RU2776523C1 - Method for controlling flight of aircraft with fixed wing with possibility of performing vertical takeoff and landing - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to aviation technology, in particular to methods for controlling vertical take-off and landing aircrafts. The method for controlling an aircraft with a fixed wing with the possibility of performing vertical takeoff and landing is characterized by that, at stages of takeoff, landing, hovering, transition to an airplane flight mode and when flying in the airplane mode, all control moments in all control channels (pitch, roll, course) are created by a differential change in the thrust of lifting power plants. The thrust required for horizontal flight is created by a marching power plant. As the horizontal flight speed increases, the thrust of lifting power plants gradually decreases, and, at the end of the transition mode, at flight speeds of more than 1.2…1.3 of the stall speed, it is set to the lowest possible.

EFFECT: improvement of stability and controllability characteristics are achieved in all aircraft flight modes, including at low speeds, at high wing angles of attack and under the influence of atmospheric turbulence.

1 cl, 1 dwg

Description

The invention relates to aviation technology, in particular to combined aircraft (LA) vertical takeoff and landing.

A patent of the Russian Federation for the invention No. 2638221 dated 12.12.2017 is known [1]. The vertical takeoff and landing aircraft contains a marching power plant for horizontal flight in airplane mode, containing at least three separate lifting power plants for generating thrust in a vertical plane. The propellers of the lifting power plants are installed in such a way that the plane of their rotation is located at an angle of 2 to 35 degrees to the bearing planes of the wing or wings. The wing and "U"-shaped tail contain aerodynamic control surfaces used in airplane flight.

The method of flight control of an aircraft is characterized by the fact that at the moment of takeoff the aircraft in hover mode is located with a positive pitch angle from 2 to 35 degrees. To gain sufficient speed on the lifting engines, the entire aircraft is tilted forward to a pitch angle that ensures horizontal flight in airplane mode. After reaching the required speed (1.1-1.5 stall speeds), the lifting motors are turned off. Further flight is carried out on the thrust of a marching power plant. Flight control in airplane mode is carried out using aerodynamic control surfaces located on the wing and tail.

In fact, the described aircraft in airplane mode bears extra weight in the form of idle lifting power plants. This significantly reduces its energy efficiency. In addition, the fixed propellers of lifting power plants create additional aerodynamic drag, which worsens the aerodynamic quality of the aircraft.

The control of the described aircraft with the help of aerodynamic control surfaces is impossible in vertical and transitional modes (from vertical takeoff to airplane mode; and also from airplane mode to vertical landing) due to the extremely low velocity pressure. In these modes, aerodynamic rudders are inoperable. It is also worth noting the low efficiency of aerodynamic controls in aircraft flight mode when they enter conditions of low speeds and high angles of attack, which can lead to a complete loss of control and loss of the aircraft itself. The listed negative phenomena can take place when the specified aircraft is exposed to atmospheric turbulence.

The closest analogue in terms of the control method is the aircraft described in the RF patent for the invention No. 2746770 dated April 20, 2021 [2]. The author of the invention proposed several variants of the aircraft:

1) A vertical take-off and landing aircraft containing at least four separate power plants for generating thrust in the vertical plane, of which at least two are also used as sustainers for level flight in airplane mode. At the same time, an even number of power plants used as mid-flight for horizontal flight in aircraft mode are fixed on both sides of at least one rocker arm with the possibility of its rotation in a plane coinciding or parallel to the plane of symmetry of the aircraft, solely due to the difference in the rods installed on it power plants.

2) An aircraft, the power plants of which, in the absence of use as sustainers for horizontal flight in aircraft mode, are made with the possibility of being used as roll and pitch controls and can be rotated relative to the bearing planes in such a way that when the pitch angle of the aircraft changes their thrust vector coincides in direction with the gravitational acceleration vector.

Moreover, all variants of this aircraft, according to the author, have the ability to take off vertically, hover and switch to airplane flight mode. However, in the described variants of the aircraft, the possibility of control in the track channel is completely absent, which makes it impossible for the controlled and safe flight of this aircraft in any of the considered modes.

The method of controlling the flight of an aircraft [2] is characterized by the fact that at the moment of takeoff of the aircraft in the hover mode, the rocker arm with power plants is placed horizontally, and after takeoff, to gain horizontal speed, it is gradually rotated due to the difference in the thrusts of the power plants installed on it, up to vertical position. At the same time, the power plants outside the rocker arm ensure the inclination of the entire aircraft in a vertical plane to a pitch angle that ensures horizontal flight in airplane mode.

In the proposed by the author method of aircraft control [2] in airplane mode, there is no possibility of control in the longitudinal channel in full. So, when the rocker is installed in a vertical position (to ensure the operation of the lifting-propulsion power plant in the propulsion mode), this aircraft is completely deprived of control in the longitudinal channel in the direction of decreasing pitch angles, because. any difference in the thrust of the upper and lower elements of the lifting-propulsion power plant will only lead to their rotation around the axis of the rocker arm, and not to the creation of moments that control the position of the aircraft.

The objective of the invention is to create a method for controlling an aircraft that provides the necessary characteristics of stability and controllability in all possible flight modes of an aircraft with a fixed wing, using the same controls for the position of the aircraft in space.

The technical result of the claimed invention is:

1. Providing the necessary characteristics of stability, controllability and maneuverability in all possible modes of operation of the aircraft.

2. Increase in the aerodynamic quality, weight return of the structure and energy efficiency of horizontal flight.

3. Improving the characteristics of stability and controllability at low speeds, at high angles of attack of the wing and under the influence of atmospheric turbulence.

4. Reducing the transition time from hovering to level flight and vice versa.

5. Simplification of the aircraft control system due to the effective use of the same controls in all possible modes of aircraft operation.

The claimed method of controlling the flight of a fixed-wing aircraft is characterized by the fact that at the stages of takeoff (and landing), hovering, transition to airplane flight mode and when flying in airplane mode, all control moments in all control channels (pitch, roll, heading) are created by a differential change in the thrust of lifting power plants. The thrust required for level flight is generated by the main power plant. As the speed of horizontal flight increases, the thrust of the lifting power plants gradually decreases and at the end of the transition mode (at flight speeds of more than 1.2 ... 1.3 stall speeds) is set to the minimum possible. At the same time, it is possible to constantly monitor the spatial position of the aircraft through all control channels in all possible modes of operation of the aircraft. Brief description of the scheme.

On FIG. 1 shows the device of an aircraft using the claimed control method, where:

1 - aircraft with a fixed wing;

2 - lifting power plants, also used as pitch, roll and heading controls in all flight modes;

3 - marching power plant.

Implementation of the invention.

The invention is implemented on the basis of an aircraft with a fixed wing, for example, a "tailless" scheme (see Fig. 1).

The aircraft 1 has four lifting power plants 2, placed in pairs ahead and behind the wing, and used to create vertical thrust and control moments in all flight modes. Also on the aircraft is installed marching power plant 3 to create thrust when flying in airplane mode.

These design features of the aircraft make it possible to solve the problem of the invention and achieve the claimed technical result.

The vertical takeoff of the aircraft 1 is carried out due to the thrust of the lifting power plants 2 (see Fig. 1). To stabilize the given values of the attitude angles of the aircraft 1 (pitch, roll and heading), a differential change in the operating mode of the lifting power plants 2 is performed, which allows (on the shoulders to the center of mass of the aircraft 1) to create control moments relative to all three axes of the aircraft 1.

The transition to airplane flight mode occurs when accelerating speed in the horizontal plane under the action of thrust generated by the propulsion power plant 3 (see Fig. 1). As the speed increases, the LA wing 1 begins to create lift, which allows (to maintain the altitude of horizontal flight) to reduce the thrust of the lifting power plants 2 in proportion to the increase in flight speed. At the end of the transition mode (at flight speeds of 1.2 ... 1.3 stall speeds), in order to reduce energy consumption, the minimum possible operating mode of lifting power plants 2 is set. During further flight in airplane mode, lifting power plants 2 continue to perform the function of flight controls.

The transition from airplane flight mode to hover mode is carried out in the reverse order: as the flight speed decreases (1.2 ... 1.3 stall speeds or less), the lift created by the wing of aircraft 1 decreases. aircraft weight 1), a proportional increase in the thrust of all lifting power plants 2 is made.

When flying in airplane mode, the creation of control moments (relative to all three axes of the aircraft 1) necessary to ensure the specified characteristics of stability and controllability is carried out using a differential change in the operating modes of the lifting power plants 2 (see Fig. 1).

The proposed control method makes it possible to implement not only vertical takeoff with subsequent transition to horizontal flight, but also flight in airplane mode, using differential thrust control of lifting power plants to provide the necessary stability and controllability characteristics in all possible modes of aircraft operation.

Sources of information

1. Patent for the invention "Vertical takeoff and landing aircraft and method of controlling its flight" No. 2638221 dated 12/12/2017.

2. Patent for the invention "Vertical takeoff and landing aircraft and method of controlling its flight" No. 2746770 dated 04/20/2021.

Claims (1)

A method for controlling an aircraft with a fixed wing with the ability to perform vertical takeoff and landing, characterized in that at the stages of takeoff, landing, hovering, transition to airplane flight mode and during flight in airplane mode, all control moments in all control channels - pitch, roll, course, they are created by a differential change in the thrust of lifting power plants, while the thrust required for horizontal flight is created by a sustainer power plant, and as the speed of horizontal flight increases, the thrust of lifting power plants is gradually reduced and at the end of the transition mode at flight speeds of more than 1.2 ... 1, 3 stall speeds are set to the lowest possible.

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