RU2656934C2 - Method of vertical displacement and aircraft hovering in air - Google Patents

Abstract

FIELD: aircraft engineering.

SUBSTANCE: present invention relates to aviation. Method of vertical displacement and aircraft hovering in air is that the air flow from propeller engines (3,4) blows the wing. Wing has a swept shape in the plan with a large elongation. Flow is separated and directed over the wing along its consoles (1,2), and then a controlled positive pitch angle is given to the aircraft.

EFFECT: invention increases the maximum speed and improves the transverse stability of the aircraft in flight mode at a cruising speed.

1 cl, 3 dwg

Description

The present invention relates to the field of aeronautical engineering, namely to airplanes, the movement of which is based on the aerodynamic principle of flight using a fixed bearing surface (wing).

An airplane’s flight, unlike a helicopter, implies its constant movement with a certain airspeed, on which the magnitude of the airplane’s wing lift (flight mode at cruising speed) directly depends. The minimum possible airspeed, at which the flight of the aircraft is still possible, otherwise it will fall under the influence of gravity, depends on many factors, and first of all on the parameters of the propeller group and wing. If it is necessary to reduce it, sometimes almost to zero, for example, to ensure vertical take-off and landing or hovering (flight mode at near-zero speed), special methods are used.

The known method on which the vertical movement and hovering of such aircraft with vertical take-off and landing, such as tiltrotor, is based. All convertiplanes can be conditionally divided into two classes: with a fixed axis of rotation of the propellers - they hang with a vertically located fuselage, or with a rotation axis of rotation of the propellers by 90 angular degrees - they hang with a horizontally located fuselage. The representative of the first class is the Aircraft of vertical take-off and landing (RU 2093422, IPC V64C 29/00). This device contains a fuselage with a wing made according to the biplane scheme, engines with propellers, rigidly mounted on pylons between the upper and lower consoles, and a rear support. The representative of the second class is the Tiltrotor (RU 2456208, IPC ВСС 37/00). This apparatus contains a fuselage, a wing, engines mounted on two pylons, which are rotatable and located at the ends of the wing, and the chassis.

The way of flying these aircraft at near-zero speed is that directly as the vertical (lifting) force, the traction force of the propellers is used, the axis of rotation of which, regardless of the position of the fuselage of the device, is located vertically. No horizontal (propulsive) force is created in this flight mode, and to suppress the possible horizontal speed of the aircraft, a transitional flight mode is used when the axis of rotation of the screws rotates from vertical to horizontal position either together with the fuselage of the device, or on rotary elements. In flight mode at near zero speed, roll, yaw and pitch control when using this method is carried out by changing the thrust of the propellers or by deflecting the air rudders blown by the flow from the propellers.

Since the requirements for the parameters of the bearing and pulling elements of aircraft for various purposes, in particular, with the hover function in the air and without it, differ significantly, the main advantage of the method is that the parameters of the propeller and wing of these devices when implementing this method do not have undergone no change regarding a conventional aircraft. Their parameters remained economical in terms of the ratio of traction, lift and aerodynamic drag for the flight mode at cruising speed.

A serious disadvantage of this method is the excess power of the engines, the necessary total thrust of the propellers of which in flight mode at near-zero speed should be slightly more than the weight of the device. While the propeller thrust required for flying at cruising speed may not exceed half the weight of the device. However, there are ways to use the load-bearing properties of the wing at a near-zero flight speed, which reduces the power of the engines in this mode.

For example, there is a known Flight Method with the possibility of vertical take-off and landing (RU 2414388, IPC В64С 29/00, IPC В64С 33/00), which includes creating an air flow by using an aerodynamic surface, which is a bearing plane, and a rotary mover with blades connected to the engine, located vertically and in a circle, occupying most of the bearing plane. The blades direct the air flow from the surrounding space radially and parallel to the surface of the bearing plane, which leads to the creation of a lifting force, while by changing the rotation angles of the vertical and horizontal control planes, the position of the aerodynamic surface in space is regulated. In the take-off and landing mode, a constant angle of attack of the blades creates a pressure drop on the bearing plane and a lifting force due to a change in pressure in the closed volume at the aerodynamic surface, and in case of horizontal flight, the changing angle of attack of the blades of the rotary mover creates a horizontal thrust force during each revolution, and the lifting the force is created due to the motion of the carrier plane at an angle of attack or partially due to a change in pressure in a closed volume at the aerodynamic surface. On the supporting aerodynamic surface there are vertical and horizontal control aerodynamic planes that act as air rudders.

In contrast to the method used in convertiplanes, the aerodynamic surface in this method and in flight mode at near-zero speed is used as a bearing plane, by which a lifting force is created due to the pressure drop on this plane with radial air flows. This allows you to reduce the power of the engines, abandoning their work as lifting, which is the advantage of this method.

However, the blades of the rotary mover used in the implementation of the method, when moving the aircraft at cruising speed with each revolution of the rotor, also move against the direction of movement, which together with the large cross-sectional size of the rotary mover increases the aerodynamic drag of the aircraft.

The Known Method for the vertical movement and hovering of an airplane in air (RU 202376, IPC V64C 21/00, IPC V64C 21/04), adopted as a prototype according to the main criterion, which consists in the fact that to create aerodynamic lifting force, air flow from a screw engine is used blowing the wing. During vertical movements and hovering of the aircraft in the air, the horizontal thrust created by the propellers of the airplane blowing around its bearing surfaces is blocked by the thrust from additional screws, blowing off the bearing surface and creating horizontal thrust in the opposite direction, while the air flows from the screws in the forward and reverse directions are mutually compensate for the horizontal component of the thrust and increase the lifting force. At the rear of the aircraft there are air rudders intensively blown by the stream.

Here, as in the previous method, the creation of additional lifting force by the air blown part of the wing allows to reduce the engine power in the airplane’s flight mode at near-zero speed, abandoning their operation as lifting engines. Another advantage of the method is the use of propellers instead of rotary propulsors. This replacement can significantly reduce the aerodynamic drag of the aircraft in flight mode at cruising speed.

But the wide and short wing, necessary for the implementation of this method, is a wing of small elongation, which in flight mode at cruising speed has its drawbacks. Compared to a narrow wing equal to it in surface area, the wide wing has a greater aerodynamic drag, which reduces the maximum speed of the aircraft. In addition, the shorter the wing, the lower the shoulder relative to the center of mass of the aircraft the lifting forces of the wing consoles act, worsening the lateral stability of the aircraft in flight mode at cruising speed.

Therefore, the basis of the invention is the implementation of a method of vertical movement and hovering of an aircraft in the air, ensuring the use of the load-bearing properties of a wing of high elongation at a near-zero flight speed to increase maximum speed and improve lateral stability of the aircraft in flight mode at cruising speed.

To solve the problem in the known method of vertical movement and hovering of an aircraft in the air, which consists in the fact that to create aerodynamic lifting force, air flow from screw engines blowing the wing is used, the wing is used in an arrow-shaped plan with a large elongation, first the flow is divided and directed above the wing along its consoles, and then give the aircraft a controlled positive pitch angle.

Due to the use of an arrow-shaped wing in plan with large elongation and separation of air flows over the wing, the flow from screw engines is directed over the entire wing along its consoles. At the same time, at the near-zero airspeed of the aircraft, aerodynamic rudders are blown and an additional lifting force acts on the wing, which is used to keep the aircraft in equilibrium. Controllability of the aircraft in speed is ensured by giving it a controlled positive pitch angle, which directly affects the increase in the angle of attack of the wing, which causes an increase in the aerodynamic drag of the wing, which blocks the speed of the aircraft, and an increase in the lift of the wing, which compensates for the loss of lift of the wing from a decrease in speed free flow of air. Due to the fact that the flow above the wing is first changed, and then the pitch angle of the airplane is increased, the process of transition of an airplane’s flight from one speed mode to another occurs without loss of balance.

The invention is illustrated by several figures:

- in FIG. Figure 1 shows the position of the propeller engines and the direction of air flow from the propellers in airplane flight mode at cruising speed.

- in FIG. 2 shows the position of the propeller engines and the direction of the air flows from the propellers in airplane flight mode at near-zero speed.

- in FIG. 3 shows the forces acting on the right side of the aircraft when flying at near-zero speed with a positive pitch angle (type A in Fig. 2), here are the following notation:

α is the angle of attack of the wing;

Ft — propeller thrust force;

Fp - the lifting force of the wing console from the incoming air flow;

Fs is the aerodynamic drag force of the wing console;

Fo is the lifting force of the wing console from the flow of the propeller blowing over the upper surface of the wing console;

Fe is the force that creates the control moment (lifting force on the air steering wheel);

Fg - gravity acting on the entire aircraft;

CV - the center of rotation of the propeller;

CD - the center of pressure of the wing console;

Tsd is the elevon pressure center;

CM - the center of mass of the aircraft.

The possibility of implementing the method is described by the example of a flight of an aerodynamic “tailless” aerodynamic scheme, which is characterized by the absence of a tail. The functions of the stabilizer in this case are partially fulfilled by the wing, modified in plan. On the wing, there are also horizontal rudders that control the position of the aircraft in roll and pitch. Typically, these rudders are located on the trailing edge of the wing consoles, closer to their ends. To ensure the longitudinal and lateral stability of the tailless in flight at marching speed, one of the variants of its wing has a swept shape in plan with high elongation (see Fig. 1). Engines 3 and 4 with propellers 5 and 6, mounted on rotary devices 7 and 8 on top of consoles 1 and 2, are located in front of the consoles 1 and 2 that make up the wing of the aircraft. The rotation axes of devices 7 and 8 are perpendicular to the wing plane. The end parts of the wing consoles are air rudders - elevons 9 and 10, the deviation of which in one direction affects the pitch of the aircraft, and their deviation in different directions - on its roll.

In airplane flight mode at marching speed, the thrust of propellers 5 and 6 is directed along the longitudinal axis of the aircraft. Accordingly, the air flow from them, consisting of two parts 11 and 12, blows across the wing and blows only small areas of the upper surface of the wing consoles 1 and 2 (see Fig. 1). Although blowing the upper surface of the wing is one of the energy ways to increase the lifting force of the wing, which is based on the use of the energy of a rotating propeller, the lifting force arising from the blowing of a small part of the wing is small. And the main part of the wing’s lifting force is formed due to the incoming air flow 13 and a small angle of attack of the wing (several angular degrees) in the presence of high speed, which the aircraft acquires under the influence of the thrust of screws 5 and 6. Therefore, this is the flight mode of the aircraft of this design practically does not differ from the flight of an ordinary aircraft, when, at a constant speed of the aircraft and changes in the angle of attack of the wing in the region of small values, the wing's lift force changes more than the aerodynamic drag tivleniya. The aircraft in flight mode at marching speed is kept in equilibrium due to its good stability, which is ensured by high flight speed, the presence of a wing of high elongation and a small angle of attack of the wing. Elevons 9 and 10 are used to balance and control the aircraft in roll and pitch.

The inventive method can be understood by considering for this aircraft the transition from flight mode at cruising speed to flight mode at near-zero speed (see Fig. 2). In this case, we assume that the speed of the aircraft in the mode of cruising speed is horizontal and constant, and the speed of rotation of the propellers 5 and 6 is constant at all speed modes of flight. During the transition from one flight mode to another, engines 3 and 4 gradually turn on rotary devices 7 and 8 parallel to the wing plane, with screws 5 and 6 in the direction of the plane of symmetry of the aircraft, at an angle close to the angle of sweep of the wing. Together with the propellers, their traction forces are rotated, so the total propulsive power of the propellers decreases, and the speed of the aircraft gradually decreases. Since the axis of rotation of the screws 5 and 6 rotate in different directions, the air flow from them is divided. The separated streams 11 and 12 begin to blow around the upper surface of the wing consoles 1 and 2, not already across them, but along (see Fig. 2). Due to the use of a wing of large elongation, the area of the blown surface of the consoles at the same time increases several times with the additional lifting force of the wing, which will partially compensate for the lifting force generated by the flow of ambient air running on the wing 13.

For almost complete cancellation of the horizontal speed of the aircraft, despite the continued propeller thrust Ft, and full compensation of the wing lift, the aircraft is given a controlled positive pitch angle (see Fig. 3). This makes it possible to significantly increase the angle of attack of the wing α (by tens of angular degrees). A significant increase in the angle of attack of the wing α causes a noticeable increase in the lift of the wing Fp due to the increased effect of the incoming air flow 13 on the lower surface of the wing, which completely compensates for the loss of lift that the aircraft had in cruising speed mode. At the same time, the aerodynamic drag force Fs increases very much due to the increased cross-sectional area in the direction of the incoming air flow 13, which can completely zero out the horizontal speed of the aircraft at the corresponding pitch angle. Losses of equilibrium and stalling on the wing under the influence of gravity Fg are dangerous for airplanes at large, as in this case, angles of attack of the wing a and low speed of the aircraft, because the phenomenon of a sharp drop in the total lifting force of the wing due to the stall of incoming air flow over the wing does not occur here due to the presence of additional lifting force Fo from blowing the entire upper surface of the wing with flows of propellers 5 and 6. During the steady flight of the aircraft at near-zero speed, all the forces and moments acting on it walk in equilibrium (see Fig. 3).

The flight mode of an aircraft of this design at near zero speed is very different from that of a conventional aircraft, because with a constant aircraft speed and changes in the angle of attack of the wing α in the region of large values, the wing lift Fp changes weaker than the drag force Fs. The stability of the aircraft in flight mode at near-zero speed is significantly impaired. Therefore, to maintain balance in this flight mode, he needs constant balancing. The roll and pitch control at all high-speed flight modes of an aircraft of this design occurs in the same way and with the help of the same controls and air rudders - elevons 9 and 10. They are in the way of the divided air flows of 11 and 12 screw engines 3 and 4 and intensively blown by them from above. Since, basically, the control moments are created by the pressure of the air flows on the aerodynamic rudders that are deflected in the right direction, the axis of rotation of the elevons 9 and 10 are located at approximately the same acute angle to the incident air flow 13, which is directed along the longitudinal axis of the aircraft, and to turned along the wing consoles blown flows 11 and 12 of the propellers 5 and 6, that is, in their middle position.

An exception is the situation in which in flight mode at near-zero speed, the elevon 10 deviates downward (see Fig. 3). In this situation, the elevon 10 is not under the pressure of the air stream 12. But the necessary control moment is still created, because the air stream 12, blowing the upper surface of the wing console 2, is deflected down, following the deflected elevon 10. In accordance with the Coanda effect, sticking occurs air stream 12 to the curved surface of the wing console 2, and the lifting force in this area Fe changes its direction, remaining perpendicular to the upper surface of the elevon 10. The proposed arrangement of the axes of rotation of the elevons in this situation allows you to effectively create the necessary control moment. Thus, by controlling the deviation of the elevons in flight mode at near-zero speed, you can not only compensate for the roll of the plane due to external influences, but also maintain a predetermined pitch angle that provides the necessary vertical and horizontal speeds of the aircraft.

The advantage of the proposed method is that it allows you to increase the maximum speed and improve lateral stability of the aircraft in flight mode at cruising speed through the use of a wing of large elongation to create lift at all high-speed flight modes.

Claims (1)

The method of vertical movement and hovering of an aircraft in the air, namely, to create aerodynamic lift using air flow from screw engines, blowing the wing, characterized in that the wing is used arrow-shaped in plan with a large elongation, the flow is first divided and directed above the wing along its consoles, and then give the aircraft a controlled positive pitch angle.

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