Small unmanned aerial vehicle low-gas launch device

Abstract

The application provides a small unmanned aerial vehicle low-overload gas launching device, which comprises a launching cylinder, a base, a piston, a plurality of gas generators and a control system. The base is connected to the bottom of the launching cylinder, and the piston is coaxially arranged in the launching cylinder. The base, the piston and the launching cylinder form a closed chamber. The plurality of gas generators are installed to the base in the closed chamber and are controlled to be ignited in stages by the control system. The interval time of the staged ignition of the plurality of gas generators is determined according to an algorithm. The application can reduce the launching overload of the small unmanned aerial vehicle to below 100g, and increase the launching speed to 25-35m / s. Compared with the development of a required gas generator, the structure of the application can greatly shorten the development cycle, reduce the development and test cost, reduce the weight of the launching system and the body structure by more than 30%, reduce the standard grade of the on-board equipment, and reduce the overall unmanned aerial vehicle platform development cost by more than 30%.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle launch technology, specifically relating to a low-overload gas launch device for a small unmanned aerial vehicle. Background Technology

[0002] Small drones are mostly launched by catapult and are mainly used for reconnaissance and surveillance missions. They are suitable for individual soldier carrying or platform cluster launch modes.

[0003] Small UAV catapult launch methods can be divided into various types according to the power source, such as pneumatic-hydraulic catapult, rubber band catapult, and electromagnetic catapult. The gas catapult + launch tube mode has been a research hotspot in recent years. However, the launch overload in the existing launch technology is relatively high, basically around 150g, or even as high as 200g, which puts high demands on the UAV structure, airborne equipment and launch tube structure. The launch speed is generally 18-25m / s, which is difficult to meet the initial launch speed requirements of high-performance aircraft. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of high launch overload and low launch speed of small UAVs using gas cannons in the prior art, and to provide a low overload gas launcher for small UAVs. This device can reduce the launch overload of small cannon-launched UAVs to below 100g and increase the launch speed to 25-35m / s.

[0005] To achieve the above objectives, the technical solution provided by this invention is:

[0006] A low-overload gas launcher for small unmanned aerial vehicles includes a launch tube, a base, a piston, multiple gas generators, and a control system.

[0007] The base is connected to the bottom of the launch tube, and the piston is coaxially installed inside the launch tube. The base, piston, and launch tube together form a sealed chamber.

[0008] Multiple gas generators are installed on a base in a sealed chamber and are controlled by a control system to perform staged ignition. The interval between the staged ignition of the multiple gas generators is determined according to the following algorithm:

[0009] Step 1: Establish the equations of motion for the piston and the drone within the launch tube:

[0010]

[0011] In the formula, m1 is the total weight of the piston and the drone, a is the acceleration of the piston and the drone inside the cylinder, X is the piston stroke, f1 is the thrust of the gas in the sealed chamber acting on the piston, f2 is the external atmospheric pressure force, f3 is the frictional force between the piston and the drone and the launch cylinder, and S cLet P be the cross-sectional area inside the cylinder and P be the gas pressure in the closed chamber. Calculate using the following equation of state:

[0012] P = x p (R g m g +R a m a )T / V′

[0013] In the formula, x p m are the correction coefficients for the state equation. g and m a These represent the mass of the fuel gas at different times and the mass of the air in the initial free volume, respectively. T is the temperature inside the sealed chamber, and R is the mass of the fuel gas at different times and the mass of the air in the initial free volume. g and R a These are the gas constants for the fuel gas and air, respectively, and V′ is the free volume of the launch tube, V′=X*S c ;

[0014] Step 2: Select the initial ignition interval time, and obtain the time-launch overload curve and the time-launch velocity curve under the initial ignition interval time based on the established motion equation and state equation.

[0015] Step 3: Determine whether the launch overload and launch speed meet the requirements. If not, adjust the ignition interval time with the preset ignition interval time adjustment accuracy and return to Step 2 until the required ignition interval time is obtained.

[0016] Furthermore, the number of gas generators is two.

[0017] Furthermore, the gas generators are connected in series.

[0018] Furthermore, the preset ignition interval time adjustment accuracy is 1 to 5 ms.

[0019] Furthermore, the preset ignition interval time adjustment accuracy is 1.5ms.

[0020] Furthermore, the ignition interval of the gas generator was determined to be 10–65 ms.

[0021] Furthermore, the ignition interval of the gas generator was determined to be 25–45 ms.

[0022] The advantages of this invention are:

[0023] The present invention discloses a low-overload gas launch device for small unmanned aerial vehicles (UAVs). This device is equipped with multiple gas generators that ignite in stages. Through theoretical calculations and experimental verification, an optimal ignition interval for the gas generators was determined, balancing the low overload and high launch speed of the UAV. This reduces the launch overload of the small cannon-launched UAV to below 100g and increases the launch speed to 25-35m / s. Compared to developing a gas generator that meets the requirements, this invention significantly shortens the development cycle, reduces development and testing costs, reduces the weight of the launch system and fuselage structure by more than 30%, lowers the standard level of airborne equipment, and reduces the overall UAV platform development cost by more than 30%. Attached Figure Description

[0024] The above and / or other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, which are not drawn to scale and some features are enlarged or reduced to show details of specific parts.

[0025] Figure 1 This is a schematic cross-sectional view of the low-overload gas launch device for a small unmanned aerial vehicle (UAV) according to the present invention;

[0026] Figure 2 This is a comparison chart of the time-launch overload curves of the present invention in Example 1;

[0027] Figure 3 This is a comparison chart of the time-emission velocity curves of the present invention in Example 1;

[0028] Figure 4 This is a comparison chart of the time-launch overload curves of the present invention in Example 2;

[0029] Figure 5 This is a comparison chart of the time-emission velocity curves of the present invention in Example 2;

[0030] In the diagram: 1-launching tube; 2-base; 3-piston; 4-gas generator; 5-control system; 6-sealed chamber. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments thereof. It should be noted that the following detailed description of the present invention is for illustrative purposes only and is not intended to limit the scope of the invention.

[0032] This invention provides a low-overload gas launcher for small unmanned aerial vehicles (UAVs), which is used to launch small UAVs in a tube via gas launch, aiming to reduce the launch overload of the UAV and increase the launch speed of the UAV.

[0033] Reference Figure 1As an exemplary embodiment of the present invention, a low-overload gas launcher for a small unmanned aerial vehicle includes a launch tube 1, a base 2, a piston 3, multiple gas generators 4, and a control system 5.

[0034] The launch tube 1 is made of composite material and is the main structure of the launching device. The base 2 is connected to the bottom of the launch tube 1 and serves to support the launch tube. The piston 3 is coaxially arranged inside the launch tube 1. The base 2, piston 3 and launch tube 1 together form a sealed chamber 6.

[0035] The gas generator 4 is the power source for the entire launching device. Multiple gas generators 4 are installed on the base 2 within the sealed chamber 6 and are controlled by the control system 5 for staged ignition. That is, after a certain interval following the ignition of the previous stage gas generator, the next stage gas generator is ignited. The gas generators 4 can be connected in series or in parallel. Preferably, there are two gas generators 4.

[0036] When launching the drone, the control system sends a signal to the gas generator, which then starts working, producing high-pressure gas. This rapidly increases the pressure in the sealed chamber 6, pushing the piston 3 towards the cylinder opening. The piston 3 then propels the drone to accelerate within the cylinder until it exits. This invention controls the gas generators to start operating at different times. By supplementing the gas supply through multiple stages of generators, the rapid decrease in piston thrust during piston movement is reduced, achieving acceleration to a higher speed within a shorter launch stroke while avoiding instantaneous high overload.

[0037] The interval between staged ignitions of the gas generator 4 can be determined according to the algorithm described below.

[0038] The algorithm includes: Step S1, establishing the state equations for the motion of piston 3 and drone within launch tube 1:

[0039]

[0040] In the formula, m1 is the total weight of the piston and the drone, a is the acceleration of the piston and the drone inside the cylinder, X is the piston stroke, f1 is the thrust of the gas in the sealed chamber acting on the piston, f2 is the external atmospheric pressure force, f3 is the frictional force between the piston and the drone and the launch cylinder, which can be determined empirically, and S c Let P be the cross-sectional area inside the cylinder, and P be the pressure of the gas in the sealed chamber. The pressure is calculated using the following formula:

[0041] P = x p (R g m g +R a m a )T / V′

[0042] In the formula, x pm are the correction coefficients for the state equation. g and m a These represent the mass of the fuel gas at different times and the mass of the air in the initial free volume, respectively. T is the temperature inside the sealed chamber, and R is the mass of the fuel gas at different times and the mass of the air in the initial free volume. g and R a These are the gas constants for the fuel gas and air, respectively, and V′ is the free volume of the launch tube, V′=X*S c .

[0043] After establishing the equations of motion and the equations of state, proceed to step S2: select the initial ignition interval time, and obtain the time-launch overload curve and the time-launch velocity curve under the initial ignition interval time based on the established set of equations.

[0044] Then proceed to step S3: determine whether the launch overload and launch speed meet the requirements. If not, adjust the ignition interval time with the preset ignition interval time adjustment accuracy and return to step S2 until the required ignition interval time is obtained.

[0045] The initial ignition interval can be a time interval value that increases from 0 to a preset ignition interval adjustment precision. The preset ignition interval adjustment precision can be 1 to 5 ms, preferably 1.5 ms, and more preferably 1 ms. For example, if the preset ignition interval adjustment precision is 1 ms, then the initial ignition interval can be 1 ms. Alternatively, a preset ignition interval range can be set, such as 0 to 100 ms, in which case the ignition interval can start from 1 ms and gradually increase to 100 ms according to the preset ignition interval adjustment precision.

[0046] By obtaining the time-launch overload curve and time-launch speed curve, the operating sequence of each gas generator can be flexibly adjusted to achieve a balance between low overload and high speed, thus obtaining the required ignition interval time.

[0047] Next, we will combine the above theoretical calculations and simulation experiments to verify and determine the ignition interval time that meets the requirements. Only two examples are given here.

[0048] Example 1

[0049] Applying the design concept and scheme provided by this invention, a 12kg-class small UAV gas-fired launch device was designed. It employs two gas generators connected in series. The initial sealed chamber volume is 2.6L. At time t0, the first-stage generator starts, and at t0+40ms, the second-stage generator starts. Based on theoretical calculations and experimental verification, the launch device achieves a launch overload of 74g and a launch velocity of 25m / s under a launch distance of 0.7 meters. Detailed comparisons of the optimized time-launch overload and time-launch velocity curves are available in [link to relevant documentation]. Figure 2 , Figure 3 .fromFigure 2 , Figure 3 As can be seen, when using a single gas generator, the overload is greater than 100g and the speed is less than 20m / s; when using two gas generators in series with a time interval of 30ms, the speed is significantly improved, but the overload is still greater than 100g; when using two generators in series with the time interval adjusted to 40ms, the overload is significantly reduced and the speed reaches 25m / s, which is better than the first two schemes and meets the design requirements.

[0050] Example 2

[0051] Applying the design concept and scheme provided by this invention, a 10kg-class small UAV gas-fired launch device was designed. It employs two gas generators connected in series. The initial sealed chamber volume is 3.0L. At time t0, the first-stage generator starts, and at t0+30ms, the second-stage generator starts. According to theoretical calculations and experimental verification, the launch device achieves a launch overload of 93g and a launch velocity of 36m / s under a launch distance of 1.0 meter. Since this example requires a higher velocity, two generators are directly connected in series, and their interval time is optimized. See the time-launch overload curve and time-launch velocity optimization comparison chart for details. Figure 4 , Figure 5 .from Figure 4 , Figure 5 As can be seen, when two generators are connected in series with a time interval of 20ms, the overload is greater than 120g and the speed is 40m / s; when the time interval is 25ms, the speed decreases, but the overload is still greater than 100g; when the time interval is adjusted to 30ms, the speed continues to decrease, but is still greater than 35m / s, and the overload is reduced to below 100g, which meets the design requirements.

[0052] Through extensive testing, the ignition interval of the gas generator 4 can be determined to be 10–65 ms, particularly 25–45 ms. A specific suitable ignition interval can be calculated for specific situations.

[0053] Therefore, the small UAV gas launch device of the present invention includes multiple gas generators that ignite at different times. By obtaining a gas generator ignition interval that balances the low overload and high launch speed of the UAV, the launch overload of the small cannon-launched UAV can be reduced to below 100g and the launch speed can be increased to 25-35m / s. Compared with developing a gas generator that meets the requirements, this structure of the present invention can significantly shorten the development cycle, reduce development and testing costs, reduce the weight of the launch system and fuselage structure by more than 30%, reduce the standard level of airborne equipment, and reduce the overall UAV platform development cost by more than 30%.

[0054] Finally, it should be noted that the features mentioned and / or shown in the above description of exemplary embodiments of the present invention can be combined in the same or similar manner with one or more other embodiments, combined with features in other embodiments, or substituted for corresponding features in other embodiments. These combined or substituted technical solutions should also be considered to be included within the scope of protection of the present invention.

Claims

1. A low-overload gas launcher for a small unmanned aerial vehicle, characterized in that: It includes a launch tube, base, piston, two gas generators, and control system; The base is connected to the bottom of the launch tube, and the piston is coaxially disposed inside the launch tube. The base, the piston, and the launch tube together form a sealed chamber. The two gas generators are installed on the base in the sealed chamber and are controlled by the control system to perform staged ignition. The two gas generators are connected in series, and the interval between the staged ignition of the two gas generators is determined according to the following algorithm: Step 1: Establish the equations of motion for the piston and the drone within the launch tube: In the formula, The total weight of the piston and the drone. The acceleration of the piston and the drone within the cylinder. For piston stroke, The thrust exerted by the gas in the sealed chamber on the piston. Force exerted by external atmospheric pressure. The friction between the piston and the drone and the launch tube, The cross-sectional area inside the cylinder is... The gas pressure in the sealed chamber is calculated using the following equation of state: In the formula, These are the correction coefficients for the state equation. and These represent the mass of fuel gas and the mass of air in the initial free volume at different times. The temperature inside a sealed room. and These are the gas constants for fuel gas and air, respectively. For the free volume of the launch tube, ; Step 2: Select the initial ignition interval time, and obtain the time-launch overload curve and the time-launch velocity curve under the initial ignition interval time based on the established motion equation and state equation. Step 3: Determine whether the launch overload and launch speed meet the requirements. If not, adjust the ignition interval time with the preset ignition interval time adjustment accuracy and return to Step 2 until the required ignition interval time is obtained.

2. The low-overload gas launcher for small unmanned aerial vehicles according to claim 1, characterized in that: The preset ignition interval time adjustment accuracy is 1 to 5 ms.

3. The low-overload gas launcher for small unmanned aerial vehicles according to claim 2, characterized in that: The preset ignition interval time adjustment accuracy is 1.5ms.

4. The low-overload gas launcher for small unmanned aerial vehicles according to claim 1 or 2, characterized in that: The ignition interval of the gas generator is determined to be 10–65 ms.

5. The low-overload gas launcher for small unmanned aerial vehicles according to claim 4, characterized in that: The ignition interval of the gas generator is determined to be 25–45 ms.

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