RU2726217C1 - Method to increase lifting force of copter with open propellers - Google Patents

Abstract

FIELD: aviation.SUBSTANCE: invention relates to aircraft engineering, particularly, to methods for increasing lifting force of rotary-wing aircraft. Proposed method comprises fixing on copter an aerodynamic screen with holes for rotary propellers in proximity to said propellers in plane parallel to plane of rotation of copter propellers. During rotation of propellers above surface of aerodynamic screen air flows are created, directed to axis of rotation of propellers, which create region of low air pressure above upper surface of aerodynamic screen in compliance with Bernoulli's principle.EFFECT: creation of additional lifting force of vertical takeoff and landing open rotor copter.1 cl, 6 dwg

Description

The technical field to which the invention relates: the proposed method relates to copters - aircraft with vertical take-off and landing.

The prior art:

A device for vertical take-off and landing (analogue) is known (US 2013/0062454 A1, 03/14/2013, B64C 29/00, description of paragraphs [0025] - [0037], [0047] - [0048], Fig. 1-9, total 21 c), in which air is blown between the cones 20 and 30 using a motor and a propeller, which leads to a decrease in pressure between the cones, but does not create additional lifting force, while the inventive method aims to increase the lifting force.

In the known prototype, it is proposed to install an engine with a propeller in each conical structure, while in the claimed method it is proposed to fix the aerodynamic screen in a plane parallel to the plane of rotation of the propellers with holes for the rotating propellers in the immediate vicinity of these propellers. Thus, in the inventive method, it is proposed to fix a single aerodynamic screen to the copter, which, according to the author, maximizes the use of the effect of increasing the lifting force from its installation.

Known aircraft for vertical take-off and landing (analogue) (US 2016/0368600 A1, 12/22/2016, B64C 29/00, description of paragraphs [0007] - [0010], [0111] - [0113], Fig. 2, total 31 c, comprising at least one first wing portion providing lift during horizontal flight; at least one wing hole located on the vertical axis of at least one first wing portion; and at least one mover based a propeller, including a screw mounted on the rim, without a central hub and located inside at least one wing hole to provide vertical thrust during vertical flight. Thus, it is proposed to make through holes in the horizontal tail of the aircraft and install them in them propellers in the plane of the horizontal tail of the aircraft, and the horizontal tail of the aircraft provides lift during horizontal flight, whereas, in declare In this method, the aerodynamic screen is not a wing and is not intended to provide lift during horizontal flight. The purpose of the claimed aerodynamic screen and method of its use is to increase the lifting force of the copter, due to the reduced air pressure in the boundary air layer above the upper surface of the claimed aerodynamic screen during rotation of the propellers.

A known aircraft for vertical take-off and landing (analogue) US 2017/0158322 A1, 06/08/2017, B64C 29/00, description of paragraphs [0011] - [0012], [0022] - [0025], FIG. 2-6, total 14 s. in the wing of which there are air ducts and in each of which there is a propeller and motor, each air duct equipped with a movable cover that closes when using the free flow to create lift, while in the inventive method it is not proposed to use an aerodynamic screen as a wing, i.e. to. the aerodynamic screen and the method of its use are not intended to provide lifting force due to the use of the incoming flow, for example, during horizontal flight. The purpose of the claimed aerodynamic screen and method of its use is to increase the lifting force of the copter, which is provided by the propellers of the copter, including during horizontal flight.

Known Combined aircraft (analogue) RU 2012512 C1, 05/15/1994, B64C 29/00, description p. 4 line 40 - s. 5 line 21, FIG. 1.2, a total of 11 s., Comprising a body made in the form of a thick central wing with an asymmetrical transverse profile, having a tunnel with open inlet and outlet openings, in which a lifting screw, side wings and tail unit, marching propellers, and a power plant for drive marching and lifting propellers and landing device on an air cushion covering the exit from the tunnel, characterized in that it is equipped with a system for changing the total and cyclic pitch of the blades of the lifting screw, and the cross-sectional area of the tunnel in the plane of rotation of the lifting screw is 0.3-0, 8 from the area of the air cushion of the landing device, while the inlet of the tunnel is formed by a torus surface mating with the upper surface of the central wing.

Despite the apparent similarity of the known combined aircraft with a copter after modernization according to the proposed method, namely, fixing an aerodynamic screen on the copter in a plane parallel to the plane of rotation of the propellers with holes for rotating propellers in the immediate vicinity of these propellers, the claimed method does not increase the lift a body is used made in the form of a thick central wing with an asymmetric transverse profile having a tunnel with open inlet and outlet openings, in which a lifting screw is installed. Also, in the inventive method of increasing the lifting power of the copter, it is not proposed to use a system for changing the total and cyclic pitch of the blades of the lifting screw, but it is proposed to fix the aerodynamic screen in a plane parallel to the plane of rotation of the propellers with holes for rotating propellers in the immediate vicinity of these propellers.

A known method of regulating the lifting force of an aircraft (prototype) (RU 2647363 C2, 09/12/2016, B64C 21/00, F15D 1/12) by adjusting the thrust of the aircraft engine and changing the wing profile, or reducing the pressure in the upper part of the wings during landing and take-off, characterized in that during landing and take-off above the upper part of the wings, mainly above the leading edges, and the fuselage, the pressure is reduced by spraying a cryogenic liquid, for example, liquid nitrogen or air. The specified method is selected as a prototype, because it uses a similar approach to the claimed invention, aimed at increasing the lift of the aircraft, by reducing the pressure above the upper surface of the wing, However, in the known method, the reduction of pressure above the upper surface of the wing is achieved by spraying a cryogenic liquid, for example, liquid nitrogen or air, mainly above the leading edges [of the wing], while in the inventive method of increasing the lifting force of the copter is achieved by fixing the aerodynamic screen in a plane parallel to the plane of rotation of the propellers with holes for the rotating propellers in the immediate vicinity of these screws.

The Known Method for the formation of lifting force (analogue) (RU 2 577 753 C1, 03/17/2015, IPC ВСС 21/06, B64D 27/02) by controlling the boundary layer in the upper part of the wing of the aircraft, made with a system of flanged holes in the form of a hollow a truncated figure with a decreasing cross-section of the holes in the wing. The suction of the boundary layer from the upper part of the wing is performed separately for the starboard side by a radial fan of unilateral suction of the right rotation and for the left side by a radial fan of unilateral suction of the left rotation.

The specified method is selected as an analogue, because it uses an approach similar to the claimed invention, aimed at increasing the lift of the aircraft, by reducing the pressure above the upper surface of the wing, However, in the known method, the reduction of pressure above the upper surface of the wing is achieved by suction of the boundary layer from the upper part of the wing, whereas the claimed method of increasing the lifting force of the copter is achieved by fixing the aerodynamic screen in a plane parallel to the plane of rotation of the propellers with holes for rotating propellers in the immediate vicinity of these propellers.

Disclosure of invention

The objective of the proposed method is to increase the lifting force of the copter. To achieve this, in the plane parallel to the plane of rotation of the propellers, an aerodynamic screen with holes for rotating propellers in the immediate vicinity of these propellers is fixed on the copter (Fig. 1). As a result, over the specified aerodynamic screen, when the propellers rotate, a reduced air pressure occurs in accordance with Bernoulli's law and, as a result, an additional lift force of the copter arises.

The essence of the Bernoulli law, in particular for a compressible ideal gas, is to lower the pressure in the gas stream with an increase in the velocity of this gas stream. Found on the Internet 11.11.2018):

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The physical experiment with two parallel sheets of paper, between which the experimenter blows air from his mouth, can serve as a vivid illustration of the operation of the Bernoulli law (Fig. 2). As a result, sheets of paper try to get closer to each other. The attraction of the sheets to each other is explained by Bernoulli's law, because the air speed between the sheets is higher than the air speed on the outside of the sheets (there the air has zero speed), therefore, in accordance with Bernoulli’s law, the air pressure between the sheets becomes lower than the air pressure on the outside of the sheets.

Thus, the fastening in the immediate vicinity of the propeller propellers of the claimed aerodynamic shield with holes for these propellers in a plane parallel to the plane of rotation of the propeller propellers leads to the fact that with rotating propellers in the border region above the surface of the aerodynamic shield there are air flows speed, directed to the axis of rotation of the propellers of the copter, which, in turn, in accordance with Bernoulli's law, leads to the effect of lowering air pressure above the upper surface of the claimed aerodynamic screen and, as a result, leads to an increase in the lifting force of the copter.

Moreover, according to the author, this positive effect is realized to the maximum extent at zero horizontal speed of the copter, which can be especially useful for video and photo shooting from the copter, for example, the earth’s surface, in the mode of hovering of the copter.

The directions of the air flows resulting from fixing the declared aerodynamic screen on the copter in a plane parallel to the plane of rotation of the propellers of the copters are shown in FIG. 3, 4, and 5. As can be seen from the figures, the aerodynamic screen can be either of a flat shape or of a curved shape. It is the decrease in air pressure above the upper surface of the claimed aerodynamic screen during rotation of the propeller propellers that creates the additional lift force of the copter, as claimed in this invention.

The technical result of placing the aerodynamic screen in a plane parallel to the plane of rotation of the propeller propellers is to create additional lifting force during the rotation of the propellers by creating a lower air pressure above the declared aerodynamic screen in accordance with Bernoulli’s law.

The invention as a technical solution is as follows.

In the plane parallel to the plane of rotation of the propellers of the copter, an aerodynamic screen is fixed with holes for rotating propellers in the immediate vicinity of these screws (Fig. 1). During the rotation of the propeller propellers in the boundary layer above the surface of the aerodynamic screen, air flows are generated (Figs. 3, 4 and 5), which, in turn, in accordance with Bernoulli's law, create a region of lowered air pressure above the aerodynamic screen. The specified lowered air pressure also creates the additional lift of the copter, as claimed in this invention.

A brief description of the drawings.

FIG. 1 A copter with a fixed aerodynamic screen in a plane parallel to the plane of rotation of the propellers in the immediate vicinity of these propellers. FIG. 2 Represents a demonstration of Bernoulli's law, in which an increase in the air flow rate between the sheets leads to a decrease in pressure between the sheets and, as a result, leads to their convergence

FIG. 3 represents the directions of the air flows in the boundary air layer above the upper surface of the claimed aerodynamic screen (top view) FIG. 4 Represents the direction of air flow in the boundary layer above the surface of a flat aerodynamic screen (side view, section along a vertical plane passing through the axis of the engine)

FIG. 5 Represents the direction of air flow in the boundary layer above the surface of a curved aerodynamic screen (side view, section along a vertical plane passing through the axis of the engine)

FIG. 6 Test bench to determine the optimal size of the claimed aerodynamic screen

The implementation of the invention.

The aerodynamic screen is rigidly fixed to the copter body in a plane parallel to the plane of rotation of the propeller propellers. The relative position of the aerodynamic screen and each of the horizontal propeller screws is shown in FIG. 1. It is important that the size of the holes in the aerodynamic screen is sufficient to rotate the screws, taking into account the possible deflection of the motors during maneuvering the copter.

During horizontal movement of the copter, the negative angle of attack of the aerodynamic screen in the direction of movement of the copter should not generate negative lift due to the absence of increased pressure above the upper surface of the aerodynamic screen due to the presence of constant lower air pressure (with rotating screws) above the upper surface of the claimed aerodynamic screen (with rotating screws) Bernoulli's law.

Report on the obtained experimental data

In order to identify the optimal size of the aerodynamic screen, a test bench (torsion dynamometer) was created. A photograph of the stand is shown in FIG. 6. The traction force developed by an electric motor with a propeller was measured by a torsional dynamometer on a relative scale, expressed in degrees of rotation of the arrow of the torsional dynamometer. The vertical axis of rotation of the torsion dynamometer is set on a plumb line.

Initial data for the experiment:

1. The diameter of the propeller is 36 mm

2. The diameter of the flat aerodynamic shield 1 is equal to 52.5 mm (+ 46% of the diameter of the propeller)

3. The diameter of the flat aerodynamic shield 2 is 70 mm (+ 94% of the diameter of the propeller)

4. The diameter of the curved aerodynamic shield 3 is 70 mm (+ 94% of the diameter of the propeller)

5. The diameter of the flat aerodynamic shield 4 is 84 mm (+ 133% of the diameter of the propeller)

6. The diameter of the flat aerodynamic screen 5 is 116 mm (+ 222% of the diameter of the propeller)

As a result of the experiments, the following results were obtained:

1. The increase in traction force developed by an electric motor with a screw and with a flat aerodynamic screen 1 (0 52.5 mm) amounted to 0%

2. The increase in traction force developed by an electric motor with a screw and with a flat aerodynamic screen 2 (0 70 mm) amounted to 7%

3. The increase in traction force developed by an electric motor with a screw and with a curved aerodynamic screen 3 (0 70 mm) amounted to -11.5%

4. The increase in traction force developed by an electric motor with a screw and with a flat aerodynamic screen 4 (0 84 mm) amounted to - 7%

5. The increase in traction force developed by an electric motor with a screw and with a flat aerodynamic screen 5 (0116 mm) amounted to 7%

6. Changing the shape of the outer edges of the flat screens, for example, bent forward by the movement of the screw or bent back by the movement of the screw, does not lead to a noticeable increase in traction.

7. Thus, the optimal diameter of the aerodynamic shield for a single propeller lies in the range: from “screw diameter + 50%” to “screw diameter + 100%”. A further increase in the diameter of the aerodynamic screen does not lead to a noticeable increase in the traction force of the electric motor with a propeller.

8. According to the inner diameter, the aerodynamic screen should have a smooth bend towards its lower surface, to exclude the occurrence of the Bernoulli effect on the lower surface of the aerodynamic screen, it is shown in FIG. five.

9. A curved aerodynamic screen showed a greater increase in traction force (+ 11.5%) than a flat aerodynamic screen of the same diameter (+ 7%). However, a less efficient flat aerodynamic screen can also find its application because of the simplicity of its manufacture.

A brief description of the experiment:

1. The traction force of an electric motor with a screw was measured by a torsional dynamometer with a vertical arrangement of a twisting spring. This design was chosen in order to minimize the measurement errors caused by gravity and to increase the sensitivity of the dynamometer.

2. The trajectory of the electric motor with a propeller during the experiment has the shape of a circle (sector) in the horizontal plane.

3. An electric motor with a propeller is rigidly mounted on the shoulder of a torsional dynamometer. The axis of the motor shaft lies in a horizontal plane. The axis of rotation of the torsional dynamometer lies in a vertical plane. The shortest distance between the axis of the electric motor and the axis of the torsional dynamometer passes along the beam of the torsional dynamometer, on which the electric motor is mounted.

4. The vertical axis of rotation of the torsion dynamometer is set vertically.

5. To reduce measurement errors caused by imperfect vertical axis of rotation of the dynamometer, as well as to reduce friction, the weight of the electric motor with a propeller is balanced by a load of the corresponding mass placed on the opposite arm of the torsion dynamometer.

6. The angle of deviation of the measuring arrow of the torsion dynamometer is proportional to the traction force of the electric motor with a propeller.

7. All measurements were carried out in angular degrees, and the final result was calculated in relative terms: "The increase in traction force in percent." This approach allows you to not measure the exact value of the traction force in newtons.

8. To reduce the influence of non-linear measurement errors, the bench parameters are selected so that the deflection of the arrow with the maximum traction force of the electric motor with a propeller lies within 1/3 (60 degrees) of the entire available measurement scale, equal to 180 degrees.

9. The whole design of the torsion dynamometer is suspended on a steel needle abutting in a conical recess of hardened metal to reduce friction and reduce the deadband.

10. The error in measuring the angle of rotation from the influence of the connecting electric wires was not taken into account under the assumption that this effect is equally valid when measuring both a propeller with an aerodynamic screen and when measuring for a propeller without an aerodynamic screen. To reduce the mechanical effect of the electrical wires, they are twisted into spirals that are placed as close as possible to the axis of rotation of the torsion dynamometer.

11. Replacement of aerodynamic screens was carried out without stopping the electric motor. Replacement of aerodynamic screens was carried out as quickly as possible - within 5-8 seconds. Quick replacement of aerodynamic screens was provided by double-sided tape previously fixed on aerodynamic screens in the places of contact. Refusal to stop the motor during the experiment aims at eliminating transients in the motor during its stop and start.

12. Measurement of traction was carried out first without an aerodynamic screen, then with an installed aerodynamic screen, then control measurement again without an aerodynamic screen, and so sequentially for all five aerodynamic screens of various sizes and shapes. This was done to eliminate the influence of voltage surges in the electrical network. All readings were recorded.

13. The traction force of an electric motor with a screw without aerodynamic screens in all experiments remained stable and constant for 8-10 minutes of the experiment, which confirms the frequency of the experiment.

14. The electric motor was powered from an industrial power supply with the following characteristics:

INPUT: AC100-240 v, 50-60 Hz

OUTPUT: DC12 v, 1500 mA

15. The current consumed by the electric motor was 250 mA, the voltage at the motor terminals was 12.47 v, i.e. the power supply has the necessary power reserve for a guaranteed and uninterrupted power supply of the electric motor for a long time.

16. The oscillatory process of the measuring needle relative to the equilibrium point decayed independently without external influence (braking) due to the specially increased aerodynamic drag of the shoulders of the torsional dynamometer.

All of the above approaches and technical solutions provided sufficient measurement accuracy and 100% repeatability of the experiment.

Conclusion: The application of the claimed invention allowed to increase the traction force of an electric motor with a propeller by 11.5% when using a curved aerodynamic screen with a diameter 94% larger than the diameter of the propeller.

Claims (1)

A method of increasing the lift of a vertical takeoff and landing copter with open screws, characterized in that in order to increase the lift of the copter, an aerodynamic screen is fixed on the copter in a plane parallel to the plane of rotation of the propellers, with holes for rotating propellers in the immediate vicinity of these propellers.

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