Held on Saturday, October 21, 1995 at the HALO Rocket Motor Test Facility
The following text was taken, with permission, from an article by Tim Pickens and Ronnie Lajoie, which was published in the November-December 1995 issue of the Southeastern Space Supporter, newsletter of HAL5.
The eighth Project HALO rocket motor test day was held on a chilly Saturday, October 21. After a month of arduous preparation, we were ready to test four new enlarged hybrid rocket motors.
As expected, it took all morning to set up and check out all of the new test equipment. It was noon by the time we finished, so we decided to take a lunch break, courtesy of Herman Pickens.
The only real problem we encountered was that we ran short on nitrous oxide. This new motor really does consume a lot of laughing gas. This, of course, was no laughing matter at the time since no one sells N2O on a Saturday!
We did however get some relevant data from the single test we performed. We successfully test fired our first new enlarged motor (all-asphalt, a 11/2-inch core diameter, and a 15-inch length), observed the burn characteristics, achieved the desired chamber pressure of 550 psi, observed the new N2O mass flow rate (flux), and evaluated the overall new motor design. Since the N2O pressure was low, we did not see (nor expected to see) the desired 340 pounds of thrust. That would have to wait for another day.
Because of the cold tank temperatures and the resulting low N2O static pressure, we decided to place band heaters (glorified heating pads) on our supply tanks. This really worked well for us. With all the new changes that had taken place since the smaller motor (200-pound thrust), we felt that it was a pretty good test day.
One other test we were able to perform involved a trail usage of hydroxyl-amine-nitrate (HAN) as an oxidizer for McDonnell Douglas HTPB-based hybrid rocket motor fuel. HAN is mostly water (up to 95% by weight) and yields a lower specific impulse; but since it is as dense as water, yields a higher density specific-impulse than either N2O or even LOX. Another benefit is that it is the most environmentally friendly oxidizer around.
Dr. David Dean and I worked out a way to use our nitrogen supply tank to pressurized some HAN in a small container. The first test was mostly a learning experience, since much of the HAN dripped out of the nozzle instead of burning. (Have you ever tried setting fire to water??!) We did see a small purplish flame for a second though, and agreed to try again later.
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