1. A landing leg mechanism for liquid rocket recovery, for supporting a liquid rocket engine during liquid rocket substage recovery, comprising a protective leg uniformly arranged along a circumferential surface of the liquid rocket substage, and a fixing bracket connected with the protective leg for fixing the protective leg on the liquid rocket substage, wherein,

the protection leg comprises a main leg structure and an auxiliary opening mechanism, the auxiliary opening mechanism is used for driving the main leg structure to move towards the outer side far away from the liquid rocket substage, one end of the main leg structure is connected with the fixed support, and the other end of the main leg structure is used for extending and unfolding the main leg structure so as to stabilize the liquid rocket substage to the landing platform.

2. The landing leg mechanism for liquid rocket recovery of claim 1, wherein said main leg structure comprises a booster cylinder and a protective shell located outside said booster cylinder for protecting said booster cylinder.

3. The landing leg mechanism for liquid rocket recovery of claim 2, wherein said protective case comprises a main case and a secondary case of an integrally formed design, said secondary case being located at one end of said main case and adjacent to one side of said fixed bracket.

4. The landing leg mechanism for rocket motor recovery of claim 3, wherein said main housing is a main housing with two ends open and a passage for said boost cylinder to extend and retract is provided inside, one side of said auxiliary housing away from said rocket secondary axis is a conical structure, and the large end side of said conical structure is connected to said main housing.

5. The landing leg mechanism for liquid rocket recovery of claim 1, wherein the booster cylinder comprises a first pneumatic cylinder structure; the auxiliary opening mechanism comprises a second pneumatic cylinder structure, one end of the second cylinder structure is fixedly connected with the secondary side wall of the liquid rocket through a fixing strip, the other end of the second cylinder structure is connected with the main leg structure, and the main leg structure is driven to be opened or folded in an auxiliary mode through the telescopic motion of the second cylinder structure.

6. A landing leg mechanism for liquid rocket recovery as claimed in claim 1, wherein said fixed bracket is further provided with an inner groove for engaging said main leg structure, said inner groove being disposed circumferentially along said fixed bracket and being recessed toward a central side of said fixed bracket.

7. The landing leg mechanism for liquid rocket recovery of claim 1, wherein said stationary bracket comprises a first ring and a second ring equally spaced axially along said liquid rocket substage, said first ring and said second ring each being fixedly attached to a sidewall of said liquid rocket substage; the auxiliary opening mechanism comprises an upper pneumatic cylinder and a lower pneumatic cylinder, one end of the upper pneumatic cylinder and one end of the lower pneumatic cylinder are respectively connected with the first ring body and the second ring body, and the other end of the upper pneumatic cylinder and one end of the lower pneumatic cylinder are respectively connected with the main leg structure; the upper pneumatic cylinder and the lower pneumatic cylinder are used for pushing the main leg structure to move towards the outer side far away from the liquid rocket and jointly stably support the main leg structure.

8. The landing leg mechanism for liquid rocket recovery of claim 1, wherein said main leg structure is connected to said fixed bracket by a connector, wherein,

the connector comprises a sleeve, a first folding part and a second folding part, and connecting holes for connecting the first folding part and the second folding part in a matching manner with a rotating shaft are respectively formed at the ends, close to each other, of the first folding part and the second folding part; one end of the first folding part is connected with the fixed support, the other end of the first folding part is connected with one end of the second folding part, the other end of the second folding part is connected with the main leg structure, the length of the first folding part is larger than that of the second folding part, and the sleeve is sleeved on the first folding part;

before the rocket secondary stage is landed, the main leg structure moves towards the outer side far away from the liquid rocket secondary stage, so that the connector in the folding state is opened, in the process that extension lines of central lines of the first folding part and the second folding part are overlapped, the sleeve moves towards the second folding part, a part of the sleeve is sleeved on the outer side of the second folding part, one end of the sleeve is abutted to the surface of the main leg structure, and the other end of the sleeve is sleeved on the first folding part.

9. The landing leg mechanism for liquid rocket recovery of claim 8, wherein the first fold and the second fold are cylindrical and the sleeve is configured to slide freely along the surfaces of the first fold and the second fold during deployment of the main leg structure; one side, far away from the second folding part, of the sleeve is connected with an elastic piece, the elastic piece is sleeved on the surface of the first folding part, and two ends of the elastic piece are respectively connected with the fixed support and the sleeve; in the process that the main leg structure is unfolded to drive the connector to be unfolded, the elastic piece applies force towards the direction of the main leg structure to the sleeve, so that one end of the sleeve is abutted to the main leg structure.

10. A launch vehicle comprising a landing leg mechanism for recovery of a liquid rocket as recited in any one of claims 1-9.

Background

With the rapid development of the aerospace industry, various technologies related to rockets also realize the rapid advance. Currently, as the primary vehicle for launching satellites into space, the continued reduction in rocket manufacturing and launch costs is a pursuit goal of various large commercial space companies.

Taking rocket recovery as an example, in order to reduce cost, a main body can recover all the sub-stages of the rocket. For example, each substage of the rocket is internally provided with a parachute pack, and when each substage of the rocket is separated, the parachute pack is opened to ensure that each substage of the rocket is safely landed, so that each substage of the rocket is recovered. In order to make each substage of the rocket land more stably and ensure the completeness of internal devices, landing support legs can be designed in each substage of the rocket. By unfolding the landing support legs in the rocket sublevel landing process, each sublevel of the rocket can be assisted to land stably at the landing point, and therefore the fact that devices inside the sublevels are intact is guaranteed. The rocket can be reused after being cleaned, maintained and tested. In order to make efficient use of space and avoid aerodynamic disturbances to the rocket flight process, landing legs can often be designed in a folded configuration. In the landing process of the rocket, the landing leg folding structure is blocked, so that the landing leg cannot be smoothly unfolded, and the rocket is not recovered. In addition, if the landing leg structure is unstable, damage or deflection of the landing leg may be caused when each substage of the rocket lands, and the safe recovery of each substage of the rocket is affected.

Therefore, how to provide a landing leg for a rocket, which has reasonable design, stable structure, safety and reliability, can protect the integrity of a liquid rocket engine, and is a problem to be solved at present.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a landing leg mechanism for recovering a liquid rocket. The structure has reasonable design, stable structure, safety and reliability, and further ensures that the engine in each substage of the rocket is intact so as to be recycled.

One aspect of the present invention provides a landing leg mechanism for liquid rocket recovery, for supporting a liquid rocket engine during liquid rocket substage recovery, comprising a protection leg uniformly disposed along a circumferential surface of the liquid rocket substage, and a fixing bracket connected to the protection leg for fixing the protection leg to the liquid rocket substage, wherein,

the protection leg comprises a main leg structure and an auxiliary opening mechanism, the auxiliary opening mechanism is used for driving the main leg structure to move towards the outer side far away from the liquid rocket substage, one end of the main leg structure is connected with the fixed support, and the other end of the main leg structure is used for extending and unfolding the main leg structure so as to stabilize the liquid rocket substage to the landing platform.

Furthermore, the main leg structure comprises a boosting cylinder and a protective shell which is positioned outside the boosting cylinder and used for protecting the boosting cylinder.

Further, the protective housing comprises a main housing and an auxiliary housing which are integrally formed, and the auxiliary housing is located at one end of the main housing and close to one side of the fixing support.

Furthermore, the main shell is provided with a passage which is communicated with the two ends and is internally provided with the boosting cylinder for stretching, one side of the auxiliary shell, which is far away from the secondary axis of the liquid rocket, is of a conical surface structure, and the large end side of the conical surface structure is connected with the shell main body.

Further, the boosting cylinder comprises a first pneumatic cylinder structure; the auxiliary opening mechanism comprises a second pneumatic cylinder structure, one end of the second pneumatic cylinder structure is fixedly connected with the liquid rocket sublevel side wall through a fixing strip, the other end of the second pneumatic cylinder structure is connected with the main leg structure, and the main leg structure is driven to be opened or closed in an auxiliary mode through the telescopic motion of the second pneumatic cylinder structure.

Further, the fixed bolster still is equipped with and is used for cooperating the inner groovy of main leg structure, the inner groovy is followed fixed bolster circumference sets up and to the central side of fixed bolster is recessed.

Further, the fixed support comprises a first ring body and a second ring body which are arranged at equal intervals along the axial direction of the liquid rocket substage, and the first ring body and the second ring body are fixedly connected with the side wall of the liquid rocket substage; the auxiliary opening mechanism comprises an upper pneumatic cylinder and a lower pneumatic cylinder, one end of the upper pneumatic cylinder and one end of the lower pneumatic cylinder are respectively connected with the first ring body and the second ring body, and the other end of the upper pneumatic cylinder and one end of the lower pneumatic cylinder are respectively connected with the main leg structure; the upper pneumatic cylinder and the lower pneumatic cylinder are used for pushing the main leg structure to move towards the outer side far away from the liquid rocket and jointly stably support the main leg structure.

Further, the main leg structure is connected to the fixed bracket by a connector, wherein,

the connector comprises a sleeve, a first folding part and a second folding part, and connecting holes for connecting the first folding part and the second folding part in a matching manner with a rotating shaft are respectively formed at the ends, close to each other, of the first folding part and the second folding part; one end of the first folding part is connected with the fixed support, the other end of the first folding part is connected with one end of the second folding part, the other end of the second folding part is connected with the main leg structure, the length of the first folding part is larger than that of the second folding part, and the sleeve is sleeved on the first folding part;

before the rocket secondary stage is landed, the main leg structure moves towards the outer side far away from the liquid rocket secondary stage, so that the connector in the folding state is opened, and after extension lines of central lines of the first folding part and the second folding part are overlapped, the sleeve moves towards the second folding part, so that one end of the sleeve is abutted to the surface of the main leg structure.

Further, the first folding part and the second folding part are cylindrical in shape, and the sleeve can freely slide along the surfaces of the first folding part and the second folding part; the connector is in fold condition before opening, the sleeve pipe is kept away from second folding portion one side is connected with the elastic component, the elastic component cover is established first folding portion surface and both ends respectively with the fixed bolster with bushing.

Another aspect of the invention provides a launch vehicle comprising a landing leg mechanism for liquid rocket recovery as described above.

The landing leg of the liquid rocket has at least one of the following technical effects:

(1) the landing leg mechanism for liquid rocket recovery is used for supporting a liquid rocket engine during liquid rocket secondary recovery. The protection legs are uniformly arranged on the circumferential surface of the liquid rocket sublevel, and the supporting mechanism is additionally arranged on the surface of the liquid rocket sublevel, so that the probability of damage to a liquid rocket engine caused by direct contact with a landing platform during sublevel recovery of the liquid rocket can be reduced.

(2) The protection legs are connected with the protection legs through the fixing supports and are used for fixing the protection legs on the liquid rocket sublevels, and the protection legs are firmly fixed through the matching of the fixing supports and the protection legs, so that the protection legs are prevented from moving in the unfolding or folding process, and the safe flight of the liquid rocket is ensured.

(3) The protective leg comprises a main leg structure and an auxiliary opening mechanism for driving the main leg structure to move towards the outside away from the liquid rocket substage. One end of the main leg structure is connected with the fixed support, and the other end of the main leg structure is used for expanding through extension so as to stabilize the liquid rocket sublevel to the landing platform. The auxiliary opening mechanism drives the main leg structure to open, so that on one hand, the opening posture of the main leg structure can be accurately controlled, and the recovery of the liquid rocket sublevel is facilitated; on the other hand, the auxiliary opening mechanism can also play a role in decomposing pressure, so that the pressure borne by the main leg structure is reduced, the main leg structure is prevented from being deformed due to overlarge pressure, and the secondary-level safe recovery of the liquid rocket is ensured.

(4) The landing support leg is reasonable in design, stable in structure, safe and reliable, can ensure that engines of all sub-stages of the rocket are intact in the recovery process, improves the stability of the rocket recovery process, can be recycled, and saves cost.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a schematic view of the construction of a parachuting liquid rocket stage and a protective leg according to a first embodiment of the present invention;

FIG. 2 is a schematic view of the configuration of the liquid rocket substage and the protective legs in a first embodiment of the present invention;

FIG. 3 is a schematic view of the configuration of the liquid rocket substage and the auxiliary opening mechanism in the first embodiment of the present invention;

FIG. 4 is a schematic view of a first embodiment of the present invention with the guard legs open;

FIG. 5 is a schematic view of a fixing bracket according to a first embodiment of the present invention;

FIG. 6 is a schematic view of the construction of a liquid rocket substage and a protective leg according to a second embodiment of the present invention;

FIG. 7 is a schematic view of an auxiliary opening mechanism and connector opening in a second embodiment of the invention;

FIG. 8 is a schematic view of a second embodiment of the invention showing the liquid rocket stages and the protective legs after they have been opened;

FIG. 9 is a schematic view of a connector according to a second embodiment of the present invention;

fig. 10 is a schematic view showing the opening of the connector according to the second embodiment of the present invention.

Description of reference numerals:

1 liquid rocket secondary 2 protection leg

3 main leg structure of fixed support 4

5 auxiliary opening mechanism 6 boosting cylinder

7 protective housing 8 main casing

9 auxiliary shell 10 rotating shaft

11 fixing strip 12 inner groove

13 first ring body 14 second ring body

15 upper pneumatic cylinder and 16 lower pneumatic cylinder

17 connector 18 sleeve

19 first fold 20 second fold

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

One aspect of the present invention provides a landing leg mechanism for liquid rocket recovery, as shown in figures 1, 2, 3, 4 and 5, for supporting a liquid rocket motor during liquid rocket substage 1 recovery. The landing leg comprises protection legs 2 uniformly arranged along the circumferential surface of the liquid rocket substage 1 and a fixing bracket 3 connected with the protection legs 2 and used for fixing the protection legs 2 on the liquid rocket substage 1. The protection legs 2 comprise main leg structures 4 and auxiliary opening mechanisms 5, the auxiliary opening mechanisms 5 are used for driving the main leg structures 4 to move towards the outer sides far away from the liquid rocket substages 1, one ends of the main leg structures 4 are connected with the fixing supports 3, and the other ends of the main leg structures are used for extending and unfolding to stabilize the liquid rocket substages 1 to the landing platform.

In particular, the landing leg mechanism for liquid rocket recovery provided by the embodiment of the invention adds the supporting mechanism on the surface of the liquid rocket secondary stage 1, so that the probability of damage to the liquid rocket engine caused by direct contact between the liquid rocket secondary stage 1 and a landing platform during recovery can be reduced. The protection legs 2 are connected with the protection legs through the fixing supports 3 and are used for being fixed on the liquid rocket sublevel 1, and the protection legs 2 are fixed firmly through the matching of the fixing supports 3 and the protection legs 2, so that the movement of the protection legs is avoided, and the safe flight of the liquid rocket is facilitated.

The protection leg 2 comprises a main leg structure 4 and an auxiliary opening mechanism 5, the auxiliary opening mechanism 5 is used for driving the main leg structure 4 to move towards the outer side far away from the liquid rocket substage 1, one end of the main leg structure 4 is connected with the fixed support 3, the other end of the main leg structure is used for being unfolded through extension to stabilize the liquid rocket substage to a landing platform, and the main leg structure 4 is driven to be opened through the auxiliary opening mechanism 5. The design of the main leg mechanism and the auxiliary opening mechanism can accurately control the opening posture and position of the main leg structure on one hand, and is beneficial to the stable landing of the liquid rocket sublevel in the recovery process; on the other hand, the auxiliary opening mechanism can also play a role in decomposing the pressure on the main pushing structure 4, so that the main leg structure is prevented from deforming due to overlarge pressure, and the safe recovery of the liquid rocket sublevel is ensured.

It should be noted that in the first embodiment, as shown in fig. 1, 2, 3, 4 and 5, the main leg structure 4 includes the boost cylinder 6. In order to protect the booster cylinder 6 from rocket stage or booster cylinder breakage, the main leg structure 4 further comprises a protective casing 7 located outside the booster cylinder 6 for protecting the booster cylinder 6, for example.

It should be noted that, as shown in fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, in order to stabilize the whole structure of the protective casing 7, for example, the protective casing 7 includes a main casing 8 and a sub-casing 9 which are integrally formed, and the sub-casing 9 is located at one end of the main casing 8 and at a side close to the fixing bracket 3.

It should be further noted that, for convenience of use with the boost cylinder 6, for example, the main housing 8 is provided with a passage communicating at both ends and provided with a passage for the boost cylinder 6 to extend and retract. In order to reduce the resistance of air to the protective shell 7 during the flight of the liquid rocket, for example, the side of the secondary shell 9 away from the axis of the liquid rocket secondary 1 is of a conical structure, and the large end side of the conical structure is connected with the shell main body 8.

In the present embodiment, in order to facilitate the opening of the assist cylinder 6, for example, the assist cylinder 6 includes a first pneumatic cylinder structure. For example, the first pneumatic cylinder may be supplied with gas under pressure from a compressed air tank in the liquid rocket to accomplish the expansion and contraction of the first pneumatic cylinder structure.

Further, in the present embodiment, the auxiliary opening mechanism 5 includes a second pneumatic cylinder structure. In order to fix the second cylinder structure and the side wall of the liquid rocket substage 1 firmly, for example, one end of the second cylinder structure is fixedly connected with the side wall of the liquid rocket substage 1 through a fixing strip 11, and the other end is connected with the main leg structure 4, and the main leg structure 4 is driven to open or close by the aid of telescopic motion of the second cylinder structure. It should be noted that the shape of the fixing strip 11 may be a cuboid, and the surface (e.g., curved surface) connected with the side wall of the liquid rocket stage 1 is closely attached to the side wall of the liquid rocket stage, and the two may be fixedly connected by welding or bolts.

In the present embodiment, in order to connect the fixing bracket 3 and the liquid rocket substage 1 tightly and avoid the inclination of the fixing bracket 3, for example, the fixing bracket 3 is connected to the liquid rocket substage 1 along the circumferential inner surface of the liquid rocket substage 1.

It is particularly emphasized that, in order to make the fixing bracket 3 fit with the liquid rocket substage 1 more closely and fix the liquid rocket substage more firmly, for example, the fixing bracket is of a ring body structure (matched with the inner wall of the liquid rocket substage 1) and is screwed on the inner wall of the liquid rocket substage 1 through bolts.

In the present embodiment, for the convenience of the application of the main leg structure 4, the main leg structure 4 is prevented from shaking during the unfolding process (the end of the main leg structure 4 close to the fixed bracket 3 slides along the surface of the fixed bracket 3), for example, the fixed bracket 3 is further provided with an inner groove 12 for matching with the main leg structure 3. The inner groove 12 is circumferentially arranged along the fixed support 3 and is concave downward towards the center side of the fixed support 3, one end of the main leg structure 4 is positioned in the inner groove 12, and the main leg structure 4 is limited to rotate and move along the surface of the fixed support 3 by taking the fixed support 3 as a rotating shaft.

In order to cushion the pressure of the main leg structure 4 when it is in contact with the landing platform, for example, the end of the main leg structure 4 remote from the fixed support is provided with a bumper and a horseshoe-shaped holder connected to the bumper, and the two ends of the bumper are respectively welded to the main leg structure 4 and the horseshoe-shaped holder. In order to further avoid ensuring the buffer to deform in the radial direction in the high-pressure shape, for example, a concave part is arranged at one end of the main leg structure 4 connected with the buffer, and the concave part is concave towards one side far away from the buffer along the axial direction of the main leg structure 4, namely, one end of the buffer is positioned in the concave part, and the concave part plays a role in guiding, so that the buffer is tightly attached to the inner wall of the concave part in the compression or extension process, the radial movement of the buffer is further reduced, and the integrity of the boosting structure is protected. The U-shaped fixer can be provided with a sinking part, the sinking part is concave towards one side far away from the buffer, one end of the buffer is positioned in the sinking part, and the sinking part is used for reducing the probability of deformation of the buffer in the radial direction in high-pressure shape. The sinker is similar to the recess process and will not be illustrated here. In order to ensure the stable structure of the horseshoe-shaped fixer and increase the contact area between the horseshoe-shaped fixer and the landing platform and reduce the sliding probability when the main leg structure 4 is in contact with the landing platform, for example, the horseshoe-shaped fixer is cylindrical, the end face of one end of the horseshoe-shaped fixer is circular, the end face of the other end of the horseshoe-shaped fixer is oval, one side of the circular end face is connected with the buffer, and the oval end face is connected with the landing platform. In the present embodiment, the buffer is a spring, and it is further described that, in order to increase the elastic force of the spring, for example, the spring includes a double-layer spring, i.e., an inner spring and an outer spring, and the outer spring is sleeved outside the inner spring.

The invention also provides a second embodiment which is a further improvement on the first embodiment, as shown in fig. 6, 7, 8, 9 and 10, in the second embodiment, the fixed bracket 3 comprises a first ring body 13 and a second ring body 14 which are arranged at equal intervals along the axial direction of the liquid rocket substage 1, and the first ring body 13 and the second ring body 14 are fixedly connected with the side wall of the liquid rocket substage 1. In order to protect the rocket motor from being damaged during parachute landing when the rocket stages are inclined during landing, for example, the auxiliary opening mechanism may include upper and lower pneumatic cylinders 15 and 16, and the upper and lower pneumatic cylinders 15 and 16 are connected to the first and second rings 13 and 14 at one ends and to the main leg structure at the other ends, respectively. The upper pneumatic cylinder 15 and the lower pneumatic cylinder 16 are used for pushing the main leg structure to move towards the outer side far away from the liquid rocket and stably supporting the main leg structure together.

In a second embodiment, as shown in fig. 6, 7, 8, 9 and 10, in order to tightly connect the main leg structure 4 with the fixed bracket 3, for example, the main leg structure 4 is connected with the fixed bracket 3 by a connector 17. In this embodiment, the connector 17 comprises a sleeve 18, a first folding portion 19 and a second folding portion 20, and the first folding portion 19 and the second folding portion 20 are respectively provided with a connecting hole near each other for connecting the first folding portion 19 and the second folding portion 20 by matching with the rotating shaft 10 (the first folding portion 19 and the second folding portion 20 can rotate along the surface of the rotating shaft 10). The first fold 19 is connected at one end to the fixed bracket 3 and at the other end to one end of a second fold 20, the other end of the second fold 20 being connected to the main leg structure 4.

Before the rocket stage lands, the main leg structure 4 is moved to the outside away from the liquid rocket stage 1 so that the connector 17 in the folded state is opened. The length of the first folded part 19 is greater than that of the second folded part 20, and the sleeve 18 is sleeved on the first folded part 19. When in use, the support of the main leg structure 4 is increased while the connector 17 is opened, for example, when the extension lines of the central lines of the first folding portion 19 and the second folding portion 20 are overlapped (the first folding portion 19 and the second folding portion 20 are in the same straight line after being straightened), the sleeve 18 moves towards the second folding portion 20 (since the sleeve is sleeved on the first folding portion, when the first folding portion 19 and the second folding portion 20 are unfolded and straightened, the sleeve can freely slide along the outer surfaces of the first folding portion 19 and the second folding portion 20, that is, the sleeve slides along the surface of the first folding portion 19 towards the end of the second folding portion 20. since the length of the first folding portion 19 is greater than that of the second folding portion 20, the rotating shaft 10 for connecting the first folding portion 19 and the second folding portion 20 is located inside the sleeve, the first folding portion 19 and the second folding portion 20 can be prevented from rotating along the surface of the rotating shaft 10, and further facilitating the first folding portion 19 and the second folding portion 20 to decompose the pressure on the main leg structure 4, thereby reducing the stress on the main leg structure 4, reducing the deformation probability of the main leg structure 4, facilitating the protection of the engines of each sub-stage of the rocket in the recovery process, and improving the stability of the rocket recovery process), and in the opening process of the connector 17, in order to stabilize the sleeve 18, for example, one end of the sleeve 18 is abutted against the surface of the main leg structure 4.

The sleeve 18 is sleeved outside the first folding part 19 and the second folding part 20, on one hand, the sleeve 18 is designed to prevent the first folding part 19 and the second folding part 20 from rotating along the rotating shaft 10; on the other hand, the rigidity of the whole connector 17 is increased, and the bent connector which is unbent can be avoided. The whole connector 17 can decompose partial pressure borne by the main leg structure 4 and the landing platform, so that the main leg structure 4 is prevented from being deformed due to overlarge pressure at the moment of landing, and the protection of the liquid rocket engine is facilitated.

In an embodiment, the first fold 19 and the second fold 20 are cylindrical in shape, and the sleeve 18 may slide freely along the surfaces of the first fold 19 and the second fold 20; the connector 17 is in a folded state before being opened, and for facilitating the movement of the sleeve, for example, the sleeve 18 is connected to an elastic member at a side thereof away from the second folded portion 20, the elastic member is sleeved on a surface of the first folded portion 19, and both ends of the elastic member are connected to the end surfaces of the fixing bracket 3 and the sleeve 18, respectively. The elastic member may be a spring, a bellows, or the like.

In the present embodiment, the number of the protection legs is 4, but may be 4, 5, 6, or the like in actual use. On the premise of not influencing the set load capacity of the rocket, a large number of experiments show that when A is more than or equal to 4 and less than or equal to 6, the protection of the protection legs on the secondary stage of the rocket can be met, and the safe flight of the rocket is facilitated.

The above embodiments may be combined with each other with corresponding technical effects.

Another aspect of the invention provides a liquid rocket engine including a landing leg mechanism as above for liquid rocket recovery.

The foregoing is merely an illustrative embodiment of the present invention, and any equivalent changes and modifications made by those skilled in the art without departing from the spirit and principle of the present invention should fall within the protection scope of the present invention.