Patent Publication Number: US-2023140889-A1

Title: Separable clamped hdrm interface for managing torsion loads

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application for patent claims priority to EP Application No. EP21207532.9 entitled “A SEPARABLE CLAMPED HDRM INTERFACE FOR MANAGING TORSION LOADS” filed on Nov. 10, 2021, assigned to the assignee hereof, and expressly incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a Hold Down Release Mechanism, HDRM, interface, as well as a method for mounting a spacecraft to an adjacent structure of a launch vehicle or of another spacecraft using a singular or plurality of HDRM interfaces. 
     The HDRM interface according to the disclosure can be arranged for releasably attaching a spacecraft, such as a satellite or spaceship to a launch vehicle, such as a rocket or high altitude airplane. 
     The HDRM interface comprises first and second connector parts that are arranged to be separated on command, for example via pyrotechnical separation bolt or the like. 
     BACKGROUND 
     A carrier rocket may be used as a launch vehicle for transporting one or more spacecrafts, such as satellites or payloads, into space. The carrier rocket typically consists of several engine stages, which one at a time propel the rocket so as to carry it to an orbital point where the satellite is separated from the carrier rocket. During launching, when one rocket carrier engine stage is expended the next one takes over, whereupon the part of the carrier rocket comprising the expended engine stage detaches from the rest of the carrier rocket. 
     A spacecraft carrier structure, such as for example a dispenser structure or an adapter structure, is typically mounted above the engine stage, which powers the carrier rocket the final part of its path towards the orbital point where the spacecraft is to be detached. The dispenser/adapter structure have for example the shape of a hollow cylinder or a straight truncated, circular cone, or the like. The dispenser/adapter structure acts as an interface between the carrier rocket and spacecraft and the spacecraft is attached to the dispenser/adapter structure by means of a singular or plurality of individual releasable connections, known as Hold Down Release Mechanism, HDRM, interfaces. A HDRM interface comprises first and second connector parts that are clamped together by a release bolt or the like, for example a pyrotechnical release bolt. 
     During spacecraft separation, a release bolt of the HRDM interface is activated, whereby the first and second connector parts of the each HDRM interface becomes disconnected substantially simultaneously, and the spacecraft becomes separated from the dispenser/adapter structure. 
     One example design of a cup and cone multi-point HDRM interface is known from document US 2011/113605 A1. 
     However, in the field of HDRM interfaces for single-point or multi-point releasably attachment of a spacecraft to the dispenser/adapter structure, there is a continuous demand for further improved HDRM interfaces in terms of various operating parameters, such as robustness, reliability, low weight, manufacturing cost, play-free connection and force transfer capability. 
     SUMMARY 
     An object of the present disclosure is to provide a separable clamped interface with improved management of torsion loads. The interface may be referred to as a Hold Down Release Mechanism, HDRM, interface. A further object of the present disclosure is to provide a method for mounting a spacecraft to an adjacent structure of a launch vehicle or of another spacecraft using a singular or plurality of HDRM interfaces with improved management of torsion loads. This object is at least partly achieved by the features of the independent claims. 
     According to a first aspect of the present disclosure, there is provided a Hold Down Release Mechanism, HDRM, interface for attachment of a spacecraft to an adjacent structure of a launch vehicle or of another spacecraft, wherein the HDRM interface is configured for forming part of a single-point or multi-point releasable attachment of the spacecraft to said adjacent structure. The HDRM interface comprising a first connector part and a second connector part, wherein one of the first and second parts is configured to be fastened to said adjacent structure, and the other of the first and second parts is configured to be fastened to the spacecraft, wherein the first connector part has a tapered projection with a non-circular external surface, wherein the second connector part has a matching formed tapered recess with a non-circular interior surface configured for form-lockingly receiving the tapered projection, for enabling transfer of at least torsion load and shear load between the first and second connector parts, when the projection is inserted in the recess and the first and second connector parts are pressed together, and wherein both the tapered projection of the first connector part and the tapered recess of the second connector part have a central through-hole for receiving a release bolt configured to clamp the first and second connector parts together. 
     According to a second aspect of the present disclosure, there is provided a method for mounting a spacecraft to an adjacent structure of a launch vehicle or of another spacecraft using a singular or plurality of Hold Down Release Mechanism, HDRM, interfaces forming part of a single-point or multi-point attachment of the spacecraft to said adjacent structure. The method comprising: providing a singular or plurality of HDRM interfaces, each having a first connector part having a tapered projection with a non-circular external surface and a central through-hole, and a second connector part having a matching formed tapered recess with a non-circular interior surface configured for form-lockingly receiving the tapered projection, for enabling transfer of at least torsion load and shear load between the first and second connector parts, when the projection is inserted in the recess and the first and second connector parts are pressed together, wherein also the second connector part has central through-hole; providing a singular or plurality of release bolts and inserting a release bolt through the central through hole of the first and second connector parts of each of the singular or plurality of HDRM interfaces and clamping the first and second connector parts together by means of said release bolt to form a singular or plurality of assembled HDRM interfaces; and attaching one of the first and second parts of the singular or plurality of HDRM interfaces to said adjacent structure and attaching the spacecraft to the other of the first and second parts of the singular or plurality of HDRM interfaces. 
     Prior art multi-point HDRM interface solutions known as cup &amp; cone design generally includes first and second connectors parts having the shape of a cup and a cone, respectively, that are circular symmetric for enabling simplified mounting and assembly and for enabling transfer shear loads over the connector parts while cancelling rotational stiffness. 
     However, it has been determined that, even if the conventional cup and cone interface provides excellent shear load transfer capability, the lack of rotational support of the conventional cup and cone design may be undesirable in certain implementations, such as for example when carrying spacecrafts having relatively low internal structural stability, because these types of spacecrafts may then be structurally damaged when being exposed to high torsional loads. 
     The HDRM interface according to the disclosure solves this problem by combining the excellent shear load transfer capability of the cup and cone interface with torsional load transfer capability, thereby supporting the spacecraft against structural damages caused by torsional loads acting on the spacecraft, especially in the region adjacent the HDRM interface. 
     In other words, the HDRM interface according to the disclosure solves the problem by providing a form-locking structure between the first and second connector parts that is able to transfer a torsion load over the joint and still allow for a reliable separation. 
     It has come to the inventor’s knowledge that such needs exists, since some spacecraft are designed such that they generate a relatively high, and possibly damaging, torsion load at the separable interface joint, and that such relatively high torsion load cannot be transferred with a classical cylindrical cup and cone interface. 
     It has also come to the inventor’s knowledge that merely providing the conventional circular cup and cone interface with serrated plates or similar type of rotational-locking means at flat surfaces arranged in a plane perpendicular to an intended release direction, i.e. displaced from the lateral cup and cone surface, generally results in rotational play between the cup and cone interface due to the difficulty in manufacturing such an cup and cone interface. Specifically, it has been found that it particularly difficult to provide a play-free connection between the conventional circular cup and cone interface while simultaneously providing a play-free connection between the rotational-locking plates of the first and second connector parts. 
     These problems are at least partly solved by the HDRM interface according to the disclosure, by providing the HDRM interface with first connector part having a tapered projection with a non-circular external surface and the second connector part with a matching formed tapered recess with a non-circular interior surface configured for form-lockingly receiving the tapered projection, for enabling play-free transfer of at least torsion load and shear load between the first and second connector parts. 
     The problems of the prior art cup and cone interface solutions, such as play-free torsional locking, highly complex interface with difficult and costly manufacturing, challenges in the many tolerances at the interface, increased part count, and/or increased cost and weight, are thus at least partly overcome. 
     Further advantages are achieved by implementing one or several of the features of the dependent claims. 
     In some example embodiments, a lateral surface area of the tapered projection of the first connector part is defined by a set of substantially flat lateral sides, specifically an odd number of lateral sides, and more specifically three lateral sides, mutually connected via sharp or rounded or bevelled lateral edges, i.e. corner regions, and wherein a lateral surface area of the tapered recess of the second connector part is defined by a set of substantially flat lateral sides, specifically an odd number of lateral sides, and more specifically three lateral sides, mutually connected via sharp or rounded or bevelled lateral edges, i.e. corner regions. Insert advantages here and below. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, the tapered projection of the first connector part has a shape of truncated or non-truncated pyramid with odd number of main lateral sides, and the tapered recess of the second connector part has the shape of an inverse truncated or non-truncated pyramid with odd number of main lateral sides. 
     The pyramid shape enables transfer of both torsion and shear loads and has no play in the mounted state due to the three-sided configuration. A four-sided pyramid would generally not provide similarly play-free connection due to manufacturing tolerance outcome and the over-determined design. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, the tapered projection of the first connector part has the shape of a truncated or non-truncated substantially triangular pyramid, and the tapered recess of the second connector part has the shape of a truncated or non-truncated inverse substantially triangular pyramid. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, the tapered projection of the first connector part has the shape of a truncated triangular pyramid, and the tapered recess of the second connector part has the shape of a truncated inverse triangular pyramid. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, an exterior outline of a cross-section of the tapered projection of the first connector part, in a plane perpendicular to a release direction of the HDRM interface, has three substantially straight lateral sides that are mutually connected by sharp or rounded and/or bevelled lateral edges, i.e. corners. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, an exterior outline of a cross-section of the tapered recess of the second connector part, in a plane perpendicular to a release direction of the HDRM interface, has three substantially straight lateral sides that are mutually connected by rounded and/or bevelled lateral edges, i.e. corners. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, an exterior outline of a cross-section of the tapered projection of the first connector part, in a plane perpendicular to a release direction of the HDRM interface, has three substantially straight sides with substantially equal length. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, an effective minimal contact length of a straight side of an exterior outline of a cross-section of the tapered projection of the first connector part, in a plane perpendicular to a release direction of the HDRM interface, is at least 50%, specifically at least 75%, and more specifically at least 90%, of a length of oppositely facing straight side of the tapered recess of the second connector part, in said plane. A high level of contact length provides improved coupling and force-transfer between the first and second connector parts. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, an effective minimal total contact length of an exterior outline of a cross-section of the tapered projection of the first connector part, in a plane perpendicular to a release direction of the HDRM interface, is at least 50%, specifically at least 75%, and more specifically at least 90%, of a length of oppositely facing interior outline of a cross-section of the tapered recess of the second connector part, in said plane. A high level of contact length provides improved coupling and force-transfer between the first and second connector parts. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, an exterior surface of a flat side of the tapered projection of the first connector part define a tapering angle, relative to a release direction of the HDRM interface, in the range of 5 - 45°, specifically in the range of 10 - 30°. This tapering angle generally provides high level of shear transfer capability while still enabling smooth and reliable separation of the HDRM interface. 
     In some example embodiments, that may be combined with any one or more of the above-described embodiments, the non-circular external surface of the tapered projection of the first connector part, and the matching formed tapered recess of the second connector part, jointly provides a play-free connection between the first and second connector parts, when the projection is inserted in the recess and the first and second connector parts are pressed together by a release bolt or the like. Thereby, stress concentration and vibrations of the spacecraft structure will not be equally problematic for the HDRM interface. 
     The disclosure also relates to a launch vehicle having a longitudinal direction and a radial direction and comprising a dispenser structure carrying at least one spacecraft, which is releasably attached to an adjacent structure of a launch vehicle or of another spacecraft by means of a singular or plurality of HDRM interfaces in a single-point or multi-point attachment of the spacecraft for enabling controlled release of the at least one spacecraft, wherein each of the singular or plurality of HDRM interfaces is defined according to any of the embodiments described above, wherein one of the first and second parts of each of the singular or plurality of HDRM interfaces is fastened to the said adjacent structure, and the other of the first and second parts of each of the singular or plurality of HDRM interfaces is fastened to the spacecraft, and wherein a release bolt extends through the central through-holes of the first and second connector parts of each of the singular or plurality of HDRM interfaces and clamps said parts together. 
     Further features and advantages of the invention will become apparent when studying the appended claims and the following description. The skilled person in the art realizes that different features of the present disclosure may be combined to create embodiments other than those explicitly described hereinabove and below, without departing from the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The HDRM interface and associated method according to the disclosure will be described in detail in the following, with reference to the attached drawings, in which: 
         FIG.  1    shows a launch vehicle carrying a dispenser structure and a plurality of spacecrafts, 
         FIG.  2    shows a dispenser structure with a single spacecraft, 
         FIG.  3    shows a dispenser structure with multiple spacecrafts, 
         FIG.  4    shows a cross-section of a spacecraft attachment via HDRM interfaces, 
         FIG.  5    shows the torsion load acting on a spacecraft, 
         FIG.  6 A  shows a spacecraft attached to another spacecraft carried by the launch vehicle, 
         FIG.  6 B  shows a cross-section of the launch vehicle of  FIG.  6 A , 
         FIGS.  7 A- 9 B  show various views of an example embodiment of the HDRM interface, 
         FIG.  10    shows a section line through a connector part, 
         FIG.  11 A -13Bshow a cross-sections of various example embodiments of the HDRM interface in connected and separated state, 
         FIGS.  14 - 25    show cross-sections of various example embodiments of the HDRM interface in connected state, and 
         FIG.  26    shows the main steps for mounting a spacecraft to an adjacent structure of a launch vehicle or of another spacecraft using a plurality of HDRM interfaces. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Various aspects of the disclosure will hereinafter be described in conjunction with the appended drawings to illustrate and not to limit the disclosure, wherein like designations denote like elements, and variations of the described aspects are not restricted to the specifically shown embodiments, but are applicable on other variations of the disclosure. 
       FIG.  1    schematically shows a side view of one example embodiment of a launch vehicle  1  comprising a dispenser structure  2 , with a set of spacecrafts  3 . The launch vehicle  1  has an extension in a longitudinal direction  4  and a radial direction  5 , a final engine structure  6 , also known as an upper stage, and a fairing  7  covering the dispenser structure  2  and spacecrafts  3 . A lower side of the dispenser structure  2  may be bolted to the final engine structure  5  and configured for carrying a plurality of spacecrafts  3  during their transport from earth to space. 
     In the example illustrated in  FIG.  1   , the dispenser structure  2  may have a cylindrical shape with an axial direction parallel with the longitudinal direction  4  of the launch vehicle  1 . The dispenser structure  2  may have a plurality of spacecrafts  3  mounted around its cylindrical outer surface, as well as on a top side thereof. 
     A spacecraft  3  mounted on the cylindrical surface of the dispenser structure  2  may be configured to the be released sideways, as illustrated by first release arrows  9 , and a spacecraft  3  mounted on the top side of the dispenser structure  2  may be configured to the be released forwards, i.e. in the longitudinal direction  4 , as illustrated by second release arrow  10 . However, depending the design of the dispenser structure  2 , spacecraft  3  and launch vehicle  1 , the release direction of a spacecraft  3  may be different from the longitudinal and radial directions  4 ,  5  of the launch vehicle  1 , and may be virtually any direction relative to a launch vehicle  1 . 
     According to the example embodiment, a plurality of Hold Down Release Mechanism, HDRM, interfaces  8  are used for attachment of at least one spacecraft  3  to an adjacent structure of the launch vehicle, such as the dispenser structure  2 . The HDRM interface  8 , which is also known as separator device, typically include at least a first connector part  11  and a second connector part  12 , wherein one of the first and second parts  11 ,  12  is configured to be fastened to the dispenser structure  2 , and the other of the first and second parts  11 ,  12  is configured to be fastened to the spacecraft  3 . 
     The release of a spacecraft  3  is typically performed after the launch vehicle  1  has set the spacecraft  3  in a proper position and after the fairing  7  has been removed. The HDRM interface  8  may include a release mechanism that enables separation of the first and second connector parts  11 ,  12  from each other, for example via a pyrotechnical device. The release of the spacecraft is for example controlled by an electrical signal and all HDRM interfaces  8  holding the same spacecraft are released simultaneously for ensuring a safe release of the spacecraft from the dispenser structure  2  and launch vehicle  1 . 
     The launch vehicle  1  is for example a space rocket having multiple propulsion stages. 
     The dispenser structure  2  may have virtually any form and shape and serve to mount the spacecraft to the launch vehicle. 
     The spacecraft  3 , also known as a payload, may be various types of apparatus or equipment configured for being located and operating in space, such as orbiting satellites, space exploration spacecrafts, etc. 
       FIG.  2    shows a perspective side view of an example embodiment of a cylindrical hollow dispenser structure  2  having a bottom side  14  for attachment to the launch vehicle  1  and a top side  15 , plurality of attachment rings  13  for mounting a plurality of spacecrafts thereto. However, in  FIG.  2    only a single spacecraft  3  in mounted state is shown. In the example embodiment of  FIG.  2   , four individual HDRM interfaces  8  are used for releasably attaching the spacecraft  3  to the dispenser structure, but other number of HDRM interfaces  8  may be alternatively be used, depending on the specific circumstances and requirements and type of spacecraft, etc. 
       FIG.  3    shows a top view of an example embodiment of a cylindrical hollow dispenser structure  2  having a plurality of spacecrafts  3  mounted thereto. Each spacecraft  3  is releasably mounted to the dispenser structure  2  via a multi-point attachment using a plurality of separate HDRM interfaces  8 . The first release arrows  9  in  FIG.  3    illustrates the release direction of the individual spacecrafts  3 . 
       FIG.  4    schematically shows a cross-sectional view of an example embodiment of a cylindrical hollow dispenser structure  2  having an attachment ring  13  attached thereto for enabling mounting of at least one spacecrafts  3  thereto. Each HDRM interface  8  comprises first and second connector parts  11 ,  12  assembled and clamped together by means of a release mechanism  16  including a release bolt. The first connector part  11  has a tapered projection  19  with a non-circular external surface, and the second connector part  12  has a matching formed tapered recess  20  with a non-circular interior surface configured for rotational form-lockingly receiving the tapered projection  19 , for enabling transfer of at least torsion load and shear load between the first and second connector parts  11 ,  12 , when the projection  19  is inserted in the recess  20  and the first and second connector parts  11 ,  12  are pressed together. 
     Upon release activation of the release mechanism  16 , the first and second connector parts  11 ,  12  become released from the each other and the spacecraft  3  may become separated from the dispenser structure  2  and associated attachment ring  13 . 
       FIG.  5    schematically shows a spacecraft  3  mounted to attachment rings  13  of a dispenser structure  2  via four individual HDRM interfaces  8 . During launch of and flight of the launch vehicle, the spacecraft  3  is exerted to high acceleration forces, which may cause the spacecraft to deform structurally, as schematically illustrated by the dotted curved lines in  FIG.  5   , unless the HDRM interfaces  8  are capable of providing rotational support to the spacecraft  3 . In other words, the HDRM interfaces  8  according to the disclosure blocks rotational motion of the spacecraft at the attachment location of the HDRM interfaces  8 , as illustrated by rotational arrows  17  in  FIG.  5   , and thereby also assists in preventing torsional deformation of the spacecraft that may cause permanent damage or weakening of the structural rigidity of the spacecraft. 
       FIG.  6 A  illustrates schematically another implementation of the HDRM interface  8  according to the disclosure, namely as an interface for attachment of a spacecraft  3  to an adjacent structure of another spacecraft  54  that is carried by the launch vehicle  1 . 
     In  FIG.  6 A , the launch vehicle  1  carries two spacecrafts  3 : A lower spacecraft  54  attached to the final engine stage structure  6  of the launch vehicle  1  via a first set of HDRM interfaces  8 , and an upper spacecraft  3  attached to the lower spacecraft  54  via a second set of HDRM interfaces  8 . 
     The lower spacecraft  54  attached to the final engine stage structure  6  via a dispenser structure  2 , which is also sometimes referred to as an adapter structure, and represents all types of rigid intermediate superstructure used as carrier structure for connecting a spacecraft  3 ,  54  to a launch vehicle  1 . 
     The HDRM interfaces according to the disclosure may thus be used both for attachment of a spacecraft  54  to an adjacent structure of an adapter structure, and for attachment of a spacecraft  3  to an adjacent structure of another spacecraft  54 . 
       FIG.  6 B  shows a cut along section A-A in  FIG.  6 A , and shows schematically a cross-section of the upper spacecraft  3 , as well as the underlying second set of HDRM interfaces  8 , which may include for example include four virtually identical and evenly distributed HDRM interfaces  8 . 
     Consequently, with reference to  FIG.  1    - 6B, the present disclosure relates to a HDRM interface  8  for attachment of a spacecraft  3  to a launch vehicle  1 , in particular to a dispenser structure  2  or adapter structure of a launch vehicle  1 , or attachment of a spacecraft  3  to another spacecraft  54  carried by the launch vehicle. The HDRM interface  8  is configured for forming part of multi-point releasable attachment of the spacecraft  3  to said launch vehicle  1  or another spacecraft  54 . The HDRM interface  8  comprises a first connector part  11  and a second connector part  12 , wherein one of the first and second parts  11 ,  12  is configured to be fastened to said launch vehicle  1  or to another spacecraft  54 , and the other of the first and second parts  11 ,  12  is configured to be fastened to the spacecraft  3 . The first connector part  11  has a tapered projection  19  with a non-circular external surface, and the second connector part  12  has a matching formed tapered recess  20  with a non-circular interior surface configured for form-lockingly, specifically rotational form-lockingly, receiving the tapered projection  19 , for enabling transfer of at least torsion load and shear load between the first and second connector parts  11 ,  12 , when the tapered projection  19  is inserted in the recess  20  and the first and second connector parts  11 ,  12  are pressed together. Furthermore, both the tapered projection  19  of the first connector part  11  and the tapered recess  20  of the second connector part  12  have a central through-hole for receiving a release bolt configured to clamp the first and second connector parts  11 ,  12  together. 
     The feature stating that the first connector part  11  has a tapered projection  19  with a non-circular external surface means that a cross-section of the tapered projection  19 , in a plane that is perpendicular to a projection direction of the tapered projection  19 , has a non-circular external surface, because this ensure that the tapered projection provides rotational form-locking when engaged in the matching recess  20 . 
     In other words, the tapered projection  19  may be deemed having finite rotational symmetry, i.e. a limited amount of angular positions having identical external surface shape. 
     One example embodiment of the HDRM interface, including the first and second connector parts  11 ,  12 , is described below with reference to  FIGS.  7 A- 7 B,  8 A- 8 B and  9 A- 9 B , wherein  FIGS.  7 A and  7 B  show perspective views of the first and second connector parts  11 ,  12 , respectively,  FIGS.  8 A and  8 B  show top views of the first and second connector parts  11 ,  12 , respectively,  FIG.  9 A  shows a cross-sectional perspective view of the first and second connector parts in disconnected state, and  FIG.  9 B  shows a cross-sectional perspective view of the first and second connector parts in connected state. 
     The tapered projection  19  of the first connector part  11  has the shape of a truncated substantially triangular pyramid, and the tapered recess  20  of the second connector part  12  has the shape of a truncated inverse substantially triangular pyramid. 
     As mentioned above, both the tapered projection  19  of the first connector part  11  and the tapered recess  20  of the second connector part  12  have a central through-hole  22 ,  23  for receiving a release bolt configured to clamp the first and second connector parts  11 ,  12  together. 
     The HDRM interface has a release direction  21 , i.e. a direction along which one or both of the first and second connectors parts is configured to move during a release event of the HDRM interface. The release direction  21  is generally parallel with an axial direction of the central through-hole  22  of the tapered projection  19  and the central through-hole  23  of the tapered recess  20 . 
     The truncated triangular pyramid-shaped tapered projection  19  of the first connector part  11  has a substantially triangular base  24 , three lateral sides  25 , three lateral edges  26 , wherein each lateral edge  26  connects two neighbouring lateral sides  25 . The top side  27  of the pyramid is truncated, i.e. made flat or at least substantially flat. 
     The lateral edges  26  are rounded for enabling use of rounded edges in the recess  20  of the second connector part  12 , thereby simplifying manufacturing of the recess  20  using cutting tools. The rounded lateral edges  26  of the projection also assists in reducing stress concentrations. 
     Due to the above-mentioned rounded edges  26  the base of the pyramid is not fully triangular in terms of strict polygon geometrical form having only straight lines, but rather substantially triangular. However, the overall shape of the pyramid-shaped tapered projection is clearly triangular. Hence, the first connector part  11  may be deemed having the shape of a truncated triangular pyramid. 
     The inverse truncated triangular pyramid-shaped tapered recess  20  of the second connector part  12  has a substantially triangular opening  28 , three lateral sides  29 , three lateral edges  30 , wherein each lateral edge  30  connects two neighbouring lateral sides  29 . The bottom side  31  of the inverse pyramid is truncated, i.e. made flat or at least substantially flat. 
     The lateral edges  30  are rounded for simplifying manufacturing of the recess  20  using cutting tools. The rounded lateral edges  30  of the recess also assists in reducing stress concentrations. 
     Due to the above-mentioned rounded edges  30  the opening  28  of the inverse pyramid is not fully triangular in terms of strict polygon geometrical form having only straight lines, but rather substantially triangular. However, the overall shape of the inverse pyramid-shaped tapered recess  20  is clearly triangular. Hence, the second connector part  12  may be deemed having the shape of a truncated inverse triangular pyramid. 
     The three lateral sides  25  of the pyramid and three lateral sides  29  of the recess  19  are flat to provide good rotational form-locking between the tapered projection  19  and tapered recess  20 , for enabling transfer of high torsion load. 
     The triangular pyramid-shaped tapered projection  19  of the first connector part  11 , the inverse triangular-shaped tapered recess  20  of the second connector part  12  provides a reliable form-locking feature that is able to transfer a torsion load over the HDRM interface, while still enabling a reliable separation. It has come to the inventor’s knowledge that such needs exist, since some spacecrafts are designed such that they generate a relatively high torsion load at the separable interface joint, i.e. at the HDRM interface. Such torsion load cannot be transferred with a conventional non-rotationally locked cup and cone interface. The present disclosure replaces the conventional circular cup and cone design with a three-sided pyramid-shaped HDRM interface. The pyramid shape allows for transfer of high torsion loads combined with transfer of high shear loads. 
     Furthermore, due to the pyramid-shaped interface being three-sided, the HDRM interface provides a rotationally locked connection free from play that is otherwise generally difficult to achieve due to manufacturing tolerances in the mounted state. For example, a four-sided pyramid-shaped tapered projection  19  would typically not provide an equally play-free connection because manufacturing tolerances will often generate a certain level of play between two of the four lateral sides  25 ,  29 . Keeping the play between the first and second connector parts  11 ,  12  at a minimum level is generally desirable in view of the dynamic environment the HDRM interfaces are subjected to and for which the HDRM interface shall be qualified. 
     Consequently, the non-circular external surface of the tapered projection  19  of the first connector part  11 , and the matching formed tapered recess  20  of the second connector part  12 , jointly provides a play-free connection between the first and second connector parts  11 ,  12 , when the projection  19  is inserted in the recess  20  and the first and second connector parts  11 ,  12  are pressed together by a release bolt  47  or the like. 
     The terms lateral side and lateral edge herein refers to sides and edges directed or facing sideways of the first and second connector parts  11 ,  12 . In other words directed or facing in a direction primarily associated with a direction perpendicular to said release direction  21 , or at least directed or facing in a direction having a component that is perpendicular to said release direction  21 . 
     The first connector part  11  may have a first attachment flange  32  for attachment to an adjacent structure of the spacecraft  3  or launch vehicle  1 . The first attachment flange  32  may for example have a plurality of free-running or threaded holes  33  for receiving fasteners, such as threaded members or bolts, for attaching the first connector part  11  to an adjacent structure of an object. 
     Similarly, the second connector part  12  may have a second attachment flange  34  for attachment to an adjacent structure of the spacecraft  3  or launch vehicle  1 . The second attachment flange  34  may for example have a plurality of free-running or threaded holes  35  for receiving fasteners, such as threaded members or bolts, for attaching the second connector part  12  to an object. 
     The first connection part  11  may further have a forward facing surface  36  located next to the projection  19 . This forward facing surface  36  may form part of the first attachment flange  32 . Similarly, the second connection part  12  may also have a forward facing surface  37  located next to the recess  20 . The forward facing surface  36  of the first connector part  11  will face, and possibly abut, the forward facing surface  37  of the second connector part  12 . The forward facing surface  37  of the second connector part  12  may form part of the second attachment flange  34 , or forming a protrusion on the second attachment flange  34 . 
     According to some example embodiments, one, or both, of said forward facing surfaces  36 ,  37  of the first and second connection parts  11 ,  12 , will be substantially free from structures or features that provide rotational-locking between the first and second connector parts  11 ,  12  in mutually connected state. For example, one, or both, of said forward facing surfaces  36 ,  37  of the first and second connection parts  11 ,  12 , may be substantially flat for avoiding any type of rotational-locking between the first and second connector parts  11 ,  12  in mutually connected state. 
     Consequently, rotational locking is solely provided by the tapered projection and the matching formed tapered recess configured for rotational form-locking connection of the first and second connector parts  11 ,  12 . By providing rotational form-locking solely by means of the projection/recess, any undesirable interference in terms of rotational locking of the first and second connector parts  11 ,  12 , caused by the forward facing surfaces  36 ,  37  of the first and second connection parts  11 ,  12 , is avoided, thereby reducing risk for undesirable play between the first and second connector parts  11 ,  12 , in mutually connected state. 
     Similarly, according to some example embodiments, one or both of the top side  27  of the pyramid and the bottom side  31  of the inverse pyramid will be substantially free from structures or features that provide rotational-locking between the first and second connector parts  11 ,  12  in mutually connected state. For example, one or both of the top side  27  of the pyramid and the bottom side  31  of the inverse pyramid may be substantially flat for avoiding any type of rotational-locking between the first and second connector parts  11 ,  12  in mutually connected state. Consequently, rotational locking is solely provided by the tapered projection and the matching formed tapered recess configured for rotational form-locking connection of the first and second connector parts  11 ,  12 , thereby reducing risk for undesirable play between the first and second connector parts  11 ,  12 , in mutually connected state, as described above. 
       FIG.  10    shows schematically a top view of the first connector part  11  with tapered projection  19 , as well as a cross-sectional line B-B extending over the projection  19  for better describing the form and function of the projection and recess of the HDRM interface. Specifically, a cross-section of one example embodiment of the HDRM interface along section B-B is illustrated in  FIGS.  11 A and  11 B , wherein  FIG.  11 A  shows the HDRM interface in connected state, and  FIG.  11 B  shows the HDRM interface in disconnected state, such as for example shortly after separation as illustrated by dotted separation arrows in  FIG.  11 B . 
     An exterior surface of a flat lateral side  25  of the tapered projection  19  of the first connector part  19  defines a tapering angle  38 , relative to the release direction  21  of the HDRM interface  8 , in the range of 5 - 45°, specifically in the range of 10 - 30°. The tapering angle  38  is measured in a plane that is perpendicular with the flat lateral side  25  and parallel and coincides with an axis of the through hole  22  of projection  19 . 
     Similarly, an interior surface of a flat lateral side  29  of the tapered recess  20  of the second connector part  20  defines a tapering angle  39 , relative to the release direction  21  of the HDRM interface  8 , in the range of 5 - 45°, specifically in the range of 10 - 30°. 
     For ensuring a play-free connection between the first and second connector parts  11 ,  12 , the tapering angles  38 ,  39  of the first and second connector parts  11 ,  12  are preferably selected to be equal, i.e. the same. 
     In some example embodiments, the size and shape of the projection  19  and the recess  20  may be selected, such that the top side  27  of the projection  19  is spaced apart from the bottom side  31  of the recess  20  in connected state of the HDRM interface. This is illustrated by a first gap  44  in  FIG.  11 A  and may assist in providing a tighter fit between the lateral sides  25 ,  29  of the projection  19  and recess  20 , thereby reducing risk for undesirable play between the first and second connector parts  11 ,  12 . 
     In addition, in some example embodiments, the size and shape of the projection  19  and the recess  20  may be selected, such that the forward facing surface  36  of first connector part  11  is spaced apart from the forward facing surface  37  of second connector part  12  in connected state of the HDRM interface. This is illustrated by a second gap  45  in  FIG.  11 A  and may further assist in providing a tighter fit between the lateral sides  25 ,  29  of the projection  19  and recess  20 , thereby reducing risk for undesirable play between the first and second connector parts  11 ,  12 . 
     However, in some example embodiments, the size and shape of the projection  19  and the recess  20  may be selected, such that the top side  27  of the projection  19  abuts the bottom side  31  of the recess  20  in connected state of the HDRM interface, and/or such that the forward facing surface  36  of first connector part  11  abuts the forward facing surface  37  of second connector part  12  in connected state of the HDRM interface, for enabling transfer of high loads in the release direction  21 . 
     A cross-section of a further example embodiment of the HDRM interface along section B-B of  FIG.  10    is described below with reference to  FIGS.  12 A and  12 B , wherein  FIG.  12 A  shows the HDRM interface in connected state, and  FIG.  12 B  shows the HDRM interface in disconnected state, such as for example shortly after separation as illustrated by dotted separation arrows in  FIG.  12 B . Features having some reference signs as in  FIGS.  11 A-B  are not repeated here. 
     In this example embodiment, the tapering angle  38  is significantly smaller and a length  40  of a contact overlap of the projection  19  and recess  20  in the release direction  21  in connected state is significantly larger, thereby enabling transfer of increased torsion and shear load. 
     In some example embodiments, the length  40  of the contact overlap of the projection  19  and recess  20  in the release direction  21  in connected state is at least 10%, specifically at least 20%, and more specifically at least 30%, of a maximal diameter of the projection  19  within said overlap. The term contact overlap means of the portion of the overlap having contact between the projection  19  and recess  20 . 
     In this example embodiment, the HDRM interface  8  is illustrated connected with the spacecraft  3  and a carrier structure in form of a launch vehicle  1 , a dispenser structure, an adapter structure or another spacecraft  54 . Specifically, the first connector part  11  may have a first attachment flange  32  with a plurality of holes with fasteners  46 , which clamp the first connector part  11  to an adjacent structure of for example the spacecraft  3  to be releasably attached by means of the HDRM interface  8 . 
     Furthermore, the second connector part  12  may have a second attachment flange  34  with a plurality of holes  35  for receiving fasteners  46 , such as threaded members or bolts, for attaching the second connector part  12  to an adjacent structure of a launch vehicle  1  or another spacecraft  54 . 
     In  FIG.  12 A , a release bolt  47  extends through the through-hole  22 ,  23  of the projection  19  and recess  20 , respectively, and clamps the first and second connector part  11 ,  12  together, and a release mechanism  16  with a set of electrical terminals  48  are provided for enabling activation of release mechanism  16 . 
     A cross-section of a further example embodiment of the HDRM interface along section B-B of  FIG.  10    is described below with reference to  FIGS.  13 A and  13 B , wherein  FIG.  13 A  shows the HDRM interface in connected state, and  FIG.  13 B  shows the HDRM interface in disconnected state, such as for example shortly after separation as illustrated by dotted separation arrows in  FIG.  13 B . Features having some reference signs as in  FIGS.  11 A-B  are not repeated here. 
     This example embodiment schematically illustrates the lateral sides  25  of the projection  19  may deviate from being a flat surface to a certain extent. For example, as long as the release functionality and load transfer capability of the HDRM interface is acceptable, the lateral sides  25  of the projection may have a slightly convex form, as showed in  FIGS.  13 A and  13 B , or a concave form. The tapering angle  38  of a curved lateral side  25  corresponds to an average tapering angle  38  over a full length  50  of said lateral side  25 , in the release direction  21 . The form, shape and curvature of the lateral side  29  of the recess  20  has a matching shape to provide a play-free connection. 
     This example embodiment schematically illustrates that also the top side  27  of the projection  19  may deviate from being a flat surface to a certain extent. For example, the top side  27  may have a slightly convex form, as showed in  FIGS.  13 A and  13 B , or a concave form. The form, shape and curvature of the bottom side  31  of the recess  20  may have a matching shape, especially in embodiments in which the top and bottom sides  27  make contact in connected state. Otherwise, the shape of the bottom side  31  of the recess  20  may deviate from the shape of the top side  27  of the projection  19 . 
       FIGS.  14 - 25    schematically illustrates cross-sections of the tapered projection  19  of the first connector part  11  and the recess  20  of the second connector part  12 , in a plane perpendicular to a release direction of the HDRM interface, as showed by cross-sectional line C-C in  FIG.  12 A , for various alternative example embodiments of the HDRM interface  8 . 
     With reference to  FIGS.  14 - 22   , an exterior outline of a cross-section of the tapered projection  19  of the first connector part  11 , in a plane perpendicular to a release direction of the HDRM interface  8 , may have three substantially straight lateral sides  25  that are mutually connected by sharp or rounded and/or bevelled lateral edges  26 . 
     The three substantially straight lateral sides  25  and associated sharp or rounded and/or bevelled lateral edges  26  may extend over all, or at least a substantial portion of the projection  19  in the release direction  21 . 
     The three substantially straight lateral sides  29  that are mutually connected by rounded and/or bevelled lateral edges  30  may extend over all, or at least a substantial portion of the recess  20  in the release direction  21 . 
     With reference to  FIGS.  14 - 21   , an exterior outline of a cross-section of the tapered projection  19  of the first connector part  11 , in a plane perpendicular to a release direction of the HDRM interface, may have three substantially straight sides with equal length  51 . This length  51  of lateral side, in a plane perpendicular to a release direction of the HDRM interface  8 , is illustrated in  FIG.  20    and  FIG.  21   . 
     The three straight lateral sides  25  of the projection  19  are either straight or substantially straight, and the three lateral sides  29  of the recess  20  are straight or substantially straight, in a plane perpendicular to a release direction of the HDRM interface  8 . For example, the exterior outline of a cross-section of the tapered projection  19  and recess is straight in the example embodiments of  FIGS.  14 - 16 ,  18 - 22    and the exterior outline of a cross-section of the tapered projection  19  and recess  20  is curved and substantially straight in the example embodiment of  FIG.  15   . 
     As mentioned above, the exterior outline of a cross-section of the tapered projection  19 , in a plane perpendicular to a release direction of the HDRM interface, has sharp or rounded or bevelled lateral edges  26 . For example, the embodiment of  FIG.  15    show sharp lateral edges  26 , the embodiments of  FIGS.  14 ,  16 - 18 ,  20 - 22    have rounded lateral edges  26 , and the embodiments of  FIGS.  18  and  19    have bevelled lateral edges  26 . 
     Similarly, the exterior outline of a cross-section of the tapered recess  20 , in a plane perpendicular to a release direction of the HDRM interface, has sharp or rounded or bevelled lateral edges  30 . For example, the embodiment of  FIG.  15    show sharp lateral edges  30 , the embodiments of  FIGS.  14 ,  16 - 19 ,  21 - 22    have rounded lateral edges  26 , and the embodiments of  FIGS.  18  and  20    have bevelled lateral edges  30 . 
     Furthermore, in some example embodiments, the tapered projection  19  has a different number of lateral sides  25  compared with the number of lateral sides  29  of the recess  20 . In the example embodiment of  FIG.  23   , the tapered projection  19  has six lateral sides  25  and the recess  20  has three lateral sides  29 . 
     Furthermore, in some example embodiments, the projection  19  and recess  20  may have other form-locking shapes. In the example embodiment of  FIG.  24   , an exterior outline of a cross-section of the tapered projection  19 , in a plane perpendicular to a release direction of the HDRM interface  8 , may have four substantially straight lateral sides  25  that are mutually connected by sharp or rounded and/or bevelled lateral edges  26 , and the recess  20  has four matching lateral sides  29 . 
     In the example embodiment of  FIG.  25   , an exterior outline of a cross-section of the tapered projection  19 , in a plane perpendicular to a release direction of the HDRM interface  8 , may have five substantially straight lateral sides  25  that are mutually connected by sharp or rounded and/or bevelled lateral edges  26 , and the recess  20  has five matching lateral sides  29 . 
     In other words, in view of the various possible alternative designs of the projection and recess, while still providing a form-locking feature, the lateral surface area of the tapered projection  19  of the first connector part  11  may be defined by a set of flat, or substantially flat, lateral sides  25 , specifically an odd number of lateral sides  25 , and more specifically three or five lateral sides  25 , wherein the lateral sides  25  of the projection  19  are mutually connected via sharp or rounded or bevelled lateral edges  26 , i.e. corner regions. Furthermore, the lateral surface area of the tapered recess  20  of the second connector part  12  may be defined by a set of flat, or substantially flat, lateral sides  29 , specifically an odd number of lateral sides  29 , and more specifically three or five lateral sides  29 , wherein the lateral sides  29  of the recess  20  are mutually connected via sharp or rounded or bevelled lateral edges  30 , i.e. corner regions. 
     Specifically, the tapered projection  19  of the first connector part  11  may have a shape of a truncated or non-truncated pyramid with odd number of main lateral sides  25 , such as in particular three or five or seven main lateral sides  25 , and the tapered recess  20  of the second connector part  12  may have the shape of an inverse truncated or non-truncated pyramid with odd number of main lateral sides  29 , such as in particular three, five or seven main lateral sides  29 . 
     With reference  FIG.  21   , in some example embodiments of the disclosure, an effective minimal contact length  51  of a straight lateral side  25  of an exterior outline of a cross-section of the tapered projection  19  of the first connector part  11 , in a plane perpendicular to a release direction of the HDRM interface, is at least 50%, specifically at least 75%, and more specifically at least 90%, of a length  52  of an oppositely facing straight lateral side  29  of the tapered recess  20  of the second connector part  12 , in said plane. A relatively large effective contact length  51  is generally better in view of form-locking and torsion load transfer capability. 
     Similarly, with reference  FIG.  20   , in some example embodiments of the disclosure, an effective minimal total contact length  51 , i.e. accumulated total length  51  of all lateral sides  25 , of an exterior outline of a cross-section of the tapered projection  19  of the first connector part  11 , in a plane perpendicular to a release direction of the HDRM interface, is at least 50%, specifically at least 75%, and more specifically at least 90%, of a total length  53  of oppositely facing interior outline of a cross-section of the tapered recess  20  of the second connector part, in said plane. A relatively large effective accumulated contact length  51  is generally better in view of form-locking and torsion load transfer capability. 
     With reference to for example  FIGS.  1 - 4  and  6 A- 6 B , the disclosure also relates to a launch vehicle  1  having a longitudinal direction  4  and a radial direction  5  and comprising a dispenser structure  2  carrying at least one spacecraft  3 , which is releasably attached to an adjacent structure of a launch vehicle  1  or of another spacecraft  54  by means of a plurality of HDRM interfaces  8  in a multi-point attachment of the spacecraft  3  for enabling controlled release of the at least one spacecraft  3 , wherein each of the plurality of HDRM interfaces  8  is defined as described above, wherein one of the first and second parts of each of the plurality of HDRM interfaces  8  is fastened to the said adjacent structure, and the other of the first and second parts  11 ,  12  of each of the plurality of HDRM interfaces  8  is fastened to the spacecraft  3 , and wherein a release bolt  47  extends through the central through-hole  22 ,  23  of the first and second connector parts  11 ,  12  of each of the plurality of HDRM interfaces  8  and clamps said parts together. 
     The disclosure also relates to a method for mounting a spacecraft to an adjacent structure of a launch vehicle, such as a dispenser structure or adapter structure of a launch vehicle, or of another spacecraft  54 , using a singular or plurality of HDRM interfaces forming part of a single-point or multi-point attachment of the spacecraft  3  to said adjacent structure.  FIG.  26    shows the main steps of the method, wherein a first step S1 involves providing a singular or plurality of HDRM interfaces  8 , each having a first connector part  11  having a tapered projection  19  with a non-circular external surface and a central through-hole  22 , and a second connector part  12  having a matching formed tapered recess  20  with a non-circular interior surface configured for form-lockingly receiving the tapered projection  19 , for enabling transfer of at least torsion load and shear load between the first and second connector parts  11 ,  12 , when the projection is inserted in the recess and the first and second connector parts are pressed together, wherein also the second connector part has central through-hole. 
     The method further comprises a second step S2 of providing a singular or plurality of release bolts  47  and inserting a release bolt through the central through hole of the first and second connector parts  11 ,  12  of each of the singular or plurality of HDRM interfaces  8  and clamping the first and second connector parts together by means of said release bolt to form a singular or plurality of assembled HDRM interfaces. 
     The method further comprises a third step S3 of attaching one of the first and second parts of the singular or plurality of HDRM interfaces  8  to said adjacent structure and attaching the spacecraft  3  to the other of the first and second parts of the singular or plurality of HDRM interfaces  8 . 
     It will be appreciated that the above description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. 
     Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out the teachings of the present disclosure, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims. Reference signs mentioned in the claims should not be seen as limiting the extent of the matter protected by the claims, and their sole function is to make claims easier to understand.  
     
       
         
           
               
               
             
               
                 REFERENCE SIGNS 
               
             
            
               
                 1. Launch vehicle 
                 30. Lateral edge of recess 
               
               
                 2. Dispenser structure 
                 31. Bottom side of recess 
               
               
                 3. Spacecraft 
                 32. First attachment flange 
               
               
                 4. Longitudinal direction 
                 33. Holes of first attachment flange 
               
               
                 5. Radial direction 
                 34. Second attachment flange 
               
               
                 6. Final engine structure 
                 35. Holes of second attachment flange 
               
               
                 7. Fairing 
               
               
                 8. HDRM interface 
                 36. Forward facing surface of first connector part 
               
               
                 9. First release arrow 
               
               
                 10. Second release arrow 
                 37. Forward facing surface of 
               
               
                 11. First connector part 
                 second connector part 
               
               
                 12. Second connector part 
                 38. Tapering angle of projection 
               
               
                 13. Attachment ring 
                 39. Tapering angle of recess 
               
               
                 14. Bottom side 
                 40. Overlap in release direction 
               
               
                 15. Top side 
                   
               
               
                 16. Release mechanism 
                 44. First gap 
               
               
                 17. Rotational force 
                 45. Second gap 
               
               
                 46. Fastener 
               
               
                 19. Tapered projection 
                 47. Release bolt 
               
               
                 20. Tapered recess 
                 48. Electrical terminals 
               
               
                 21. Release direction 
                 49. Axis of the through hole of projection 
               
               
                 22. Through hole of first connector part 
               
               
                 50. Length of lateral side of projection in release direction 
               
               
                 23. Through hole of second connector part 
               
               
                 51. Length of lateral side of projection in cross-section 
               
               
                 24. Base of projection 
               
               
                 25. Lateral side of projection 
                 52. Length of lateral side of recess in cross-section 
               
               
                 26. Lateral edge of projection 
               
               
                 27. Top side of projection 
                 53. Total length of recess in cross-section 
               
               
                 28. Opening of recess 
               
               
                 29. Lateral side of recess 
                 54. Another spacecraft