Published online by Cambridge University Press: 28 March 2006
Approximate methods are used in a theoretical investigation of piston acceleration, peak pressure and piston oscillations in a gun tunnel. Behaviour in all these respects, at a given ratio of initial driver and test gas pressures, is related to the value of a ‘gun tunnel parameter’, Λ, and the ratio of the speeds of sound in driver and test gases. It is shown that large values of Λ must be combined with an enhanced speed of sound in the driver if high performance is to be achieved with manageable peak pressures. With air as test gas, using values of Λ achieved in current practice and a suitable driver gas, the analysis indicates that piston speeds approaching four times the speed of sound in air may be obtained.