Supersonic Passenger Aircraft (SPS)
A supersonic passenger aircraft (SPS) is an airplane capable of flying at a speed exceeding the speed of sound in the air (flight with Mach number M = 1.2-5). The Mach number is the ratio of the flow velocity at a given point of the gas flow to the local velocity of sound propagation in a moving medium. After the appearance in the 1940s of jet fighters in front of aircraft designers, the task was to further increase their speed. Higher speed has expanded the combat capabilities of both fighter aircraft and bombers
The idea to create a civil supersonic aircraft is not new. In the USSR, work on SPS began in the late 50's. Basically, these were the drafts of passenger variants of the supersonic bombers of the OKB A.N. Tupolev and V.M. Myasishchev. But in March 1960, with his SPS project, Il-66 went to the Council of Ministers of S.V. Ilyushin. A year later the Ulyushin workers began work on a 40-60-seat supersonic IL-72 liner. And yet the preference was given to the Tupolev firm: September 16, 1962, almost a month before the creation of the Anglo-French alliance, the chairman of the USSR State Committee for Aviation Engineering PV Dementiev issued an order entrusting the development of the ATP project with NK-135 engines to the general designer A.N. Tupolev. And less than a year later, on July 16, 1963, a decree issued by the Central Committee of the CPSU and the Council of Ministers of the USSR " Tupolev ATP Tu-144 with four jet engines and the construction of a batch of these aircraft."
The supersonic passenger aircraft Tu-144 was developed by the KB Tupolev. In 1969, it became the first passenger airliner in history to overcome the sound barrier at an altitude of 11,000. In the same year, the British-French analog - the supersonic liner Concorde - was launched into the air. Both of them flew in the civil aviation segment. In the process of a desperate and costly struggle for speed, engineering and technology, the Americans launched the Boeing 2707 and Lockheed L-2000 projects.
For transonic and supersonic flight, highly swept wings are considered preferrable because aerodynamic drag may be greatly reduced thereby, and other advantages are also obtained. For example, even during high altitude subsonic cruise the highly swept wing configuration develops a comparatively low drag coefficient, while still developing the required lift coefficient. It has been experimentally shown that lift/drag ratios of 10 to 12 may be obtained with the highly swept wing at supersonic high altitude cruise thus making such flights economically feasible even in the case of commercial transport aircraft.
The highly swept wing configuration is also preferred for supersonic flight at low levels, where the combination of high dynamic pressure at the high frequency end of the gust spectrum may establish the structural strength requirements of the aircraft, since the gust loads imposed on a highly swept wing are much smaller than on a more or less straight wing due to a smaller change in lift force resulting from change in the angle of attack. This result is due to the fact that a moving aircraft experiences atmospheric turbulence only as the result of sudden changes in the angle of attack which may be said to be in the direction of the resultant of the vertical component of gust velocity and horizontal component of aircraft velocity.
For achievement of improved supersonic cruise efficiency, a preferred supersonic aircraft configuration employs highly swept (subsonic) leading edge wings. However, this design creates particular problems relative to high lift conditions typical of climb-out and approach where high angles of attack are required. More particularly, these highly swept wings develop two leading edge vortices which, while increasing lift, also result in an increase in drag, resulting in a poor lift to drag (L/D) ratio.
However, a swept wing aircraft designed solely on the basis of supersonic high performance flight will obviously not perform satisfactorily for subsonic cruise, take-off and landing. Even present day supersonic aircraft are designed with aspect ratios higher than that considered optimum for supersonic cruising flight in order to make take-off and landing feasible. These supersonic aircraft must also climb to cruise altitude at subsonic speeds to prevent heavy shock wave ground damage and they must do this at the expense of increased fuel consumption since the relatively low aspect ratio of the wing results in increased drag due to lift while in the climb. For example, it is not unusual for a supersonic swept wing transport on a transatlantic flight to expend 30% or more of its total fuel requirement during take-off and climb to cruise altitude at subsonic speed.
Various attempts have been made to enable the wing configuration of an aircraft to be modified in flight so as to optimize both the low speed and high speed performance of the aircraft. These solutions, however, have the inherent disadvantages that the swiveling of the wings results in a shift in the center of pressure of the aerodynamic forces exerted thereon as well as in a displacement of the center of gravity of the aircraft. Furthermore, the position of the center of lift is effected by the flight speed with the transition from subsonic to supersonic speed notably resulting in a large rearward shift of the center of pressure of the force exerted on the wing. In addition, the structural components necessary to accommodate a wing pivoted at a point near one of its ends requires the use of massive bearings which must carry the wing root bending moment.
The delta wing family also has recognized disadvantages; and because it has been the sole candidate for SSTs, these disadvantages are widely assumed to be unavoidable for all SSTs. Two of these disadvantages are the delta wing's high drag due to lift at subsonic speed and low maximum lift even at an uncomfortably high angle of attack. These traits lead to the need for high power and high speed during takeoff and landing, resulting in high noise levels.
The commercial career Tu-144 was short-lived - in 1978, Aeroflot terminated supersonic passenger flights. According to the official version, the accident was caused by the crash of the prototype TU-144D, but unofficially the reason was unprofitability of such flights: even taking into account the fact that tickets for such planes cost 1.5 times more than usual, the funds received from their sale did not cover even part of the operating expenses, caused by high fuel consumption and difficult maintenance. Concorde flew a little longer - Air France and British Airways ceased sonic flights in 2003 due to higher prices for aviation fuel. It turns out supersonic aviation was at a dead end. The French decided not to develop the new Concord, the Americans also closed the program "Sonic Cruiser" (and 30 years ago - a similar "Supersonic"), there was a joint project of Russian Tu-144 and NASA (but NASA is now itself in deep, sorry, ass, and after the last catastrophe, and under the fire of criticism, in general, the project had long been curtailed), the operating aircraft will not fly more, and indeed from the very beginning the whole project was called a grandiose commercial failure. In total, twenty planes (for comparison - Tupolev Tu-144 had a total of 16].
In the 1960s OKB Mikoyan (now RAC "MiG") worked on the CAC project based on the interceptor MiG-25. Later, in the 80s, the Mikoyans made another attempt to enter the supersonic administrative aviation market by offering a civilian version of the interceptor project "701" and CAC "210" that was being developed. All these works, however, did not come out of the most preliminary stage.
As early as June 18, 1989, at an airshow in Le Bourget, the American firm Gulfstream and the Russian Design Bureau named after. BY. Sukhoi signed an agreement on the joint development, production and marketing of a supersonic service aircraft capable of carrying 10 passengers to a distance of 9200 km at a speed twice that of the sound one.
Around the same time OKB Sukhoi together with TsAGI has started to explore the possibility of creating an intercontinental supersonic business aircraft (MSDS) with a flight range of 8,000 km. The project of the firm "Sukhoi" under this program received the designation C-51.
Following the Concord, Tu-144 and the failed Boeing 2707 programs came the "second wave" - ??an attempt to create the so-called SPS-2 - supersonic second-generation airliner. To study the possibility of implementing the SPS-2 program, an international alliance was created, including Boeing (USA), BAE (Great Britain), DASA (Germany), Aerospatial (France), Alenia (Italy), and Russian and Japanese companies. In January 1999, the "final" meeting of the alliance participants was held in Seattle. According to American experts, the technologies, materials and technical solutions developed at that time do not yet allow the creation of ATP-2, which could provide real life prospects in terms of cost, mass and environmental impact.
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