Ground Testing of Rocket Motors

by Frank Joy

Western NY Pyrotechnic Association

Using a 2" X 2" wood apparatus (shown in diagram) to test rocket motors without flight provides a lot of useful information.

Taping the motor snugly against the stop block with the nozzle down, ignition is via any convenient method.

- Electrical ignition allows the entire setup to be covered by a 50 gallon plastic drum to contain explosion "products" and/or reduce noise

- After testing, motors can be checked for nozzle erosion and case condition.

- If no drum is covering the motor, the thrust and delay times can be accurately measured.

- New Batches of black powder rocket fuel can be quickly charcoal adjusted for maximum power without explosion. This can be done even in windy weather, and rocket sticks aren't blown into toothpicks as often.

- Whistle rockets can be ground tested, but won't make the ripping sound unless the motor is permitted to move away from the listener. This demonstrates the doppler effect. If the rocket were fired at the listener, the pitch of the whistle should increase, probably above the range of human hearing. Once the rocket passed the listener, the normal "ripping" should start.