Suborbital aeroscience studies-- nozzle and fuel grain material study/over the summer of 2004, several tests (6) were performed to analyze the performance of various nozzle/fuel grain combinations…

Suborbital aeroscience studies-- nozzle and fuel grain material study/over the summer of 2004, several tests (6) were performed to analyze the performance of various nozzle/fuel grain combinations (refer to proposal NNJ04VC15G suborbital aeroscience studies nozzle and fuel grain material study). The tests revealed critical information regarding the oxidizer flow system hardware and its performance. During the tests, a dirty burn was noticed and a low oxidizer flow rate was suspected. Upon investigation, calculations were reviewed and cold-flow tests were performed and IT was found that the inner diameter of the oxidizer feed hoses were not consistent and caused pressure differences and cavitations - resulting in the confirmation of a low oxidizer flow. A new oxidizer tank, new hoses, a new solenoid, and some simple modifications were applied to fix the mass flow rate problem. The solenoid, a $15,000 1-inch piloted solenoid donated by moog, was sufficient for the proper oxidizer mass flow rate. Results from these preliminary tests prompted several additional modifications to the test facility to provide more research capabilities and enable better data acquisition. These modifications included four more cameras being installed to record the test, bringing the total number of cameras to eight, so the capabilities exist to review the recordings and see any anomalies experienced during the testing. In 2005, testing for five-seconds was completed for the roofing TAR, stanford's paraffin, and htpb (hydroxyl-terminated polybutadiene) fuel grains and the graphite, havaflex, and ceramic-coated aluminum nozzles. Results of these tests showed that the needed oxidizer flow was not being reached. In 2006, the calculations were then reworked and IT was found that the original calculations were incorrect and the proper modifications were made. However, when there were still anomalies in the data, IT was decided that both the injection and the nozzle calculations were to be revisited. When these number were revisited (2007-2008), IT was discovered the injection orifice (not the nozzle) needed to be increased by 68%. When this change was made, a very successful TAR-graphite test ensued. Presently, work is in progress to have real-time digital camera feed to a computer that records the burn in-sync with the pressure transducers, the load cell data, and time, so any anomalies concerning instability, pressure spikes, or hardware failure can be located in the data. These modifications will further enhance the testing process and better enable abilities to evaluate the data results.