Propulsion stage of a launch vehicle, launch vehicle and method for controlling a propulsion stage

Abstract

The invention relates to a propulsion stage of a launch vehicle, in particular a reusable propulsion stage, comprising a rocket body (2) having longitudinal axis (Z), wherein the propulsion stage (3) is provided with at least one jet propulsion drive (36; 36A, 36B) acting predominantly parallel to the longitudinal axis (Z), and wherein the propulsion stage (3) has a plurality of rotor arrangements (33) which can each be driven by an electrical rotor drive, which has at least one electric motor (33'; 33'A, 33'B), which is electrically conductively connected to at least one power storage unit (62) for the supply of electrical energy, wherein the at least one power storage unit (62) can be shifted within the propulsion stage, characterised in that, for the purpose of said shifting, the at least one power storage unit (62) can be moved in a direction (R) lying perpendicular to the longitudinal axis (Z) in a plane or having a dominant direction component extending in a radial direction perpendicular to the longitudinal axis (Z).

Description

[0001] Propulsion stage of a launch vehicle, launch vehicle and method for controlling a propulsion stage

[0002] TECHNICAL FIELD

[0003] The present invention relates to a propulsion stage of a launch vehicle according to the preamble of claim 1. In particular, the invention relates to a reusable propulsion stage. Furthermore, the invention relates to a launch vehicle with at least one such propulsion stage. Finally, the invention also relates to a method for controlling such a propulsion stage, which is particularly applicable during a free fall of the propulsion stage.

[0004] BACKGROUND OF THE INVENTION

[0005] Launch vehicles intended for flight into space are typically multi-stage, with a first propulsion stage equipped with recoil thrusters propelling the launch vehicle into the upper regions of the troposphere, up to the upper region of the stratosphere, or even beyond, at approximately 50 to 70 km altitude. A second propulsion stage is then ignited, transporting the rocket into orbit or onto an interplanetary trajectory. The first propulsion stage falls back to Earth after the engines burn out, and the second propulsion stage typically burns up upon re-entry into the atmosphere.

[0006] For several years, successful attempts have been made to land first stages equipped with thrusters in a controlled manner after burnout, allowing them to be reused. Such reuse of rocket stages is desirable for economic reasons. The reusable rocket stages known to date land with the aid of controlled operation of their rocket engines and, to ensure sufficient deceleration of these thrusters intended for rocket launch, must be brought into a suitable position during the fall back to Earth. This requires the provision of additional control nozzles. Furthermore, fuel reserves must still be available for the planned landing upon return to Earth (and possibly even upon re-entry into the Earth's atmosphere).

[0007] STATE OF THE ART

[0008] WO 2020 / 094640 A1 discloses a two-stage launch vehicle for space flight. In addition to a thruster, it is equipped with electric ducted fans along the cylindrical first-stage fuselage, whose duct and rotation axes extend orthogonally to the launch vehicle's longitudinal axis. These fans can act as generators during the stage's return to Earth, recharging the batteries for the fan motors. The fans facilitate a controlled landing of the returned stage.

[0009] The provision of electric fans and their associated fan motors in addition to a thruster increases the mass to be transported into space or higher atmospheric layers, thus reducing the launch vehicle's payload. Control of the first stage, which falls back to Earth, is not planned. Only at the beginning of the descent phase, i.e., when the fan motors are activated for the approach and landing to generate lift, does the first stage become controllable again.

[0010] DE 10 2014 010 109 A1 shows and describes a rocket with a central recoil drive provided in a cylindrical rocket body and four electric propeller drives arranged around the rocket body. An electrical energy storage device inside the cylindrical rocket body is designed to be movable along the axis of the rocket body in order to be able to shift the center of gravity of the rocket along the axis. WO 2017 1021 758 A1 shows and describes a multicopter-like carrier aircraft with electrically driven rotors for a rocket, which is designed to bring the rocket to a level of several kilometers in the atmosphere using the rotors of the carrier aircraft, from which the rocket is then launched. The electrical energy for the rotors is supplied from outside the carrier aircraft via cables from the ground or from escort aircraft.

[0011] PRESENTATION OF THE INVENTION

[0012] The object of the present invention is to provide a launch vehicle propulsion stage of this type, as well as a launch vehicle equipped therewith, which is mass-optimized and controllable even during the fall back to Earth before reaching the landing phase. Furthermore, the object of the invention is to provide a method for controlling such a propulsion stage.

[0013] The part of the problem directed at the drive stage is solved by a drive stage having the features of patent claim 1.

[0014] A propulsion stage of a launch vehicle, in particular a reusable propulsion stage, with a rocket body having a longitudinal axis, wherein the propulsion stage is provided with at least one recoil drive acting predominantly parallel to the longitudinal axis and wherein the propulsion stage has a plurality of rotor assemblies, each of which can be driven by an electric rotor drive which has at least one electric motor which is electrically conductively connected to at least one power storage device for supplying electrical energy, and wherein the at least one power storage device is displaceable within the propulsion stage, is characterized according to the invention in that the at least one power storage device is displaceable for the purpose of displacement in a direction which lies in a plane at right angles to the longitudinal axis or which has a dominant directional component which extends in the radial direction at right angles to the longitudinal axis.A thruster is understood here to be a generally known arrangement consisting of a combustion chamber and a rigid or pivoting thruster nozzle, and a rotor assembly is understood to be an atmospheric propeller with propellers or rotor blades that is driven by a rotor drive. The power storage device can comprise accumulators and / or capacitors, for example, so-called supercapacitors (supercapacitors), but it can also comprise at least one fuel cell for generating electrical energy.

[0015] ADVANTAGES

[0016] The actively displaceable arrangement of at least one power storage device inside the propulsion stage relative to the longitudinal axis makes it possible to shift the center of mass of the propulsion stage during flight, particularly during the inherently passive fall of the propulsion stage back to Earth, by actively shifting the power storage device, thereby changing the flight attitude of the propulsion stage in space. Such a change in flight attitude, i.e., a change in the position and orientation of the propulsion stage in space, caused by the active center of gravity shift according to the invention, causes a change in the flight path of the propulsion stage via the resulting change in the aerodynamic airflow to the propulsion stage.The propulsion stage can therefore be steered in flight, particularly during a fall back into and through the atmosphere not influenced by control nozzles or aerodynamic control elements, by actively changing the position of the mass of at least one power storage device, i.e. by actively shifting the center of gravity.

[0017] Further preferred and advantageous design features of the drive stage according to the invention are the subject of subclaims 2 to 8.

[0018] The direction of travel of the power storage device preferably has a dominant directional component that extends radially at right angles to the longitudinal axis. The direction of travel can also lie in a plane that is perpendicular to the longitudinal axis.

[0019] Preferably, the at least one power storage device is movable in a direction extending at an angle between 90° and 60°, preferably between 90° and 75°, to the longitudinal axis.

[0020] It is particularly advantageous if the at least one power storage device can be moved on a rail arrangement.

[0021] Preferably, at least one drive device is provided for moving the at least one power storage device.

[0022] It is particularly advantageous if the at least one drive device designed as an electric motor or having an electric motor is electrically connected to a control or regulating device for moving the at least one power storage device.

[0023] In a preferred development of the propulsion stage, the control and regulation device is part of a flight attitude control system of the propulsion stage and / or the launch vehicle. This makes it possible, particularly during the fall back to Earth, to control or regulate the flight attitude of the propulsion stage by shifting the at least one power storage device within the propulsion stage and thus by shifting the center of mass of the propulsion stage. Such a shift of the center of mass can also be used to a limited extent as part of the control system during the launch vehicle's ascent.

[0024] In an advantageous embodiment of the invention, which can be combined with other embodiments, the rail arrangements each run radially to the longitudinal axis. This variant is particularly advantageous when the drive stage has a plurality of power storage devices. Alternatively, the at least one rail arrangement forms a ring around the longitudinal axis, which is particularly advantageous when only one or two power storage devices are provided. Preferably, a plurality of, for example two, annular rail arrangements can also be provided, preferably concentrically around the longitudinal axis, the respective power storage devices of which can be moved in the same or opposite directions on the respectively assigned annular rail arrangement.

[0025] The part of the task directed at the launch vehicle is solved by a launch vehicle with at least one propulsion stage according to the invention. Thus, the launch vehicle as a whole can also be controlled using the center of mass shift in the propulsion stage.

[0026] To solve the part of the problem directed at the method, a method for controlling a drive stage is provided, which is used in particular during a free fall of the drive stage and which is characterized in that the position of the center of mass of the drive stage is changed by displacing at least one power storage device, thereby changing the flight attitude of the drive stage in space and thus the flight path. Thus, during the flight of the drive stage or during the free fall of the drive stage, a controlled displacement of at least one of the power storage devices is carried out by means of the associated control and regulation device (flight attitude control) in order to thereby displace the center of mass of the drive stage, whereupon the position and, if applicable, also the inclination of the drive stage in space changes.This in turn changes the course of the air flow around the propulsion stage, thereby deflecting the trajectory of the propulsion stage.

[0027] Preferred embodiments of the invention with additional design details and further advantages are described and explained in more detail below with reference to the accompanying drawings.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS It shows:

[0029] Fig. 1 is a vertical section through a first embodiment of a drive stage according to the invention along the line ll in Fig. 2 and

[0030] Fig. 2 shows a horizontal section through the drive stage designed according to the invention along the line ll-ll in Fig. 1.

[0031] PRESENTATION OF PREFERRED EMBODIMENTS

[0032] Fig. 1 shows a vertical section through a launch vehicle 1 with a rocket body 2 having a propulsion stage 3 and an upper stage 4.

[0033] The upper stage 4 is essentially formed by a cylindrical casing 40, which is provided with a foldable or unfoldable conical upper tip 41. In the upper region of the upper stage 4, a payload compartment 42 is formed for accommodating a payload N, which is accessible by folding open the conical tip 41, so that the payload N can be released into space from the payload compartment 42.

[0034] In the lower region of the upper stage 4, i.e., on the underside facing away from the conical tip 41, a propulsion engine 43 is provided, the outlet nozzle 44 of which is directed downwards and arranged coaxially to the vertical longitudinal axis Z of the launch vehicle 1. Between the propulsion engine 43 and the payload compartment 42, a supply compartment 45 is provided, in which a plurality of propellant tanks 46, 46' are arranged. These tanks contain the propellants for operating the propulsion engine 43 of the upper stage and are connected to the propulsion engine 43 of the upper stage via corresponding propellant lines (not shown). The lower region 40' of the cylindrical housing shell 40 of the upper stage 4, facing away from the conical tip 41, engages in a matching cylindrical receiving opening 31 in the top side of the housing shell 30 of the propulsion stage 3 and is removably inserted there. The upper stage 4 is connected to the drive stage 3 in this way in a decoupleable manner.

[0035] The casing shell 30 of the propulsion stage 3 has a spherical sector-like shape with a convex lower wall 30' facing away from the upper stage 4. The reusable first rocket stage of the launch vehicle 1, formed by the propulsion stage 3, has the shape of a flat truncated cone with a convex base, similar to an Apollo capsule. The outer diameter of the propulsion stage 3 is significantly larger than the outer diameter of the cylindrical upper stage 4. In the example shown, the outer diameter of the propulsion stage 3 is approximately four times the outer diameter of the upper stage 4.

[0036] In its radially outer region, near the largest circumferential edge of the housing shell 30 of the propulsion stage 3, a plurality of rotor assemblies 33 (Fig. 2) are provided, axially parallel to the longitudinal axis Z of the launch vehicle 1, spaced apart from one another in the circumferential direction, the respective rotor axes ZR of which run parallel to the longitudinal axis Z of the launch vehicle 1. The rotor assemblies 33 are located within the housing shell 30 and are covered by shell sections 30" of the housing shell 30, which can each be moved radially outwards to operate the associated rotor assembly 33 and thereby release an air duct between themselves and the remaining central part of the housing shell 30, which air duct runs essentially parallel to the longitudinal axis Z and in which at least one rotor assembly is located. In the section shown in Fig.In the example shown in Figure 2, a pair of such rotor arrangements is located in an axially parallel air duct formed in this way, with four radially outwardly movable casing sections 30" being provided, distributed over the circumference at an angle of 90° to one another.

[0037] Alternatively, the housing shell 30 can have a plurality of vertically extending air ducts distributed over the circumference of the drive stage 3, each of which contains a rotor assembly 33. The upper and lower openings of the air ducts can be closed by protective flaps in the area of ​​the housing shell 30.

[0038] Preferably, eight propeller-like rotor assemblies 33 are provided, each electrically driven by a rotor drive with a motor configured as an electric motor (Fig. 2). Each of these rotor assemblies 33 has an upper rotor 34 and a lower rotor 34', which, in a motor-driven operating state, can be driven in the same direction or in opposite directions (depending on the type of the respective propeller-like rotor 34, 34') to generate a vertical airflow—in the lift direction or in the downforce direction.

[0039] Radially within the rotor assemblies 33, a plurality of thrusters 36 are provided in a respective engine compartment, with each thruster 36 being assigned to a rotor assembly 33. The outlet nozzle of the respective thruster 36, forming a thrust nozzle, is directed away from the payload compartment 42 and opens downwards. The engine compartment, which is open downwards during operation of the thrusters 36, can be closed by at least one protective flap (not shown). These protective flaps close the respective engine compartment, particularly during a dive of the reusable propulsion stage 3 back to Earth.

[0040] In a central interior area 37 radially inside and above the engine compartments, a central fuel tank 38 for storing a fuel and an annular fuel tank 38' for storing an oxidizer for supplying the thrusters 36 are arranged.

[0041] Essentially radially outside the recoil drives 36, a power supply unit 6 is provided between each of the circumferentially adjacent pairs of rotor assemblies 33 in those regions of the drive stage 3 that lie between two circumferentially adjacent, radially outwardly movable casing sections 30". Each power supply unit 6 has a rail arrangement 35 that extends in the radial direction and is inclined to the longitudinal axis Z, on at least one rail of which a movable power storage device 62 is displaceably provided. In the example shown, four power supply units 6 are provided with rail arrangements 35 arranged at a circumferential distance of 90° from one another; however, fewer or more power supply units with corresponding rail arrangements and power supply devices can also be provided.The displaceability of the power storage devices 62 in the displacement direction R is symbolically represented by the double arrows in Fig. 1.

[0042] Each power supply unit 6 has a drive device, preferably comprising an electric motor or designed as an electric motor, as a displacement drive 64 for displacing the power storage device 62 along the associated rail arrangement 35. The respective displacement drive 64 is designed, for example, as a spindle drive known per se to those skilled in the art and, for this purpose, has a drive motor and a threaded spindle driven by the drive motor, into which a spindle nut coupled to or fixedly connected to the associated power storage device 62 engages. Other translational drives can also be provided for displacing the power storage device 62 along the associated rail arrangement 35, for example, a linear motor as a translational drive or a toothed belt drive.

[0043] The displacement drives 64 are electrically connected to a common control or regulation device 60, which controls or regulates the translational displacement of the individual power storage devices 62 and thus causes a displacement of the center of mass of the propulsion stage 3. The control or regulation device 60 is part of a higher-level flight attitude control or regulation of the propulsion stage 3 and / or the launch vehicle 1.

[0044] By displacing at least one power storage device 62 in the radial direction - as in the example of the figures - or along an annular rail arrangement not shown in the figures, which is arranged, for example, between the recoil drives 36 and the rotor arrangements 33 concentrically around the longitudinal axis Z, the position of the center of mass of the drive stage 3 is changed, whereby the flight attitude of the drive stage 3 in space and thus its flight path changes.

[0045] Reference signs in the claims, the description and the drawings serve only to improve the understanding of the invention and are not intended to limit the scope of protection.

[0046] List of reference symbols

[0047] They refer to:

[0048] 1 launch vehicle

[0049] 2 rocket bodies

[0050] 3 drive stage

[0051] 4 Upper School

[0052] 6 Power supply unit

[0053] 30 Housing shell of the drive stage

[0054] 30' convex lower wall

[0055] 30" jacket section

[0056] 31 cylindrical receiving opening

[0057] 33 Rotor arrangement

[0058] 33' electric motor

[0059] 33'A electric motor

[0060] 33'B electric motor

[0061] 34 upper rotor

[0062] 34' lower rotor

[0063] 35 Rail arrangement

[0064] 36 recoil drive

[0065] 36A recoil drive

[0066] 36B recoil drive

[0067] 37 central interior area

[0068] 38 central fuel tank

[0069] 38' annular fuel tank

[0070] 40 cylindrical casing of the upper stage

[0071] 40' lower section of the cylindrical casing shell

[0072] 41 conical upper tip

[0073] 42 payload space

[0074] 43 Upper stage recoil drive

[0075] 44 Outlet nozzle 45 Supply chamber

[0076] 46 Fuel tank

[0077] 46' fuel tank

[0078] 60 Control or regulating device

[0079] 62 electricity storage device

[0080] 64 Sliding drive

[0081] N payload

[0082] R direction

[0083] Z longitudinal axis

[0084] ZR rotor axis

Claims

Claims: Propulsion stage of a launch vehicle, in particular a reusable propulsion stage, with a rocket body (2) having a longitudinal axis (Z), wherein the propulsion stage (3) is provided with at least one reaction drive (36; 36A, 36B) acting predominantly parallel to the longitudinal axis (Z), and wherein the propulsion stage (3) has a plurality of rotor assemblies (33), each of which can be driven by an electric rotor drive, which has at least one electric motor (33'; 33'A, 33'B) that is electrically connected to at least one energy storage device (62) for supplying electrical energy, wherein the at least one energy storage device (62) is displaceable within the propulsion stage, characterized in that the at least one energy storage device (62) is movable for the purpose of displacement in a direction (R) which lies in a plane perpendicular to the longitudinal axis (Z) or which has a dominant directional component.extending radially at right angles to the longitudinal axis (Z). Drive stage according to claim 1, characterized in that the at least one energy storage device (62) is movable in a direction (R) extending at an angle (a) between 90° and 60°, preferably between 90° and 75°, to the longitudinal axis (Z). Drive stage according to claim 1 or 2, characterized in that the at least one energy storage device (62) is movable on a rail arrangement (35). Drive stage according to claim 3, characterized in that that at least one drive unit (64) is provided for moving the at least one energy storage unit (62). Drive stage according to claim 4, characterized in that the at least one drive unit (64) is electrically connected to a control unit (60) for moving the at least one energy storage unit (62). Drive stage according to claim 5, characterized in that the control unit (60) is part of a flight attitude control unit of the drive stage (3) and / or the launch vehicle (1). Drive stage according to any one of claims 3 to 6, characterized in that the rail arrangements (35) extend radially to the longitudinal axis (Z). Drive stage according to any one of claims 3 to 6, characterized in that the at least one rail arrangement forms a ring around the longitudinal axis (Z). Launch vehicle with at least one drive stage (3) according to any one of the preceding claims.Method for controlling a drive stage according to one of claims 1 to 8, in particular in the case of a free fall of the drive stage, characterized in that. that by relocating at least one energy storage device (62) the position of the center of mass of the drive stage (3) is changed, thereby changing the flight attitude of the drive stage (3) in space and thus the flight path.

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