Vertical landing reusable solid rocket booster

Abstract

This invention discloses a vertical-landing reusable solid rocket booster. The combustion chamber includes a descent section and an ascent section. The descent section includes a descent combustion chamber shell with an inner wall providing insulation. The descent combustion chamber shell contains descent propellant and an igniter. Air rudders are located outside the descent combustion chamber shell. The ascent section includes an ascent combustion chamber shell with an inner wall providing insulation. The ascent combustion chamber shell contains ascent propellant. A soft pulse isolation layer is installed between the descent and ascent combustion chamber shells, and they are connected by a flange. This invention offers high landing accuracy, low impact upon landing, and good environmental adaptability. The booster has a simple overall structure, is easy to disassemble and assemble, and has a low cost for reuse after recovery, achieving optimal energy distribution.

Description

Technical Field

[0001] This invention proposes a vertical landing reusable solid rocket booster, which can change the situation that traditional solid rocket boosters are difficult to recover after launch and can only be used once. It is a key technology for reusable solid rocket boosters and belongs to the field of aircraft technology. Background Technology

[0002] Traditional rocket or missile boosters are typically disposable, keeping launch costs high for a long time. With the development of deep-thrust liquid rocket engines and advanced guidance algorithms, liquid-fueled launch vehicles (especially booster stages) have successfully achieved "vertical launch, vertical recovery, and reusability." This model not only significantly reduces launch costs but also promises to make space travel as frequent as flights.

[0003] Despite this, vertical recovery currently typically employs liquid rocket designs, with solid rocket designs rarely used. Solid rocket engines are characterized by high propellant density, simple structure, convenient storage, and rapid start-up, making them widely used in boosters for various aircraft (such as launch vehicles, space shuttles, sounding rockets, and fixed-wing UAVs). However, due to the difficulty in deeply adjusting thrust, the challenge of extinguishing the flame after ignition, and the difficulty in re-igniting it after extinguishing, energy management and control are far more complex than with liquid rocket designs. With the emergence of vertical recovery mission objectives, it is imperative that solid rocket boosters possess characteristics similar to liquid rocket boosters, such as deeply adjustable thrust and multiple ignition capabilities. In addition, the overall design needs to be optimized to minimize the overall weight of the vehicle.

[0004] Current solid rocket boosters typically employ parachute recovery rather than a secondary ignition deceleration-vertical recovery method. While parachute recovery is simple and easy to implement, it suffers from lower landing accuracy and greater impact upon impact, usually requiring splashdown on sea or water surfaces. This places higher demands on the corrosion resistance of materials and subsequent manual recovery techniques. Furthermore, the effectiveness of parachute recovery is also affected by the altitude of the landing site. Due to lower air pressure at high altitudes, larger and heavier parachutes are needed for recovery, increasing the inert mass to some extent.

[0005] In contrast, vertical recovery schemes offer high landing accuracy, minimal impact, and good environmental adaptability, but require matching thrust adjustment technology, making the scheme complex and technically challenging. Thrust adjustment technology for solid rocket motors has always been a difficult problem for engineers to overcome: solid rocket motors using multi-pulse propellants can provide multi-stage thrust through staged combustion as needed, but it's difficult to adjust individual thrust stages; electronically controlled solid rocket propulsion technology can achieve repeated engine start-stop and thrust adjustment, but it has high propellant requirements and relatively low specific impulse, making it difficult to achieve engineering applications in the short term; the principle of throat-plug type thrust adjustment is to drive the throat plug along the nozzle axis to change the nozzle throat area, thereby controlling the flow rate and thrust. Throat-plug type solid rocket motors can achieve stepless thrust adjustment, offering high flexibility in thrust control. Although throat-plug type motors have been applied to some extent, they still suffer from many problems such as complex structure, significant combustion chamber pressure fluctuations, and difficulty in providing vector control, making them unsuitable for vertical recovery missions.

[0006] In addition, there is currently no overall design method and process for vertical landing reusable solid rocket boosters, and there is a lack of calculation process for key parameters, nozzle layout scheme, propellant selection scheme and lightweight optimization method. Summary of the Invention

[0007] Based on the aforementioned technical background, this invention discloses a vertical landing reusable solid rocket booster, primarily applicable to boosting missions for small and medium-sized fixed-wing UAVs and sounding rockets. It employs a dual-pulse propellant scheme to meet the different thrust requirements of the ascent and descent phases, a four-unit, large-angle rotating nozzle "+" configuration to meet the depth-variable thrust and thrust vectoring requirements of vertical recovery missions, and a forward-mounted aerodynamic rudder configuration to achieve attitude control and roll suppression during the aerodynamic deceleration phase.

[0008] The specific technical solution is as follows:

[0009] A vertical landing reusable solid rocket booster includes a combustion chamber for storing solid propellant charges, and the combustion chamber includes a descent section and an ascent section;

[0010] The descent section includes a descent section combustion chamber shell, the inner wall of which is provided with a descent section combustion chamber insulation layer, the descent section combustion chamber shell contains descent section propellant and is equipped with a descent section igniter; an air rudder is provided outside the descent section combustion chamber shell;

[0011] The ascending section includes an ascending section combustion chamber shell, the inner wall of which is provided with an ascending section combustion chamber insulation layer, and the ascending section combustion chamber shell is filled with ascending section propellant;

[0012] A soft pulse isolation layer is installed between the descending combustion chamber shell and the ascending combustion chamber shell, and they are connected by a flange.

[0013] The ascending phase uses an inner and outer tube combustion propellant to provide a large flow rate and high thrust, and the igniter is provided by the ground launch system; the descending phase uses an end-face combustion propellant to provide a small flow rate and low thrust, and the descending phase igniter adopts a ring-shaped propellant charge structure.

[0014] The ascent phase is also equipped with landing arms and four rotatable nozzles at the tail end; the four rotatable nozzles are arranged in a cross shape.

[0015] Driven by electromechanical actuators and linkage mechanisms, the rotatable nozzles can vary in angle between the axis of each rotatable nozzle and the engine axis from 0° to 90°. The four rotatable nozzles work together to adjust the thrust vector and magnitude.

[0016] This invention provides an overall design for a vertically landing, reusable solid rocket booster. Its advantages are:

[0017] (1) The booster is recovered using a vertical recovery method. Compared with the traditional non-recoverable method, this method can reduce costs to a certain extent. Compared with the traditional parachute method, it has higher landing accuracy, less impact upon landing, and better environmental adaptability.

[0018] (2) The booster has a simple overall structure, is easy to disassemble and assemble, and has a low cost for recycling and reuse. It is suitable for application scenarios that require cost reduction through reuse, such as boosting missions for small and medium-sized fixed-wing UAVs and sounding rockets.

[0019] (3) The use of dual-pulse charging solves the problem of requiring two ignitions in the vertical recovery scheme. The ascending stage charging adopts inner and outer tube combustion charging to provide a large flow rate and a large thrust, while the descending stage charging adopts end face combustion charging to provide a small flow rate and a small thrust, thus achieving a better energy distribution.

[0020] (4) The use of four rotatable nozzles that can rotate on a single axis solves the problem of the difficulty in deep thrust variation of solid rocket engines. Compared with the traditional throat-plug type thrust variation scheme, this scheme not only has a simple structure and small combustion chamber pressure fluctuation, but also has the ability to control the thrust direction at the same time. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the external appearance of the vertical landing reusable solid rocket booster of the present invention.

[0022] Figure 2 This is a cross-sectional view of the vertical landing reusable solid rocket booster of the present invention;

[0023] Figure 3This is an exploded cross-sectional view of the vertical landing reusable solid rocket booster of the present invention; wherein, 1-descent stage combustion chamber shell, 2-descent stage combustion chamber insulation layer, 3-descent stage propellant, 4-air rudder, 5-descent stage igniter, 6-pulse isolation layer, 7-ascent stage propellant, 8-ascent stage combustion chamber insulation layer, 9-ascent stage combustion chamber shell, 10-landing bracket, 11-linkage mechanism, 12-electromechanical actuator, 13-rotatable nozzle. Detailed Implementation

[0024] The present invention aims to provide a solid rocket booster design that can be ignited twice, has variable thrust, and has thrust vector control, for application in booster missions of small and medium-sized fixed-wing UAVs and sounding rockets.

[0025] The invented solid rocket booster consists of a descent combustion chamber shell 1, a descent combustion chamber insulation layer 2, a descent propellant charge 3, an air rudder 4, a descent igniter 5, a pulse isolation layer 6, an ascent propellant charge 7, an ascent combustion chamber insulation layer 8, an ascent combustion chamber shell 9, a landing support 10, a linkage mechanism 11, an electromechanical actuator 12, and four rotatable nozzles 13.

[0026] The combustion chamber, consisting of a descending section and an ascending section, stores the solid propellant charge. It employs a single-chamber, dual-pulse charging system, allowing for flexible loading. The ascending section charge 7 uses an inner and outer tube combustion system, providing high flow rate and thrust; its igniter is provided by the ground-based launch system. The descending section charge 3 uses an end-face combustion system, providing low flow rate and low thrust; its igniter uses a ring-shaped propellant charge structure. A soft pulse isolation layer 6 is installed between the descending section combustion chamber shell 1 and the ascending section combustion chamber shell 9, connected by a flange. The pulse isolation layer 6 withstands pressure from the ascending section combustion chamber and provides flame retardancy, achieving physical isolation between the ascending section charge 7 and the descending section charge 3.

[0027] To achieve adjustment of thrust magnitude and direction, four rotatable nozzles 13 are installed at the rear of the engine. Driven by the electromechanical actuator 12 and the linkage mechanism 11, the angle between the axis of each rotatable nozzle 13 and the engine axis can vary between 0° and 90°. The four rotatable nozzles 13 can cooperate with each other to achieve adjustment of thrust vector and magnitude.

[0028] The payload attachment point can be on the side, such as on a fixed-wing UAV, or on the nose, such as on the second stage of a sounding rocket. If the payload is mounted on the side, an aerodynamic nose cone needs to be selected for the booster to reduce aerodynamic drag, and it must be ensured that the rotatable nozzle angle 13 is pre-adjusted at launch to align the resultant thrust axis with the center of mass of the entire system. After the propellant 7 in the booster's ascent stage has burned out, the payload separates from the booster, and the mechanical / electrical connection at the attachment point is immediately disconnected.

[0029] The equipment bay, located at the nose of the booster, houses the onboard computer, power supply, and guidance and navigation equipment. It controls the rotation angle of the four rotatable nozzles 13 to achieve the desired thrust magnitude and direction, and also controls the aerodynamic rudders 4 to achieve attitude control and suppress roll during aerodynamic deceleration. The landing gear 10, mounted at the tail of the booster, helps mitigate landing impact.

[0030] The booster's insulation layer and rotatable nozzle 13 are both removable and replaceable. When designing, a dual-base propellant with a lower gas temperature and a lower metal content should be selected to reduce the ablation of the insulation components and maximize the service life of the insulation layer and rotatable nozzle 13.

[0031] The working process of a vertical landing reusable solid rocket booster is as follows:

[0032] 1. The ascending stage igniter ignites the ascending stage propellant 7. The ascending stage propellant 7 burns, and the resulting gas is discharged from the rotatable nozzle 13, generating thrust to lift the booster and payload into the air.

[0033] 2. After the propellant charge in the ascending stage is completely burned off, the payload separates from the booster.

[0034] 3. Under the action of the air rudder 4, the attitude of the booster is adjusted to achieve aerodynamic deceleration.

[0035] 4. Under the guidance command, the igniter 5 of the descent stage ignites, igniting the explosive charge 3 of the descent stage and breaking through the pulse isolation layer 6.

[0036] 5. Use electromechanical actuator 12 and linkage mechanism 11 to adjust the rotation angle of the four rotatable nozzles 13 so that the booster generates thrust of the magnitude and direction that meets the guidance command.

[0037] 6. The landing support 10 contacts the ground, the booster completes vertical landing, and the rotation angle of all rotatable nozzles 13 is adjusted to 90° to generate no thrust until the propellant 3 in the descent stage is completely burned off.

[0038] 7. After recovering the booster, clean the combustion chamber and rotatable nozzle 13, and reprocess the insulation layer 2 of the descending combustion chamber and the insulation layer 8 of the ascending combustion chamber.

[0039] 8. Install the new ascending section charge 7, descending section charge 3, pulse isolation layer 6, and descending section igniter 5 into the combustion chamber respectively.

[0040] 9. Load the payload and prepare for the next launch.

[0041] The overall design flow of a vertical landing reusable solid rocket booster is as follows:

[0042] 1. Given the design specifications, including the weight of the payload such as the weight of a fixed-wing UAV, the weight of the second stage or above of a sounding rocket, the thrust-to-weight ratio for landing, the thrust-to-weight ratio for takeoff, and the combustion time of the ascent stage, select the outer diameter of the propellant charge on the end face of the descent stage and the combustion chamber pressure of the descent stage according to the actual situation.

[0043] 2. Based on experience, we can make a preliminary estimate of the weight of the engine casing, the rotatable nozzle 13, the inert structure, and the propellant charge 7 in the ascending section.

[0044] 3. Calculate the thrust during descent based on the landing thrust-to-weight ratio.

[0045] 4. Use the uniformly decelerated external ballistic formula to estimate the combustion time during the descent phase.

[0046] 5. Under the pressure of the combustion chamber and atmospheric back pressure during the descent phase, use Newton's method to find the optimal pressure ratio and area ratio of the rotatable nozzle 13 to maximize the thrust coefficient.

[0047] 6. Calculate the throat area of ​​the rotatable nozzle 13 using the relationship between thrust and combustion chamber pressure.

[0048] 7. Calculate the burning rate of charge 3 in the descending stage using the equilibrium pressure formula.

[0049] 8. Calculate the length and weight of the charge 3 in the descent stage based on the combustion time of the descent stage.

[0050] 9. Calculate the ascent thrust based on the takeoff thrust-to-weight ratio, i.e., the takeoff thrust.

[0051] 10. Determine the combustion chamber pressure during the ascent phase based on the takeoff thrust.

[0052] 11. Calculate the burning rate of charge 7 in the ascending section based on the combustion time of the ascending section.

[0053] 12. Use the balanced pressure formula to calculate the burning surface area, charge length, and charge weight of the rising section.

[0054] 13. Calculate the insulation layer thickness and weight based on the total combustion time.

[0055] 14. Calculate the thickness and weight of the combustion chamber shell based on the maximum combustion chamber pressure.

[0056] 15. Return to step 3 until the iteration converges, and the design is complete.

[0057] The following is a method for lightweighting and optimizing vertical-landing reusable solid rocket boosters:

[0058] Plot a phase diagram of the total weight of the booster in a two-dimensional plane, with the outer diameter of the propellant charge (or the outer diameter of the booster) as the x-axis and the combustion chamber pressure in the descent phase as the y-axis. The lightest design point can be found in the phase diagram.

[0059] Table 1

[0060]

[0061] Specifications: Payload weight 100kg, takeoff thrust-to-weight ratio 3.0, boost phase duration 5s, landing thrust-to-weight ratio 3.0.

[0062] The booster outer diameter was selected as 160 mm, and the combustion chamber pressure in the descent stage was 2.5 MPa. The overall design was completed using the proposed overall design process, and the design results are shown in Table 1.

Claims

1. A vertical-landing reusable solid rocket booster, comprising a combustion chamber for storing a solid propellant charge, characterized in that, The combustion chamber includes a descending section and an ascending section; The descending section includes a descending section combustion chamber shell (1), the inner wall of which is provided with a descending section combustion chamber insulation layer (2), the descending section combustion chamber shell (1) is filled with descending section charge (3) and equipped with a descending section igniter (5); an air rudder (4) is provided outside the descending section combustion chamber shell (1); The ascending section includes an ascending section combustion chamber shell (9), the inner wall of the ascending section combustion chamber shell (9) is provided with an ascending section combustion chamber insulation layer (8), and the ascending section combustion chamber shell (9) is filled with ascending section charge (7); A soft pulse isolation layer (6) is installed between the descending combustion chamber shell (1) and the ascending combustion chamber shell (9) and connected by a flange; The tail of the ascent phase is also equipped with landing gear (10) and four rotatable nozzles (13), which are arranged in a cross shape.

2. The vertical landing reusable solid rocket booster according to claim 1, characterized in that, The ascending section charge (7) adopts an inner and outer tube combustion charge to provide a large flow rate and a large thrust, and the igniter is provided by the ground launch system; the descending section charge (3) adopts an end face combustion charge to provide a small flow rate and a small thrust, and the descending section igniter (5) adopts an annular charge structure.

3. The vertical landing reusable solid rocket booster according to claim 1, characterized in that, Driven by the electromechanical actuator (12) and the linkage mechanism (11), the rotatable nozzle (13) can vary the angle between the axis of each rotatable nozzle (13) and the axis of the engine from 0° to 90°. The four rotatable nozzles (13) cooperate with each other to adjust the thrust vector and magnitude.

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