Supersonic Passenger Jet Tu-144

Concorde, Tu-144, Aircraft
  1. Tupolev Tu-104:

While the three major US, European, and former-USSR powers all designed supersonic transports, that of the latter was really the first to fly. But its development was complex and it ultimately ended in failure.

Seeking to increase speeds and reduce travel times on scheduled routes, all of which were flown by Aeroflot, the nation stepped up to pure-jet technology with its first such airliner, the Tupolev Tu-104, when it first flew in prototype form on June 17, 1955.

The low-wing monoplane, incorporating many of the elements of the army Tu-16 twin turbojet bomber to reduce development time, featured a glazed nose navigator’s station, a 35-degree swept wing mounted with significant anhedral, dual wing root buried, 14,881 thrust-pound Mikulin RD-3 or AM-3 eight-stage, axial-flow turbojets, and quad-wheel primary undercarriage units that retracted into wing underside fairings.

Inaugurated into service on September 15, 1956 on the Moscow-Umsk-Irkutsk route, it seriously reduced flying times over the piston types it replaced.

“At the time of its entry into service, the Tu-104 was the only turbojet-powered transportation in airline service,” according to John Stroud in”Soviet Transport Aircraft since 1945″ (Putnam and Company, Ltd., 1968, p. 199),”the de Havilland Comet 1 and 1A types having been withdrawn from service in 1954. It wasn’t till the autumn of 1958 that BOAC introduced Comet 4s and Pan American World Airways Boeing 707-120s.”

Like the states in the West, the former Soviet Union thought that a supersonic transport was the next logical evolution of commercial aviation.

  1. Myasishchev M-52:

The foundation for a Russian supersonic transport was laid from the Myasishchev Design Bureau’s M-52 intercontinental bomber. Powered by four Solovy’ev turbojets, two of which were pylon-mounted to the large, swept wings and two of which were attached to their tips, it was intended for at least Mach 2 cruise speeds.

Although the only example ever built publicly appeared in Tuscino in 1961, or a year after the design agency which had given birth to it had been abolished, commercial feasibility studies of it had been commenced. While its high-wing configuration was considered inappropriate for passenger-carrying services and its range was insufficient for these operations, this logic, at least in the Soviet Union, was sounder than might initially be considered, since both the turboprop Tupolev Tu-114 and pure-jet Tu-104 had been civilian versions of, respectively, the Tu-95 and Tu-16 bombers.

  1. Tupolev Tu-144:

An all-new supersonic design was clearly needed. Since Myasishchev’s proposal was improper and Ilyushin was preoccupied with all of the issues with its Il-62 long-range, pure-jet passenger airplane, Tupolev, the nation’s long established military and commercial manufacturer, was selected to produce it.

The outcome, the Tu-144, was among the few aircraft up to this time and exclusively designed for commercial operations.

Powered by four 38,500 thrust-pound engines, the aircraft featured a 188.5-foot overall length, an 83.10-foot span of its delta wing, and a 330,000-pound gross weight. Although still only in prototype form and resembling, as anticipated, Concorde in configuration, there were several differences between the two.

The fuselage, first and foremost, integrated 18 percent of titanium in its construction to cater to the expected expansion and contraction cycles that resulted from the frictional heat buildup and internal pressurization, and it was wider, with a flatter cabin floor, for five-abreast coach seating. Its single-droop nose, deflecting to the 12-degree place, sported top windows.

In planform, its double-delta wing comprised an ogival or s-shaped leading edge and trailing edge elevons, but was devoid of camber or twist with a flat bottom.

Its NK-144 turbojets, grouped in barely separated pairs, were air entered through its six-foot rectangular inlets on the top edge and stretched across over 17 feet to its exhaust pipes in the trailing edge.

Undercarriage consisted of a two-wheeled, aft-retracting nose unit and two 12-wheeled, forward-retracting primary units mounted outboard of the engine ducts and rotating 180 degrees before settling in their airfoil bays.

First flying from Moscow’s Zhukovsky Airfield after implementing a 25-second acceleration roll-which marked the world’s first commercial supersonic flight of any design-the prototype, amount 68001, remained airborne for 28 minutes, with its landing gear extended the whole time. Unpressurized, it internally carried flight test gear.

Although no photographs were released at the time, it’s believed that another airframe, numbered 68002, was damaged during its flights and a third party, 68003, was used for static testing.

Fuel thirsty and range deficient, the kind, requiring consistent, 100-passenger load factors to even meet breakeven costs, indicated the need for an extensive redesign of a production version, which more closely represented Concorde.

Stretched, the fuselage, now using a 215.5-foot span and sporting 34 compared to the previous 25 dividers, eased accommodation of around 140, and its droop nose, of greater length, introduced side windows.

Two canards, installed on the upper fuselage immediately behind the cockpit, extended out- and – forward to enhance the aircraft’s low-speed handling features.

The compound swept, full delta wing, 94.5 feet in length, offered variable camber and sculpting and a round underside.

The engines, with square inlets, were repositioned further outboard and there was greater separation between their pairs, while the main undercarriage units, of shorter length, retracted into them.

Range, using a 33,000-pound payload, was projected as 2,000 miles.

Numbered 77101, the first prototype of this extensively redesigned version first flew in August of 1972, while the second, 77102, was the first exhibited in the West in the 1973 Paris Air Show. Its pride was short lived, however.

During a demonstration flight on June 3, the aircraft made a low pass with its canard surfaces and undercarriage extended, before executing a steep, afterburner-augmented climb. Appearing to experience a stall at 3,000 ft, however, it commenced a dive, abruptly leveling off just a few feet above the ground, at which point the right wing tore off at the root.

Spitting flames from its engines, it rolled and another wing dislodged itself from the structure. Exploding and plummeting to the earth, it impacted, killing both crew members on board, eight on the floor, and damaging over a hundred buildings in Goussainville, France.

Though no official cause was ever found, it was thought that the Tu-144 tried to land on the incorrect runway, starting a go-around when the error was discovered, which placed it on a collision course with a Mirage fighter. Diving to avoid it, it had been subjected to g-forces past the airframe’s capability and too little altitude remained in which to recover. Its structural failure was therefore not attributed to any design defect or deficiency.

After operating cargo and mail root proving flights between December of 1975 and 1976, the Tupolev Tu-144 entered scheduled service on the 2,400-mile segment between Moscow and Alma-Ata, Kazakhstan, on November 1 of the following year, operating 102 such services with a mean of 70 passengers, before they were stopped on June 6, 1978.

Still excessively fuel thirsty, it was only able to cover the 2,400-mile route with half its payload capability, attained by deliberately leaving half its eats unoccupied, and the cabin noise level, due to the engines and the air conditioning necessary to counteract the external, skin friction created heat, was intolerable.

A fire in the abandoned engines, propagating to the fuselage, left inadequate power to reach an alternate airport, causing the aircraft to careen into a field and explode. Of the five crew members aboard, two were killed and three were injured.

Although the type started route proving flights on the 3,480-mile sector from Moscow to Khabarovsk on June 23 of the next year and it covered the distance in 3 hours, 21 minutes, it never proceeded to scheduled status. The noise, fuel consumption, and range parameters of supersonic flight couldn’t be transcended for industrial operations, leaving the one prototype, the two pre-production, the nine production Tu-144s, and the five generation Tu-144Ds as the only testaments to this fact.

  1. Tupolev Tu-144LL:

The National Aeronautics and Space Administration (NASA) teamed with US and Russian aerospace industries within a five-year period to perform a joint international research program to develop appropriate technology for an early-21st century supersonic transport that would resolve the obstacles plagued by both Boeing 2707, Aerospatiale-British Aerospace Concorde, and Tupolev Tu-144 real and still-borne designs.

Cornerstone of it was the previous Tu-144D, constructed in 1981 and sporting tail number 77114, which itself never entered commercial service, but logged 82 hours, 40 minutes during research and test flights.

Modified for the joint application to Tu-144LL Flying Laboratory standard, it had been retrofitted with four 55,000 thrust-pound Kuznetsov, afterburner-equipped NK-321 turbofans originally produced for the Tupolev Tu-160 Blackjack bomber, resulting in a Mach 2.3 rate and 3,500 nautical mile range with 224,000 pounds of fuel at a 410,000-pound maximum take off weight.

Other modifications included the addition of thermocouples, pressure sensors, microphones, and skin friction gauges to assess the aerodynamic boundary layer, an emergency crew escape system, along with a Damian digital data collection system which replaced the earlier analog one.

The first of this two-phase program, running from June of 1996 to February of 1998, entailed two ground engine and six flight experiments, which necessitated 19 airborne sorties to finish, from the Zhukovsky Air Development Center near Moscow, and involved research concerning the aircraft exterior surface, the inner structure and powerplant, temperatures, border airflows, interior and exterior noise, airfoil ground effect characteristics, and varying flight profile handling features.

The second stage, taking place between September of 1998 and April of 1999, entailed six fights, which not only facilitated greater understanding of the original six airborne experiments, but also provided analysis of fuselage and wind deflections, angles-of-attack, sideslip angles, and nose boom pressures.

Though no bonafide US supersonic airliner designs are established, with those appropriate for the business jet segment more likely to precede them, these Tu-144LL aerodynamic, structural, acoustic, and operating environment experiments may pave the way for long-range, higher-capacity, economic fight which minimizes ozone layer deterioration, and the ground-experienced sonic boom.

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