Machine for excising a specimen of rocket propellant

Abstract

A machine performs in situ excision of a specimen of tough and highly elac solid propellant from a fin of the propellant disposed within a cavity extending from the nozzle opening of a rocket motor. The machine is mounted at the opening and has a rod extended into and moved generally axially of the cavity by an actuator assembly. A knife is mounted at one side of the rod end within the chamber. A mounting assembly supports the actuator assembly on the rocket motor and provides selective positioning of the actuator assembly axially of the cavity, of the angle of rod movement to the cavity axis, and of the knife position rotationally within the cavity. The actuator assembly has a guide received in the mounting assembly. The rod extends through the guide which prevents rotation of the rod while guiding it axially. From the guide, the rod extends successively to and through an air cylinder and a hydraulic dampening cylinder to a rod end bearing an adjustable stop for selecting the axial movement of the rod. A valve selects the degree of hydraulic dampening. Preferably, the knife is stirrup-shaped with a cutting edge facing either direction axially of the rod, and the air cylinder is double acting. Cuts may be thus made by extending or retracting the rod with a force and rate selected by the pressure applied to the air cylinder and by the degree of hydraulic dampening.