The society held a launch event at the Mojave Test Area on June 19th. With many people having other plans, we were sparsely attended but able to get a few things done. The winds were very low and sun was very hot that day (105 F) making it a challenge to operate at the site, but with each other’s help we managed. I was the pyrotechnic operator in charge that day. I had intended to bring my hybrid rocket for this event but wasn’t able to complete the rocket in time. It would be Bill Inman’s Solar Cat, a pair of micrograin alphas and witnessing the UCLA Prometheus team launch their hybrid rocket after getting a replacement nozzle from the motor supplier.
BILL INMAN’S SOLAR CAT
Bill Inman and Jon Wells made the journey from Nevada to demonstrate a new sun tracking system improvement to better automate the solar heating process with the parabolic mirror. Unfortunately, there were several problems with the installation that ultimately went unresolved for that day. A series of benchtop tests would be needed before bringing his combined solar collector and rail launcher back to the MTA for a launch.
Bill had also expressed concerns about vibration from over-the-road travel taking its toll on the structure. He was already considering a major rebuild of his parabolic collector with a wider aperture. The next iteration of the Solar Cat is also supposed to be larger in diameter and capacity. With the Solar Cat work at a halt, Bill and Jon came over to assist Manny Marquez and myself with the loading of a pair of RRS standard alphas.
A PAIR OF ALPHAS
Osvaldo Tarditti was unable to attend this event, but he did measure out the zinc and sulfur in separate pre-weighed bags and provided a clean pair of alpha parts complete with the nozzles and well-painted, turned and recovered aluminum nosecones. For our new members, the society likes to give the experience of micrograin rocketry. Manny, Bill and Jon would have their first experience loading and firing an alpha that day. The society hasn’t launched many micrograin rockets since before the pandemic.
Manny was a big help getting the equipment out and running. I was able to train him in the old RRS tradition of micrograin rocketry. With only two rockets, we gave the loading duties to Bill and Jon. For their handling of the dirty task of slowly loading the propellant tubes, they each got the honor of finishing the build and preparing for launch.
I was able to teach Bill, Jon and Manny the safe procedure for hooking up back to the control box in the blockhouse. With a well rehearsed procedure including air-and-road checks, we notified FAR in advance of firing our two alphas for that day to prevent anyone from wandering downrange before we fired.
We each got a good lesson in the value of teamwork and a renewed respect for the heat of summer. The micrograin rocket is a simple but powerful initiation into experimental rocketry.
Our next event has not been scheduled but we do plan to return to the MTA in July 2021. For members interested in planning the next event at the MTA, contact the RRS president and the executive council.
by Dave Nordling, Secretary, Reaction Research Society
The RRS had our last launch event of the year this Saturday, December 7, 2019, at the Mojave Test Area (MTA). We were hosts again to the Los Angeles Police Department (LAPD) Community Safety Partnership (CSP) and this time with 99th Street Elementary.
The RRS has been reworking some of our rails including our trusted and reliable alpha rail launcher. Months of use had slowly built up uneven layering of zinc-sulfide on the rail surfaces making loading difficult but protecting the steel surfaces from the slow corrosion of the dry salt lake bed just a few miles away. Osvaldo did great work in giving our alpha rail launcher a new lease on life. Thanks also to Russell Hoffing and his kids for helping out with the installation before the event crew arrived.
The winter seasonal rains have arrived a little early to southern California, but the weather began to clear today just before we started. The winds were very low which was excellent for launching rockets. From the washing action of the rain this week, the loose sand drifted into a vein-like pattern over the harder sand below which gave the ground a slightly “Martian” quality. It was cool but not cold and a great day for a launch.
We had a minor problem from the rainwater gathering in the bunker. It wasn’t more than an inch or two deep, but on a cool December morning, it would be a miserable place for our guests. The RRS was grateful to some of the Friends of Amateur Rocketry who let us borrow a small sump pump to pull the standing water out.
We gave the students the standard safety briefing about how to avoid the dangers at the site. We also gave them a live demonstration of how the micrograin zinc and sulfur powder burns in the open showing the brilliant yellow color. Larry Hoffing had also prepared a small sample of solid composite propellant made with ammonium perchlorate and an iron oxide accelerant.
Larry Hoffing and his grandsons had a few model rockets to try out at the event. After setting up the launch wire and clamping the smaller 6-foot long 1010 rail to a suitable rigid and weighted base. Winds were very light all day so we had few problems from the elements.
Larry flew a classic Estes model, Big Bertha, which is always a crowd-pleaser. This vintage model design is slowly powered at take-off by a C6-3 commercial motor then gains traction after its fins start working. It has flown to couple hundred feed then at apogee made a nice parachute recovery.
The high-powered fiberglass bodied rocket launched on a 1010 C-rail was boosted by a vintage Flight Systems F6-7 motor, but failed to move vertically up the rail by more than a couple of feet before settling nicely on the launch pad with an impressive 6-inch exhaust flame. It will be back to the drawing board for that model with the possible addition of a more powerful G-sized AP motor or a H-sized hybrid. The students at 99th Street Elementary witnessed the launch, but the biggest part of the event was yet to begin.
The ten RRS standard alpha rockets from the students were already loaded the night before. A last minute addition of another alpha painted by their teacher was included. Osvaldo showed me his latest propellant loading approach that minimizes external powder contamination on the person loading. Using zinc-sulfur is simple, but it has it’s own problems. Many of our spouses and friends are not pleased with the persistent odor of brimstone (raw sulfur) on our clothes upon our return to the city. Osvaldo has known this problem for years and found a simple method of blocking the migrating propellant dust using a simple pillowcase shield. He has also improved the mating funnel and with a steady light bouncing of the propellant tube on a wood block, the propellant tube can be filled with its 3.2 pounds of zinc-sulfur mixture.
Our alpha launch operations were conducted a little differently at this event. Osvaldo did the loading at the rails, while I was manning the launch switch in our observation bunker with everyone else safely under cover. By California law, the person on the launch switch is the pyro-op in charge. With our experienced team doing road and air space checks before each firing, we had a good safe launch and a lot of fun.
We had ten alpha rockets plus one extra painted by the teacher for this event. All of them looked really sharp with bright colors easy to spot when recovered from the desert floor. 99th Street Elementary really enjoyed the five weekly classes and were very exciting to have the last class at the Mojave Test Area to see real demonstrations of rocket propellants and the micrograin powder in each of the rockets propelling them into the gray sky one by one.
Most of the alpha flights were perfect. The flight times were consistent and given the low winds we could hear the whooshing return and the thump on nearly every one to confirm impact.
We had one particularly troublesome flight which is a rarity with the RRS standard alpha after all of the years spent perfecting that design. The second rocket sputtered and hesitated a lot before taking off slowly from and rails and flopping back to the ground. No obvious cause was found on that rocket, no unusual burn pattern or melting and the propellant tube seemed intact. After inspecting the rocket more thoroughly upon its recovery just a few feet from the launch rail, it was clear that the nozzle mounting screws must not have been installed. No damage was seen to either the propellant tube or the nozzle. The nozzle throat was in tact which indicates it must not have been present to choke the fiery exhaust flow. This also explains the profound lack of thrust, but yet even without a nozzle the micrograin rocket was able to generate enough pressure to lift itself out of the rails. The nozzles often fit very tightly into the propellant tubes which might have been how someone could have failed to notice the missing attachment screws during transport to the launch pad. This is quite an error which will not be repeated.
We said goodbye to our visitors and prepared to clean up the site. In the winter months, the sun sets quickly so we didn’t have a lot of time to search for the alphas. Frank had a lot of luck finding six of the eleven launched that day. Some of the parts can be reused with a little work.
We’ll surely discuss the results of the launch event at the next RRS monthly meeting which is next Friday, December 13th. Also, we’re already planning the next MTA launch event which will happen in January. We are expecting more launches in this next year, 2020. Thanks for reading!
The Reaction Research Society held another launch event with the LAPD CSP. This event was with the students of Boyle Heights. We had ten standard alphas launched into the blue Mojave sky that day including some model rockets made by Russell Hoffing and my grandson.
We had students from the CSU Long Beach liquid rocket team come out to make some measurements for sub-system testing that they are planning at the RRS MTA this year.
Returning RRS member, John Krell, had worked up two prototype instrumentation packages for flights in the ninth and tenth RRS standard alphas on that day. Both rockets were recovered and the results were impressive.
Materials have been acquired to repair the adjustable rail launcher that was damaged in early August this year. Osvaldo has been busy at work on the repairs. The RRS has several facility improvement projects in the works and we hope to bring this rail launcher back to service soon for larger rockets (4 to 6 inches).
John will hopefully have a full report and an overview of his design. Both Bill Behenna and Brian Johnson are also working on their own instrumentation designs for the RRS standard alpha. With this recent progress, this should help our others members take better data.
We’ll discuss more of the results of this event in detail at the next RRS meeting on October 11, 2019. The RRS meets every 2nd Friday at the Ken Nakaoka Community Center in Gardena, California. Stop in and see how things went.