Ground combined jacking device and method for large-tonnage tilting rotorcraft

Abstract

The invention belongs to the technical field of aircraft ground tests, and particularly relates to a large-tonnage tilting rotorcraft ground combined jacking device and method. Comprising a first jacking mechanism, a second jacking mechanism, a tail jacking mechanism and a control unit which are symmetrically arranged on the two sides correspondingly. The distance between the first jacking mechanism and the second jacking mechanism is determined according to the distance between the left wing nacelle and the right wing nacelle of the testing machine; the top ends of the first jacking mechanism and the second jacking mechanism are provided with a first displacement sensor and a second displacement sensor respectively, and the top ends of the first jacking mechanism and the second jacking mechanism can ascend and descend in the direction perpendicular to the ground. The tail jacking mechanism is arranged in the pit shaft relative to the central surfaces of the first jacking mechanism and the second jacking mechanism; a third displacement sensor is installed at the top end of the tail jacking machine, and the top end of the tail jacking machine can ascend and descend in the direction perpendicular to the ground. The first displacement sensor, the second displacement sensor and the third displacement sensor are in communication connection with the control unit. And rapid switching between the test and the test flight can be rapidly realized.

Description

Technical Field

[0001] This invention belongs to the field of aircraft ground testing technology, specifically relating to a ground-based combined lifting device and method for a large-tonnage tiltrotor aircraft. Background Technology

[0002] Helicopter ground joint testing is a large-scale comprehensive test characterized by high technical difficulty, large investment, and extensive coordination, making it a crucial test project in the helicopter model development process. Typically, for ground joint test rigs of conventional single-rotor helicopters with a tail rotor, the helicopter is fixed to the main test rig frame via linkages, supports, and joints. Specifically, a ground rail array is set up in the center of the test site, and the main metal test rig frame is fixed to the load-bearing ground rail array with anchor bolts. After the helicopter's landing gear is removed, it is lifted above the main test rig by a crane and connected to the main test rig via transition connectors at the three landing gear joints. A tail rotor force balancing device is installed at the tail rotor to counteract tail rotor thrust. During power spectrum-based start-up tests, the lift, hub moment, and torque generated by the helicopter's main rotor are transmitted through the fuselage via transition connectors to the metal test rig and then to the load-bearing ground rails. The lift generated by the tail rotor is transmitted to the load-bearing ground rails via the force balancing device.

[0003] The overall layout of this test bench can meet the ground joint test requirements of conventional configuration helicopters, but it has the following disadvantages: (1) The helicopter must be lifted onto the test bench by a crane, and the main rotor blade and tail rotor blade must be removed and counterweights added to maintain balance during the lifting process, which poses a high safety risk; (2) After the test machine is installed and modified for testing, it is extremely inconvenient to disassemble and assemble the test machine; (3) The connecting parts generally borrow the installation position of the landing gear, the helicopter's airborne landing gear needs to be removed, and test subjects such as landing gear retraction and extension need to be carried out on an additional test bench.

[0004] To achieve high-speed flight, tiltrotor aircraft have no protruding objects such as lifting rings on their fuselage surface, making overall hoisting more difficult. The distinctive configuration of a tiltrotor aircraft features a main rotor on each side of the wing, resulting in a force transmission path that differs significantly from conventional helicopter configurations during testing. Tiltrotor aircraft operate in three modes: helicopter mode, transitional mode, and turboprop aircraft mode. To ensure a safe distance between the main rotor blade tips and the ground in turboprop aircraft mode, the installation height of a tiltrotor aircraft must be significantly greater than that of a conventional helicopter. Therefore, the installation methods and structural forms of conventional helicopters on ground-based joint test rigs are unsuitable for the ground-based joint testing requirements of large-tonnage tiltrotor aircraft. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a ground-based combined lifting device and method for large-tonnage tiltrotor aircraft, which can complete the testing of tiltrotor aircraft in helicopter mode, transition mode and turboprop aircraft mode, and can fully meet the testing requirements.

[0006] The technical solution of the present invention: According to a first aspect of the present invention, a ground-based combined lifting device for a large-tonnage tiltrotor aircraft is proposed, comprising a first lifting mechanism, a second lifting mechanism, a tail lifting mechanism, and a control unit symmetrically arranged on both sides; the distance between the first lifting mechanism and the second lifting mechanism is determined according to the distance between the left and right wing nacelles of the test aircraft; the bottom ends of the first lifting mechanism and the second lifting mechanism are slidably connected to a ground rail array and fixed by anchor bolts; the top ends of the first lifting mechanism and the second lifting mechanism are respectively equipped with a first displacement sensor and a second displacement sensor, and their top ends can move up and down in a direction perpendicular to the ground; the tail lifting mechanism is disposed in a pit shaft on the center plane relative to the first lifting mechanism and the second lifting mechanism, its bottom end is slidably connected to the ground rail array and fixed by anchor bolts; the top end of the tail lifting mechanism is equipped with a third displacement sensor, and its top end can move up and down in a direction perpendicular to the ground; the first displacement sensor, the second displacement sensor, and the third displacement sensor are communicatively connected to the control unit.

[0007] In one possible embodiment, the top ends of the first lifting mechanism and the second lifting mechanism adopt a ball joint configuration, including an onboard ball joint mounting seat, a ball head, and a lifting ball joint mounting seat; the onboard ball joint mounting seat and the lifting ball joint mounting seat are detachably connected to form a complete inner surface of the ball head; the bottom end of the onboard ball joint mounting seat is fixed to the lower surface of the tiltrotor wing nacelle, and the lifting ball joint mounting seat is pre-installed on the ball head.

[0008] In one possible embodiment, the ball head of one of the first lifting mechanisms and the second lifting mechanism is in clearance fit with the onboard ball joint mounting seat and the lifting ball joint mounting seat; the ball head of the other mechanism is in clearance fit with the onboard ball joint mounting seat and the lifting ball joint mounting seat along the flight direction, and in small clearance fit with the onboard ball joint mounting seat and the lifting ball joint mounting seat along the wingspan direction.

[0009] The difference between the two sides is that, in order to prevent over-constraint on the test machine, the ball joint mounting seat on one side is completely fitted with the ball head, while the cross section of the ball joint mounting seat and the ball head socket connector on the other side in the YZ plane is an oblong hole, which allows the ball head to slide slightly within the oblong hole, thereby releasing the lateral internal force generated by the deformation of the wing during the ground joint test.

[0010] The tail lifting mechanism differs significantly in structure from the first and second lifting mechanisms. Firstly, their roles in the tiltrotor's lifting process differ. The first and second lifting mechanisms bear most of the tiltrotor's weight, while the tail lifting mechanism, in addition to bearing part of the tiltrotor's weight, needs to coordinate with the first and second lifting mechanisms to maintain the tiltrotor's attitude. Secondly, the tail lifting mechanism experiences different forces during tiltrotor testing. In the tiltrotor's transition mode, the first and second lifting mechanisms bear most of the thrust and bending moment generated by the left and right rotors, while the tail lifting mechanism only bears axial tension / compression to counteract the tiltrotor's pitching moment.

[0011] In one possible embodiment, the tail lifting mechanism includes an electric cylinder, a tail-end double-ear joint, an upper pin, a lower pin, and a bottom double-ear mounting joint; the upper and lower ends of the electric cylinder are single-ear joints with spherical bearings, the upper part is connected to the tail-end double-ear joint of the fuselage via the upper pin, and the bottom part is connected to the bottom double-ear mounting joint via the lower pin; the axes of the upper and lower pins are along the wingspan direction to ensure a large angular range of motion of the joint, and correspondingly ensure a large pitch attitude adjustment range of the tiltrotor.

[0012] In one possible embodiment, the first, second, and tail lifting mechanisms have two modes: individual control and synchronous control. In the individual control mode, the piston rod of one lifting mechanism can be independently controlled to extend / retract by a certain displacement. In the synchronous control mode, the piston rods of the three lifting mechanisms extend / retract by the same displacement simultaneously.

[0013] In one possible embodiment, the surface of the pit shaft is provided with a cover.

[0014] According to a second aspect of the present invention, a ground-based combined lifting method for a large-tonnage tiltrotor aircraft is provided, employing the aforementioned ground-based combined lifting device for a large-tonnage tiltrotor aircraft, comprising the following steps: Step 1: Tiltrotor towing position; Place the piston rods of all three lifting mechanisms in the fully retracted state, retract the piston rod of the tail electric cylinder below the ground, and fasten the pit cover and opening. Use a towing vehicle to tow the tiltrotor to the test area until all three tires are within the pre-painted positioning marks on the ground, and the relative position of the wing ball joint and ball head is within the allowable error range. If the requirements are not met, the test machine should be towed again to meet the requirements. Step 2: Achieve precise positioning and connection of the tiltrotor aircraft through the automatic alignment function of the ball joint of the left lifting mechanism and the ball joint mounting seat on the aircraft; Place the three lifting mechanisms in individual control mode, control the piston rod of the left lifting mechanism to gradually extend until the ball joint of the left side falls into the corresponding ball joint mounting seat on the aircraft, and install the wing ball joint and the connecting plate and bolt and nut connecting parts of the lifting mechanism; Step 3: Connect the ball head of the right lifting mechanism to the onboard ball joint mounting seat; keep the three lifting mechanisms in individual control mode, control the piston rod of the right lifting mechanism to gradually extend until the ball head of the right side falls into the corresponding onboard ball joint mounting seat, and install the wing ball socket joint and the connecting plate and bolt and nut connectors of the lifting mechanism; Step 4: Connect the tail section connector to the tail lifting mechanism; open the cover above the tail lifting mechanism, keep the three lifting mechanisms in individual control mode, control the piston rod of the tail lifting mechanism to extend gradually, align the center hole of the joint bearing of the tail section connector with the center hole of the fork lug of the lifting mechanism, apply low temperature grease to the upper pin of the fork lug connector and install it in place, tighten the pin mounting nut as required; Step 5: Lift the tiltrotor aircraft off the ground; Set the three lifting mechanisms to synchronous control mode, control the piston rods of the three lifting mechanisms to extend synchronously, gradually raise the aircraft until the wheels and tires leave the ground, and measure the angle between the rotor shaft and the ground; Step 6: Adjust the tiltrotor pitch attitude; Set the tail lifting mechanism to independent control mode, and adjust the pitch attitude of the test aircraft by adjusting the extension of the piston rod of the tail lifting mechanism, so that the rotor shaft of the tiltrotor is perpendicular to the ground; Step 7: Continue to lift the test aircraft to the test height; put the three lifting mechanisms into synchronous control mode, and continue to lift the tiltrotor aircraft to the required test height. During the process, observe the pitch angle of the test aircraft to ensure that the tiltrotor aircraft attitude meets the requirements.

[0015] Beneficial technical effects of the present invention: The test aircraft can enter and leave the test area by towing the entire aircraft. The entire process does not require the removal of the propellers or hoisting. The test aircraft has a short disassembly and assembly cycle on the test stand and low cost, and can quickly switch between testing and flight testing. The tiltrotor aircraft positioning and lifting operations are safe and convenient, and can meet the tiltrotor aircraft lifting requirements.

[0016] By raising the tiltrotor to the test height, the safe distance between the tip of the main rotor blade and the ground can be fully guaranteed in turboprop aircraft mode.

[0017] The connection between the tiltrotor aircraft and the test bench is robust and reliable, fully meeting the load transfer requirements during different modes of tiltrotor aircraft testing.

[0018] The disassembly and assembly time of the testing machine on the ground joint testing platform has been reduced from about a week in the traditional way to less than 2 hours, which greatly improves the disassembly and assembly efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the installation of a conventional configuration helicopter on a ground-based joint test stand.

[0021] Figure 2 Schematic diagram of the overall layout of the ground joint test rig for tiltrotor aircraft (test aircraft not installed). In the diagram, 1-Control room, 2-Safety net, 3-Left side lifting mechanism, 4-Pit plate of tail lifting mechanism, 5-Top cover of tail lifting mechanism, 6-Right side lifting mechanism, 7-Camera, 8-Test site.

[0022] Figure 3 A schematic diagram of the overall layout of the ground joint test rig for tiltrotor aircraft. In the diagram, 100-left wing, 3-left side lifting mechanism, 200-right wing, 6-right side lifting mechanism, and 9-tail lifting mechanism.

[0023] Figure 4 Schematic diagram of the pit for the tail lifting mechanism.

[0024] Figure 5 A cross-sectional view of the ball joint assembly at the left wing in the XZ plane. In the figure, 100-left wing, 102-onboard ball joint mounting seat, 103-lifting ball joint mounting seat, 9-1-ball joint of the lifting mechanism, 104-fastener, 9-2-piston rod of the left lifting mechanism.

[0025] Figure 6 Cross-sectional view of the ball joint in the XZ plane in the assembled state of the ball joint at the right wing; 6-1-Spanning waist-shaped hole interface of ball joint mount.

[0026] Figure 7 A diagram showing the ground markings for the parking area for aircraft wheels and tires.

[0027] Figure 8 The tail lifting mechanism electric cylinder, 9-2 in the figure is the single-ear joint with a spherical bearing on the upper part of the electric cylinder, and 9-3 is the single-ear joint with a spherical bearing on the lower part of the electric cylinder.

[0028] Figure 9 A schematic diagram of the connection structure between the tail lifting mechanism and the fuselage and the head. In the diagram, 300 is the tail fuselage structural frame beam, 9-3 is the fuselage double fork lug joint, 9-4 is the connecting pin, and 9-2 is the single lug joint with a spherical bearing at the upper end of the tail lifting mechanism. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0031] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0033] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] This invention innovatively designs a lifting device and method for a ground-based joint test rig for large-tonnage tiltrotor manned aircraft, which can well meet its complex test requirements.

[0035] like Figure 2As shown, the overall layout of the ground-based combined lifting device for a large-tonnage tiltrotor aircraft according to the present invention is as follows: 1. The testing machine is tied to the core area. For example... Figure 3 As shown, a lifting mechanism is installed below the nacelles of the left and right wings and near the tail wheel of the test aircraft, namely the left lifting mechanism 3, the right lifting mechanism 6, and the tail lifting mechanism 5. The main function of the lifting mechanism is to realize the lifting and lowering of the tiltrotor aircraft, and to ensure that there is a sufficient safe distance between the blade tip and the ground when the rotor shaft is horizontally forward in tiltrotor mode.

[0036] 2. Set up a T-shaped ground rail array below the left rotor 100 and the right rotor 200 to install the left lifting mechanism 3 and the right lifting mechanism 6 on the ground rail array by anchor bolts; the wings of the large-tonnage tiltrotor aircraft will deform under the gravity of the engine section nacelle and its internal components, and due to the unavoidable positional error of the embedded parts of the civil engineering foundation, the left and right lifting mechanisms must be adjusted in lateral installation position on the T-shaped ground rail according to the site conditions to ensure accurate positioning and connection between the test aircraft and the lifting mechanism.

[0037] 3. For example Figure 4 As shown, a pit shaft is set up near the tail wheel for the installation and maintenance of the tail lifting mechanism. The tiltrotor aircraft is towed to the test area by a tractor. To avoid interference between the tail wheel and the tail lifting mechanism during towing, the tail lifting mechanism 5 must be fully retracted below ground level. Therefore, a pit shaft is set up, with sufficient space to allow one installer to smoothly complete the hoisting, positioning, and nut tightening of the tail lifting mechanism. During the hoisting process, the pit cover is opened, and the installer enters the pit to position and install the tail lifting mechanism. After installation, the installer leaves the pit and installs the pit cover and opening. When the test aircraft is not installed or during towing, the tail lifting mechanism is fully retracted in the pit shaft, and the pit opening remains closed. After the test aircraft is towed into position, the pit opening at the top of the tail lifting mechanism is opened, and the piston rod of the tail lifting mechanism extends and connects with the test aircraft, achieving the installation and mooring of the test aircraft.

[0038] like Figure 5 As shown, the top ends of the first lifting mechanism and the second lifting mechanism adopt a ball joint configuration, including an onboard ball joint mounting seat 102, a ball head 9-1, and a lifting ball joint mounting seat 103; the onboard ball joint mounting seat 102 and the lifting ball joint mounting seat 103 are detachably connected to form a complete inner surface of the ball head; the bottom end of the onboard ball joint mounting seat 102 is fixed to the lower surface of the tiltrotor wing nacelle, and the lifting ball joint mounting seat 103 is pre-installed on the ball head 9-1; the onboard ball joint mounting seat 102 and the lifting ball joint mounting seat 103 are connected by fasteners 104.

[0039] like Figure 6As shown, the ball head of one of the left lifting mechanisms 3 is in clearance fit with the on-board ball joint mounting seat and the lifting ball joint mounting seat; the ball head of the right lifting mechanism 6 is in clearance fit with the on-board ball joint mounting seat and the lifting ball joint mounting seat along the flight direction, and in small clearance fit with the on-board ball joint mounting seat and the lifting ball joint mounting seat along the wingspan direction, such as the waist-shaped hole interface 6-1 of the ball joint mounting seat in the wingspan direction, forming a capsule-shaped space.

[0040] like Figure 8 , Figure 9 As shown, the tail lifting mechanism includes an electric cylinder, a tail-end double-ear connector, an upper pin, a lower pin, and a bottom double-ear mounting connector. The upper and lower ends of the electric cylinder are single-ear connectors with spherical bearings. The upper part is connected to the tail-end double-ear connector 9-2 via the upper pin, and the bottom part is connected to the bottom double-ear mounting connector 9-3 via the lower pin. The axes of the upper and lower pins are along the wingspan direction to ensure a large range of angular movement of the connector, thereby ensuring a large range of pitch attitude adjustment for the tiltrotor.

[0041] 4. The stroke of the piston rods of the left, right and tail lifting mechanisms should be sufficient to lift the test aircraft until all three wheels are off the ground, ensuring that the propeller tips are at a safe distance from the ground in turboprop aircraft mode.

[0042] 6. Safety Net. The safety net for the tiltrotor ground test rig has two hexagonal support columns. Based on the standard helicopter safety net, the net in the area directly opposite the rotor disk plane in turboprop aircraft mode needs to be extended to ground level. High-definition cameras and lighting devices are installed on the safety net columns.

[0043] 8. Test Workshop. The ground joint test rig test workshop for tiltrotor aircraft (including test control room 1, power distribution room, and tool room, etc.) is located outside the safety protection net. The power distribution room is mainly used for the installation of electrical equipment such as the test rig power distribution cabinet and the lifting mechanism control cabinet.

[0044] 9. Remote control of the test aircraft. This is the first time that a large-tonnage tiltrotor aircraft has been tested on the ground in China. The test is of high risk. To ensure the safety of the flight personnel, a remote control system for the test aircraft should be set up so that the test personnel can safely perform control actions and monitor parameters such as engine start-stop and propeller pitch control in a control room far away from the test aircraft.

[0045] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A ground-based combined lifting device for a large-tonnage tiltrotor aircraft, characterized in that, The system includes a first lifting mechanism, a second lifting mechanism, a tail lifting mechanism, and a control unit, symmetrically arranged on both sides. The distance between the first and second lifting mechanisms is determined based on the distance between the left and right wing nacelles of the test aircraft. The bottom ends of the first and second lifting mechanisms are slidably connected to a ground rail array and fixed with anchor bolts. The top ends of the first and second lifting mechanisms are respectively equipped with a first displacement sensor and a second displacement sensor, which can move up and down in a direction perpendicular to the ground. The tail lifting mechanism is located in a pit shaft on the center plane relative to the first and second lifting mechanisms. Its bottom end is slidably connected to the ground rail array and fixed with anchor bolts. The top end of the tail lifting mechanism is equipped with a third displacement sensor, which can move up and down in a direction perpendicular to the ground. The first, second, and third displacement sensors are communicatively connected to the control unit.

2. The ground-based combined lifting device for a large-tonnage tiltrotor aircraft according to claim 1, characterized in that, The top of the first lifting mechanism and the second lifting mechanism adopts a ball joint configuration, including an onboard ball joint mounting seat, a ball head, and a lifting ball joint mounting seat; the onboard ball joint mounting seat and the lifting ball joint mounting seat are detachably connected to form a complete inner surface of the ball head; the bottom end of the onboard ball joint mounting seat is fixed to the lower surface of the tiltrotor wing nacelle, and the lifting ball joint mounting seat is pre-installed on the ball head.

3. The ground-based combined lifting device for a large-tonnage tiltrotor aircraft according to claim 2, characterized in that, The ball head of one of the first lifting mechanisms and the second lifting mechanism is in clearance fit with the on-board ball joint mounting seat and the lifting ball joint mounting seat; the ball head of the other mechanism is in clearance fit with the on-board ball joint mounting seat and the lifting ball joint mounting seat along the flight direction, and in small clearance fit with the on-board ball joint mounting seat and the lifting ball joint mounting seat along the wingspan direction.

4. The ground-based combined lifting device for a large-tonnage tiltrotor aircraft according to claim 1, characterized in that, The tail lifting mechanism includes an electric cylinder, a tail-end double-ear connector, an upper pin, a lower pin, and a bottom double-ear mounting connector. The upper and lower ends of the electric cylinder are single-ear connectors with spherical bearings. The upper part is connected to the tail-end double-ear connector of the fuselage via the upper pin, and the bottom part is connected to the bottom double-ear mounting connector via the lower pin. The axes of the upper and lower pins are along the wingspan direction to ensure a large angular range of motion of the connector, which in turn ensures a large pitch attitude adjustment range for the tiltrotor.

5. The ground-based combined lifting device for a large-tonnage tiltrotor aircraft according to claim 1, characterized in that, The first, second, and tail lifting mechanisms have two modes: individual control and synchronous control. In individual control mode, the piston rod of a single lifting mechanism can be extended / retracted by a certain displacement independently. In synchronous control mode, the piston rods of all three lifting mechanisms extend / retract by the same displacement simultaneously.

6. The ground-based combined lifting device for a large-tonnage tiltrotor aircraft according to claim 1, characterized in that, The surface of the pit shaft is equipped with a cover.

7. A ground-based combined lifting method for a large-tonnage tiltrotor aircraft, characterized in that, The ground-based combined lifting device for a large-tonnage tiltrotor aircraft, as described in any one of claims 1-6, comprises the following steps: Step 1: Tiltrotor towing position; put the piston rods of the three lifting mechanisms in the fully retracted position, retract the piston rod of the tail electric cylinder below the ground, and tow the tiltrotor to the test area by a towing vehicle; Step 2: Set the three lifting mechanisms to individual control mode, and control the piston rod of the first lifting mechanism or the second lifting mechanism to gradually extend until the ball head falls into the corresponding on-machine ball joint mounting seat. Then fix the on-machine ball joint mounting seat to the lifting ball joint mounting seat. Step 3: Control the piston rod of the tail lifting mechanism to extend gradually, align the center hole of the joint bearing of the tail body with the center hole of the lifting mechanism fork lug, apply low temperature grease to the upper pin at the fork lug joint and install it in place, and tighten the pin mounting nut as required. Step 4: Set the three lifting mechanisms to synchronous control mode, control the piston rods of the three lifting mechanisms to extend synchronously, gradually raise the rotor wheels until they leave the ground, and measure the angle between the rotor shaft and the ground; Step 5: Set the tail lifting mechanism to independent control mode, and adjust the pitch attitude of the test aircraft by adjusting the extension of the piston rod of the tail lifting mechanism, so that the rotor shaft of the tiltrotor is perpendicular to the ground; Step 6: Continue to lift the test aircraft to the test height; put the three lifting mechanisms into synchronous control mode, and continue to lift the tiltrotor aircraft to the required test height. During the process, observe the pitch angle of the test aircraft to ensure that the tiltrotor aircraft attitude meets the requirements.

8. The ground-based combined lifting method for a large-tonnage tiltrotor aircraft according to claim 7, characterized in that, In step 1, the tiltrotor aircraft is towed to the test area by a tractor vehicle after the tire positioning marks are pre-painted on the ground within the test area. The tiltrotor aircraft is towed to the test area until all tires are within the pre-painted tire positioning marks on the ground. If the requirements are not met, the test aircraft is towed again until the requirements are met.

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