RU2844721C1 - Method of controlling aerodynamic moments of single-rotor helicopter - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to aircraft engineering, particularly, to control over helicopters. Proposed method of controlling a single-rotor helicopter comprises control over helicopter pitch, bank and yaw moments. Helicopter comprises rotor with rotary drive, two tubular tail booms jointed to helicopter fuselage and spaced apart on both sides of helicopter mirror plane, jet control system including controlled nozzles arranged at beam ends. Pitch moment is created by synchronous rotation of nozzles and/or change of area of their exit sections. Bank moment is created by differently directed rotation of nozzles and/or by changing the area of their outlet sections. Yaw moment is created by differently directed change of pressure or air flow rate through nozzles of left and right beams of the vehicle. Wherein rotor reactive moment is compensated by operation of supercirculation system slotted nozzles.

EFFECT: simplification of the rotor system, increasing its reliability, trouble-free operation and service life.

1 cl, 3 dwg

Description

The present invention relates to a method for controlling aerodynamic moments: pitch, roll and yaw, of a rotary-wing aircraft - a single-rotor helicopter with a jet control system.

The prior art includes single-rotor helicopters and control systems for such helicopters CN 101433766 B, 04.01.2012; IT 1303441 B1, 06.11.2000.

Helicopter control systems are complex mechanical systems containing a large number of elements (including such complex ones as swashplates) without which control of helicopters of traditional schemes is impossible. Elements of control systems are subject to large constant and variable loads, which reduces the reliability and service life of the system and imposes significant restrictions on the parameters and layout of the rotor blades.

In addition, helicopters with traditional design and aerodynamic configurations with control systems based on swashplates have fundamental shortcomings that reduce controllability (and, accordingly, flight safety) in some modes. For example, helicopters with traditional configurations, when maneuvering with high overloads, can enter the so-called "pickup" mode, in which the helicopter's pitch control becomes ineffective, which makes these modes unsafe. The proposed technical solution allows for control of pitch and yaw moments of helicopters in all flight modes, which increases flight safety.

The present invention proposes an alternative method for controlling a single-rotor helicopter in pitch, roll and yaw using a jet control system in different versions of such a control system.

A jet system of directional control of a single-rotor NOTAR helicopter (without a tail rotor) is known, described in patent US 4948068 A, 14.08.1990. Such a system of directional control of a single-rotor helicopter is used instead of a tail rotor, providing compensation for the reactive moment of the main rotor and control in the yaw channel. The NOTAR jet system consists of an air intake, a fan installed in the rear part of the fuselage, an air duct in the tail boom, a system of air slot nozzles of the supercirculation system located along the generatrices of the tail boom, and a tail nozzle of variable area.

The disadvantage of such a solution is its single-channel nature, i.e. the impossibility of creating helicopter roll and pitch control moments using such a system, which leads to the need to use a swash plate and other interacting elements of the mechanical control system in the helicopter control system.

Also known is a jet system for controlling the roll and yaw moments of vertical takeoff and landing aircraft Yak-36, Yak-38, Yak-141, AV-8 Harrier, F-35, etc., consisting of two air ducts for compressed air extraction from the engine, located along the span of the wing consoles and two controlled jet nozzles at the ends of the wing consoles. Control of the roll moments of a vertical takeoff and landing aircraft is carried out by differentially changing the pressure and air flow through controlled nozzles directing compressed air downwards, and control of the yaw moments is carried out by deflecting the axes of the controlled nozzles from the vertical by relatively small angles (different in sign for the right and left nozzles) in planes approximately parallel to the plane of symmetry of the aircraft.

Such a jet system also does not solve the problem of controlling pitch, roll and yaw moments without using swashplates in the mechanical control system of a single-rotor helicopter.

The task, which the proposed technical solution is aimed at, is to develop a method for controlling pitch, roll and yaw moments of single-rotor helicopters using a design without swashplates and other elements interacting with them.

The technical result is a simplification and reduction in the cost of the screw system, an increase in its reliability, trouble-free operation and service life.

The technical result is achieved due to the method of controlling the aerodynamic moments of a single-rotor helicopter having a rotor with a rotation drive, two tubular tail booms attached to the fuselage of the helicopter and spaced apart on different sides from the plane of symmetry of the helicopter, a jet control system including controlled nozzles located at the ends of the booms. The method of controlling the moments of the said helicopter is characterized by the fact that the pitch moment is created by synchronous rotation of the nozzles and/or by changing the area of their outlet sections, the roll moment is created by multidirectional rotation of the nozzles and/or by changing the area of their outlet sections, the yaw moment is created by multidirectional change in pressure or air flow through the nozzles of the left and right booms of the apparatus, wherein compensation for the reactive moment of the rotor is ensured by the operation of the slot nozzles of the supercirculation system.

Let us consider the proposed method of controlling aerodynamic moments using the example of a small-sized unmanned helicopter without swashplates with a jet control system.

Fig. 1 shows a schematic diagram of a small-sized unmanned helicopter with a single-rotor design without a swash plate and a jet control system.

The positions in Fig. 1 indicate:

1 - fuselage with a power plant located in it (electric or based on an internal combustion engine);

2 - fixed-pitch rotor without swashplate;

3 - tail booms;

4 - rotary jet nozzles with controlled area;

5 - slot nozzles of the supercirculation system;

6 - air intakes of the jet control system;

7 - rotor blades;

8 - payload compartment;

9 - chassis.

Fig. 2 shows a diagram of the simplest rotary nozzle.

Fig. 3 shows a rotating nozzle with a variable outlet cross-section area.

The helicopter (Fig. 1) contains:

- fuselage 1, which houses the main systems and units of the helicopter and compartments for payload 8, power plant (electric or based on internal combustion engines), transmission, fan (fans) of the jet system, energy reserve (for example, battery or fuel cells);

- air intakes 6 located on the surface of the fuselage, providing the jet control system with the required air flow, including that necessary for cooling the units;

- a main rotor consisting of blades 7 and a hub 8 without a control system for the general and cyclic pitch of the blades (swashplate);

- two tubular tail booms 3, spaced apart on different sides from the plane of symmetry of the helicopter, the axes of which can be located at acute angles to the plane of symmetry of the helicopter, or can be parallel, wherein the distance from the plane of symmetry of the helicopter to the outlet section of the nozzles is selected in the range of 0.3 - 0.8 of the radius of the main rotor, and the distance from the plane perpendicular to the plane of symmetry of the helicopter and passing through the axis of the main rotor, to the outlet section of the nozzles is selected in the range of 0.5 - 1.2 of the radius of the main rotor;

- a jet control system, which includes sequentially located air intakes, a fan (fans) either with individual electric drives (impellers) or driven by the transmission, internal air ducts located in the tail booms and controlled nozzles 4 at their ends;

- slot nozzles 5, located on the side surfaces of the tail booms along their axes, providing a reduction in the power required to compensate for the reactive torque of the main rotor;

- chassis 9.

A power plant based on an internal combustion engine, compared to an electric one, leads to a certain complication of the design and operating conditions, but provides a significant increase in the duration and range of the flight.

In practice, if a serial impeller or power fan does not satisfy the performance requirement, two or more impellers or two or more power fans can be installed in the jet control system.

Let us consider the operating principle of the device for controlling the aerodynamic moments of a single-rotor helicopter and the stages of the method for controlling such a helicopter.

Air from the air intakes enters the air ducts and is then forced into the nozzles by the appropriate device. These are either impellers with individual drives located inside the fuselage near the root sections of the tail booms, or a power fan located inside the fuselage near the root sections of the tail booms. The jet system simultaneously performs the functions of cooling the power plant (PU): electric motors or an internal combustion engine and transmission, i.e. the jet control system is integrated with the power plant of the apparatus. Controllable nozzles installed on the ends of the tail booms attached to the fuselage of the helicopter are equipped with rotation mechanisms and/or bypass windows to change the area of the outlet section, to create vertical and horizontal components of the thrust force.

The rotation of the nozzle and the change in the area of the bypass windows are carried out using an electric servo drive or any mechanical device connected to the automatic control system.

The values of the reactive thrust forces of the tail nozzles required for balancing and controlling the helicopter are regulated by controlling the flow rate and/or pressure of the air coming from the device for pumping air of the jet system into its channels and then into the tail nozzles. Such a device may be, for example, a fan with rotating blades of the inlet guide vane, driven by a cruising piston engine, or with rotating blades of the working wheel, in which the flow rate and pressure are controlled by changing the installation angles of the corresponding blades. A structurally simpler device may be an impeller - a fan in an annular channel, driven by a separate electric motor, in which the flow rate and pressure are controlled by changing the rotation frequency.

As a result, it is possible to control the reactive forces of the helicopter jet system nozzles in the horizontal and vertical planes in such a way that, combining their possible combinations, they provide the necessary values of the roll, pitch and yaw moments both for balancing and for controlling the angular position of the helicopter. By changing the rotation angles of the nozzles synchronously, the pitch moment is controlled, and asynchronously - the roll moment. By changing the air flow through the nozzles, the values of the reactive forces are changed (with a synchronous change in flow rates through the impellers), and the yaw moment is controlled (with an asynchronous change in flow rates). Slot nozzles are located on the side surfaces of the tail booms. The air flowing out of them tangentially to the surfaces of the booms provides supercirculation flow around the booms with a flow induced by the main rotor. As a result, significant lateral forces are created on the booms, providing compensation for the reactive moment of the main rotor with moderate power costs. This method ensures maximum simplification (and, accordingly, reduction in cost) of the design and increases its reliability.

The tail jet nozzles of a helicopter without swashplates with a jet control system solve the problems of creating vertical and horizontal components of jet forces. Tail nozzles can be of different designs. Fig. 2 shows a diagram of the simplest rotary nozzle.

The orientation of the outgoing air stream of such a nozzle sets the ratio of the vertical and horizontal components of its thrust force, and the magnitude of the nozzle thrust force is determined by the momentum of the outgoing air stream, the area of its outlet cross-section, and the excess air pressure at its section. The required combination of horizontal T _g and vertical T v components _of the nozzle thrust force is achieved by turning the nozzle by an angle θ = arctg (T _v /T _g ) relative to the plane of the helicopter's construction horizontal using a special mechanical or electric drive of any known suitable design.

Thus, the required ratio of the vertical and horizontal components of the reactive force of each nozzle is achieved by turning the reactive nozzles around their axis of rotation relative to the axis approximately parallel to the helicopter's construction horizontal at angles determined by the moments required for control. And the magnitude of the reactive force is controlled by changing the pressure and air flow rate of the jet system.

A nozzle variant containing windows on the upper and lower surfaces of the beam is also possible (Fig. 3). In this case, the vertical component of the total reactive force of the nozzle is controlled by changing the ratio of the areas of the upper and lower windows, for example, by means of a rotary shutter. If it is necessary to create a horizontal component of the reactive force, similar windows are placed on the side surfaces of the beam end. This nozzle variant can provide an increase in the speed of the control system, since it does not require a mandatory change in the performance (flow rate/pressure) relative to the inertial impeller or power fan.

Depending on the technical task at hand, it is possible to combine both methods of controlling the magnitude of the vertical and horizontal components of the thrust forces of the jet nozzle (both rotation and change in the area of the outlet cross-section) in the nozzle design, or to increase the number of nozzles.

The value of the resultant reactive thrust force of the nozzle required for balancing and controlling the helicopter is achieved by controlling the mass flow rate and air pressure in its jet control system, changing the rotation frequency of the air injection device (impellers or power fan) or changing the installation angles of its working blades - both the rotor wheel and the guide and/or straightening apparatus.

In this case, in all variants, the components of the reactive forces of the thrusts of the controlled jet nozzles on the corresponding arms, parallel to the plane of the helicopter's construction horizontal, create yaw moments, and the components of the reactive forces of the thrusts of the controlled jet nozzles on the corresponding arms, perpendicular to this plane, create pitch and/or roll moments.

Thus, by means of the device of the two-beam jet system of the helicopter, it is possible to create pitch, roll and yaw moments, both for balancing and for controlling the angular movement of the helicopter:

- by controlling the sum of the horizontal components of the tail nozzle thrusts, the helicopter yaw moments are controlled;

- by controlling the sum of the vertical components of the tail nozzle thrusts, control of the helicopter pitch moments is realized;

- control of roll moments is carried out by means of differential (directed in different directions) control of the vertical components of the tail nozzle thrust forces, spaced in opposite directions relative to the plane of symmetry of the helicopter.

The proposed method allows for the spatial orientation of a helicopter, in particular, by controlling aerodynamic moments, namely pitch, roll and yaw moments of a helicopter without using swashplates and other elements interacting with them, which simplifies and reduces the cost of the propeller system and increases its reliability, trouble-free operation and service life.

To test the proposed method, an experimental demonstrator apparatus was created at the NIC KI and RVKLA TsAGI. It is an unmanned helicopter with a takeoff weight of about 100 kg and a rotor diameter of 2 m. The power plant includes a piston engine RMZ-650, a gearbox providing a drive for the rotor and two power fans pumping air into the tail booms attached to the fuselage. Rotary nozzles controlled by servo drives are installed at the ends of the tail booms. The design of the nozzles corresponds to that shown in Fig. 2. When manually controlling the apparatus, using a signal from the control stick "away from you" or "towards you", the nozzles synchronously deflect downwards or upwards, respectively, creating the required pitch moment. When deflecting the control stick, for example, to the left, the left nozzle deflects upwards and the right one downwards, creating a roll moment to the left. Thus, the pitch moment is controlled by synchronous rotation of the nozzles, and the roll moment is controlled by their asynchronous rotation. Coordinated nozzle deflections during simultaneous control of both roll and pitch are provided by the onboard computer of the automatic control system (ACS). The ACS, using signals from inertial sensors (linear and angular velocities and accelerations), also provides compensation for random disturbances during flight, which significantly improves the stability and controllability characteristics of the apparatus.

The jet system fan also provides air circulation through the fuselage and, accordingly, cooling of the power plant components.

Claims (1)

A method for controlling the aerodynamic moments of a single-rotor helicopter having a rotor with a rotary drive, two tubular tail booms attached to the fuselage of the helicopter and spaced apart on different sides of the plane of symmetry of the helicopter, a jet control system including controlled nozzles located at the ends of the booms, characterized in that the pitch moment is created by synchronous rotation of the nozzles and/or a change in the area of their outlet sections, the roll moment is created by multidirectional rotation of the nozzles and/or a change in the area of their outlet sections, the yaw moment is created by multidirectional change in pressure or air flow through the nozzles of the left and right booms of the apparatus, wherein compensation for the reactive moment of the rotor is ensured by the operation of the slot nozzles of the supercirculation system.