EXPERIMENTAL super-maneuverable

AIRCRAFT X-31A

Experience Air Combat neighbors shows that as the energy loss due to abrupt maneuvers aircraft gradually lost height and speed and, ultimately, winning the plane, kept better control, at low altitudes and speeds.Among the aircraft manufacturing companies a leading role in improving the maneuverability of fighters in a dogfight at low speeds plays a West German concern MVV.His research studies in this area began in 1977 at the Hanover Air Show 1980.( ILA -80) concern MBB presented configuration perspective highly maneuverable fighter aircraft TC F , which was the forerunner of Western European fighter EFA .

A distinctive feature of the aircraft was TKF control aerodynamic forces and moments at supercritical angles of attack.

In 1983, the firm Rockwell (USA) began to cooperate with the concern MVV in research program development project highly maneuverable aircraft demonstration.Result of the research was concluded that only the rotation of the thrust vector engine can create forces and moments to ensure controlled flight at low speed gradients.It was also established that the basis for the development of the thrust vector deflection can be used as swivel nozzle doors - panels ( paddles), applied by the U.S. Navy to improve the control of the aircraft F -14 during the demonstration test on a tailspin.The firm offered to equip the new Rockwell experimental aircraft forced a highly Turbofan engines (two engines) General Electric F 404 - GE -400, providing high thrust and allowing air flow disturbances at the entrance.

The attempt made ​​by Rockwell research program has led to a demonstration sample configuration aircraft, received the abbreviated name SNAKE ( Super - Normal Altitude Kinetic Enhancement ).This configuration was tested in a full-scale wind tunnel (WT) with the size of the working part of 9.15 x 18.3 meters, installed in the center of them.Langley NASA (Virginia).

In November 1984, Advanced Research Department of Defense DARPA has granted the company a contract to Rockwell to study the feasibility of the concept of highly maneuverable aircraft.As a subcontractor named MBB concern, and for the program as a whole meet the U.S. Air Force.With the support of Congress, provided the program in mid-1986 signed a protocol agreement between the U.S. and Germany, and in September 1986. DARPA has granted us to contact Rockwell schematic design highly maneuverable aircraft demonstration sample, which February 23, 1987 U.S. Department of Defense has assigned designation X-31A.

A highly maneuverable fighter program EFM ( Enhanced Fighter Manwuverability ) consisted of four stages:

Phase 1 - Feasibility Study concept and design specifications for the plane X-31.

Phase II - Evaluation of the concept and schematic design.

Phase III - detailed design, construction of two aircraft and the X-31A flight test program is limited (LI).

Stage IV - the main program for the study of Lee to the possibility of powered flight in the field of supercritical angles of attack for a short-range air combat with the same type of aircraft and polytypic and develop tactics to maneuver on the extra-large angles of attack.

In addition to demonstrating supermaneuverability and other flight characteristics, as well as the study of the effect of increasing mobility on the effectiveness of aerial combat (as a ratio shot down enemy planes and their own), the program E F M includes the development of requirements for design and development of a database for the design of advanced fighter aircraft.In addition, the EFM program provided an opportunity to test the concept of a prototype aircraft at minimum cost.

It was envisaged that the program would cost approximately EFM $ 75 million to 80% of this amount should provide the U.S. and 20% - Federal Republic of Germany.

By mid-1990 the expected cost of the program EFM reached $ 194 million (135 million - the U.S. and 59 million - Germany).Financing the American part of the program by DARPA through the command of aircraft weapons systems Navy, and the financing of the program is provided by the West German Federal Ministry of Defence.Appropriations for the U.S. and Germany, respectively, received firm Rockwell and MBB concern.Overall management of the program is assigned to DARPA.

Parent organization is a firm Rockwell is both responsible for the aerodynamics, the design and manufacture of the fuselage, the front horizontal tail (CHR) and the vertical stabilizer (IN).LEV Group is responsible for the design and manufacture of the wing panels to deflect the thrust vector and for developing control laws for flight (the control system creates a firm Rockwell).

Increased maneuverability fighters, realized in the program EFM, has six features:

1) The maneuverability;

2) the ability to decrease the steep path (with possible use in the landing on the deck of an aircraft carrier);

3) improved maneuverability in normal flight conditions;

4) improved performance by turning the sight of all housing in isolation from other kinds of movement of the aircraft;

5) more efficient braking in flight;

6) the ability to create a higher negative overload.

Calculated characteristics of the X-31 aircraft as follows:

Wing span, m 7.27

Fuselage length

(Without rod receiver aircraft

pressures, but with the panels to deflect the thrust vector), m 13.21

Height, m ​​4.46

The base chassis, 3.54 m

Wheel track, m 2.25

Wing area (with the ventral part), 21 m

Area CHR (with ventral part), 2.19 m

Area BO, 3.49 m

Elongation

2.3-wing

CHR-3.18

AT-1.23

Sweep angle of the leading edge, deg:

- The wing root 56.6

- Wing panels 45

CHR 45

- IN 50

The relative thickness of the profile:

- Wing 5.5

- GTO 5.0

- IN 5.0

Overload takeoff weight, kg 7227

Maximum takeoff weight, kg 6645

Weight of airframe aircraft, kg 2402

Empty weight, kg 5175

Maximum fuel weight, kg 1950

                                                                           (According to other sources - 1875)

Normal weight of fuel, kg 1496

The relative weight of fuel 0.225

Unit load on the wing.Pa 3170

The specific load on the wing at half

reserve fuel.Pa 2700

Thrust, kN 71

Thrust 1.1

Maximum calibrated airspeed

(To a height of 8535m), km / h 900

The maximum number of M (starting from a height of 8535 m) 1.3

Maximum operating load from 9.0 to -4.0

The flight speed during landing, km / h 240

The maximum specific excess thrust

(SEP - specific excess power), m / to                                                     225

The maximum angular velocity, deg / s:

- Steady turning 17

- Unsteady turning                                                     28

The maximum radius of the transient, front 335.

Aerodynamic design aircraft X-31A is based on the configuration of the proposed LEV Concern for future of West European fighter EFA .It is characterized by a triangular wing in terms of double-swept wingtips clipped and PGO with a large front wing removal.The wing has a rounded front edge, socks and two sections deflected flaps, outer sections which serve as ailerons (the system of rotation of the thrust vector engine does not create a rolling moment), and the inner section of the flap is used as the aerodynamic surfaces of longitudinal control.Particular attention was paid to the effectiveness of the external sections at high angles of attack.

Successful implementation of supermaneuverability requires that the aircraft can rotate around its velocity (around the flight path), without lateral sliding.To do this, coordinated movement of the longitudinal axis of the aircraft to yaw and roll.Aircraft control surface to maintain sufficient performance at high angles of attack in case of withdrawal of aircraft from an unusual position for engine failure or a system of thrust vector control.X-31 is the first aircraft on which the thrust vector control is used to generate pitch and yaw moments.It can be piloted only with a pen, but directional control pedal only serve to create an intentional side-slip and for crosswind landings.

Flap with the longitudinal control is coordinated with the deviation of CHR.Last weakly loaded aerodynamic forces and is mainly used to restore the pitch angle in the derivation of the maneuver.Position deflected socks programmed as a function of the angle of attack and Mach number of the balancing minimization of resistance in a supersonic flight, achieved by creating a 5% negative second instability.

All fuel is placed in a fuselage tank, installed above the center of gravity of the aircraft.Devices for the IS are located in the forward fuselage, and antispin parachute - at the tail of the aircraft (flaps over the nozzle thrust vector control system).

Engine air intake is designed using the data presented concern MBB.It has a movable bottom edge of the shell, which significantly reduces the perturbation of the flow at the inlet at high angles of attack.In supersonic flight, this edge is deflected upward, reducing the resistance of the discharge air.

Engine F 404 has a high ratio of thrust to weight ratio and can run at maximum capacity even when extra-large angles of attack, thanks to variable geometry air intake.

Three thrust vector control valves were originally developed for U.S. Navy aircraft F -14, intended to demonstrate shtopornyh regimes.They are made ​​of heat-resistant carbon-carbon composite material, while immersed in a stream of gas engine only for a very short time.The deviation of the valves at an angle of 10 ° leads to a rotation of the thrust vector by 17 ° in any transverse direction.

Digital-wire control system (EDSU) with full responsibility rests on the control laws developed by MBB concern during extensive modeling of the generalized configuration of super-maneuverable aircraft.The structure consists of a triply redundant EDSU digital computer.Fourth-board computer is used as a communication device with data bus and for additional redundancy.The control system allows you to fly the aircraft with a change in angular position of the fuselage regardless of the trajectory of motion.Digital computer software written in jovial , but not Ada , adopted by the U.S. Department of Defense.Language JOVIAL makes better use of existing programs.

On the red-dot display special symbols displayed, protecting the pilot from spatial disorientation when performing unusual maneuvers.Additional characters include mark the direction of the velocity vector of the aircraft, which can be provided at a steep angle to the longitudinal axis of the fuselage.Incidentally, this feature makes it difficult to forecast the trajectory of an enemy airplane X-31.According to official statements, the super-maneuverable aircraft-quality X-31.provide attack targets in the forward hemisphere and the firing of guns at a target at a large perspective, aiming through his whole body aircraft - regardless of the trajectory of motion.This feature is more than double the efficiency of super-maneuverable aircraft in close air combat.

The concept of maneuvering the aircraft X-31 on extra-large supercritical angles of attack is illustrated in Fig C .2, where super-maneuverable X-31 can make a turn with a very small radius in the near and supercritical angles of attack.

Numerals indicate:

1 - normal fighter;

2 - position of an ordinary fighter at the time of launch guided missile from an aircraft X-31;

3 - X-31 super-maneuverable;

4 - launch;

5 - equal time intervals.

Expect that the maneuverability will double the number of the first shots and triple the ratio shot down enemy planes and their own.Increased flexibility should be reduced by 15% of non-combat losses and to improve the ratio of 160% shot down in combat aircraft.Engineers involved in the program EFM, predict a fourfold improvement in this ratio in gun attacks.In their view, a steep decrease in super-maneuverable aircraft altitude when attacking ground targets will lead to a decrease of 75% loss of aircraft fire from the ground.

According to information from another source, the Luftwaffe pilots and Air Force participating in the flight simulation super-maneuverable fighter.held in Germany and the firm McDonnell Aircraft((in Saint-Louis (USA), believes that thanks to super maneuverability can improve the ratio of twice the aircraft shot down in combat, "one-on-one" and increase the efficiency of destruction of enemy aircraft at conduct an air fight with two or more super-maneuverable fighter against numerous enemy planes. It was done over 25,000 sessions simulation (with indifference and pilots) in order to study control efforts in maneuvering super-maneuverable fighter aircraft, as well as the choice of a generalized configuration of the aircraft, which has super maneuverability.

In an effort to reduce the cost of designing and building aircraft X-31A was decided to use a variety of ready-made components and systems of existing aircraft, including:

device for air conditioning - from F -5E;

fuel pumps, directional control pedal, the emergency power unit, pneumatic front wheel - on the F-16;

actuators are deflected leading edge of the wing, canopy and folding of the canopy cockpit, ejection seat, the generators of the primary power supply and a box of drives - from the F / A-18;

Pneumatic main landing gear wheels - from the A-7;

Emergency engine start system - from F -20;

lift the flaps and flap control modules - from V -22;

wheels and brakes - from the aircraft Cessna Citation ;

onboard digital computer flight control system of a flying laboratory Lockheed HTTB .A total of 603 such units make up 43% by weight of the empty aircraft X-31A.

The design of the airframe are widely used new materials: grafitoepoksidnye (17% by weight), aluminum-lithium (4%), carbon-carbon (2%), steel (5%) and titanium (5%).51% of the construction is made of aluminum alloys.

In the end, two experimental aircraft X-31A built around the same price as two serial fighter F -16.The cost of tooling for the production of X-31 was only one-third the amount normally expended for a new airplane in its class.In order not to build the third model aircraft for strength tests, DARPA, the German Ministry of Defense and the U.S. Navy agreed to expose a static test flying model aircraft X-31A, bringing its loading to 110% of the estimated maximum operational load.Certification of aircraft X-31A assigned to the West German administration ML and the U.S. Navy.

The primary aerodynamic design aircraft, designated P-20 was tested in 1985 at the Federal Aviation Plant ADT Switzerland (city of Emmen).Another model in the configuration of P-20 was tested on the torsion balance in shtopornoy ADT Center.Langley NA S A, was obtained in this preliminary information about the characteristics of stall, spin susceptibility and the way the output of a corkscrew.Based on the results of pipe testing the bow of the aircraft was given a more rounded (in cross section) form, and the area of AT was increased.What was the b done to improve antispin characteristics.Further tests were carried out in low-speed WT firm Rockwell.During the tests, it was finally determined the position of the wing, while ensuring low-speed negative margin of the longitudinal static stability, equal to - 5% of the MAR.Were further established root nodules, designed to improve the range of flow regimes in the transition to fly at supercritical angles of attack and to reduce the longitudinal moment to dive at high angles of attack.

The tests in WT NASA , used for experimental research units of vertical and short takeoff and landing, showed the need for rearrangement of the bar with a ramjet axis of the fuselage under the nose cone, as in the original position of the bar ramjet adverse effect on lateral stability, especially at high angles of attack.Was followed by more tests in the transonic WT firm Rockwell and water channels in the company Tgasog.

Due to adverse vorticity arising at the junction of the lantern to the contours of the fuselage fairings, it was decided to abandon the fairings and lay the wiring and electrical control inside the fuselage.

Tests of various models have allowed brush up on a large array of data about the behavior of the aircraft in a range of angles of attack from -20 ° to + 20 °, and at grazing angles up to 20 °.Additional tests were also conducted on races extension of the study area of angles of attack up to - 90 °.

Static strength tests were carried out under the design load on the first sample plane in El Segundo in September-October 1989, then the aircraft was handed over to the factory companyRockwell in g.Palmdeyl (Calif.), where the March 1 1990.held an official ceremony marking the completion of construction of the first plane.March 23 1990.conducted its first taxi test.

According to the available plans, software prototypes two DOES X-31A is designed for 1.5 - 2 years and 400 flights.Initially, Lee should be held in the flight test center (OF) at the air base im.Edvardsa U.S. Air Force, and then in the U.S. Navy PARTY g.Pataksent River (Md.).First flight of first prototype X-31A took place on October 11, 1990, the Palmdale airport with five months later than planned.The delay in carrying on the work of Lee debugging EDSU.The flight lasted 38 minutes.In flight, the speed has been reached 540 km, / h and the height of 3000 m. The first flight proceeded almost without defects.All maneuvers were performed faster than planned.Chassis in flight has been removed.

Challenge if the first plane is to assess the applicability of the battle at low speeds and high angles of attack.Most of the tests to simulate the characteristics of maneuverability at low speeds to be associated with a system of rotating nozzle flaps, panels, which are planned to be installed on the aircraft before the fifth flight.

In g.Palmdeyl must be carried out around 100 flight test program the initial assessment of airworthiness.On the program of flight research in the field of supercritical regimes play 200 flights.80 flights will be devoted to choosing and developing the tactics of the super-maneuverable fighter combat use, and 40 flights - a final assessment of military aircraft.Military assessment will be carried out not only in the Patuxent River PERSONS, but on measuring polygons tracks with simulated dogfights against regular (not super-maneuverable) fighters, as well as fighting between the two experimental aircraft X-31A.

Manufacturer Rockwell is responsible for Lee, conducted on its airfield and include extension of the flight regimes.She will oversee the determination of flight performance and maneuverability in normal modes.The pilots will demonstrate concern MVV maneuver of the aircraft at supercritical conditions.

The second plane X-31A was due to Lee by the end of 1990.

Testing will begin super maneuverability in Palmdale, and will continue in 1991.in Patuxent River, where Lee will be involved and the U.S. Navy pilots.EFM program should be completed in early 1992

The second flight of the first prototype X-31A took place on October 17, 1990 For the first time in flight was included afterburner.The flight lasted 52 minutes.The aircraft reached an altitude of 6100 m and M = 0.6.Lee pursue further suggest a rate of six flights per month.Are high (about 315 km, / h), takeoff and landing speed of the aircraft, explained by the selected aerodynamic design with a delta wing and the limitations on the corner of the pitch (to avoid injury when touching the runway tail)

A.M. Murashkevich