Vertical landing type recoverable solid rocket booster

Abstract

The invention discloses a vertical landing type recoverable solid rocket booster. A combustion chamber comprises a descending section and an ascending section; the descending section comprises a descending section combustion chamber shell, a descending section combustion chamber heat insulation layer is arranged on the inner wall of the descending section combustion chamber shell, descending section charge is arranged in the descending section combustion chamber shell, and a descending section igniter is arranged in the descending section combustion chamber shell; an air rudder is arranged outside the descending section combustion chamber shell; the ascending section comprises an ascending section combustion chamber shell, an ascending section combustion chamber heat insulation layer is arranged on the inner wall of the ascending section combustion chamber shell, and ascending section charge is arranged in the ascending section combustion chamber shell; a soft pulse isolation layer is installed between the descending section combustion chamber shell and the ascending section combustion chamber shell, and the descending section combustion chamber shell and the ascending section combustion chamber shell are connected through flanges. The method is high in drop point precision, small in landing impact and good in environmental adaptability; the booster is simple in overall structure, easy to disassemble and assemble and low in cost of repeated use after being recycled, and better energy distribution is achieved.

Description

Technical Field

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

[0002] The boosters of traditional launch vehicles or missiles are usually disposable, which has kept the launch cost high for a long time. With the development of deep variable thrust liquid rocket engines and advanced guidance algorithms, liquid launch vehicles (especially booster-stage rockets) have successfully achieved "vertical launch, vertical recovery, and reuse." This model not only greatly reduces the launch cost, but also has the potential to achieve "flight-like" access to and from space.

[0003] Despite this, liquid rocket solutions are usually used for vertical recovery at present, and solid rocket solutions are rarely used. Solid rocket engines have the characteristics of high propellant density, simple structure, convenient storage, and fast startup, and are widely used in boosters of various aircraft (such as launch vehicles, space shuttles, sounding rockets, fixed-wing drones, etc.). However, since its thrust size is difficult to adjust deeply, it is difficult to shut down after ignition, and it is difficult to ignite again after shutting down, and the difficulty of energy management and control is much greater than that of liquid rocket solutions. With the proposal of vertical recovery mission goals, solid boosters are bound to be required to have similar characteristics as liquid boosters, such as deep thrust size adjustment and multiple ignitions. In addition, the overall plan needs to be optimized to minimize the weight of the whole machine.

[0004] At present, solid rocket boosters usually adopt parachute recovery scheme rather than secondary ignition deceleration-vertical recovery scheme. Parachute recovery has the advantage of being simple and easy, but its landing point accuracy is low and the landing impact is large. It usually needs to splash down on the sea / water surface, which puts higher requirements on the corrosion resistance of the material and the subsequent manual salvage technology. In addition, the parachute recovery effect is also affected by the altitude of the landing point. Due to the lower air pressure in high-altitude areas, it is necessary to design larger and heavier parachutes to achieve recovery, which increases the inert mass to a certain extent.

[0005] In contrast, the vertical recovery scheme has high landing point accuracy, small landing impact, and good environmental adaptability, but it requires a matching thrust size depth adjustment technology, the scheme is complex and technically difficult. The thrust adjustment technology of solid rocket engines has always been a difficult problem that engineers have been constantly overcoming: solid engines using multi-pulse charges can burn in stages according to demand and provide multi-stage thrust, but it is difficult to adjust the single-stage thrust; electronically controlled solid propulsion technology can achieve repeated engine start and stop and thrust adjustment, but it has high requirements for propellants and relatively low specific impulse, and it is difficult to achieve engineering application in a short time; the principle of thrust adjustment of the throat plug engine is to drive the throat plug along the nozzle axis to change the nozzle throat area, thereby achieving control of flow and thrust. The throat plug solid engine can achieve stepless adjustment of thrust size and has high flexibility in thrust control. Although the throat plug engine has been used, it still has many problems such as complex structure, significant pressure fluctuations in the combustion chamber, and difficulty in providing vector control, and is not suitable 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 processes for key parameters, nozzle layout plans, charge selection plans, and lightweight optimization methods. Summary of the invention

[0007] Based on the above technical background, the present invention discloses a vertical landing recoverable solid rocket booster, which is mainly used for boosting missions of small and medium-sized fixed-wing UAVs and sounding rockets. A dual-pulse charge scheme is adopted to meet the different thrust requirements of the ascending and descending stages, a "cross" layout scheme of four large-angle rotating nozzles is adopted to meet the deep variable thrust and thrust vector requirements of the vertical recovery mission, and a front air rudder layout is adopted to achieve attitude control and roll suppression in the aerodynamic deceleration stage.

[0008] The specific technical solution is:

[0009] A vertical landing recoverable solid rocket booster, including a combustion chamber for storing a solid propellant charge, the combustion chamber including a descent section and an ascent section;

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

[0011] The ascending section comprises 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 provided with ascending section charge;

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

[0013] The ascending stage charge uses inner and outer tube burning charges to provide large flow and large thrust, and the igniter is provided by the ground launch system; the descent stage charge uses end face burning charges to provide small flow and small thrust, and the descent stage igniter uses an annular charge structure.

[0014] The tail of the ascending stage is also equipped with a landing bracket and four rotatable nozzles; the four rotatable nozzles are arranged in a "cross" shape;

[0015] The rotatable nozzle is driven by an electromechanical actuator and a connecting rod mechanism. The angle between the axis of each rotatable nozzle and the engine axis can vary between 0° and 90°. The four rotatable nozzles cooperate with each other to achieve the adjustment of thrust vector and size.

[0016] The present invention provides a general scheme for a vertical landing recyclable solid rocket booster. The advantages are:

[0017] (1) Use vertical recovery scheme to complete booster recovery. Compared with the traditional non-recoverable scheme, it can reduce costs to a certain extent. Compared with the traditional parachute scheme, it has high landing point accuracy, small landing impact, and good environmental adaptability.

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

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

[0020] (4) The use of four uniaxially rotatable nozzles solves the problem of the difficulty of deep thrust variation in solid rocket engines. Compared with the traditional throat plug type variable thrust solution, this solution not only has a simple structure and small combustion chamber pressure fluctuation, but also has the ability to control the thrust direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the appearance of the vertical landing recoverable solid rocket booster of the present invention;

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

[0023] Figure 3It is a cross-sectional exploded view of the vertical landing recoverable solid rocket booster of the present invention; wherein, 1-descending stage combustion chamber shell, 2-descending stage combustion chamber insulation layer, 3-descending stage charge, 4-air rudder, 5-descending stage igniter, 6-pulse isolation layer, 7-ascending stage charge, 8-ascending stage combustion chamber insulation layer, 9-ascending stage combustion chamber shell, 10-landing bracket, 11-connecting rod mechanism, 12-electromechanical actuator, 13-rotatable nozzle. DETAILED DESCRIPTION

[0024] The present invention aims to provide a solid rocket booster design scheme that can be ignited twice, has deeply variable thrust, and has thrust vector control, so as to be applied to the boosting missions of small and medium-sized fixed-wing UAVs and sounding rockets.

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

[0026] The combustion chamber is composed of a descending section and an ascending section, and is used to store solid propellant charges. A single-chamber dual-pulse charge is used, and the charge can be loaded freely. The ascending section charge 7 uses inner and outer tube combustion charges to provide large flow and large thrust, and its igniter is provided by the ground launch system; the descending section charge 3 uses end-face combustion charges to provide small flow and small thrust, and its igniter uses an annular package 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, and is connected by a flange. The pulse isolation layer 6 can withstand the pressure from the ascending section combustion chamber and play a flame retardant role to achieve physical isolation between the ascending section charge 7 and the descending section charge 3.

[0027] In order to adjust the thrust size and direction, four rotatable nozzles 13 are installed at the tail of the engine. Driven by the electromechanical actuator 12 and the connecting rod mechanism 11, the angle between the axis of each rotatable nozzle 13 and the engine axis can be changed between 0° and 90°. The four rotatable nozzles 13 cooperate with each other to adjust the thrust vector and size.

[0028] The payload attachment point can be on the side, such as a fixed-wing drone, or on the head, such as the second stage of a sounding rocket. If the payload is placed on the side, it is also necessary to select an aerodynamic nose cone for the booster to reduce aerodynamic drag and ensure that the angle of the rotatable nozzle 13 is pre-adjusted during launch so that the thrust force axis coincides with the center of mass of the entire system. After the booster's ascending stage charge 7 is burned out, the payload is separated from the booster, and the mechanical / electrical connection at the attachment point is immediately cut off.

[0029] The equipment cabin is located at the head of the booster and is used to install the onboard computer, power supply, and guidance and navigation equipment. On the one hand, it is used to control the rotation angle of the four rotatable nozzles 13 to obtain the expected thrust size and thrust direction, and on the other hand, it is used to control the air rudder 4 to achieve attitude control and suppress rolling during the aerodynamic deceleration stage. The landing bracket 10 is installed at the tail of the booster to reduce the impact of landing.

[0030] The thermal insulation layer and rotatable nozzle 13 of the booster are both detachable and replaceable. During the design, a double-base propellant with a lower gas temperature and a lower metal addition amount should be selected to reduce the ablation of the thermal insulation components and maximize the service life of the thermal insulation layer and the rotatable nozzle 13.

[0031] The vertical landing reusable solid rocket booster workflow is as follows:

[0032] 1. The ascent stage igniter ignites, igniting the ascent stage charge 7. The ascent stage charge 7 burns, and the generated gas is discharged from the rotatable nozzle 13, generating thrust, so that the booster and the payload are lifted into the air.

[0033] 2. The ascent stage charge 7 is burned out and the payload is separated 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 descent stage igniter 5 ignites, ignites the descent stage charge 3, and breaks through the pulse isolation layer 6.

[0036] 5. Use the electromechanical actuator 12 and the connecting rod mechanism 11 to adjust the rotation angle of the four rotatable nozzles 13 so that the booster can generate thrust of the magnitude and direction that meets the guidance instructions.

[0037] 6. The landing support 10 touches the ground, the booster completes the vertical landing, and the rotation angle of all rotatable nozzles 13 is adjusted to 90° without generating thrust until the descent stage charge 3 is burned out.

[0038] 7. After the booster is recovered, the combustion chamber and the rotatable nozzle 13 are cleaned, and the insulation layer 2 of the descent stage combustion chamber and the insulation layer 8 of the ascending stage combustion chamber are reprocessed.

[0039] 8. Load 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. Mount the payload and prepare for the next launch.

[0041] The overall design process of the vertical landing recyclable solid rocket booster is as follows:

[0042] 1. Given the design indicators, including payload weight such as the weight of fixed-wing UAVs, the weight of the second stage and above of sounding rockets, the landing thrust-to-weight ratio, the take-off thrust-to-weight ratio, and the ascent phase combustion time, the outer diameter of the end face combustion charge of the descent phase and the combustion chamber pressure of the descent phase are selected according to the actual situation.

[0043] 2. Based on experience, make a preliminary guess at the weight of the engine casing, the weight of the rotatable nozzle 13, the weight of the inert structure, and the weight of the ascending section charge 7.

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

[0045] 4. Use the uniform deceleration exterior ballistics formula to estimate the burning time during the descent phase.

[0046] 5. Under the combustion chamber pressure and atmospheric back pressure in the descent phase, use Newton's method to find the best 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. Use the equilibrium pressure formula to calculate the burning rate of charge 3 in the descending section.

[0049] 8. Calculate the length and weight of the descent section charge 3 based on the descent section burning time.

[0050] 9. Calculate the ascent thrust, also known as the takeoff thrust, based on the takeoff thrust-to-weight ratio.

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

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

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

[0054] 13. Calculate the thickness and weight of the insulation layer based on the total burning 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 completed.

[0057] The lightweight optimization method of vertical landing recyclable solid rocket booster is as follows:

[0058] With the outer diameter of the end burning charge (or the outer diameter of the booster) as the horizontal coordinate and the combustion chamber pressure of the descending section as the vertical coordinate, a phase diagram of the total weight of the booster is drawn in a two-dimensional plane. The lightest design point can be read from the phase diagram.

[0059] Table 1

[0060]

[0061] Index requirements: Payload weight 100kg, take-off thrust-to-weight ratio 3.0, boost phase working time 5s, landing thrust-to-weight ratio 3.0.

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

Claims

1. A vertical landing recoverable solid rocket booster, comprising a combustion chamber for storing a solid propellant charge, characterized in that: The combustion chamber comprises a descending section and an ascending section; The descending section comprises a descending section combustion chamber shell (1), the inner wall of which is provided with a descending section combustion chamber heat insulation layer (2), the descending section combustion chamber shell (1) is filled with descending section charge (3) and is equipped with a descending section igniter (5); an air rudder (4) is provided outside the descending section combustion chamber shell (1); The ascending section comprises an ascending section combustion chamber shell (9), the inner wall of which is provided with an ascending section combustion chamber heat 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 casing (1) and the ascending combustion chamber casing (9), and the two are connected via flanges; The tail of the ascending section is also provided with a landing support (10) and four rotatable nozzles (13), and the four rotatable nozzles (13) are arranged in a "cross" shape.

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

3. The vertical landing recoverable solid rocket booster according to claim 1, characterized in that: The rotatable nozzle (13) is driven by an electromechanical actuator (12) and a connecting rod mechanism (11), and the angle between the axis of each rotatable nozzle (13) and the engine axis can be changed between 0° and 90°. The four rotatable nozzles (13) cooperate with each other to achieve the adjustment of the thrust vector and size.

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