Held on Saturday, April 13, 1996 at the Barrens Test Range in Manchester, Tennessee
The following text was taken, with permission, from an article by Ronnie Lajoie, which was published in the May-June 1996 issue of the Southeastern Space Supporter, newsletter of HAL5.
In the last issue, Tim reported on the successful static firing our of rocket propulsion system on February 24. The last issues Calendar listed a number of HALO Rocket Work Party days between that time and the ground launch on April 13. Believe me, those were not the only days that HALO team members worked to prepare for the ground launch. Many worked at home and several unannounced Work Party days had to be added as well. The successful results speak for themselves.
With the propulsion system design proven, the team concentrated there efforts in five areas: (1) rocket nose cone and payload section, (2) rocket parachute deployment system, (3) rocket composite motor case and fuel grain, (4) rocket composite aerodynamic fins, and (5) rockoon gondola (or rocket launch tube). Alfred Wright and Tim Pickens both did an outstanding job of coordinating the design and development in all areas.
Tim and Al led this activity, but almost all team members were involved at one point or another. The fiberglass nose cone was purchased from Rocket Science of South Carolina. The length was fine, but the bottom diameter was too wide for our first rocket. We decided to cut off the lower section enough to bring the bottom diameter closer towards that of the oxidizer tank it would be mounted to.
A perfect diameter match would have left us with a short nose cone with too little internal volume, so a compromise was reached. The excess diameter of about one-inch would be handled by a wooden adapter ring, which was epoxied to the inside of the nose cone. Four small holes were drilled into the right and then reinforced with metal guides for the attachment screws.
Since we dare not drill mounting holes into the oxidizer tank, a wood and aluminum adapter ring was constructed and epoxied to the top of the tank. Four tiny angle brackets were cut from metal and screwed into the ring, placed to match the one inside the nose cone. (These tiny screws later proved grossly insufficient in handling the 10-g launch loads. Stress analysts, we need you!)
Since oxidizer fueling and venting would be done from the top of the tank, we drilled many holes into the lower side of the nose cone to allow for access to plumbing valves and venting ports. We also drilled holes for access to the payload section electronics. Ronnie used his computer to print color labels for the many holes and also painted our HALO logo onto the side (see Figure 1).
Clay Sawyer, Project HALOs newest team member, jumped right into the task of preparing the rocket electronics. Greg Allison, who had led this activity prior to recruiting Clay, continued to play an active role in payload design and testing, as did Gene Hornbuckle.
The payload, or payloads rather, consisted of the following: one IA-X95 single-axis accelerometer purchased from The Cambridge Group, one loud homing beacon purchased from Radio Shack, and one radio transmitter loaned from Bill Brown. The IA-X95 was entrusted with collecting data from the flight (acceleration, velocity, and distance traveled versus time) and firing the parachute door release mechanism (just after apogee). The homing beacon and radio transmitter were crucial for locating the rocket once it landed. (An additional radio transmitter was loaned to us in Manchester, which allowed us later to track down the payload section.)
As shown in Figure 2, these three payloads were glued to either side of a wooden plate (or its bottom disk), which later would be slid into the nose cone and screwed onto the nose cones adapter ring. Three 9V batteries, one a lithium, were also glued to the plate in various spots. Epoxy was not used since we wanted to reuse the parts. (Gluing parts also later proved insufficient in handling the launch loads.)
Plugs were passed through the side holes drilled in the nose cone, and wiring was passed through bottom holes drilled in the adapter ring. Tests were then performed to verify the electronics.
The neck connection area of our two bottle oxidizer tank provided a unique place for the parachute. Located near the center of mass, the area would allow the spent rocket to parachute back to Earth in a horizontal position and soften its impact on the ground.
Ron Creel and Tim worked together to design and build the parachute door -- a short flat piece of sheet metal rolled around the tanks and tied off shoelace-style. The parachute stuffed inside would provide the internal pressure to push away the door once Thermolite burned through the string. Ron successfully tested the door release prior to the ground launch (see Figure 3).
To get the dry weight of the rocket down and the propellant mass fraction up, we reluctantly switched from cheap aluminum pipe to a more expensive composite motor case. The phenolic tubing used previously as an insert would be the case itself. We hired John Pavlick of Advanced Composites to wrap two phenolic tubes with composite fibers and oven-cure it with an epoxy-resin. Sound high tech? Yes it does, but a bargain at only $400 (including setup) -- versus the thousands of dollars such work used to cost. Before he left, Steve Mustaikis crafted aluminum end-caps for the two cases, for attaching to tank and nozzle.
Peter Ewing and I, under Tims watchful eye, performed the delicate, yet messy, operation of lining the interior wall of the case with asbestos paper and a high-temperature cement affectionately called black goop. We then made a special jig so that Gene could pour in the melted asphalt and make the fuel grain (see Figure 4).
Meanwhile, Tim carved out a special graphite nozzle optimized for the ground launch. The nozzle extension to be used for the space launch would not be used for the ground launch.
Gene was not sitting idle while waiting for me and Peter to prepare the case. He was busy making three rocket fins. Gene started by carving foam insulation board into the size specified by Al Wright, with a wedge airfoil-shape. He then epoxied fiberglass strips over it to give it the required strength.
Meanwhile, Al was preparing a home for them; making a fin jig -- a large board with a hole in the middle for the case fastening screw. On the board, Al drew out the guiding lines for placing the fins. Once the fins arrived, Tim and Al checked the final alignment. The fins, sized for the high-altitude launch, were 10-times oversized for the ground launch (100 times the surface area) -- a slight misalignment could rip them off the rocket and potentially destabilize it.
In Operation Attach Fins, first Al and Ron Creel, then also Tim, Peter, Ronnie, and whoever else was on hand; hurried to epoxy the fins to the motor case, and (the next day) to epoxy fiberglass support strips to secure the fins. The final assembly looked more like a scene from Operation Petticoat once Al was through securing Genes pink fin holders around the fin and fiberglass combination (see Figure 5).
Once the shape and size of the rocket were determined by Tim and Al, Larry Scarborough began the effort of making the full-sized launch tube, which would eventually be the foundation of the balloon gondola. With help from Ron Creel, the 8-foot-tall finished product was a latticework of wood, wire, and string (see Figure 6), with guides for both the fin tips and the main body. Many fit checks were performed and adjustments were made. Though only weighing less than 10 pounds, the gondola was very sturdy (as the successful ground launch proved). (For more on the gondola, see Larrys article later in this issue.)
When Tim said the above statement, he wasnt kidding! After writing this, I am amazed we did all this and more in just 6 weeks -- after work hours! I am proud to say that I am part of this team of hard-working, dedicated space enthusiasts; and I am now convinced that we will indeed succeed in our space launch efforts. Ad Astra per HAL5!
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