HAD Hotfire Test Stand

After deciding to launch a high altitude solid motor test rocket to reach SEB's goal of reaching space with a liquid bipropellant rocket, we realized that we had to manufacture and characterize custom propellant grains to achieve the altitudes required to successfully test high Mach structures and high altitude recovery and avionics. This test stand design is a result of the need to test a large P-impulse class experimental rocket motor during a static fire to qualify the motor for flight. This project served to adapt our motor casing and data acquisition hardware with the infrastructure of the Friends of Amateur Rocketry (FAR) test site and perform a static fire that would give us confidence in the accuracy of our simulations and the performance of our propellant grains for a flight vehicle. 

Nozzle Retention: The nozzle retainer assembly was used to keep the motor constrained from the forward end if the forward closure of the motor failed and the motor produced thrust in the opposite intended direction. Using a simple assembly of two plates and gusset L-brackets, we constrained the motor from the forward end without any axial force applied to confound thrust measurements. 

Because of the simplicity of this design, the entire test stand was transported down to FAR in the Mojave Desert in a small sedan, and integration of the propellant grains, motor casing, and sub-assemblies at FAR was completed within a few hours. 

The static fire went smoothly, recording an average thrust of approximately 6500N and a total impulse of roughly 49,000 Ns. This data correlates to a projected HAD flight vehicle altitude of 110,000 feet (33,500 meters) and maximum velocity exceeding Mach 3.