Unmanned aerial vehicle rocket boost launch thrust axis design

Abstract

The application provides a UAV rocket booster launching thrust axis design, comprising the following steps: according to the selected rocket booster, designing a reasonable UAV launching angle and rocket booster installation angle; comprehensively considering the actual preparation process, determining the fuel consumption before launching, calculating and determining the influence of the consumed fuel on the UAV gravity center; simulating and calculating the influence of the selected rocket booster thrust on the deformation of the UAV bearing structure during launching; comprehensively analyzing the thrust line influence factors, setting a pre-bias angle on the thrust axis, so that the rocket booster thrust axis can pass through the actual gravity center during launching; the application comprehensively considers the actual launching working condition, designs a reasonable thrust axis pre-bias angle on the basis that the rocket booster thrust axis completely passes through the UAV system gravity center, ensures that the thrust axis can pass through the UAV system actual gravity center after the fuel system consumption and structural deformation influence, and increases the system launching safety margin.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of unmanned aerial vehicle launching, and particularly relates to a design of a rocket-assisted launching thrust axis of an unmanned aerial vehicle. BACKGROUND

[0002] Small and medium-sized unmanned aerial vehicles usually adopt a rocket-assisted launching mode to complete the take-off process. This take-off mode can make the unmanned aerial vehicle rapidly reach an ideal climbing flight state from a static state in a short time, realize zero-length take-off, and has the advantages of convenient operation, rapidness, low requirement for a launching site, and the like, thus bringing a lot of convenient conditions for using the unmanned aerial vehicle in a field environment.

[0003] However, the rocket-assisted launching has certain risks. During the time of the huge thrust of the rocket booster, the speed and attitude angle of the unmanned aerial vehicle change dramatically, and the distribution of the center of gravity and mass also presents a complex change rule with the combustion of the rocket booster. In the initial stage of launching and taking off (within 1 second after launching), the flight speed of the unmanned aerial vehicle is low, the aerodynamic performance is poor at this time, the moment generated by the operation of the rudder surface is small, and the thrust line of the rocket booster deviating from the center of gravity is likely to cause attitude out of control.

[0004] The launching thrust axis of the unmanned aerial vehicle directly affects the safety of the launching process. Under the existing thrust axis adjustment condition, reasonable design of the thrust axis angle is particularly important. By comparing and analyzing the ground thrust axis measurement and adjustment and the two states before the unmanned aerial vehicle launching, the actual assembly angle deviation of the rocket booster, the thrust axis measurement error, the fuel consumption of the engine before launching, and the influence of the rocket thrust on the structural deformation will all cause the actual thrust axis to deviate from the center of gravity.

[0005] The traditional launching simulation modeling mode performs launching simulation through modeling, generally only considers the influence of the rocket thrust, the engine thrust, the control system operation and the aerodynamic characteristics of the unmanned aerial vehicle, obtains the actual assembly angle deviation range and the control margin of the rocket booster, and however, to ensure the safety of launching, the assembly deviation of the rocket booster, the fuel consumption before the launching of the unmanned aerial vehicle, and the influence of the structural deformation during launching should be comprehensively considered. SUMMARY

[0006] OBJECTIVE OF THE INVENTION

[0007] In view of the above technical problems, the present application provides a design of a rocket-assisted launching thrust axis of an unmanned aerial vehicle to solve the technical problems mentioned in the background.

[0008] TECHNICAL SCHEME

[0009] In order to achieve the above-mentioned purpose, the technical scheme provided by the present application is as follows: a design of a rocket-assisted launching thrust axis of an unmanned aerial vehicle, comprising the following steps,

[0010] Step 1: according to the selected rocket booster, design reasonable unmanned aerial vehicle launch angle and rocket booster installation angle;

[0011] Step 2: considering the actual preparation process, the consumption of fuel before launch is determined, and the influence of consumed fuel on the center of gravity of the unmanned aerial vehicle is calculated and determined;

[0012] Step 3: simulate the influence of the selected rocket booster thrust on the deformation of the bearing structure of the unmanned aerial vehicle during launching;

[0013] Step 4: comprehensively analyze the thrust line influencing factors, and set a pre-offset angle on the thrust axis, so that the rocket booster thrust axis can pass through the actual center of gravity during launching.

[0014] Further improvement is that in step 1, the unmanned aerial vehicle body structure model is established according to the Cartesian coordinate axis system, the actual unmanned aerial vehicle weight and center of gravity data and the rocket booster weight and center of gravity data are adopted, the rocket booster bearing structure station, the engine thrust axis, the unmanned aerial vehicle size and the rocket booster size are combined, and the reasonable angle between the rocket booster thrust axis and the body axis and the unmanned aerial vehicle launch angle are iterated out.

[0015] Further improvement is that in step 2, the influence of fuel consumption on the change of the center of gravity is calculated by using an equivalent model, and the change amount of the rocket booster thrust axis is converted.

[0016] Further improvement is that in step 3, the strength simulation calculation structure deformation amount and deformation direction are carried out, and the change amount of the rocket booster thrust axis is converted.

[0017] Further improvement is that in step 4, the thrust line influencing factors are comprehensively analyzed, and a pre-offset angle is set on the thrust axis in the pitch direction, so that the rocket booster thrust axis can pass through the actual center of gravity during launching.

[0018] Further improvement is that the thrust line influencing factors also include the influence of fuel tank movement and deformation.

[0019] Further improvement is that the thrust line influencing factors also include the influence of the launching frame.

[0020] Further improvement is that the thrust line influencing factors also include the influence of the rocket weight change during launching.

[0021] Beneficial effects

[0022] The technical scheme provided by the application has the following beneficial effects compared with the prior art:

[0023] The application comprehensively considers actual launch conditions, and on the basis that the thrust axis of the rocket booster completely passes through the gravity center of the unmanned aerial vehicle system, a reasonable thrust axis pre-bias angle is designed to ensure that the thrust axis can pass through the actual gravity center of the unmanned aerial vehicle system after fuel system consumption and structural deformation influence, and the launch safety margin of the system is increased.

[0024] The application designs and analyzes the influence of fuel consumption and structural deformation and the like, reasonably adjusts the thrust line angle to reduce the degree of thrust deviation from the gravity center of the rocket booster during launching, and ensures that the unmanned aerial vehicle is launched more safely. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is the test figure of the flip hanging method of the application;

[0026] Figure 2 It is a ground thrust line schematic diagram of the application. DETAILED DESCRIPTION

[0027] In the description of the application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "page", "bottom", "inner", "outer", "clockwise", "counterclockwise", "coaxial", "bottom", "one end", "top", "the other end", "one side", "front", "both ends", "both sides" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0028] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0029] In the application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing", "provided with" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0030] Reference will now be made to the drawings wherein like numerals refer to like components throughout the several figures. The size and relative scale of the various elements illustrated in the figures are not necessarily to scale, with emphasis instead being placed upon illustrating the principles of the application. The drawings are merely schematic representations, not intended to portray specific structural details of the application. Embodiments

[0031] The present embodiment provides a UAV rocket booster launch thrust axis design, comprising the following steps,

[0032] Step 1: According to the selected rocket booster, design a reasonable UAV launch angle and rocket booster installation angle;

[0033] Step 2: Considering the actual preparation process, determine the consumption of ground fuel before launch, and calculate the impact of consumed fuel on the center of gravity of the UAV;

[0034] Step 3: Simulate the impact of the selected rocket booster thrust on the deformation of the UAV load-bearing structure during launch;

[0035] Step 4: Comprehensive analysis of the thrust line influencing factors, set the pre-offset angle of the thrust axis, so that the rocket booster thrust axis can pass through the actual center of gravity during launch.

[0036] Wherein, the order of steps 2 and 3 can be adjusted, as long as the thrust line influencing factors are comprehensively analyzed before launch.

[0037] Specifically, in step 1, a UAV body structure model is established according to the Cartesian coordinate axis system, the actual UAV weight and center of gravity data and the rocket booster weight and center of gravity data are used, combined with the rocket booster load-bearing structure station, engine thrust axis, UAV size and rocket booster size, to iteratively determine the angle between the rocket booster thrust axis and the body axis and the UAV launch angle.

[0038] Wherein, the thrust line influencing factors also include fuel tank movement and deformation effects.

[0039] Fuel tank movement and deformation effect estimation: According to different fuel tank system designs, the impact of the flip-hanging method is also different, as shown in Figure 1 The flip-hanging method is a conventional technical means in the art, and will not be described here. Based on the body coordinate axis system, the center of gravity position is set as (x0, y0, z0) when the whole machine is weighed, the weight is m0, the angle between the body axis and the fuselage longitudinal axis is θ when flip-hanging, the initial fuel tank is in close contact with the bottom of the body structure, and the fuel tank is in close contact with the back of the body structure after flip-hanging. The fixed position is the movement amount Δz in the body axis direction, and the center of gravity of the aircraft at this time is (x0, y0, z0+ Δz). 0+ Δz).

[0040] After the body posture is stabilized, the fuel tank length is set as ΔL, ΔV0 of fuel flows from the rear fuel tank to the front fuel tank under the influence of gravity, the volume of the front fuel tank expands, and the top of the rear fuel tank is filled with air. At this time, the movement amount of the center of gravity along the x-axis is Δx, and the center of gravity of the aircraft moves to (x0-Δx, y0, z0+Δz).

[0041] At this time, the center of gravity of the aircraft moves to (x0-Δx, y0, z0+Δz). By ignoring the measurement error of the tooling, the deflection of the thrust line measurement angle caused by the movement and deformation of the fuel tank is Δα1.

[0042] In step 2, the engine is generally adjusted to the "maximum" throttle state before the unmanned aerial vehicle is launched, and the transfer of the unmanned aerial vehicle may cause fuel system vent line leakage, jet engine oil consumption during starting, and engine oil consumption during starting. After the engine is started, system check is carried out, and the engine works in different throttle states, which will all cause fuel consumption. There is a great longitudinal overload during the launch of the unmanned aerial vehicle (not considering the influence of fuel tank deformation), which will cause the fuel in the front of the fuel tank to flow to the rear. The influence of fuel consumption on the change of the center of gravity can be calculated by using an equivalent model, and the change amount of the thrust axis of the rocket booster can be converted.

[0043] The influence of fuel change on the center of gravity during launch: it is assumed that the amount of fuel leaked through the vent line during transportation and the process of installing the aircraft to the launch rail is ΔV1L, the amount of fuel consumed during engine starting is ΔV2L, the amount of fuel consumed in the "slow vehicle" state is ΔV3L, and the amount of fuel consumed during the launch of the engine is ΔV4L. The total fuel consumption before launch is ΔV=ΔV1+ΔV2+ΔV3+ΔV4L, which is converted into weight

[0044] The unmanned aerial vehicle is launched at a determined launch angle, and there is a large longitudinal overload during launch. Under the longitudinal overload, the fuel will move backward, causing the center of gravity of the aircraft to move to the rear , which will eventually cause the aircraft to lift its head. Through the above data, the fuel consumption and flow during launch can be calculated, the total weight of the aircraft during launch is m1=m0-Δm, and the center of gravity moves to . Through the above data, the deflection of the rocket booster thrust line is Δα2.

[0045] In step 3, the structure of the body that bears the rocket booster thrust is only affected by the weight of the unmanned aerial vehicle during ground thrust line measurement and adjustment, and can be considered to have no deformation. However, during launch, the structure is deformed by the huge rocket thrust, and strength simulation is required to calculate the deformation amount and direction of the structure, and to convert the change amount of the rocket booster thrust axis.

[0046] ​The influence of the deformation of the launch bearing structure: according to the average thrust of the rocket booster provided by the rocket booster manufacturer, the deformation of the launch bearing structure such as the launch cone is calculated by finite element simulation of the aircraft structure, and the change of the thrust line caused by the structural deformation Δα3 is evaluated.

[0047] The influence factors of the thrust line also include the influence of the launch stand.

[0048] The launch stand locks the aircraft fulcrum during launch, but the aircraft needs to cut off the shear pin through the rocket thrust when it leaves the launch stand, and the front fulcrum lock hook is opened after the launch stand is tilted at a certain angle. During this process, the aircraft will appear to be lowered after leaving the stand. According to the statistical test data, the tilting launch stand will eventually cause the pitch angle of the unmanned aerial vehicle to decrease by about 5° after leaving the stand.

[0049] The influence factors of the thrust line also include the influence of the rocket weight change during launch. The weight gradually decreases during the rocket boosting process, which is modeled in the launch simulation, which is ignored here.

[0050] In step 4, the influence factors of the thrust line are comprehensively analyzed, and a pre-bias angle is set on the thrust axis in the pitch direction, so that the thrust axis of the rocket booster can pass through the actual center of gravity during launch, that is, all the factors affecting the thrust line are analyzed, and the deviation vector is calculated , which is put into the actual thrust line design. On the basis of the design of the thrust line angle, the thrust line is pulled and biased in the launch simulation, and the final simulation result is used for actual thrust line measurement and adjustment, which can finally ensure the safety of the launch.

[0051] As shown in Figure 2 , when measuring and adjusting the thrust axis on the ground, the measuring cylinder and the hanging rope are not offset along the side of the aircraft body (i.e. ΔB=0 as shown in Figure 2 ), and the thrust axis on the symmetric plane of the aircraft body is offset from the center of gravity of the measuring cylinder by a certain position, so that the center of gravity can pass through the thrust axis after the change during launch (i.e. ΔA≠0 as shown in Figure 2 ).

[0052] The above-described embodiments only express certain embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the present patent; it should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application; therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A UAV rocket boost launch thrust axis design, characterized by, The method comprises the following steps, Step 1: according to the selected rocket booster, design reasonable unmanned aerial vehicle launch angle and rocket booster installation angle; Step 2: considering the actual preparation process, determine the consumption of ground driving fuel before launch, and calculate the influence of consumed fuel on the center of gravity of the unmanned aerial vehicle; Step 3: simulate the influence of the selected rocket booster thrust on the deformation of the bearing structure of the unmanned aerial vehicle during launch; Step 4: comprehensively analyze the thrust line influence factors, and set a pre-offset angle on the thrust axis, so that the rocket booster thrust axis can pass through the actual center of gravity during launch.

2. The thrust axis design for rocket assisted launch of UAVs as claimed in claim 1, wherein, In step 1, the unmanned aerial vehicle body structure model is established according to the Cartesian coordinate axis system, the actual unmanned aerial vehicle weight and center of gravity data and the rocket booster weight and center of gravity data are adopted, the rocket booster bearing structure station, the engine thrust axis, the unmanned aerial vehicle size and the rocket booster size are combined, and the reasonable angle between the rocket booster thrust axis and the body axis and the unmanned aerial vehicle launch angle are iterated.

3. The thrust axis design for rocket assisted launch of UAVs of claim 1, wherein, In step 2, the influence of fuel consumption on the change of the center of gravity is calculated by using the system equivalent model, and the change amount of the rocket booster thrust axis is converted.

4. The thrust axis design for rocket assisted take-off of a UAV according to claim 1, wherein, In step 3, the strength simulation is performed to calculate the deformation amount and direction of the structure, and the change amount of the rocket booster thrust axis is converted.

5. The thrust axis design for rocket assisted take-off of a UAV as claimed in claim 1, wherein, In step 4, the thrust line influence factors are comprehensively analyzed, and a pre-offset angle is set on the thrust axis in the pitch direction, so that the rocket booster thrust axis can pass through the actual center of gravity during launch.

6. The thrust axis design for rocket assisted take-off of a UAV according to claim 1, wherein, The thrust line influence factors also include the influence of fuel tank movement and deformation.

7. The thrust axis design for rocket assisted take-off of a UAV as claimed in claim 1, wherein, The thrust line influence factors also include the influence of the launch stand.

8. The thrust axis design for rocket assisted take-off of a UAV according to claim 1, wherein: The thrust line influence factors also include the influence of the rocket weight change during launch.

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