RU2826663C1 - Multi-rotor vertical take-off and landing aircraft - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to aircraft engineering, particularly, to VTOL unmanned aerial vehicle. Multi-rotor VTOL aircraft comprises left and right side compartments connected by inner side walls by means of wings. Groups of front, rear, first central and second central engine-engine-propeller pairs, containing at least one propeller and one engine, are symmetrically located on the left and right side compartments using rigid brackets. First central and second central engine-propeller pairs are secured on outer lateral sides of side compartments in opposite directions from aircraft vertical axis.

EFFECT: improved flight characteristics of aircraft, reduced power consumption in all flight modes.

2 cl, 7 dwg

Description

The invention relates to the field of aviation, namely to an unmanned aerial vehicle with vertical takeoff and landing.

Unmanned aerial vehicles (hereinafter referred to as UAVs) are currently used to solve a wide range of civil and military tasks. These include the transportation of various cargoes, monitoring of objects, performing geodetic tasks, use in agriculture for processing crops, etc.

Some types of UAV applications dictate the need to improve a number of flight and technical characteristics, which may include flight range, flight altitude, loitering time, payload weight, etc. At the same time, the ability to hover in place and perform vertical takeoff and landing must often be maintained.

Classic multirotor systems (copters in which the main functional elements are located in the center of the apparatus, and the propeller-motor groups are located along the perimeter), which are widely used at present, have relatively low flight range and loitering time compared to vertical takeoff and landing UAVs of the aircraft type, but have advantages in terms of flight time and maneuverability in hovering modes, as well as in compactness.

There are a number of aircraft known as convertiplanes, which switch from hovering to horizontal flight by rotating the wing or propeller-motor groups. These aircraft contain turning mechanisms, which complicates the design and makes it less reliable.

A number of multirotor aircraft are known, in which the lifting force for horizontal flight is created jointly by propellers and a fixed wing. The claimed invention pertains to this group of aircraft.

Several technical solutions can be identified as the closest analogues.

An aircraft is known (patent RU 2693362, published 02.07.2019), comprising two or more spaced longitudinal load-bearing elements, two or more wing consoles located along the longitudinal axis of the aircraft, and a multi-engine power plant. The air movers are installed at a fixed angle to the vertical plane in two or more rows relative to the longitudinal axis of the aircraft.

A rotorcraft is known (patent RU 2720746, published 13.05.2020), comprising front and rear wings fixed to the fuselage, propeller-motor groups, each of which includes a motor and a propeller installed in a tricopter configuration. Two propellers are fixed to the ends of the front wing, one propeller is fixed to the tail boom.

A tandem-configured rotary-wing unmanned aerial vehicle is known (patent RU 2771195, published on 28.04.2022), which comprises a front wing with propellers mounted on its ends, inclined forward in flight, and a rear wing. A cross beam with propellers mounted on its ends is installed behind the rear wing.

The disadvantages of the described technical solutions include a fairly high energy consumption in horizontal flight mode, since the axes of the propeller-motor groups, due to which horizontal flight is achieved, are not inclined from the vertical axis at an angle that is large enough, which leads to energy consumption for creating lift by the propeller, and not by the wing.

The objective of the present invention is to increase the flight time and range of a multirotor aircraft with a fixed takeoff weight, without using complex kinematic mechanisms and drives to perform horizontal flight.

The technical result of the claimed invention is a reduction in the weight of the structure, an improvement in the flight characteristics of the aircraft and, as a consequence, a reduction in energy consumption in all flight modes.

A multirotor vertical takeoff and landing aircraft comprises left and right side sections connected by internal side walls using wings. On the left and right side sections, groups of front, rear, first central and second central propeller-motor pairs are symmetrically arranged using rigid brackets, containing at least one propeller and one engine. The first central and second central propeller-motor pairs are secured to the outer sidewalls of the side sections at an angle in opposite directions from the vertical axis of the aircraft.

The side compartments are arranged in mirror image to each other.

Between the side compartments there may be a central compartment connected to the side compartments by wings.

For the purpose of describing the claimed technical solution, the following definitions are used:

Horizontal flight is a flight "like an airplane", in which part of the lift force is created by wings integrated into the design.

Hover mode is a flight mode in a "copter" configuration, in which lift is created only by the propellers, and movement in space is carried out without the wings creating lift.

A propeller-motor pair is a propeller with electric motors whose rotation axes are on the same line.

The essence of the claimed invention is further explained by the drawings Figs. 1-7.

Fig. 1 shows an isometric view of the aircraft.

Fig. 2 shows an isometric view of an aircraft with a central compartment.

Fig. 3 shows a top view of the aircraft.

Fig. 4 shows a side view of the aircraft.

Fig. 5 shows a cross-section of the aircraft along the wing consoles.

Fig. 6 shows the logic of operation of the propeller-motor groups in the loitering mode, side view.

Fig. 7 shows the distribution of forces acting on an aircraft in horizontal flight.

The following symbols are used in the figures:

1 - left side compartment;

2 - right side compartment;

3 - wings;

4 - front propeller-motor pair;

5 - rear propeller-motor pair;

6 - first central propeller-motor pair;

7 - the second central propeller-motor pair;

8 - central compartment;

10 - aerodynamic drag;

11 - uncompensated weight;

12 - vertical axis of the aircraft;

13 - axis of the cruise propeller-motor groups;

100 - flight direction;

101 - thrust of the rear propeller-engine group in horizontal flight mode;

102 - thrust of the first central propeller-motor group in horizontal flight mode.

The multirotor vertical takeoff and landing aircraft comprises left (1) and right (2) side sections, between the inner side walls of which wings (3) are located, at least four groups of propeller-motor pairs, representing a group of front (4) propeller-motor pairs, a group of rear (5) propeller-motor pairs, a group of first central (6) propeller-motor pairs and a group of second central (7) propeller-motor pairs. Each propeller-motor pair includes motors and propellers. Each propeller-motor pair is secured by an engine using a rigid bracket on the side sections (1) and (2) (see Fig. 4).

The front (4) propeller-motor pairs are secured with brackets on the front ends of the side sections (1) and (2), and the rear (5) propeller-motor pairs are secured with brackets on the rear ends of the side sections (1) and (2). The first (6) central and second (7) central propeller-motor pairs are installed with brackets on the outer walls of the side sections (1) and (2) at an angle relative to the vertical axis of the aircraft. The second (7) central propeller-motor pair is tilted in the opposite direction relative to the first (6) central propeller-motor pair.

The left (1) and right (2) side compartments are mirror images of each other.

To accommodate the payload, a central compartment (8) may be located between the left (1) and right (2) side compartments. In this case, the wings (3) are located between the central compartment (8) and the side compartments (1) and (2) in such a way that they connect the side compartments (1) and (2) with the central compartment (8).

The claimed aircraft is adapted for two operating modes - hovering mode and horizontal flight mode. The transition from the hovering mode to the horizontal flight mode is carried out by tilting the aircraft forward (deflecting the vertical axis (12) of the aircraft from the Y axis of the associated coordinate system) due to the creation of a diving moment by the propeller-motor pairs in such a way that the wing profile is at an optimal angle of attack for patrolling, flying at maximum range or flying at maximum speed. As the speed is gained, some of the propeller-motor pairs are switched off or switched to idle mode to prevent autorotation. The transition from the horizontal flight mode to the hovering mode is carried out by combining the Y axis of the associated coordinate system with the vertical axis (12) of the aircraft, at which the wings go beyond the critical angle of attack and stop creating the lift force necessary for horizontal flight, and the increased drag contributes to a decrease in the speed of the aircraft. All propeller-motor pairs are then activated and compensate for the lack of lift on the wings.

The described transition modes between the hover mode and the horizontal flight mode are unstable in speed, i.e. steady horizontal flight is not provided for in them.

The operation of the rear (5) propeller-motor pairs ensures the balance of the apparatus. The installation of the first central (6) and second central (7) propeller-motor pairs at an angle relative to the vertical axis of the aircraft, with the first central (6) propeller-motor pair being performed with an inclination in the opposite direction relative to the inclination of the second central (7) propeller-motor pair (Fig. 6), allows:

- significantly reduce energy consumption in loitering mode and during maximum range flight by installing the first central (6) propeller-motor pair at an angle;

- ensure an acceptable level of controllability along the yaw channel, since in the declared aircraft, due to the side sections being sufficiently distant from the center of mass, the moment of inertia relative to the vertical axis is significantly higher compared to copter designs, where the main elements (battery, payload, etc.) are located in the center of the aircraft.

The installation angle of the propeller-motor pairs is generally determined by the criterion of minimizing the takeoff mass for given (calculated) flight profiles. Flight profiles, in turn, are determined at the design stage based on the tasks set for the apparatus.

To optimize the loitering mode, an aerodynamic wing profile is used that implements high values of aerodynamic quality at high angles of attack at low Reynolds numbers of ~0.5*(10^6). This solution, combined with the use of cruise propellers (propellers of the first central propeller-motor pairs), which have the highest efficiency in low relative pitch modes (less than 1), allows optimizing energy consumption in the horizontal flight mode, as well as maintaining a low level of energy consumption in the hovering mode. The propeller parameters that provide the highest efficiency at the specified values of relative pitch provide an acceptable level of energy consumption in the hovering mode (such propellers are widely used on various copters), which eliminates the need for a variable-pitch propeller.

The wing areas are selected based on ensuring, in horizontal flight mode, such a lift force that the weight not compensated by the lift force would be perceived by the projection of the thrust of the first central (6) propeller-engine pairs and the balancing rear (5) propeller-engine pairs onto the Y axis, and the projection onto the X axis would compensate for the aerodynamic drag (Fig. 7).

In the presented aircraft, part of the aircraft mass is concentrated near the propellers, in the left (1) and right (2) side sections. This allows to reduce the effect of the bending moment on the wings (3) to 50%, since the path of transfer of the lifting force is shortened in comparison with the classic copter scheme.

The increase in the flight characteristics of the aircraft is achieved by integrating the wings into the design, as well as reducing the weight of the structure by using an original layout scheme. The increase in flight characteristics allows for an increase in flight time by reducing energy consumption in the corresponding flight mode. Reducing the weight of the structure allows for an improvement in the flight characteristics of the aircraft by reducing energy consumption in all modes.

Claims (2)

1. A multi-rotor vertical takeoff and landing aircraft, characterized in that it contains left and right side sections connected by internal side walls using wings, wherein on the left and right side sections, groups of front, rear, first central and second central propeller-motor pairs are symmetrically arranged using rigid brackets, containing at least one propeller and one engine, in addition, the first central and second central propeller-motor pairs are secured to the outer sidewalls of the side sections in opposite directions from the vertical axis of the aircraft. 2. A multi-rotor vertical takeoff and landing aircraft according to paragraph 1, characterized in that between the side sections there is a central section connected to the side sections by wings.