RU2803674C2 - Method for controlling the pitch of a tiltrotor - Google Patents

Abstract

FIELD: aircraft construction.

SUBSTANCE: invention concerns a method for adjusting the pitch of a tiltrotor. Due to the location of the rudder plate in the tail part of the tiltrotor directly behind the fan, a pitching moment is created, which appears due to the aerodynamic force acting on the shoulder from the centre of mass of the tiltrotor to the centre of pressure of the rudder plate and resulting from the air blown by the fan flowing around the rudder plate. The installation angle of the rudder plate is adjusted by changing the magnitude and/or direction of the aerodynamic force that occurs when air flows around the rudder plate. Moreover, the fan blades are rotatable to regulate the speed of the air pumped by the fan.

EFFECT: increase in manoeuvrability, longitudinal stability and safety is achieved during the transition from vertical flight to horizontal/horizontal flight to vertical during take-off and landing, including throughout the entire flight.

1 cl, 6 dwg, 1 tbl

Description

The invention relates to the field of aircraft construction, and more precisely to methods and systems for controlling the pitch of a tiltrotor, and can be used to control the pitch of a tiltrotor.

The technical solution “Three-propeller tiltrotor” is known (patent No. RU2656957C1, IPC B64C 37/00, published 06/07/2018). A three-propeller tiltrotor consists of a fuselage with a wing attached to it according to the high-wing design, a two-fin tail unit, engines with propellers located on the leading edge of the wing, and a rotary mechanism that allows you to change the thrust vector by 110° relative to the horizon to change flight modes. There is an additional power unit with a horizontal propeller located in the tail section of the horizontal fin and serves to stabilize the aircraft in pitch in helicopter flight mode, control the direction of movement of the tiltrotor, and is also equipped with a rotating mechanism that allows you to deflect the thrust vector in the vertical plane to compensate for the torque generated by the front power units and control the yaw of the aircraft in helicopter and transient flight modes.

The disadvantages of this technical solution include the vulnerability of the additional power plant with a horizontal propeller during takeoff and landing from unevenness of the underlying surface.

The closest in technical essence is the DOAK VZ-4 tiltrotor, the engine nozzle of which was mated to a pipe of the required length, which passed through the entire tail boom. A special device with several gas rudders was installed on it. Such control systems had a very simple design. At the pipe nozzle there was a frame on which movable vertical and horizontal plates-rudders were placed. Flow control was carried out by deflecting the rudders in the desired directions.

However, a significant drawback of this method of pitch control is the inability to quickly respond to changes in the vertical position of the aircraft, which can increase the risk of a tiltrotor crash.

The technical problem being solved is the creation of a highly effective method for controlling the pitch of a tiltrotor, which allows increasing the maneuverability of the tiltrotor, the longitudinal stability and safety of this aircraft during the transition from vertical flight to horizontal/horizontal flight to vertical during takeoff and landing, including throughout the entire flight.

The technical result of the invention is to increase the maneuverability, longitudinal stability and safety of the tiltrotor during the transition from vertical flight to horizontal/horizontal flight to vertical during takeoff and landing, including throughout the entire flight.

The technical result is achieved by the fact that due to the location of the rudder plate in the tail part of the tiltrotor directly behind the fan, a pitching moment is created, which appears due to the aerodynamic force acting on the shoulder from the center of mass of the tiltrotor to the center of pressure of the rudder plate, and resulting from the flow around the rudder plate air blown by a fan. The angle of installation of the rudder plate is adjusted, thereby changing the magnitude and/or direction of the aerodynamic force that occurs when air blown by the fan flows around the rudder plate and is aligned depending on which direction it is necessary to direct the pitching moment. Moreover, the fan blades are rotatable. This increases the maneuverability and pitch control of the tiltrotor, and increases the stability and safety of the tiltrotor during the transition from vertical flight to horizontal/horizontal flight to vertical during takeoff and landing and throughout the entire flight.

Description of drawings

In Fig. 1 and Fig. Figure 2 shows diagrams of the tiltrotor's horizontal flight (front and top views, respectively). Figures 3 and 4 show diagrams of the vertical flight of the tiltrotor (front and top views, respectively). Figure 5 shows a diagram of the forces and moments acting on the tiltrotor in flight.

The invention contains a fuselage 1, which serves to accommodate the target load with a wing 2 attached to it according to the high-wing design; on the leading edge of the wing 2 there are engine nacelles 3 with engines, propellers and a rotating mechanism that allows you to change the thrust vector relative to the horizon; in airplane (cruising) flight mode, the main direction of the thrust vector is horizontal and the aerodynamic force is created due to the work of the wing profile 2, and when flying in helicopter mode (hovering / vertical takeoff and landing), the main direction of the thrust vector is vertical and the lift force is created due to air mass thrown by propellers; fan 4 (the blades of which are rotatable), which serves to pump air onto the rudder plate 5, when air flows around it from the fan 4, an aerodynamic force appears, creating a pitching moment with the shoulder from the center of gravity of the tiltrotor to the center of pressure of the rudder plate 5; V-shaped tail unit 6, which serves to stabilize the aircraft in yaw and roll; air intake 7, which serves to supply air from the external environment to the fan.

The device works as follows.

Fuselage 1 serves to accommodate the target load; in airplane (cruising) flight mode, the main direction of the thrust vector is horizontal and the aerodynamic force is created due to the work of the wing profile 2, and when flying in helicopter mode (hovering / vertical takeoff and landing), the main direction of the thrust vector is vertical and the lift is created by the air mass thrown by the propellers. The V-shaped tail 6 serves to stabilize the aircraft in yaw and roll. When changing the direction of the thrust vector of the main power plants 3 from horizontal to vertical and back, as well as for hovering and vertical takeoff/landing modes, to stabilize the tiltrotor in pitch, air is pumped onto the rudder plate 5 using fan 4. Air from the external environment enters the air intake 7, then from there it is supplied to the fan 4. A pitching moment arises with a shoulder from the center of mass to the center of pressure of the rudder plate 5 from the action of the aerodynamic force that occurs when air flows around the rudder plate 5. The pitching moment aligns the aircraft relative to the horizon, and also serves to maneuver the tiltrotor in pitch. Pitch control is carried out by changing the angle of installation of the rudder plate 5, due to which it becomes possible to change the aerodynamic force that occurs when air flows around the rudder plate 5, and/or its direction, depending on which direction the pitching moment needs to be directed. It also becomes possible to quickly change the value of the pitching moment by changing the angle of installation of the fan blades 4. Increasing/decreasing the angle of installation of the fan blades leads to an increase/decrease in the speed of injection of air into the steering wheel plate 5, pumped by the fan 4, due to which the amount of aerodynamic force increases/decreases , which occurs due to the flow of air pumped by the fan 4 around the rudder plate 5.

To compensate for external torque relative to the transverse axis passing through the center of gravity O of the tiltrotor, it is necessary to create a pitching moment , expressed by equality (1):

Where

Y And L - the lifting force and the shoulder of this force, respectively.

The lifting force Y is determined by the following relationship (2):

Where

- lift coefficient depending on the angle of attack ;

- density of the oncoming flow (air forced by the fan 4 onto the steering wheel plate 5);

- area of the rudder plate;

- speed of the oncoming flow (air forced by the fan 4 onto the steering wheel plate 5).

However, with a change in the angle of attack the position of the point also changes application of lifting force Y along the chord of the rudder plate 5 relative to its leading edge. In this regard, the arm of action L of the lifting force Y also changes. Knowing the angle of attack , it is possible, based on dependence (3), to determine the position of the point application of lifting force Y along the chord of the rudder plate 5 relative to its leading edge:

Where

- moment coefficient - a number depending on the wing profile, angle of attack and the point relative to which the moment is determined.

Let the distance from the leading edge of the rudder plate 5 to the point of its attachment be .Then the arm of action L of the lifting force Y is expressed by equality (4):

Where

- distance from the center of gravity Aircraft to the fixing point A of the rudder plate 5.

Substituting expressions (2) and (4) into expression (1) we have dependence (5):

or dependence (6):

Example 1.

Let the following data be available:

• plate profile NASA-0006,

• air density ,

• free stream speed ,

• rudder plate area 5 =1 ,

• distance from center of gravity Aircraft to the fixing point A of the rudder plate 5 ,

• distance from the front edge of the rudder plate 5 to the point of its attachment =0.125 m.

Based on these data, Table 1 and Fig. 6 for greater clarity.

Figure 6 can be interpreted as follows: at the angle of attack a pitching moment is created =46848.27 N m, which can compensate for external torque = -46848.27 N m. Or to compensate for torque 262709.2 N m, it is necessary to set the rudder plate 5 at the angle of attack -24 .

Thus, the claimed technical solution makes it possible to increase the maneuverability, longitudinal stability and safety of the tiltrotor during the transition from vertical to horizontal flight, and vice versa during takeoff and landing, including throughout the entire flight. The propeller required for pitch control becomes protected due to its location inside the fuselage. This method of controlling the pitch of a tiltrotor makes it easy to use it when transporting various cargo, people, equipment, it becomes possible to land it on almost any surface (even an inclined one), and there is no need for specially equipped airfields.

Claims (1)

A method for controlling the pitch of a tiltrotor, which consists in placing a rudder plate in the tail section of the tiltrotor directly behind the fan, the deflection of which changes the magnitude and/or direction of the aerodynamic force that occurs when air flows around the rudder plate, forced by the fan, where the air enters from the external environment through the air intake, the action on the shoulder from the center of mass of the tiltrotor to the center of pressure of the rudder plate which creates a pitching moment, and with the help of rotating fan blades it becomes possible to regulate the speed of the air pumped by the fan.