Joint and payload dispenser

Abstract

A payload dispenser for a launch vehicle including a plurality of panels, wherein at least one panel includes at least one payload mounted onto the panel. The panels are attachable to each other by means of attachment means in the form of at least one payload dispenser joint whereby a self-supporting dispenser is formed.

Claims

1. A payload dispenser joint for detachably attaching to each other two adjacent panels of a payload dispenser for a launch vehicle of a satellite, wherein the joint comprises: a clamp, comprising an inner clamp portion and an outer clamp portion facing the inner clamp portion, each clamp portion comprising a through opening; and a bolt, configured to arrange in the through openings, wherein the inner clamp portion comprises a first and second inner clamp flange and an inner mid portion between the first and second inner flanges, wherein the outer clamp portion comprises a first and second outer clamp flange and an outer mid portion between the first and second outer flanges, wherein the joint comprises a first panel end portion of a first panel comprising a first end section and a second panel end portion of a second panel comprising a second end section, wherein the first and the second panels are neighboring panels of the payload dispenser, wherein the first end section comprises a first outer panel flange and a first inner panel flange, wherein the second end section comprises a second outer panel flange and a second inner panel flange, wherein the first end section comprises a first contact surface formed by a portion of an outer surface of the first outer panel flange and by a portion of an outer surface of the first inner panel flange, wherein the second end section comprises a second contact surface formed by a portion of an outer surface of the second outer panel flange and by a portion of an outer surface of the second inner panel flange, wherein the first and second contact surfaces are abutting each other in the joint forming a reference plane, wherein a first inner clamp locking surface of the first inner clamp flange is arranged at a first angle to the reference plane, wherein a first outer clamp locking surface of the first outer clamp flange is arranged at a second angle to the reference plane, wherein a second inner clamp locking surface of the second inner clamp flange is arranged at a third angle to the reference plane, wherein a second outer clamp locking surface of the second outer clamp flange is arranged at a fourth angle to the reference plane, wherein a first inner panel locking surface of the first inner panel flange is arranged at a fifth angle to the reference plane, wherein a first outer panel locking surface of the first outer panel flange is arranged at a sixth angle to the reference plane, wherein a second inner panel locking surface of the second inner panel flange is arranged at a seventh angle to the reference plane, and wherein a second outer panel locking surface of the second outer panel flange is arranged at an eighth angle to the reference plane.

2. The payload dispenser joint according to claim 1, wherein the first inner clamp flange is arranged against the first inner panel flange and the first angle is equal to or smaller or greater than the fifth angle, wherein the first outer clamp flange is arranged against the first outer panel flange and the second angle is equal to or smaller or greater than the sixth angle, wherein the second inner clamp flange is arranged against the second inner panel flange and the third angle is equal to or smaller or greater than the seventh angle, wherein the second outer clamp flange is arranged against the second outer panel flange and the fourth angle is equal to or smaller or greater than the eight angle.

3. The payload dispenser joint according to claim 1, wherein the inner clamp portion or outer clamp portion comprises a threaded through opening for allowing an at least partly threaded bolt to thread in the threaded through opening.

4. The payload dispenser joint according to claim 1, wherein the first end section of the first panel and the second end section of the second panel comprise cooperating channels forming a through opening for receiving the bolt of the joint.

5. A payload dispenser for a launch vehicle, wherein the dispenser comprises a plurality of panels, wherein at least one panel comprises at least one payload mounted onto the panel, wherein the plurality of panels includes two adjacent panels, and wherein the plurality of panels are attachable to each other by at least one payload dispenser joint according to claim 1 forming a self-supporting dispenser.

6. The payload dispenser according to claim 5, wherein at least one panel does not have a payload attached or wherein each panel of the plurality of panels comprises at least one payload.

7. The payload dispenser according to claim 5, wherein at least one panel comprises a plurality of payloads.

8. The payload dispenser according to claim 5, wherein the payload is a satellite.

9. The payload dispenser according to claim 5, wherein the payload dispenser has an extension in a longitudinal direction and in a radial direction, wherein each panel comprises an attachment in the longitudinal direction, and wherein the attachment is attachable to neighboring panels.

10. The payload dispenser according to claim 5, wherein the payload dispenser is delimited in the radial direction by the panels forming an envelope surface, wherein the panels are attachable to each other in an interface running in the longitudinal direction.

11. The payload dispenser according to claim 5, wherein the payload dispenser joints are arranged to lock in position with relation to each other to allow for the self-supporting dispenser.

12. The payload dispenser according to claim 5, wherein the payload dispenser is delimited in a lateral direction by the panels, wherein each panel has an unbroken extension in the longitudinal direction.

13. The payload dispenser according to claim 5, wherein at least one panel comprises panel portions attached to each other forming the panel.

14. The payload dispenser according to claim 13, wherein the panel portions are connected to each other in longitudinal direction and/or lateral direction.

15. The payload dispenser according to claim 13, wherein the panel portions are fixedly attached to each other.

16. The payload dispenser according to claim 5, wherein the payload is mounted onto the panel before assembly of the dispenser.

17. The payload dispenser according to claim 5, wherein the dispenser is a primary load bearing structure.

18. A method for assembly of a payload dispenser according to claim 5, wherein the method comprises the steps of: mounting at least one payload onto one panel, attaching the panels to each other via longitudinally extending attachment, and locking the attachment in position to hinder movement between the panels forming a self-supporting dispenser.

19. The method according to claim 18, wherein the method comprises the step of mounting at least one payload onto each panel before assembly of the panels.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The disclosure will be described in greater detail in the following, with reference to the attached drawings, in which

(2) FIG. 1 schematically shows a top view of a payload dispenser;

(3) FIG. 2a schematically shows a side view of a panel and payloads before assembly;

(4) FIG. 2b schematically shows a side view of a panel and payloads after assembly;

(5) FIG. 2c schematically shows a front view of a panel and payloads;

(6) FIG. 3 schematically shows a front view of two panels attached to each other;

(7) FIG. 4a schematically shows a side view of a panel and a payload before assembly;

(8) FIG. 4b schematically shows a side view of a panel and a payload after assembly;

(9) FIG. 4c schematically shows a front view of a panel and a payload;

(10) FIG. 5 schematically shows a front view of two panels attached to each other;

(11) FIG. 6 schematically shows a front view of three panels attached to each other;

(12) FIG. 7 schematically shows a side view of an assembled payload dispenser;

(13) FIG. 8 schematically shows a flow chart of a method for assembly of the payload dispenser;

(14) FIG. 9 schematically shows an enlarged view of an attachment means in form of a disassembled payload dispenser joint;

(15) FIG. 10 schematically shows an example of an attachment means in form of an assembled payload dispenser joint;

(16) FIG. 11 schematically shows an example of an attachment means in form of a disassembled payload dispenser joint;

(17) FIG. 12 schematically shows a side view of panel flanges forming through opening, and

(18) FIG. 13 schematically shows a cut away side view of interacting locking surfaces.

DESCRIPTION OF EXAMPLE EMBODIMENTS

(19) 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.

(20) FIG. 1 schematically shows a top view of a payload dispenser 1 for a launch vehicle. The dispenser 1 comprises a panel 2 and a payload 3. The dispenser 1 comprises a plurality of panels 2 wherein at least one panel 2 comprises at least one payload 3 mounted onto the panel 2. FIG. 1 shows that the panels 2 are attachable to each other via attachment means 4 forming a self-supporting dispenser 1. The attachment means 4 comprises at least one payload dispenser joint 10, as will be disclosed more in detail below. FIG. 1 shows six panels 2 attached to each other. However, any plurality of panels 2 is possible but with a minimum of three panels in order to form a dispenser 1.

(21) FIG. 1 shows that each panel 2 comprises at least one payload 3. According to another example shown in FIG. 6, one of the panels 2 in the dispenser 1 can be without any payload 3 while other panels 2 carry payload. Furthermore, as shown in FIGS. 2a-2b and 6, at least one panel 2 comprises a plurality of payloads 3.

(22) According to one example, the payload 3 is a satellite.

(23) In FIGS. 1-8, the payload dispenser 1 has an extension in a longitudinal direction X and in a radial direction R. Each panel 2 comprises attachment means in the longitudinal direction X being attachable to neighbouring panels 2.

(24) The payload dispenser 1 is delimited in the radial direction R by the panels 2 forming an envelope surface and the panels 2 are attachable to each other in an interface running in the longitudinal direction X.

(25) The attachment means 4 are arranged to lock in position with relation to each other to allow for the self-supporting dispenser 1.

(26) The dispenser 1 is a primary load bearing structure that can carry one or more payloads. The payload can be arranged to be separated from the dispenser in a controlled manner via separation means. For this to happen, the payload dispenser comprises additional equipment connecting the separation means (not shown) to a control device (not shown). The control device is arranged to control the separation means to separate and eject the payload at a certain point in time and in a pre-determined direction.

(27) FIG. 2a schematically shows a side view of a panel and payloads before assembly.

(28) FIG. 2b schematically shows a side view of a panel and payloads after assembly. FIGS. 2a and 2b shows that the payload 3 is mounted onto the panel 2 before assembly of the dispenser 1.

(29) FIG. 2c schematically shows a front view of a panel and payloads according to FIGS. 2a and 2b.

(30) FIG. 3 schematically shows a front view of two panels attached to each other. FIG. 3 shows that the payload dispenser 1 is delimited in a lateral direction Y by the panels 2. In FIG. 3, each panel 2 has an unbroken extension in the longitudinal direction X. However, as can be seen in FIG. 7, the panels 2 can be made from panel portions 5′, 5″.

(31) FIG. 4a schematically shows a side view of a panel 2 and a payload 3 before assembly, FIG. 4b schematically shows a side view of a panel 2 and a payload 3 after assembly and FIG. 4c schematically shows a front view of a panel 2 and a payload 3. FIG. 4a-4c shows the same as FIG. 2a-2c but with the difference that only one payload 3 is mounted onto the panel 2.

(32) FIG. 5 schematically shows a front view of two panels 2 attached to each other. One panel 2 is identical to what is shown in FIGS. 2a-2c and one panel is identical to what is shown in FIGS. 4a-4c. FIG. 5 thus only shows an example of that panels 2 with different amount of payloads can be combined.

(33) FIG. 6 schematically shows a front view of three panels 2 attached to each other, and in addition to the two panels 2 in FIG. 5, there is also a third panel attached to the other two without any payload to further broaden the example of the possibility to attach differently equipped panels to each other.

(34) FIG. 7 schematically shows a side view of an assembled payload dispenser. FIG. 7 shows that at least one panel 2 comprises panel portions 5′, 5″ attached to each other forming the panel 2. In FIG. 7 the panel portions 5′, 5″ are connected to each other in the longitudinal direction X and in the lateral direction Y. The panels 2 are attached to each other via the longitudinally extending attachment means 4 and the panel portions 5′, 5″ are fixedly attached to each other along the laterally extending attachment means 6. The attachment means 4, 6 are positioned in the envelope surface of the dispenser, which means that the lateral extension refers to a direction perpendicular to the longitudinal direction but along the envelope surface. In FIG. 7 the dispenser is cylindrical, but different shapes are possible. However, common for all shapes are that the attachment means 4, 6 are positioned in the envelope surface of the dispenser 1. The attachment means 4, 6 may e.g. be in form of at least one payload dispenser joint 10, as will be disclosed more in detail below.

(35) When the panels 2 are viewed separately as in FIGS. 2a-2c and 4a-4c, or attached to each other but in a flat state as in FIGS. 3, 5 and 6, then the lateral direction Y is perpendicular to the longitudinal direction as in Cartesian coordinates.

(36) FIG. 8 schematically shows a flow chart of a method for assembly of the payload dispenser.

(37) Box 801 relates to the step of mounting at least one payload 3 onto one panel 2. The step of mounting the at least one payload 3 onto one panel is advantageously done before assembly of the panels 2.

(38) Box 802 relates to the step of attaching the panels 2 to each other via longitudinally extending attachment means 4.

(39) Box 803 relates to the step of locking the attachment means 4 in position to hinder movement between the panels 2 forming a self-supporting dispenser 1.

(40) As described above, the panels 2 can be made from panel portions 5′, 5″ and the panel portions are connected to each other via laterally extending attachment means 6. The panels 2 are attached to each other via the longitudinally extending attachment means 4. The method steps in connection to Boxes 802 and 803 can then be described as follows:

(41) Box 802 relates to the step of attaching the panels 2 to each other via longitudinally extending attachment means 4. According to one example, the panel portions 5′, 5″ are attached to each other via the laterally extending attachment means 6 before the panels 2 are attached to each other via the longitudinally extending attachment means 4. According to another example, panel portions 5′, 5″ are attached to each other via the longitudinally extending attachment means 4 forming dispenser portions and the panel portions, i.e. the panel portions 5′, 5″ are then attached to each other via the laterally extending attachment means 6. In the latter example the dispenser can be built in sections where the dispenser portions are positioned on top of each other in the height direction, i.e. the longitudinal direction.

(42) Box 803 relates to the step of locking the attachment means 4, 6 in position to hinder movement between the panels 2 forming the self-supporting dispenser 1.

(43) FIG. 9 schematically shows an enlarged view of an example of an attachment means 4, 6 in form of a disassembled payload dispenser joint 10. The payload dispenser joint 10, configured for detachably attach two adjacent panels of a payload dispenser to each other, comprises a clamp 11, comprising an inner clamp portion 11a and an outer clamp portion 11b. The outer clamp portion 11b faces the inner clamp portion 11a. Each clamp portion 11a, 11 b comprise a through opening 8. The joint 10 further comprises a bolt, not shown in FIG. 9, configured to be arranged in the through openings 8.

(44) The inner clamp portion 11a comprises a first and second inner clamp flange 12a1, 12a2, and an inner mid portion 13a provided between the first and second inner flanges 12a1, 12a2. The outer clamp portion 11b comprises a first and second outer clamp flange 12b1, 12b2, and an outer mid portion 13b provided between the first and second outer flanges 12b1, 12b2.

(45) The joint 10 further comprises a first panel end portion 25′ of a first panel, comprising a first end section 9′, and a second panel end portion 25″ of a second panel comprising a second end section 9″. The first and the second panels are neighboring, or adjacently arranged, panels of a payload dispenser. The first end section 9′ comprises a first outer panel flange 14b1 and a first inner panel flange 14a1, and the second end section 9″ comprises a second outer panel flange 14b2 and a second inner panel flange 14a2.

(46) The first end section 9′ comprises a first contact surface 31′ formed by a portion of an outer surface 30′ of the first outer panel flange 14b1 and by a portion of an outer surface 30′ of the first inner panel flange 14a1, and wherein the second end section 9″ comprises a second contact surface 31″ formed by a portion of an outer surface 30″ of the second outer panel flange 14b2 and by a portion of an outer surface 30″ of the second inner panel flange 14a2, wherein the first and second contact surfaces 31 “, 31” are abutting each other in the joint 10, forming a reference plane RP. The first and second surfaces need not be flat per se, but can be curved or may comprise steps or step like elevations that takes up forces in a chosen direction. The reference plane RP is then taken along a line running from edge to edge of the contact surfaces.

(47) An essentially planar first inner clamp locking surface 20a1 of the first inner clamp flange 12a1 is arranged at a first angle A1 in relation to the reference plane RP.

(48) An essentially planar first outer clamp locking surface 20b1 of the first outer clamp flange 12b1 is arranged at a second angle A2 in relation to the reference plane RP.

(49) An essentially planar locking second inner clamp locking surface 20a2 of the second inner clamp flange 12a2 is arranged at a third angle A3 in relation to the reference plane RP.

(50) An essentially planar second outer clamp locking surface 21b2 of the second outer clamp flange 12b2 is arranged at a fourth angle A4 in relation to the reference plane RP.

(51) An essentially planar first inner panel locking surface 21a1 of the first inner panel flange 14a1 is arranged at a fifth angle A5 in relation to the reference plane RP.

(52) An essentially planar first outer panel locking surface 21b1 of the first outer panel flange 14b1 is arranged at a sixth angle A6 in relation to the reference plane RP.

(53) An essentially planar second inner panel locking surface 21a2 of the second inner panel flange 14a2 is arranged at a seventh angle A7 in relation to the reference plane RP.

(54) An essentially planar second outer locking surface 21b2 of the second outer panel flange 14b2 is arranged at an eight angle A8 in relation to the reference plane RP.

(55) The first inner clamp flange 12a1 is arranged against the first inner panel flange 14a1 and the first angle A1 is equal to or smaller or greater than the fifth angle A5.

(56) The first outer clamp flange 12b1 is arranged against the first outer panel flange 14b1 and the second angle A2 is equal to or smaller or greater than the sixth angle A6.

(57) The second inner clamp flange 12a2 is arranged against the second inner panel flange 14a2 and the third angle A3 is equal to or smaller or greater than the seventh angle A7.

(58) The second outer clamp flange 12b2 is arranged against the second outer panel flange 14b2 and the fourth angle A4 is equal to or smaller or greater than the eight angle A8.

(59) The herein disclosed example of a payload dispenser joint 10 may be used both as longitudinal attachment means 4 and as lateral attachment means 6.

(60) FIG. 10 schematically shows an example of an attachment means in form of an assembled payload dispenser joint 10. In the example shown in FIG. 10 the payload dispenser joint 10 is arranged to lock two neighboring, i.e. adjacently arranged, essentially planar panels 2′, 2″ together in longitudinal direction X at an angle B.

(61) However, the payload dispenser 10 may also be used to connect panels to each other, also referred to as arrange, assemble or lock panels to each other, at larger or narrower angles than angle B. Also, the panels do not necessarily have to be essentially planar as in the example shown in FIG. 10. According to other realizations the panels may e.g. be slightly bent outwardly.

(62) In FIG. 10 two neighboring panels 2′, 2″ are connected to each other in the longitudinal direction X, but, as previously disclosed, the payload dispenser joint 10 may also be used to connect two neighboring panels in lateral direction Y.

(63) Further, in the example shown in FIG. 10 the payload dispenser joint 10 has an essentially rectangular outer shape when being assembled and thereby connecting the panels 2′, 2″ to each other such that a dispenser is formed. However, this is just one example of a payload dispenser 10 according to the present disclosure. Other configurations, necessarily not forming an essentially rectangular payload dispenser joint, are also possible. The payload dispenser joint may e.g. adopt an essentially trapezoid, hexagonal or octagonal outer shape.

(64) The outer shape of the payload dispenser joint and the angle at which two neighboring panels are connected to each other are e.g. dependent on the configuration of the dispenser and the configuration on the panels. The size of the panels, the number of panels, the size of the dispenser, the form of the dispenser, if the panels e.g. are essentially planar or outwardly bulging, i.e. if the panels are slightly bent outwardly, if the panels are connected in longitudinal or lateral direction etc. are examples of conditions that may affect the outer shape of the payload dispenser joint and the angle at which two neighboring panels are connected.

(65) FIG. 11 schematically shows an example of an attachment means in form of a disassembled payload dispenser joint 10. According to the exemplary embodiment of a payload dispenser joint 10 disclosed in FIG. 11, the first panel end portion 25′ and the second panel end portion 25″ of the panels 2 comprises cooperating channels 50′, 50″ forming a through opening 51 configured for receiving a threaded bolt 7TH of the joint 10.

(66) FIG. 11 further shows that the inner clamp portion 11a comprises threaded through opening 8TH, allowing the threaded bolt 7TH to be threaded in the threaded opening 8TH.

(67) In FIG. 11 the through opening 8 of the outer clamp portion 11b is not threaded. However, according to other realizations, not shown, the outer clamp portion 11b may comprise a threaded through opening instead of the inner clamp portion, whereby by the bolt is configured correspondingly.

(68) FIG. 12 schematically shows a side view of a first outer panel flange 14b1, of a first end section 9′ of a panel end portion 25′, and of a second outer panel flange 14b2, of a second end section 9″ of a panel end portion 25″, forming through opening 51, wherein the through opening is configured to receive a bolt (not shown).

(69) The first end section 9′ comprises a first contact surface 31′ formed by a portion of an outer surface 30′ of the first outer panel flange 14b1 and by a portion of an outer surface 30′ of the first inner panel flange. The second end section 9″ comprises a second contact surface 31″ formed by a portion of an outer surface 30′ of the second outer panel flange 14b2 and by a portion of an outer surface 30″ of the second inner panel flange. When the payload dispenser joint is assembled the first and second contact surfaces 31′, 31″ are abutting each other, forming a reference plane RP.

(70) FIG. 13 schematically shows a cut away side view of interacting locking surfaces. In FIG. 13 a first outer panel flange 14b1, of a first end section 9′, and a second outer panel flanges 14b2, of a second end section 9″ is shown.

(71) FIG. 13 shows, as in FIG. 12, the first end section 9′ comprising a first contact surface 31′ formed by a portion of an outer surface 30′ of the first outer panel flange 14b1 and by a portion of an outer surface 30′ of the first inner panel flange. The second end section 9″ comprises a second contact surface 31″ formed by a portion of an outer surface 30′ of the second outer panel flange 14b2 and by a portion of an outer surface 30″ of the second inner panel flange. The first end section 9′ and the second end section 9″ comprise cooperating channels 50′, 50″ forming a through opening 51 for receiving a bolt 7 (not shown). When the payload dispenser joint 10 is assembled the first and second contact surfaces 31′, 31″ are abutting each other, forming the reference plane RP.

(72) In FIG. 13 is further indicated, by dotted lines, the extension of the interacting surfaces, i.e. the first inner clamp (flange) locking surface 20a1, the second inner clamp (flange) locking surface 20a2, the first outer clamp (flange) locking surface 20b1, the second outer clamp (flange) locking surface 20b2, the first inner panel (flange) locking surface 21a1, the second inner panel (flange) locking surface 21a2, the first outer panel flange (locking) surface 21b1 and the second outer panel flange (locking) surface 21b2.

(73) FIG. 13 shows the joint and panel from the outside of the dispenser, but could just the same be showing a view from the inside.

(74) Two narrowly arranged dotted lines indicate a difference in width, i.e. in the lateral direction Y, of the inner or outer mid portion 13a, 13b with relation to the corresponding and combined width of the panel flange 14b1, 14b2 portions between the contact surfaces 31 ‘and 31″ and respective panel flange locking surface 21a1, 21a2, 21b1, 21b2. The difference may depend on that the contact surfaces 31’, 31″ have not yet found their end positions, i.e. that clamp portions shall be brought further towards each other by the bolt such that further pressure will be applied on the panel flanges in the lateral direction Y, i.e. in the direction diminishing the gap between the contact surfaces 31′, 31″. The difference may also be the consequence of a chosen design with a more narrow inner or outer mid portion 13a, 13b with relation to the corresponding and combined width of the panel flange 14b1, 14b2.

(75) 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

(76) 1. payload dispenser 2, 2′, 2″. panel 3. payload 4. longitudinal attachment means 5′, 5″ first and second panel portion 6. lateral attachment means 7. bolt 7TH. threaded bolt 8. through opening 8TH. threaded through opening 9′, 9″. first and second end section 10. payload dispenser joint 11. clamp 11a. inner clamp portion 11b. outer clamp portion 12a1. first inner clamp flange 12a2. second inner clamp flange 12b1. first outer clamp flange 12b2. second outer clamp flange 13a. inner mid portion 13b. outer mid portion 14a1. first inner panel flange 14a2. second inner panel flange 14b1. first outer panel flange 14b2. second outer panel flange 20a1. first inner clamp (flange) locking surface 20a2. second inner clamp (flange) locking surface 20b1. first outer clamp (flange) locking surface 20b2. second outer clamp (flange) locking surface 21a1. first inner panel (flange) locking surface 21a2. second inner panel (flange) locking surface 21b1. first outer panel flange (locking) surface 21b2. second outer panel flange (locking) surface 25′, 25″ first and second panel end portion 30′, 30″. outer surface 31′, 31″. first and second contact surface 50′, 50″. channels 51. through opening X. panel extension in longitudinal direction R. panel extension in radial direction, i.e. thickness direction Y. panel extension in lateral direction RP. reference plane A1-A8. first-eight angle