Experimental rocket motors are best developed using static motor tests. The following setup is called JENNA, a birdcage stand designed to hold small solid rocket motors for static firing while collecting thrust and chamber pressure data.
Night shot of a static test.
This stand was developed to hold a re-loadable motor. The small radial screws are designed to sheer for safety if an overpressure event occurs.
All the guts of the motor are interchangeable and use cheap O rings with silicone grease for a good seal. This makes it easy to test different propellants, nozzles, and so fourth.
Propellant casings are spin cast into 3D printed molds. They also serve as the thermal liner to prevent heat damage to the aluminum motor case.
The bulkhead is cast around a 1/2" bolt with a hole in it, this serves as a mounting point and pressure tap into the chamber.
The pressure tap bolt feeds into a copper heat sync tube which is packed with silicone grease to protect the pressure transducer. The heat sync screws into the S beam which is mounted to the backing plate. Both sensors connect to a battery powered Arduino which saves the data to an SD card.
The birdcage design constrains the motor in case of rupture. The front bolts allow for a longer two grain motor to be installed.
Notes:
The stand was built from scrap, hence the random holes.
One could load the bolt's hole with silicone grease and get away with a smaller or aluminum heat sync
The stand can be designed to accommodate a variety of motor diameters by threading extra holes into the base plate.
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