft. Other manufacturers have envisioned small SSTs with up to 50 seats.

Aerion Corporation, a startup in Reno, Nevada, is working on an SSBJ that is designed to carry 8 to 12 passengers, with a maximum range of 7,400 kilometers (4,000 NMI) at Mach 1.5, and a maximum takeoff weight of 45,350 kilograms (100,000 pounds). The machine is technologically conservative in most respects, with no flashy features such as swing wings or drooping nose. Current configurations envision a dartlike aircraft, with wedge-style wings fitted with long leading-edge strakes, a steeply swept tailfin with a center-mounted wedge-style tailplane, and twin engines mounted on stub pylons on the rear of the wings. A fly-by-wire system will provide controllability over a wide range of flight conditions.

The wings are ultra-thin, to be made of carbon composite materials, and feature full-span trailing-edge flaps to allow takeoffs on typical runways. The currently planned engines are Pratt & Whitney JT8D-219 turbofans, each derated to 80.1 kN (8,165 kgp / 18,000 lbf). The JT8Ds are non-afterburning and use a fixed supersonic inlet configuration. The expected power-to-weight ratio at normal operating weights is expected to be about 40%, about the same as a Northrop F-5 fighter in afterburner. The Aerion SSBJ will be able to operate efficiently at high subsonic or low supersonic speeds over populated areas, where sonic boom would be unacceptable. The company believes there is a market for 250 to 300 SSBJs, and is seeking backing to get their machine on the market by 2011.

Even with the final grounding of the Concorde , the idea of the SST continues to flicker on. It's such a technologically sexy idea that the appeal never seems to go away, but the track record of the whole thing is dodgy. SSBJ activity is fairly high right now and there are reasons for optimism, but what happens next is anyone's guess.

The SST Comments

In hindsight, the SST mania that produced the Concorde sounded persuasive at the time, but it suffered from a certain lack of realism. Although the Concorde was a lovely, magnificent machine and a technological marvel even when it was retired, it was also a testimony to a certain naivete that characterized the 1950s and 1960s, when people thought that technology could accomplish anything and set out on unbelievably grand projects. Some of these projects they incredibly pulled off, but some of them turned out very differently than expected. It's still hard not to admire their dash.

There's also a certain perverse humor to the whole thing. The French and the British actually built the Concorde , while the Americans, in typical grand style, cooked up a plan to build a machine that was twice as big and faster -- and never got it off the ground. The irony was that Americans made the right decision when they killed the 2707-300. The further irony was that they did it for environmental reasons that were, if not necessarily wrong, at least far less relevant than the fact they would have lost their shirts on it.

Author: Greg Goebel