Held on Saturday, November 9, 1996 at the HALO Rocket Motor Test Facility
The following previously unpublished text would have been, given more time and space, part of the article by Ronnie Lajoie, which was published in the November-December 1996 issue of the Southeastern Space Supporter, newsletter of HAL5.
The 12th Project HALO rocket motor test day was held on Saturday, November 9. The one and only static test firing was for the all-asphalt and nitrous-oxide HALO Phase-1 hybrid rocket motor equipped with new vanes in the same nozzle extension previously used in the firing on October 12 (see HALO Rocket Motor Test Day 11). A new nozzle extension would have been preferred (even though this one survived its first test firing very well), however Tim Pickens found that the heat of the previous firing had fused the graphite nozzle to the aluminum end-cap of the phenolic nozzle extension.
James Hopkins, a new member to HAL5 and Project HALO, helped Tim Pickens devise and construct a more secure brace for the steel motor fixture.
Upon motor ignition, a louder than usual initial explosion was heard, followed by tremendous chugging of the motor during its burn. HALO members watching the static firing from a safe distance could easily see that the nozzle had somehow been forced off the motor case. The combustion process continued without generating thrust -- and obviously without any spin -- until the nitrous-oxide in the oxidizer tank ran out.
Most of the nozzle pieces were found within ten feet of the test stand. It is believed that a thinner-than-usual groove in the motor case (different from the previous firing) prevented a thicker-than-usual snap-ring to properly seat. The combustion chamber pressure at ignition was large enough to force the snap ring out of the groove and shove the nozzle towards the metal flame deflector plate below.
The graphite nozzle shattered upon slamming into the flame deflector plate. A new one will have to be carved for the space launch attempt.
Given a strong desire by the HALO team to get on with the first space launch attempt, the group relunctantly decided to halt all static motor firings related to HALO Phase 1, and to go back to the finned rocket concept which successfully flew from the ground in Manchester, Tennessee in April of 1996. Going back to this design alleviated the need for another ground launch test, thus shaving at least a month off the already tight schedule. Vanes may still be used in subsequent HALO phases; only time -- and more testing -- will tell.
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This file was last modified on Saturday, 15-Apr-2017 13:19:40 EDT