Water is used as a liquid projectile in a disruptor for destruction of various dangerous objects such as improvised explosive devices (IED’s). This weapon is light weight and experiences certain recoil during a firing action. As there is motion between a projectile and a barrel, a recoil is experienced by the weapon. The recoil of weapon works on a conservation of momentum equation which is based on Newton’s second law of motion. A water-jet is created due to intense gas generation by a propellant burning inside the cartridge. The gas energy obtained by burning the propellant is responsible for pushing the projectile in a forward direction through the barrel. Due to gas generation by propellant burning, there is forward motion of the projectile. An attempt is made to determine the theoretical recoil velocity, its energy for the projectile in a water-jet application. The minimum and maximum recoil velocities of a water-jet varies from 2.311 m/s to 2.611 m/s. The order of magnitude for the recoil velocities is small and can be compared with a recoil of small calibre weapons that these weapons experienced during a firing mode. Based on recoil velocities, minimum and maximum kinetic energies of recoil parts are determined as 3.73 kJ and 4.77 kJ, respectively. The maximum gas force experienced by the projectile is worked out as 13.46 kN. The minimum and maximum energies to overcome the resistance force are determined as 14.657 J and 18.711 J, respectively. A small exercise for spring design is also covered.

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Propellant Actuated Devices (PAD) are installed on various combat aircraft of Air Force and Naval bases to perform extremely important operations such as parachute deployment, harness and leg restrain, cable cutting, pullers, seat ejection, bomb release or fuel tanks etc. They are basically called as gas generators. Such devices produce the high temperature and pressure combustion gases on initiation and used to perform different operations. These cartridges are single-shot operating devices. The performance of such kind of PADs cannot be tested by non-destructive techniques. Hence, cartridges are designed to function with high reliability and stringent quality control checks at all levels during entire development cycle. The safety features required during handling, storage and transportation are built in the design of PAD. The cartridges are required to undergo different exhaustive design qualification tests to qualify design aspects. Total life of 6 years is assigned to cartridge after performance degradation study of the propellant which includes 2 years installed life. This paper explains about the development aspects of PAD, its use, function, testing and performance evaluation methodology in a suitable fabricated Velocity Test Rig (VTR). The maximum slug velocity is 121.14 m/s in hot condition and minimum slug velocity is 99.14 m/s in cold condition. The main objective of this paper is to device a novel method to measure actual slug velocity of the aircraft gun inside a cartridge using VTR and Doppler RADAR.

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Power cartridges are gas generators utilised to drive a liquid projectile for disruption of suspect improvised explosive devices (IED's). The purpose of a water-jet disruptor is to destroy the suspected IED. A novel method was devised for pressure measurement at the exit of the cartridge for launching liquid projectile. An experimental test set-up was designed and fabricated for measurement of projectile velocity and the propellant gas pressure in a velocity test rig (VTR). In these experiments, double base propellants having different physical and chemical properties were utilised to drive the solid projectile. This projectile was made of nylon material. This projectile velocity measurement is an important parameter in the armament field. An experimental study is the unique design feature. It is responsible for the measurement of pressure at the exit of the cartridge and the projectile velocity at the muzzle end of the barrel. The projectile velocity was measured using high speed photography. The pressure was measured using a pressure sensor.propellants have been experimentally measured as 384.23 m/s and 418.32 m/s, respectively. Experimentally the maximum pressures for spherical ball powder and NGB 051 propellants have been evaluated as 50.12 MPa and 63 MPa respectively from data gathered by the acquisition system. The standard deviation between the experimental and theoretical values for the projectile velocity varied from 12.57 to 13.88 for spherical ball powder whereas it was 5.33 to 7.09 for NGB 051 propellant. The percentage error between the experimental and the theoretical values of the projectile velocity was less than 10 for both propellants. Nomenclature: C Mass of propellant [g] d Internal diameter of VTR chamber where propellant pressure is acting on projectile or inside cartridge diameter for loading propellant mass [m] e Fluid internal energy [J] F Force constant of propellant [J/g] g Acceleration due to gravity (9.81 m/s 2 ) l Length of VTR chamber where propellant pressure is acting on projectile or inside cartridge length for loading propellant mass [mm] m Mass flow rate [kg/s] P i Internal pressure of propellant [MPa] Q Heat transfer across the system boundaries [J] V Volume of VTR chamber or volume of cartridge [cm 3 ] V 0 or V th Theoretical projectile velocity [m/s] Ws Mechanical work [J] y Datum head [m] Subscripts: i Inlet o Outlet Greek Symbols: π Constant (3.14) ρ Density [kg/m 3 ]