Stress distribution in rocket motor cases is quite complex and simple stress analysis though useful can hardly be accurate. For this reason, as well as because of the low safety factors which must be used to save weight in the rocket motor cases, any rocket motor case design must be thoroughly tested. Hydrostatic testing and propellant pressurization have been found useful in control of the rocket motor case design and in control of production acceptance criteria for the rocket motor case. Rocket motor cases are generally tested to some pressure above normal operating pressure. Known methods include the nozzle being plugged and water inserted into the rocket motor case and a load applied to the rocket motor case to meet the specified psi load. This type of text puts an increased load on the nozzle end since the area is increased by the area of the throat (A.sub.T) and since the force is the pressure times the area (A.sub.T). Therefore, there is a need for a method which more accurately duplicates and actual motor test as if the rocket motor case were being tested under actual burning of rocket motor propellant within the rocket motor case.
Therefore, it is an object of this invention to provide a method by which a rocket motor case can be tested as near as possible under actual burning pressure application to the rocket motor case.
Another object of this invention is to provide a method for testing a rocket motor case in which the rocket motor case can be pressurized from an external source or by an internal source from burning of propellant within the rocket motor case.
Still another object of this invention is to equally distribute the pressure applied in the rocket motor case as it is distributed on actual burning of propellant with the rocket nozzle open as a exhaust.
Other objects and advantages of this invention will be obvious to those skilled in this art.
USPTO Backgrounds
USPTO Backgrounds