Convertiplane

Abstract

The invention relates to the field of aeronautical engineering, specifically to convertiplanes. A convertiplane comprises a fuselage, a control system, aerodynamic outer wings with aerodynamic control surfaces, an all-moving foreplane with aerodynamic control surfaces, a tail plane, and propulsion systems with propellers. The propulsion systems with propellers are arranged rotatably on tips of the foreplane and on the tail plane. The convertiplane is designed to permit the aerodynamic centre of pressure and the resultant thrust vector to coincide. The convertiplane is designed to permit the mutual dynamic and static scalar control thereof by operating the aerodynamic control surfaces and thrust vectoring of each of the propulsion systems. The propulsion systems arranged on the tips of the foreplane are capable of counterrotation of the propeller and are capable of dynamically displacing the centre of pressure and are also capable of displacing the axis of rotation of the front propulsion systems in the ZX plane. The propulsion systems have an axial degree of freedom, and are also capable of independently of one another controlling thrust vectoring and revolutions by controlling the pitch angle of the blades and the diameter thereof.

Claims

1. A convertiplane comprising: a fuselage comprising a front horizontal wing and a tail unit; a control system; airfoil sections with aerodynamic control surfaces; a front horizontal wing with aerodynamic control surfaces; tail fins; and motor propeller groups comprising propellers, the motor propellor groups being located such that the propellers are configured to rotate at tips of the front horizontal wing and on the tail unit, wherein a center of aerodynamic pressure and a resulting thrust vector of the convertiplane are coincident and are mutually dynamically and statically scalarly controllable through the operation of the aerodynamic control surfaces and through control of the thrust vector of each of the motor propeller groups, wherein the motor propeller groups located on the tips of the front horizontal front wing are configured to counter-rotate the propellers and to provide dynamic shifting of the center of pressure, wherein the motor propeller groups comprise an axial degree of freedom and are configured such that a thrust vector, a rotation speed, and a blade pitch angle of each motor propeller group is independently controllable relative to the other motor propeller groups.

2. The convertiplane according to claim 1, characterized in that the front horizontal wing is configured to be reverse swept.

3. The convertiplane according to claim 1, characterized in that the motor propeller groups are equipped with the propeller mechanics of variable pitch propeller and variable diameter propeller.

4. The convertiplane according to claim 1, characterized in that the aerodynamic control surfaces are made in the form of ailerons.

5. The convertiplane according to claim 1, characterized in that wing consoles each comprise a vertical fin at an end thereof.

6. The convertiplane according to claim 1, characterized in that the motor propeller group located on the tail unit is configured with the ability to operate the propeller in a push mode.

7. The convertiplane according to claim 1, characterized in that it is designed according to a canard scheme or a tandem scheme or a flying wing scheme, or according to a colibri scheme.

8. The convertiplane according to claim 1, characterized in that the resulting thrust vector is controlled through shifting the axis of rotation of front engine nacelles in the plane ZX by an angular value S1 in the range of 1 and 45 degrees on both ways, wherein the shifting of the axis of rotation is held such that the plane of rotation of the engine nacelles intersect with the axis Z of the associated coordinate system at a point, which provides a parallel addition of the thrust vectors of the respective motor propeller group at roll and pitch angles.

9. The convertiplane according to claim 1, characterized in that the displacement range of the resulting thrust vector is enclosed in a triangular area formed by the position of the motor propeller groups.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The details, features, and benefits of the present invention result from the following description of embodiments of the claimed technical solution using the drawings that show:

(2) FIG. 1description of the aerodynamic layout of the convertiplane (top view);

(3) FIG. 2arrangement of the motor-propeller groups and binding of the motor-propeller group relative to CG;

(4) FIG. 3displacement area (range) of the resulting thrust vector;

(5) FIG. 4angles of the thrust vector control of the motor-propeller group;

(6) FIG. 5range of displacement of the rotary axis and the rotary nacelle of the motor-propeller group 1, 2;

(7) FIG. 6scheme of application of forces and moments in the steady flight in a helicopter mode;

(8) FIG. 7scheme of forces application in the fixed-wing aircraft mode;

(9) FIG. 8scheme of summation of the resulting thrust vector forces in front projection during transverse movement without roll.

(10) FIG. 9scheme of summation of the resulting thrust vector forces in top projection during lateral movement without roll.

(11) FIG. 10scheme of summation of the resulting thrust vector forces in front projection during static hovering at a given roll angle.

(12) FIG. 11scheme of summation of the resulting thrust vector forces during static hovering at a given roll angle;

(13) FIG. 12scheme of application of forces in hybrid flight mode;

(14) FIG. 13scheme of application of forces and moments during directional control (aircraft heading control);

(15) FIG. 14scheme of application of forces and moments during pitch control;

(16) FIG. 15scheme of application of forces and moments during roll control.

(17) The following positions are indicated by numbers on the figures:

(18) 1front right motor-propeller group; 2front left motor-propeller group; 3tail unit motor-propeller group; 4front horizontal wing; 5front horizontal wing; 6left main wing console; 7right main wing console; 8aerodynamic control surface; 9aerodynamic control surface; 10aerodynamic control surface; 11aerodynamic control surface; 12replaceable payload module; 13fuselage; 14vertical fin; 15vertical fin; 16point of intersection

Terms, Definitions, Used in the Description

(19) MPGmotor-propeller group; GCS(geostationary coordinate system) O0X0Y0Z0, right-handed Cartesian coordinate system, whose axes and its origin are fixed relative to the ground, and are chosen according to the task; FHWfront horizontal wing; ACS(associated coordinate system) OXYZ, movable coordinate system, the axes of which are fixed relative to the aircraft: OXlongitudinal, OYnormal, OZtransverse; CScoordinate system; Angle of attack ?the angle between the longitudinal axis of the vehicle and the projection of the velocity vector on the plane OXY ACS; Roll angle ?angle between the transverse axis OZ of the vehicle and the O0Z0 axis of the geostationary coordinate system; Pitch angleAngle between the longitudinal axis OX and the horizontal plane OX0Z0 of the GCS; Yaw angle ?Angle between the axis OX0 of the GCS and the projection of the longitudinal axis OX on the horizontal plane OX0Z0 of the GCS; CPthe center of pressure, the point of application of the increment of the aerodynamic forces resultant; CGcenter of gravity, the point of application of the force of gravity; AFaerodynamic focus, the point of application of the lift force increment; AuCSAutomatic control system; VPPvariable pitch propeller; VDPvariable diameter propeller; MPGmotor-propeller group X1Y1Z1associated CS of MPG(1); P1scalar value of the MPG thrust vector (1); P2scalar value of the MPG thrust vector (2); P3scalar value of the MPG thrust vector (3); pxprojection of the scalar vector onto the axis OX of the ACS; pyprojection of the scalar vector onto the OY axis of the ACS; pzprojection of the scalar vector onto the OZ axis of the ACS; S1axis of rotation of the engine nacelle with a fixed MPG (1); S2axis of rotation of the engine nacelle with a fixed MPG (2); S3axis of rotation of the engine nacelle with a fixed MPG (3); S42 axis of rotation of the engine nacelle with fixed MPG3; O1normal thrust axis in helicopter mode for MPG(1); O2normal thrust axis in helicopter mode for MPG(2); O3normal thrust axis in helicopter mode for VMG(3); ?sangular deviation relative to the normal thrust vector; Rresultant thrust vector; mggravity force.

DISCLOSURE OF INVENTION

(20) Description of the convertiplane glider according to the declared by us aerodynamic scheme. At the very beginning, the aircraft layout based on the canard aerodynamic scheme has been chosen for our convertiplane as the most efficient one and also the most convenient one in operation and in layout for onboard systems and units. But this aerodynamic layout did not fully meet the requirements laid down.

(21) Then we made the next modification, but it was no longer a canard, because it could not have a main front wing, which was used in the next modification of our aerodynamic layout. Therefore, the following aerodynamic layout was based on the tandem aerodynamic scheme, which also did not fully meet the required parameters, because the tandem scheme has a too small area of the front wing.

(22) As a result, in addition to our use of classical modifications of tandem, canard and flying wing aerodynamic schemes, we developed a new unique aerodynamic scheme. It combines the characteristics of all the above mentioned aerodynamic schemes, but at the same time is not any of them. So a new aerodynamic scheme was created, which was called Colibri.

(23) The chosen scheme ensures relative simplicity of transverse and longitudinal balancing, demonstrates the necessary stability on all axes, and provides an opportunity for aircraft control in a larger displacement range of the center of pressure, if compared with classical schemes. At the same time this new scheme is much safer, because critical modes leading to stall break (flow disruption) and loss of controllability are no longer possible, though they do happen when using classical aerodynamic schemes.

(24) In the embodiment of the claimed technical solution, the convertiplane can also be designed according to a tandem or a flying wing scheme, depending on the required flight and technical and operational characteristics.

(25) The glider is designed according to the scheme with two front wing swept aerodynamic consoles (6, 7) with tapering and with a necessary set of profiles placed along to ensure elliptical distribution of the lift force. Along the trailing edge of the front horizontal wing (4, 5) and along the trailing edges of the main wing consoles, aerodynamic control surfaces (9, 8) and (10, 11) are placed respectively. They operate in a differential control mode.

(26) In the nose section of the fuselage (13) an easily removable payload (12) is located. Such a layout ensures the largest range of angles for visual observation from onboard.

(27) On the tips of the wing consoles (6, 7) vertical fins are placed (14, 15). They reduce the total aerodynamic drag and increase directional stability (aircraft heading stability).

(28) To ensure a larger range of the possible positions of the center of pressure (and to maintain high energy efficiency while CG is being displaced), the main rotary front horizontal wing (FHW) has been designed to be reverse-swept. The wing airfoils were carefully designed to ensure stable operation under the conditions when an interference pattern of the oblique flow from the front MPGs (numbers 1 and 2) occurs.

(29) To simplify the mechanics the FHW (4, 5) is fixed stationary at the angle of highest L/D ratio, thus ensuring a steady flight mode with a given center of pressure (CP). And also aerodynamic control surfaces (9, 8) on the trailing edge of the FHW (4, 5) are designed to operate in a differential mode. Aerodynamic control surfaces (8, 9, 10, 11) are designed as ailerons operating in differential mode, which ensures control of the aircraft as well as high energy efficiency modes due to longitudinal control of the CP displacement.

(30) The combination of the aforementioned solutions has allowed to shift the critical modes of stall break beyond the operational range of permissible aerodynamic angles of attack of the aircraft. The canard stall (stall from the FHW (4, 5)) in supercritical modes causes the CP to shift from the CG towards the aft fuselage. This causes a dive moment, which leads to the aircraft gaining, so the aircraft itself returns to the operational range of permissible angles of attack. Thus we get a highly stable aircraft scheme, with high L/D ratio and a wide range of permissible speeds while maintaining controllability in critical flight modes.

(31) The layout of the claimed convertiplane glider has three cruising (mid-flight) electric motors, with VPP and VDP placed on them. They are located on the rotary engine nacelles, which provide angular deflection relative to the normal axis of the thrust vector, thus enabling full-fledged control of the thrust vector itself. Two of the three motor-propeller groups (1, 2) are located on the wingtips of the front horizontal wing (5 and 4 respectively) and the third motor-propeller group (3) is located at the aft fuselage (13).

(32) The tricopter scheme with the thrust vector control is the most efficient one in terms of energy, is easy to balance laterally and longitudinally, and is stable and reliable.

(33) Synchronizing the operation of the MPGs (1, 2, 3) through the AuCS ensures control over the resulting thrust vector, thus forming a wide range of the thrust vector displacement, the range being enclosed in a triangle with the MPGs as its vertices.

(34) Each of the MPGs is equipped with its own actuator mechanism, thus allowing independent changes of the thrust vector for each MPG. At the same time, the independent control of each MPS through the AuCS is based on the following parameters: motor-propeller group rotation speed; axial control of the thrust vector; control of the blade pitch angle; control of load on the swept surface of the rotor through VDP.

(35) The distance between the MPGs, their weight and positions are calculated and selected in such a way as to preserve the axial moments of inertia of the aerodynamic scheme, without generating resonance phenomena and without aggravating the interferential pattern of the flow from the MPGs around the glider. Because if resonance is not eliminated and if interference aggravates, all together leads to destabilization of the aircraft in the main flight modes.

(36) The wide displacement range of the resulting thrust vector ensures high stability of the convertiplane aerodynamic scheme in helicopter and transition (or hybrid) flight modes. And the control over angular component of the resulting thrust vector relative to the normal thrust vector provides high controllability and opens new possibilities for controlling roll and pitch of the aircraft during the flight at zero velocity vectors, i.e. in one place without axial displacement (FIG. 8, 9). The blades of the MPGs (1, 2, 3) have aerodynamic rebalancing opportunities in the form of VPP and VDP mechanics. Such a solution allows to rebalance the propeller blades and to implement algorithms for adapting energy efficiency in different flight modes.

(37) The axial degrees of freedom of the MPGs, meaning displacement of the axes of rotation of the MPG (1 and 2) on the angular value S1 within 1 to 45 degrees on both directions in the plane ZX, are designed in such a way that the planes of rotation of the MPG 1 and 2 intersect in the point illustrated in (FIG. 4,6). Thus this layout provides the possibility of parallel addition of thrust vectors under the given angular position of the resulting thrust vector. It also provides independent control of the thrust vector value and of its angular position relative to the normal axis of the thrust vector (FIG. 9 designation y). Through scalar addition of vectors, their calculated angular position and their required value, the AuCS ensures control of the resulting thrust vector, thus providing the following possibilities: changing the angle of the thrust vector around the longitudinal and transverse axes of the aircraft. Ensuring controlled angular changes of the resulting thrust vector opens up a possibility to maneuver without changing roll and pitch angles (FIG. 8, 9); hovering in place at the required roll and pitch angles (FIG. 10, 11), performing landings on surfaces that are inclined to the horizon or dynamically change their angle. Also such a control scheme is most suitable for landing on the swinging deck of a vessel, or providing compensation for wind and turbulence acting on the aircraft without using conventional roll and pitch maneuvering.

(38) The wide range of displacement of the thrust vector shown in (FIG. 3) provides high maneuverability and controllability of the convertiplane. The resulting thrust vector can have a position coinciding with the center of mass, thereby ensuring neutral stability which improves controllability of the aircraft in hybrid mode. The CP can have a position slightly behind (and ahead) the CG, thereby ensuring aerodynamic stability of the aircraft. When the conditions of aircraft static and dynamic stability are met, aerodynamic stability contributes to higher energy efficiency of the flight in the airplane mode. The dynamic change of the CP in the hybrid mode is provided by the fact that the loading of the aerodynamic surfaces is decreased by the rotors and vice versa (unloading the rotors by the wings).

(39) Thus we obtain the layout of the convertiplane glider according to the declared scheme, which is the most controllable of all currently existing schemes and which provides the highest stability with simple stabilization algorithms. Moreover, in maneuvering mode, it provides the highest energy efficiency and simplicity in ensuring stability under the influence of external factors. For clarity, let us consider several options of scalar addition of thrust vectors.

(40) The case of controlled movement along the transverse axis of the convertiplane with a fixed horizon. Here the axes of the GCS and the ACS coincide, and also roll, pitch and yaw angles are zero. The angular deviation and the value of vectors P1, P2 and P3 provide zero resulting moment and a transverse component, whose projection lies on the OZ axis. As a result, this sets the convertiplane in motion along its transverse axis (FIG. 9).

(41) The case of providing angular deviation in roll followed by hovering in place at a required angle. The value of the thrust vectors P1, P2 and P3 leads to a change in roll (FIG. 11). An independent angular deviation of each of the thrust vectors by the values a, b, c leads to the compensation of the resulting moment. At the same time, the resulting thrust vector is collinear to the normal axis of the GCS and compensates the force of gravity acting on the convertiplane. Such a condition ensures an equilibrium state of the convertiplane at a given roll angle with a zero resultant velocity vector.

(42) Flight Modes of the Declared Convertiplane:

(43) Helicopter mode: the weight of the aircraft is compensated by the lifting force of the three rotors (FIG. 6) (forces P1, P2, P3) together forming a resultant force that compensates for the weight of the aircraft. Two front rotors (1, 2) have counter rotation. Such a direction of rotation is determined by additional increase in the velocity gradient on the wing surface. Thus, the right front engine (1) rotates counterclockwise, the left front engine (2) rotates clockwise.

(44) The direction of rotation of the tail rotor (3) can be either clockwise or counterclockwise. Stability is provided by the dynamic displacement of the center of pressure and the different thrust of the rotors (the area of CG movement is shown in FIG. 3).

(45) Transition (or hybrid) mode: When the horizontal velocity component Vx increases, aerodynamic forces act on the surface of the convertiplane. That's due to the component of the rotor lifting force Fx, which occurs as a result of turning the engine nacelles around the transverse axis of the aircraft. The resultant of these aerodynamic forces, for convenience of perception, is decomposed into the lifting force Fl and the drag force Fd. With an increase in the velocity component Vx, there is an increase in aerodynamic forces that contribute to the compensation of the MG force (gravity force/own weight of the convertiplane), while the drag force Fd being value of L/D ratio times less than the MG force. All of this allows to fulfill a complete transition to the airplane mode using wings as an aerodynamic support, or vice versa, to fulfill a smooth deceleration with transition to the helicopter mode. The transition mode itself can be used as the main flight mode of the convertiplane. Thanks to a relatively large range of displacement of the CP, it is easier to ensure the controllability of the convertiplane, which allows flying in conditions of increased wind load, turbulence or when high maneuverability is required. The transition process is carried out through longitudinal tilt of the tail rotor, of the two front rotors, or all of the rotors simultaneously or separately. When carrying out the transition mode through longitudinal rotation of the tail rotor, its initial position should be from below (FIG. 12).

(46) Airplane Mode:

(47) The condition of the steady flight mode at the target velocity Vx is achieved by: 1) bringing the sum of aerodynamic forces Fd to an equilibrium with the resulting thrust vector R formed by components of forces F1 and F2; 2) bringing MG force to an equilibrium with the lifting force Fl created by the main wing consoles (6, 7) and the FHW (4, 5), which completely compensate the weight of the aircraft MG; 3) a longitudinal thrust vector of the engines being a sum of forces F1 and F2 (provided by longitudinal tilt around transverse axis of the aircraft), this thrust vector compensates aerodynamic drag force Fd at a speed Vx that ensures the highest efficiency. Control in this mode is provided by aerodynamic control surfaces (8, 9, 10, 11), as well as thrust vectors (FIG. 7).

(48) In the embodiment of the claimed technical solution, it is possible to use a tail mechanism having two degrees of freedom so that to provide simultaneously directional control and to decompose the scalar of the thrust vector on a longitudinal component. If the motor is located at the bottom side of the engine nacelle and if the propeller works in a pushing mode, it is possible to use a tail rotor in both airplane and helicopter modes.

(49) Such a need may arise in such a case, when it is necessary to increase the specific energy capacity in airplane mode, for example, to provide high-altitude flights or to improve the accuracy of the aircraft positioning when hovering at different angles.

(50) Ensuring Sustainability

(51) Helicopter Mode:

(52) Roll: in case of an angular error relative to the horizon, the ACS ensures a preemptive roll action, resulting in an increase in lifting force P1 and a decrease in lifting force P2 of the MPGs 1 and 2 respectively. As a result a leading moment My arises, bringing the convertiplane back to an equilibrium mode.

(53) Pitch: in case of an angular error relative to the horizon, the ACS provides a preemptive pitch action resulting in an increase in lifting forces P1, P2 and a decrease in lifting force P3 of the MPGs 1, 2 and 3 respectively. As a result a leading moment Mx arises, bringing the convertiplane back to the equilibrium mode.

(54) Yaw: in case of an angular error relative to the aircraft heading, the ACS provides a preemptive action by tilting the actuators of the rotary engine nacelles by an angular value necessary to compensate for the angular error. As a result a leading moment Mz arises, bringing the convertiplane to the required azimuth position, returning it to the set aircraft heading angle.

(55) Stability: the aerodynamic layout of the aircraft is designed the following a way. When an external impact on the aircraft in a steady flight mode occurs, resulting in angular deviation along the longitudinal axis, the equilibrium of the forces system is disrupted. So, the aerodynamic control elements create the resulting aerodynamic moments, thus leading to a preemptive impact.

(56) The transition mode is such a combination of mechanical and aerodynamic processes affecting the aircraft, that makes the aircraft fulfill the transition from the helicopter flight mode to the airplane flight mode and vice versa. Let us consider the main stages of the transition mode: Initial phasehybrid mode: at the initial stage of the transition mode, to ensure that the resulting thrust vector coincides with the longitudinal axis of the convertiplane, the rotors perform a longitudinal tilt, spreading the thrust vector so as to ensure the balance of gravity and lift forces. At the same time, an additional thrust vector arises that contributes to the aircraft gaining speed. As a result, an aerodynamic component is generated due to the oncoming flow over the wing, which in turn creates a transverse moment causing the convertiplane to pitch up. At this moment the rotors already assume the airplane position and the convertiplane starts to fly in an airplane mode. Stability in this mode is ensured by the different thrust of the rotors that provide lifting force by compensating in antiphase the moments of external forces and the inertia of the aircraft. Thereby it counteracts the destabilizing forces that generate the moment that would otherwise disrupt the system. Such a mode is advantageous for ensuring controllability at low speeds and in critical conditions for aerodynamic surfaces, while the surfaces themselves provide lift, but cannot stall. This solution ensures safe control of the convertiplane in transition modes.

(57) The final phase is aerodynamic control: as there is an oncoming flow over the wing, an aerodynamic component is generated, which in turn creates a transverse moment causing the convertiplane to pitch up. At this moment the rotors already assume the airplane position and the convertiplane starts to fly in an airplane mode. In the final stage, when lift is fully provided by aerodynamic surfaces, the convertiplane fully transitions to aerodynamic control. In this mode, the convertiplane has the highest energy efficiency, and the motor propeller groups work in the energy efficient mode, providing the necessary force to maintain the steady flight mode.