As well as a 50mm bore gun (normally used for shock and terminal ballistics studies), we have a separate light gas-gun facility with a set of interchangeable barrels. These have a range of bore sizes from 5mm to 25mm and a maximum firing velocity of 1500 m/s for a 15g (or lighter) projectile. Normally the barrel is matched to the diameter of the projectile it is desired to fire, thus avoiding the complexity of having to strip away a carrier (or sabot). But if it is desired to fire very small particles such as sand grains, for example, sabots can be used. The specimen is normally placed within an environmental and expansion chamber which can be evacuated or alternatively filled with an atmosphere of choice. The chamber has viewing ports for high-speed optical and X-ray flash photography. Electrical and optical signals can also be fed in and out through cables.
As with the large plate impact facility, the advantages of firing into a (rough) vacuum are:
- The gun is silenced.
- The target is not dislodged by an airblast ahead of the projectile.
The kind of projects that have been performed with this facility include:
- Ballistic impact on, for example, laminated windows
- 'Symmetrical' Taylor impact (for validating constitutive models of metals and other materials)
- Hailstone impact.
- Single solid-particle erosion damage studies.