Held on Saturday, October 12, 1996 at the HALO Rocket Motor Test Facility
The following text was taken and then enhanced, with permission, from an article by Ronnie Lajoie, which was published in the November-December 1996 issue of the Southeastern Space Supporter, newsletter of HAL5.
During the summer months following the successful ground launch of the HALO rocket, team members sought a way to make the space rocket lighter. By removing the fins, the rocket would be just a cylinder with a pointy nose, allowing us to move the insulation from the tanks themselves to the outer walls of a smaller and lighter launch tube.
Many members of the HALO team wrestled with that question all summer long. Suggested ideas included a tube with a large helicopter-like blade. Once dropped from the balloon, the tube would spin up, thereby spinning up the rocket inside. Analysis showed, however, that if ignition did not occur within 5 seconds, the falling tube would gain to much downward velocity for the rocket to overcome.
Larry Scarborough proposed to spin up the tube mechanically and made several successful demonstrators. The system of weights and pulleys requires only an understanding of high school physics and is still considered a viable option.
Back in the 1800s, the first advance in rocketry was made when some bright person thought of deflecting the thrust by placing vanes in the exhaust nozzle. Properly angled, the diverted thrust would generate a moment which would spin up the rocket.
This approach, while not at the high school physics level, seemed doable by the HALO team. With the analytical support of Steve Mustaikis, still in California, Ron Lajoie computed the necessary angle of attack for the vanes in the exhaust nozzle. With the guidance and support of Propulsion Lead Tim Pickens, Ron Lajoie cut and shaped the aluminum vanes and placed them in the rocket nozzle extension.
Meanwhile, Tim Pickens modified the steel motor fixture so that the rocket motor could spin freely, yet stay held down even while thrusting with 300 pounds of force.
The 11th Project HALO rocket motor test day was held on Saturday, October 12. The one and only static test firing was for the all-asphalt and nitrous-oxide HALO Phase-1 hybrid rocket motor equipped with vanes in the nozzle extension. When the rocket motor was fired, the motor performed flawlessly, but did not spin.
After the firing, HALO members examined the motor fixture to see why the motor did not spin. Apparently, a metal brace (a very thick bar of steel) bent ever so slightly under the full axial force of the thrust. This jammed against the pulley wheel that would have otherwise allowed the motor to spin. The only way to know for sure would be to try again -- another day.
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This file was last modified on Saturday, 15-Apr-2017 13:19:40 EDT