Tu-444 Supersonic Businessjet

In always the time was the singularly irreplaceable service life of humanity and each individual its representative. Especially sharply this began to be perceived at the end past century, in the epoch of world integration. When business trips became ever more frequent more distant and prolonged, precisely, then arose urgent need for the cardinal shortening of time to the transport operations. Partially this task was solved business - by aviation, whose aircraft acquired the properties of the most contemporary main passenger vessels on the speed and flying ranges. At the same time, the possibility of the realization of flight out of the timetable and the ability to be exploited on the airfields with the length of VPP not more than 2000 m made this form of transport practically for the business constituency.

However, taking into account and the fact that the significant number of flight routes they have intercontinental ranges, a question about the cardinal shortening of time to the trip so remains open. In Russia, at this problem has long ago and fruitfully worked as OKB of Tupolev together with the main branch institutes, and first of all with TsAGI (Central Institute of Aerohydrodynamics im. N Ye Zhukovskiy), relying on the wide experience of creation Tu-144, Tu-144[LL] and distant combat supersonic Tu-22[M]3 and Tu-160. Significant is and the fact that OKB of Tupolev here already more than half century works in the close cooperation with the Kazan' aviation- production association - KNOT [im]. of Gorbunov. Today this actually - the only in Russia and in Europe aircraft plant, capable of producing the high(ly)-resource thermally loaded constructions, fitted out for the work under the extreme conditions and which are characterized by the highest weight culture. In many respects therefore became possible the embodiment of the project of unique in its characteristics strategic combat complex Tu-160.

But, in spite of achieved successes in the combat and passenger aviation, to the significant reserve in SPS-2 field, it is obvious, that contemporary "draconic" requirements for the commercial airplanes in the field of ecology will not make it possible to create in the near future supersonic air bus economically acceptable.

In connection with this the most promising and real direction of the introduction of the created scientific production reserve on SPS -2 is seen the creation of small size supersonic business - aircraft ([SBS]). In OKB of Tupolev this project obtained designation Tu-444. First of all, a similar aircraft and its creation will be considerably more cheaply in comparison with the supersonic air buses. Yes even the solution of the technical problems, connected with the stringent ecological requirements, becomes more real.

According to the estimations of well-known analysts the potential market for aircraft of such type can be from 400 to 700 units when the prime cost of operation SBS will exceed this index in subsonic analogs not more than by 20 percent. Principal of the consumer properties SBS appears the possibility of the realization of trip for intercontinental range with the recovery in one day with the maximum use of operating time.

With the determination of appearance Tu-444 were considered the following factors. Analysis of possible flight routes with the greatest passenger flow, the connecting 75 most important centers of planet, carried out within the framework of studies on Tu-244, showed the following: calculated flying range it is expedient to appoint in 7000-7500 km; for the creation of hyperdistant [SBS] on 11000-12000 km there is no need for the force of the rarity of trips to this distance and the significant rise in price of aircraft; for the delivery of passengers on the hyperdistant routes it is expedient to accomplish flights with one intermediate landing. Operation of aircraft Tu-144 and Tu-160 showed the expediency of limiting cruising supersonic speed with the number Of [m]=2,0 for guaranteeing the resource of construction and limitation of cruising altitude. Work of OKB of Tupolev according to the supersonic passenger air bus Tu-244 determined the region of the optimum values of load on the wing of =320 of [kg]/[m]2. Operation of such known business - aircraft as Cessna OF THE III, the X, Learjet 60, Bae 125, Falcon 900, Chellenger, Gulfstrim OF THE II, THE III, IV, the V, Global Of express shows that an average quantity of passengers during one flight does not depend on maximum passenger capacity and composes 3- 6 people. Analysis of world airfield network shows need use VPP by length not of more than 1800 m.

As a result carried out scientific research and it is experimental - designing, the use of the obtained experience, with the creation of aircraft Tu-144, Tu-144[LL], Tu-22[M]3, Tu-160, and with the fulfillment of the complex of works on the theme Tu-244, was formed the appearance of promising series SBS Tu-444. However, it is necessary to note that in spite of enormous scientific technical and production base in the field of distant supersonic machines, the creation of highly effective SBS it is impossible without the solution of number of the complex technical problems, many of which are characteristic precisely for this aircraft type.

The basic difficulty of project Tu-444 consists of the simultaneous fulfillment of the assigned flight characteristics along the flying range (7000 - 7500 km), of along the length utilized VPP (not more than 1800 m) and the level of noise in the locality (3 (4) the head of appendix 16 ICAO) - the latter mainly because of the standard of the level of the standard of noise on the side from VPP. Especially adversely affect the achievement of the assigned characteristics on the flying range the small dimensions of aircraft (~ 2 times smaller SPS -2 according to the geometric dimensions and ~ 6 times by the weight) in combination with an increase in the relative area of the midship section of fuselage. This hampers the guarantee of required maximum lift-drag ratio Of [kmakh]~8 on the super-sound and required return on the fuel Of g[t]~ 0,51. 0,515.

Decrease in the mass of the construction of the airframe of aircraft for the purpose of an increase in the load ratio on the fuel requires the introduction of the promising construction materials, including of composites, conducting of the thorough optimization of structure diagram for obtaining: the assigned resource (vitality), the achievement of a maximally possible critical speed of flutter, minimization of the losses of the effectiveness of control elements from the elastic deformations. Is necessary also the optimization of the trajectory of climb in comparison with Tu-144.

Reduction in the weight concerns equipment; therefore the reliability of aircraft Tu-444 must be solved not due to the duplicating, but mainly due to the reliability of its elements. For example, on Tu-144 we four times duplicated up hydraulic system, and on the Concorde she was duplicated up 2,5 times.

The fulfillment of standards 3(4) the head of appendix 16 ICAO on noise in the locality with short VPP (1800 m) indicates a noise reduction relatively Tu-144 not less than to 14. 18 EPNdb in each of the control points. This it will require development and finishing of the qualitatively new system of noise suppression, mechanization of wing, search and finalizing of the order of throttling engines and procedures of piloting on the takeoff and the landing.

The use of short VPP in combination with the twin-engined power plant requires a decrease takeoff - landing speeds [SBS] to ~100 km/h in comparison with Tu-144, Tu-244. In other words takeoff and landing Tu-444 will be achieved on "the destructive" (with the use of high angles of attack, with the application of powerful mechanization of wing and effective control elements and balancing).

From the carried out works it became clear that as it is necessary never to begin works from building of aircraft - demonstrator. This aircraft will serve for the checking during the flight tests new technical of the solutions accepted, development of also unknown special features SBS, for the measurements of pressures, stresses and construction temperatures in each flight for the purpose of the exception of the creation of the complex and expensive thermal resource stand. Demonstrator is necessary for conducting the experimental flights for the purpose of the development of the optimum programs of takeoff and landing, optimization of speeds and flight altitudes in the dependence on area relief and weather conditions for the purpose of the minimization of the level of sonic boom.

For reduction in the expenditures for building of aircraft - demonstrator are permitted some retreats from the series model by the part of the simplification in the construction of airframe, the type of the utilized construction materials, the content of equipment. For example, view from the cabin of crew with the takeoff and the landing, in contrast to the production aircraft, will be achieved with the aid of the slanted downward nose fairing with the use of mechanisms of aircraft Tu-144, the construction of the cockpit canopy is analogous to construction entire the same Tu-144 and others

However, in spite of retreat on the part of the simplification in the construction, it is necessary to consider all requirements of safety, which satisfy rules AP - 25 (FAR, JAR) taking into account requirements ETOPS - 180, HIRE, HPMD, and others. It is intended to use a wide unification on the equipment, the systems and the aggregates with the aircraft, which are found in the series production and in the operation. For purposes of the guarantee (without the total volume of ground tests) of advance on the flight conditions, obtaining of the necessary volume of experimental data for the confident development of series [SBS] and certification for the flights with the official passengers, the demonstrator must be equipped with a sufficient volume of the measuring and control- recording equipment, utilized in each flight.

With the above-indicated conditions on the demonstrator it is not possible to obtain flight-performance data of series [SBS]. But its creation, ground and flying tests will give confident scientific and technical and experimental data, which prove the possibility of guaranteed obtaining of the required technical flight and economic characteristics, and it will also create production basis for the production aircraft.

Aircraft "Tu-444" is intended to carry out according to aerodynamic configuration "bobtailed aircraft" with the low- located cantilever wing with the developed root accretions. The vertical tail assembly is single tail-fin, is completely rotatable. For the purpose of an increase in the lift-drag ratio and improvement in the takeoff and landing characteristics the aircraft is projected with statically unstable in the longitudinal and side directions with the application of a multichannel remote electrical system for control. Wing is equipped with those hovering on the takeoff and the landing by elevons and by the adaptively deflecting noses edges along entire leading wing edge. Trailing section of wing concludes with powerful balancing surface. Is refined the need of using the removed front multislot destabilizer according to the type "Tu-144".

The adaptive wing leading edges, intended for increasing the lift-drag ratio, at the initial stage of the flight tests of demonstrator can be not begun to operate. Wing is characterized by the complex deformation of median surface, by variable geometric and aerodynamic twist on the spread. The thickness ratio of wing varies on the spread in the limits from 2,5 to 3,5%. Entire alluvial part of the wing is multisection integral fuel tank. In the root, between the pods are placed the sections of the harvesting of basic landing gear struts.

On the lower surface of the wing are placed the supersonic variable inlets with the vertical wedge, which are been the scale copy of the well developed air duct of aircraft "Tu-160". Turbofan engines are carried out back from under the wing torsion box and are turned to the small angle upward for the purpose of the screening of nozzle by the aft fuselage section and [kilem] for a decrease in the level of lateral noise on the takeoff. For the purpose of the expansion of the range of flight tests and creation of reserve for the promising programs, on the demonstrator will be established the reheat engines.

On the series Tu-444 is planned the use of a nonafterburning turbojet engine AL -32[m] of firm "[NPO] "Saturn". Engine is executed on the base of series [TRDDF] AL -31[f] and promising AL -41[F]-1, and it completely satisfies all basic requirements as the engine [SBS]. Fuselage by sharply pronounced "area rule" technologically [razdelen] to three parts: The nose airtight section with the pilot's cab, with the equipment bays, by the section of the harvesting of nose landing gear strut, by input tambour with the cloakroom, the kitchen, build it by well-made ladder, passenger cabin to 6-10 people (depending on planning), by toilet. The middle part, which has an integral fuel tank, in lower part of which it is isolated it cut off for conditioning system. The tail section with the sections of the electro and of hydraulic systems and by section [VSU].

Undoubtedly, the creation of series Tu-444 will require the significant attraction of forces and facilities. And in this respect to aircraft - demonstrator is removed special role as the base for finalizing not only of the technical solutions, but also the technology of the optimum cooperation of many organizations - participants in the project, enterprises in the subsidaries.