## 3 Sabot-Stopping System Conceptual Design  
In the development of an LGG system, the structural integrity of the sabot-stopping system is critical to the repeatability and accuracy of the test apparatus [45]. The sudden deceleration, subsequent high forces, and potential for misalignment can damage and fragment the sabot-stopping system, leading to target contamination. An adequate design that will not yield or partially fail due to high strain deformation is required for the characterisation of this system, specifically input/output parameters with the sabot. While there are many serviceable elements in an LGG design, the sabot-stopping system is still the most susceptible element and may require replacement after a few impacts, even under normal operation, causing significant delays to the test campaign as the system may need calibration and characterisation after each replacement. This project proposes the design of a reusable sabot-stopping system (\(>\)20 shots) to reduce the likelihood of this issue.  
The development of this concept led to the design of a technical solution where the sabot does not expand and break away, since the speed range and projectile masses involved allow for a simpler solution. It is proposed that the sabot can consist of a hollow cylinder closed at the bottom end, from which the projectile comes out after the sabot is stopped. The design of this sabot will be defined at a later stage of the described work.  
The concept of the system is schematically shown in Figure 3, which also demonstrates the dissipation mechanism principle for the impact force. A tentative configuration of the key elements is shown in Figure 4. The holder for the sacrificial impact tube assembly, which consists of an impact plate with a rubber disc surrounding it and a rubber cylinder behind it, is part of the sabot system. After the shot, the primary component in interacting directly with the sabot is the impact tube. Between the impact chamber and the LGG pump tube, the holder is inserted into a supporting frame with flanges that allow for different mounting options. Several tests can be completed in a single day due to the unique design of the single-stage LGG, whose components are not destroyed or compromised during shot operations. The novel sabot-stopping system proposed here is also designed to mechanically decouple the target from the sabot-stopping system, overcoming the transmission of unwanted vibrations to the target.  
This leads to more accurate and reliable results, making the proposed system highly suitable for use in LGG systems.  
Additionally, the suggested sabot-stopping system enables high-velocity projectile testing while minimizing system perturbations and reducing calibration and characterization time, thereby enhancing testing efficiency. Furthermore, by eliminating the risk of target contamination, it improves the accuracy of the testing process, making it applicable in various domains [46; 47]. The proposed system design carries significant implications for the progress of LGG systems, and it is expected to contribute significantly to the advancement of this field.  
Figure 2: Single-stage LGG performances at 150 bar.