Our cutting-edge, vertically mounted ballistic range at Manhattan College is designed for high-velocity penetration testing in sandy and clayey soils. We utilize a single-stage pneumatic gas gun to propel projectiles at high speeds (Fig. 1). Key features of our launcher include a very fast-acting, free-floating shuttle valve and a vertical orientation for testing granular media. The fast-acting shuttle valve enables the rapid evacuation of the helium reservoir into the breech and barrel, which is crucial for achieving high muzzle velocities. A schematic drawing of the shuttle valve is shown in Fig. 2.
Fig. 1: Vertical Ballistic Range
The pressure supplied to the reservoir initially keeps the otherwise free-floating shuttle valve closed. Upon triggering the launcher, a solenoid valve at the back of the reservoir opens briefly, allowing the shuttle valve to open and rapidly empty into the breech. This sudden depressurization efficiently propels the projectile to high velocities, enabling us to reach speeds up to 1000 m/s (~ Mach 3). Additionally, a custom-made frame was developed to vertically orient the otherwise horizontal launcher. This vertical orientation is crucial, as most soils exhibit variations in strength and behavior with depth. While most published work neglects this depth-varying property of soil, our vertically mounted launcher allows us to capture these phenomena, which is vital for understanding the soil’s response to ballistic penetration.
Fig. 2: Schematic illustration of the stages of shuttle valve operating mechanism: (a) depressurized rest position; (b) pressurized reservoir prior to launch; (c) depressurized reservoir following solenoid trigger.
We test a variety of projectiles, including rods with blunt and conical noses, and a 1/10th scale 155 mm M107 ordnance (Fig. 3), with plans to expand to other models like the M81 HE Mortar. This wide range of projectiles is necessary, as projectile geometry significantly influences penetration, particularly in terms of drag and stability.
Fig. 3: Projectiles tested; (a) Blunt and conical noses, (b) scaled M107, actual M107 shown for comparison.
References
- Giacomo, L., Grace, D., Omidvar, M., Bless, S., & Iskander, M. (2024). Vertical projectile launcher for study of rapid penetration into soil targets. Experimental Techniques.
- Omidvar, M., Dinotte, J., Giacomo, L., Bless, S., & Iskander, M. (2024). Dynamics of sand response to rapid penetration by rigid projectiles. Granular Matter, 26(3).