Impact testing system

Abstract

The impact testing system comprises a first track 101 and a second track 102. A carrier sled 104 suitable for holding an object whose impact is to be tested is driven along the track 101 before being

Description

FIELD OF THE INVENTION The present invention relates to impact testing systems, in particular to track-based systems for testing the impact of an object such as a munition against a target. BACKGROUND It is often desirable to test different parameters affecting how objects impact targets. For example, it may be desirable to test munition performance at different impact velocities or impact angles. The term “munition” as used herein means any casing that is configured to carry Inert or explosive material. A munition may be, for example: a general-purpose free fall bomb, a penetrating warhead (Tactical Penetrator, Multiple Weapon System, or Anti-Ship Lethal Package), a rocket, or a gun-launched ammunition round such as a freefall bomb or an artillery shell. The munition may in use comprise energetic materials or other materials that are configured to expand the casing on impact. Conventional impact testing systems typically comprise a track and a propulsion sled that carries the munition to the target at speed by moving along the track. The sled is typically propelled by a rocket motor. The propulsion sled is diverted down a curved section of track which is located at the end of the track and the munition detaches from the sled and travels alone towards the target. Such systems are capable for impact tests at low and high speeds. However, when releasing a munition into free flight, should said munition be unstable, in terms of aerodynamic flight, it may pitch or yaw and result in a less than desirable impact angle on the target face. It may be possible to shorten the length of free flight to ensure that the target is as close to the release point as possible so as not to affect the test. However, decreasing the distance between the end of the track and the target will have several drawbacks, including the inability to fit in such components that are relied on to ‘capture’ the propulsion sled and prevent it itself from impacting the target. Accordingly, there is a need to provide an impact testing system which is capable of performing impact testing at low and high speeds while enabling reliable control of impact angle and impact speed of the object with the target. SUMMARY OF THE INVENTION According to an aspect of the invention, there is provided an impact testing system for testing impact of an object with a target, the impact testing system comprising: a first track; a second track; and a carrier sled for supporting the object; wherein the carrier sled comprises one or more first connection points for engaging the first track in a first longitudinal section of the system, and one or more second connection points for engaging the second track in a second longitudinal section of the system which is in operative proximity to the target; and wherein the first track has a first shape in the first longitudinal section to engage the one or more first connection points and a second shape in the second longitudinal section to allow the one or more first connection points to disengage from the first track in the second longitudinal section. The impact testing system may further comprise a propulsion sled configured to interface with and drive the carrier sled along the first track. The first track may deflect at an angle from the longitudinal direction in the second longitudinal section to guide the propulsion sled away from the carrier sled and target. The propulsion sled may comprise one or more third connection points that engage the first track to retain the propulsion sled to the first track while allowing siding movement along the entire length of the first track. The first track may comprise at least one rail and one or more first tabs of the propulsion sled engage with one or more first recessed sections on a first side of the first track. The first track may comprise at least one rail and the one or more first connection points comprises one or more tabs for engaging a recessed section on a (e.g. second) side of the at least one rail to retain the carrier sled to the first track while allowing siding movement of the carrier sled along the first track in the first longitudinal section. The first shape may comprise a neck region and a rail head which is symmetrical about a mid-plane which bisects the rail, to form the recessed section that receives a tab of the carrier sled therein to retain the carrier sled to the first track. The second shape may comprise the neck region and a rail head which is asymmetrical about the mid-plane so as to allow the tab of the carrier sled to disengage and release from the first track in the second longitudinal section. The one or more second connection points for engaging the second track may comprise one or more runner sections shaped to define a space for receiving one or more rails of the second track therein while allowing sliding movement along the one or more rails of the second track. The runner sections may be lined with padded material so as to protect the runner sections from wear and tear. The first track and the second track may be arranged at fixed positions relative to one another in an intermediate longitudinal section of the system, such that the first and second connection points of the carrier sled will engage both the first track and the second track so as to be retained by both the first track and the second track in the intermediate longitudinal section. The impact testing system may further comprise a catcher element at the end of the first track for slowing onward movement of the propulsion sled. The carrier sled may comprise a clamp having at least two parts which are removably fastened together to allow the object to be received within the clamp when in an unfastened state. According to another aspect of the present invention, there is provided an impact testing method comprising using the impact testing system of any one of the preceding statements to guide an object to impact a target. The object may be guided in a first longitudinal section along the first track and is transferred from the first track to the second track before impacting the target at a position in operative proximity to the end of the second track. The carrier sled may be driven along the first track in the first longitudinal section by a propulsion sled which comprises a propulsion motor. The first track may deflect at an angle from the second track in the second longitudinal section to separate the propulsion sled and the carrier sled and to guide the propulsion sled away from the target. Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice-versa. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram illustrating a side view of an impact testing system during a first period of an impact test, in accordance with an embodiment of the present invention; Figure 2 is a schematic diagram illustrating a side view of the impact testing system of Figure 1 during a second period of an impact test; Figure 3 is a schematic diagram illustrating a side view of the impact testing system of Figure 1 during a third period of an impact test; Figure 4 is a schematic diagram illustrating an isometric view (top) and a rear view (bottom) of a propulsion sled of the impact testing system of Figure 1; Figure 5 is a schematic diagram illustrating an isometric view (top) and a rear view (bottom) of a carrier sled of the impact testing system of Figure 1; Figure 6 is a schematic diagram illustrating a rear view of the impact testing system of Figure 1 during the first period; Figure 7 is a schematic diagram illustrating a rear view of the impact testing system of Figure 1 during the second period; Figure 8 is a schematic diagram illustrating a rear view of the impact testing system of Figure 1 during a period of an impact test; and Figure 9 is a schematic diagram illustrating a rear view of the impact testing system of Figure 1 during the third period. It will be appreciated that like-reference numerals are used throughout the drawings to refer to like-features of the impact testing system. DETAILED DESCRIPTION Embodiments of the invention described below concern testing of impacts between munitions and targets. However it will be understood that the invention is not limited to impacts between munitions and targets but is applicable more widely to testing of impact between any type of object and a target. Figure 1 schematically illustrates a side view of an impact testing system 100. The system 100 comprises a first track 101, a second track 102, a propulsion sled 103, and a carrier sled 104 for holding a munition whose impact against a target 105 is to be tested. The first track 101 and the second track 102 are configured to guide the carrier sled 104 in a test direction from one longitudinal end of the system 100 to another, and direct the munition onwards therefrom to the target 105. The first track 101 is in the form of a railway track comprising two bar rails extending parallel in a longitudinal direction 106 of the system 100. The rails of the first track 101 extend longitudinally along the ground between a first end 107 and a second end 108. The first track 101 extends in a first, horizontal direction from the first end W7 to an intermediate position 109 (between the first and second ends 107, 108). Between the intermediate position 109 and the second end 108, the first track 101 an angled section which slopes at an angle downwards from the first direction and away from the second track 102. The second end 108 of,the first track 101 may comprise a blocking element or a catcher element (e.g. box) for stopping / capturing the propulsion sled 103. However, in this embodiment, the angled section of the first track 101 extends into a catcher box 110, for gradually slowing (or stopping) onward movement of the propulsion sled 103. The second track 102 is also in the form of a railway track comprising two bar rails extending parallel in the longitudinal direction 106. The second track 102 extends parallel to the first direction (i.e. generally horizontal section) of the first track 101. The second track 102 has a first end 111 at a rear side of the track 101 in the test direction and a second end 112 at the opposite side of the track 101 in the test direction. The first end 111 has a longitudinal position that is between the first end 107 and the intermediate position 109 of the first track 101. That is, a rearmost section of the second track 102 overlaps a longitudinal section of the first track 101 in that they have the same longitudinal positions. The second end 112 of the second track 102 is located in operative proximity to the target 105. The system 100 may be regarded as having three longitudinal sections: a propulsion section 113, a cross-over section 114, and a separation section 115. The propulsion section 113 and the separation section 115 are at longitudinally opposite ends of the system 100, and the cross-over section 114 is an intermediate section located therebetween. The propulsion section 113 includes the first track 101 in a longitudinal region between the first end 107 of the first track 101 and the first end 111 of the second track 102. The cross-over section 114 includes the first track 101 and the second track 102 in the longitudinal region between the first end 111 of the second track 102 and the intermediate position 109 of the first track 101. The separation section 115 includes the first track 101 and the second track 102 in the longitudinal region between the intermediate position 109 of the first track 101 and the second end 112 of the second track 102. During a first period of an impact test, the first track 101 engages the propulsion sled 103 and the carrier sled 104 in the propulsion section 113, so as to restrict their movement in the transverse and vertical directions but not the longitudinal direction 106. This engagement allows (sliding) movement of the propulsion sled 103 and the carrier sled 104 relative to and along the first track 101 in the longitudinal direction 106. The propulsion sled 103 has a forwardly facing surface that abuts the rearwards surface of the carrier sled 104 in the test direction, and further comprises a rocket motor (not shown) or other propulsion mechanism to drive the carrier sled 104 forwards from the first end 107 in the test direction. The propulsion section 113 may be set to any length depending on the nature of the impact test to be performed. The track may be up to a few kilometres in length. During a second period, as shown in Figure 2, the propulsion sled 103 and carrier sled 104 enter the cross-over section 114, in which section the carrier sled 104 engages the second track 102 as well as the first track 101. In this section, the carrier sled 104 is retained to both the first and second tracks 101, 102 but is restricted so as to allow only sliding movement along the two tracks in the test direction. The propulsion sled 103, however, does not engage the second track 102 but instead remains engaged with only the first track 101. During a third period, as can be seen in Figure 3, where the first track 101 slopes downwards in the separation section 115, the carrier sled 104 disengages the first track 101 and is thus transferred from the first track 101 to the second track 102. The propulsion sled 103 remains retained to the first track 101 and separates vertically from the carrier sled 104 as it travels down along the first track 101. After reaching the second end 112 of the second track 102, the carrier sled 104 and munition impacts the target 105. The second track 102 may be oriented to set the impact angle of the munition or set to an appropriate length to dictate the impact velocity of the munition. The propulsion sled 103, however, is slowed and eventually stopped by the catcher box 110, which is located sufficiently far away from the target so as not to affect the impact test. Indeed, by providing a system which has two tracks, it is possible to accurately control the trajectory of both the propulsion sled 103 and the carrier sled 104. For example, it is possible to set the second track to any desired location or orientation in operative proximity to the target, e.g. to minimise the length of munition free flight, for accurately controlling the impact parameters of the test, while directing the propulsion sled to a second location away from the test impact location to ensure that it does not affect the test at any impact visualisation. Further, as the carrier sled 104 does not comprise a rocket motor or associated fuel storage, the carrier sled can be made to be lightweight so that it can also impact the target but without substantially affecting the test. Accordingly, it can be seen that the present invention provides a system having increased flexibility and reliable control of impact parameters, including those to be tested at high speeds. Figure 4 is a schematic diagram illustrating an isometric view and a rear view of an exemplar propulsion sled 103 of the impact testing system of Figure 1. The propulsion sled 103 extends longitudinally between a rear end 401 and a front end 402. The sled 103 includes a rocket motor housing 403 for storing a combustion solid such as fuel. At the rear and front ends 401, 402 of the propulsion sled 103, there is a rear block 404 and a front block 405, respectively. Each block 404, 405 is a support structure that holds the rocket motor housing 403. In the illustrated embodiment, each block 404, 405 has two parts 404a, 404b 405a, 405b, in the form of ‘split blocks' which surround the outer surface of the rocket motor housing 403 and are removably connected to each other by any suitable attachment means known in the art, such as hex screws or bolts that extend through the top block 404a, 405a and the lower block 404b, 405b. The front block 405 comprises an end plate 406 which faces forwards in the longitudinal direction of the propulsion sled 103. In use, and with reference to Figure 1, the end plate 406 faces forwards away from the first end 107 in the test direction (corresponding to the longitudinal direction 106 of the system 100). The rear block 404 comprises a rocket engine or motor 407 for combusting the fuel to supply the energy for propelling the propulsion sled 103 and carrier sled 104 forwards in the longitudinal direction. Any known calibre of rocket motor can be used depending on the nature of the test and the test parameters. The front and rear blocks 404, 405 comprise connection points for engaging the first track 101 while allowing sliding movement along the first track 101. The connection points of each block include a pair of tabs 410 extending the longitudinal extent of the block 404. In particular, the block 404, 405 has a neck region 408 extending downward from the main body of the block to a shoulder region 409. The shoulder region 409 is shaped to define the tabs 410 in the form of protrusions extending from a substantially planar surface 411 of the neck region 408. The tabs 410 face substantially outwards and away from each other in a transverse direction (perpendicular to the longitudinal direction) of the propulsion sled 103. The neck and shoulder regions of both blocks 404, 405 are mutually shaped and oriented such that both blocks 404, 405 are able to engage the rails of the first track at the same time. For example, tabs 410 on the same transverse side of the front and rear blocks 404, 405 are aligned in the longitudinal direction. Figure 5 is a schematic diagram illustrating an isometric view and a rear view of the carrier sled 104 for use in the impact testing system of Figure 1. The carrier sled 104 extends longitudinally between a rear end 501 and a front end 502. At each end 501, 502, there is a clamp 503, 504 which is arranged to hold the munition (not shown) as the carrier sled 104 is driven along the tracks. In use, the end plate 406 of the propulsion sled 103 will interface and abut a rear end 501 of the carrier sled 104 so as to drive the carrier sled 104 and munition forwards along the propulsion and cross-over sections 113, 114 of the system 100. In the illustrated embodiment, each clamp 503, 504 is circularly shaped so as to snugly receive a mutually shaped munition casing. Each clamp 503, 504 has two parts 503a, 503b, 504a, 504b which are removably fastened together, e.g. with screws, to allow the munition to be easily received inside the clamp when in the unfastened state. It will be appreciated here that the clamps may have any shape suitable for receiving and retaining the munition to the carrier sled 104. Further, clamps are not necessary and the munition can be retained to the carrier sled by any suitable attachment means. Each clamp 503, 504 is shaped such that, when its two parts 503a, 503b, 504a, 504b are fastened together, the clamps 503, 504 define connection points for engaging the second track 102 while allowing sliding movement along the second track. The connection points of each block include. The connection points are in the form of runner sections 505 which extend longitudinally along the transverse sides of the carrier sled 104 for engaging the second track 102 of the system 100. Each runner section 505 is substantially C-shaped in that it has two substantially parallel side walls 506 extending outwards from a base portion 507 of the clamp 503, 504 in the transverse direction. For each clamp 503, 504, the mouth of the runner sections 505, i.e. the open end of the space defined between the side walls 506 and base portion 507, face outwards away from each other in the transverse direction. The carrier sled 104 also includes two side supports 508 extending longitudinally on each transverse side of the sled 500 and connecting the base portions 507 of the runner sections 505 on the rear clamp 503 and the front clamp 504. Each side support 508 has padded material so as to protect the C-shaped runner sections from wear and tear. The side walls 506 are also lined with padded material for the same reason. The padded material also ensures a snug fit between the runner sections and the rails of the second track which are to be received in the mouth of the runner sections 505. The front and rear clamps 503, 504 includes further connection points for engaging the first track 101 while allowing sliding movement along the first track 101. The connection points of each clamp include a pair of tabs 509 extending longitudinally along the carrier sled 104. In particular, each clamp 503, 504 has a pair of plinths 510 extending downward from the main body of the clamp 503, 504 at opposite transverse sides of the clamp 503, 504. The tabs 509 are in the form of protrusions extending from a substantially planar surface 511 of the plinths 510. The tabs 509 face substantially inwards and towards each other in the transverse direction. The tabs 509 and plinths 510 may be attached to the clamp 503, 504 by any suitable fixing means, such as a screw or bolt etc. The tabs 509 of both rear and front clamps 503, 504 are mutually shaped and oriented such that both clamps are able to engage the rails of the first track at the same time. For example, inwardly facing surfaces of the tabs 509 on the same transverse side of the carrier sled 104 are aligned in the longitudinal direction. Figure 6 schematically illustrates the impact testing system where the propulsion sled 103 and carrier sled 104 are engaged with the first track in the propulsion section 113 of the system 100 as shown in Figure 1. In the propulsion section 113 of the system, each bar rail 601 of the first track 101 comprises a shoulder section 602 attached to the ground 603 using conventional means, such as bolts, a neck section 604 and a rail head 605 which is spaced from the shoulder section 602 by the neck section 604. The rail head 605 is wider than the neck section 604 as measured in the transverse direction of the track (perpendicular to the longitudinal direction 106 of the impact testing system 100). In this way the neck section 604 and rail head 605 are shaped to define a recessed portion 606 which is set back from the rail head 605 on both transverse sides of the bar rail 601. Further, the rail head 605 is substantially symmetrical about a mid-plane 607 which extends longitudinally and bisects the bar rail 601. That is, the shape or outer profile of the bar rail 601 is substantially the same on opposite transverse sides of the mid-plane 607. The first track 101 and the propulsion sled 103 co-operate such that the outwardly facing tabs 410 of the propulsion sled 103 are received in the inwardly facing recessed portions 606 of the first track 101. The neck regions 408 of the blocks of propulsion sled 103 have a width 608 that is substantially equal to (or less than) the transverse spacing 609 between the innermost surfaces of the pair of rail heads 605 (at the same longitudinal position). Further, a width 610 between tabs 410 of the shoulder region 409 (as measured from the outermost edges of the tabs 410) is greater than the transverse spacing 609 between the rail heads 605. Further still, the neck regions 408 of the propulsion sled 103 extend downward from the main body of the blocks by an extent 611 sufficient to allow the tabs 410 to be received in the recessed portions 606. In this way, the propulsion sled 103 is retained to the bar rails 601 to restrict its movement in the transverse and vertical directions but to allow sliding movement of the tabs 410 along the recessed portions 606 of the first track 101 in the longitudinal direction 106. The first track 101 and the carrier sled 104 co-operate such that the carrier sled 104 is retained to the bar rails 601 of the first track 101 to restrict its movement in the transverse and vertical directions but to allow sliding movement in the longitudinal direction 106. This is achieved by virtue of the plinths 510 of the carrier sled 104 extending downward from the main body of the blocks by an extent 615 such that the inwardly facing tabs 509 are received in the outwardly facing recessed portions 606 of the bar rails 601, i.e. those portions 606 that face away from each other. Further, the inner planar surfaces 511 of the plinths 510 have a transverse spacing 612 that is substantially equal to (or greater than) the transverse spacing 613 between the outermost surfaces of the pair of rail heads 605 (at the same longitudinal position). Further still, the transverse spacing 614 between the innermost surfaces of the tabs 509 of the carrier sled 104is less than the transverse spacing 613 between the outermost surfaces of the rail heads 605 at the same longitudinal position. Figure 7 schematically illustrates the impact testing system where the propulsion sled 103 and carrier sled 104 are in the cross-over section 114 of the system 100 as shown in Figure 1. As shown in Figure 7, the carrier sled 104 is engaged with the first track 101 in the manner described above with respect to Figure 6. Further, in this section, the carrier sled 104 slides along the first track 101 and into sliding engagement with the second track 102, whereby the rails 701 of the second track 102 are received in the mouths of the runner sections 505 of the sled 500. The mouth of each runner section 505 and each rail 701 of the second track 102 are mutually shaped to ensure a snug fit between the runner sections 505 and the rails 701 of the second track. Although not shown, the second track 102 is held at a fixed position relative to the first track 101 and the carrier sled 104 by a wider support structure, such as a steel frame. Further, the transverse spacing 702 between runner sections 505 is substantially equal to (or less than) the transverse spacing 703 between the rails 701 at the same longitudinal position of the track. This allows the runner sections 505 and the rails 701 of the second track to be brought into sliding engagement with each other. Further this cross-over section 114 may be advantageous to ensure that the carrier sled is correctly and accurately transferred from the first track to the second track in a stable manner. Figure 8 schematically illustrates the impact testing system where the propulsion sled 103 and carrier sled 104 are at the start of the separation section 115 of the system 100 shown in Figure 1. As shown in Figure 8, an outer section of each rail head 605 is shaved or cut away such that there is a void of material on the transversely outer sides of the pair of rail heads 605 that form the first track 101, as compared to the material that is present on the transversely outer sides of the rail heads 605 in the propulsion section 113 of the first track 101. The (each) rail head 605 is therefore substantially asymmetric about the longitudinal mid-plane 607 which bisects the bar rail 601. In this way, the bar rails 601 do not have outwardly facing recessed portions on the outermost sides of the first track 101, such that the inwardly facing tabs 509 of the carrier sled 104 rail head 605 do not engage the first track 101. The transverse spacing 801 between the outermost surfaces of the rail heads 605 is substantially less than the transverse spacing 802 between the innermost surfaces of the tabs 509 at the same longitudinal position, such that the carrier sled 104 is not able to be retained to the (bar rails 601 of the) first track 101. Figure 9 schematically illustrates the impact testing system where the propulsion sled 103 and carrier sled 104 are in the separation section 115 of the system 100 shown in Figure 1. As described with respect to Figure 3, the bar rails 601 of the first track 101 slope downwards in the separation section 115, such that the propulsion sled 103 will travel down along the first track 101. The bar rails 601 have the same shape described above with respect to Figure 8, such that the carrier sled 104 will disengage from the rails 601 of the first track 101 and separate from the propulsion sled 103 vertically before travelling along the second track 102 and onwards to the target. It will be appreciated that the propulsion sled 103, the carrier sled 104, and the bar rails 601 may include a mixture of tabs and recessed portions, as appropriate. For example, the propulsion sled 103 may comprise inwardly facing tabs 410 (instead of outwardly facing ones) for engaging the outwardly facing recessed portions 606 on the bar rails 601. The carrier sled 104 may have outwardly facing tabs 509 (instead of inwardly facing ones) for engaging inwardly facing recessed portions 606 of the bar rails 601. Correspondingly, in the separation section 115, the inner sections of the rail heads 605 may be shaved or cut away (instead of the outer sections) such that there is a void of material on the transversely inner sides of the rail heads 605. The bar rails and sleds may have any combination of inwardly or outwardly facing tabs and recessed portions, as appropriate. For example, the bar rails 601 may instead comprise tabs and the propulsion sled 103 and carrier sled 104 may comprise recessed portions for receiving those tabs. However, the bar rails 601 will have a first shape in the propulsion section 113 to retain the propulsion sled 103 and carrier sled 104 to the first track 101, but a different shape in the separation section 115 (and optionally cross-over section 114) of the system, so as to retain the propulsion sled 103 to the first track 101 but to allow the carrier sled 104 to disengage therefrom and to be transferred to the second track 102. The tabs and runner sections of the propulsion sled 103 and carrier sled 104 may extend along some or all of the length of the sled. Thus the tabs and / or runner sections may extend along the entire length of the sleds, as appropriate. Additionally, it will be appreciated that although the tabs and recessed portions illustrated in the Figures are in direct contact with one another, this is not required. In some arrangements, there may be one or more bearing elements, such as ball bearings or rolling elements, between the sleds and the rails of the first and second track (i.e. between respective tabs and recessed portions). This may be advantageous to reduce friction and thus wear between the sleds and the rails. It will be understood that the invention described herein is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

Claims

1. An impact testing system (100) for testing impact of an object with a target (105), the impact testing system (100) comprising:a first track (101); 1a second track (102); and 1a carrier sled (104) for supporting the object;wherein the carrier sled (104) comprises one or more first connection points (509) for engaging the first track (101) in a first.longitudinal section (113) of the system (100), and one or more second connection points (505) for engaging the second track (102) in a second longitudinal section (115) of the system which is in operative proximity to the target (105); andwherein the first track (101) has a first shape in the first longitudinal section (113) to engage the one or more first connection points (509) and a second shape in the second longitudinal section (115) to allow the one or more first connection points (509) to disengage from the first track (101) in the second longitudinal section (115).

2. The impact testing system of claim 1, further comprising a propulsion sled (103) configured to interface with and drive the carrier sled (104) along the first track (101).

3. The impact testing system of claim 2, wherein the first track (101) deflects at anIangle from the longitudinal direction (106) in the second longitudinal section (115) to guide the propulsion sled (103) away from the carrier sled (104) and target (105).

4. The impact testing system of claim 2 or 3, wherein the propulsion sled (103) comprises one or more third connection points (410) that engage the first track (101) to retain the propulsion sled (103) to the first track (101) while allowing siding movement along the entire length of the first track (101).

5. The impact testing system of claim 4, wherein the first frack (101) comprises at least one rail (601) and one or more first tabs (410) of the propulsion sled (103) engage with one or more first recessed sections (606) on a first side of the first track (101).

6. The impact testing system of any preceding claim, wherein the first track (101) comprises at least one rail (601) and the one or more first connection points comprises one or more tabs (509) for engaging a recessed section (606) on a side of the at least one rail (601) to retain the carrier sled (104) to the first track (101) while allowing sidingmovement of the carrier sled (104) along the first track (101) in the first longitudinal section (113).

7. The impact testing system of claim 6, wherein:the first shape comprises a neck region (604) and a rail head (605) which is symmetrical about a mid-plane (607) which bisects the rail (601), to form the recessed section (606) that receives a tab (509) of the carrier sled (104) therein to retain the carrier sled (104) to the first track (101); andthe second shape comprises the neck region (604) and a rail head (605) which is asymmetrical about the mid-plane (607) so as to allow the tab (509) of the carrier sled (104) to disengage and release from the first track (101) in the second longitudinal section (115).

8. The impact testing system of any preceding claim, wherein the one or more second connection points for engaging the second track (102) comprises one or more runner sections (505) shaped to define a space for receiving one or more rails (701) of the second track (102) therein while allowing sliding movement along the one or more rails (701) of the second track (102).

9. The impact testing system of claim 8, wherein the runner sections (505) are lined with padded material so as to protect the runner sections from wear and tear.

10. The impact testing system of any preceding claim, wherein the first track (101) and the second track (102) are arranged at fixed positions relative to one another in an intermediate longitudinal section (114) of the system, such that the first and second connection points of the carrier sled (104) will engage both the first track (101) and the second track (102) so as to be retained by both the first track (101) and the second track (102) in the intermediate longitudinal section (114).

11. The impact testing system of claim 2, optionally in combination with any one of claims 3-10, further comprising a catcher element (110) at the end (108) of the first track (101) for slowing onward movement of the propulsion sled (103).

12. The impact testing system of any preceding claim, wherein the carrier sled (104) comprises a clamp (503) having at least two parts (503a, 503b) which are removably fastened together to allow the object to be received within the clamp (503) when in an unfastened state.

13. An impact testing method comprising using the impact testing system (100) of any one of claims 1 to 12 to guide an object to impact a target (105);wherein the object is guided in a first longitudinal section (113) along the first track 5 (101) and is transferred from the first track (101) to the second track (102) beforeimpacting the target (105) at a position in operative proximity to the end (112) of the second track (102).

14. An impact testing method of claim 13, wherein the carrier sled (104) is driven10 along the first track (101) in the first longitudinal section (113) by a propulsion sled (103) which comprises a propulsion motor (407).

15. The impact testing method of claim 13 or 14, wherein the first track (101) deflects at an angle from the second track (102) in the second longitudinal section (115)15 to separate the propulsion sled (103) and the carrier sled (104) and to guide the propulsion sled (103) away from the target (105).

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