Abstract: An orifice entry diverging multi vane conical venturi diffuser for a mortar tube that provides a surface at the discharge end of a mortar tube for measuring or sensing instruments. The internal,vanes comprise the primary surface and the conical venturi wall comprises the secondary surface. This apparatus allows a solid object of the equivalent diameter of the entry orifice when propelled by gas pressure to travel through the diffuser into the open atmosphere while at the same time providing an increasing volumetric flow path for the discharge of the propellant gas. The vanes axial parallel primary surface area is used to provide a port for instrumentation. The area between the primary and secondary surfaces of circumferentially spaced vanes provides the gas flow channels when the center section formed by the vanes primary surfaces is obstructed by a solid object with the equivalent diameter of the entry orifice.

Abstract: A system for precisely measuring muzzle exit velocity of a “muzzle loaded” mortar projectile fired from a mortar tube using two back-biased Hall effect sensors for projectile gas ring channel detection. The system includes a back-biased Hall effect sensor block, a digital resolver electronic circuit and a computer software interface. The back-biased Hall effect sensors are located in a calibrated sensor block attached to a mortar tube. As the projectile metal casing passes a face of the sensors, the sensors trigger and release, providing two electronic pulses. The pulse edges are captured in the resolver electronics, containing a discriminator circuit for filtering all input pulses to distinguish between a projectile loading event and a projectile firing event. Once a valid firing event is detected, an output of precision timers is presented serially to a computer where it is processed and displayed by a computer software interface.

Abstract: An isolation system for a sensitive component or apparatus affixed to a mortar tube comprising a barrel mount assembly which supports two parallel shafts. A plate parallel with each axis of the two shafts positions four bearing carrier blocks, two each containing a sleeve bearing which rides on each of the shafts to allow the plate assembly to slide freely along the length of the shafts and support an isolated cage. During firing, the travel vector is decoupled from the cage by the shafts as they move with the barrel through the bearings leaving the cage assembly in free space. The cage then accelerates under the force of gravity over the distance of the displaced travel of the shafts back to its rest position landing on steel springs or dampers, each on a shaft and seated against the lower flange end of the barrel mount assembly.