The latest meeting of the Reaction Research Society took place last Friday, June 11th and had 19 attendees – including a guest presentation from the Clarkson University Rocket Club. We kicked off the meeting saying vitrual hello’s and catching up on personal updates – Dimitri is safely in beautiful Alaska but will be down to visit California and may attend an MTA event if one is hosted.
RECENT & UPCOMING MTA EVENTS
The group kicked off society business with Dave Nordling telling us about the highlights from recent events at the MTA – including liquid and hybrid rockets from the UCLA rocket teams. More details are available in the post from Dave here.
Dave also re-iterated his desire that the Reaction Research Society host at least 1 event at the MTA every month, and asked whether other members were interested in attending an event on Saturday, June 19. A few members expressed interest – and Osvaldo agreed to prepare a few Alpha rockets for Dave to possibly launch. The weather is forecast to be 111 deg Farenheit in the desert this weekend, so anyone attending will need to bring lots of water, sun protection, and other preparations to beat the heat!
GUEST PRESENTATION – CLARKSON UNIVERSITY ROCKET CLUB
David Nagy, Benjamin Ellis, and Tyler Brooks from the Clarkson University Rocket Club were our guest presenters for this month. The club is brand-new (it became active this year!) and these students are working to turn it into a fixture at the university in northern New York state. They are currently in the process of soliciting faculty support, building a composites lab, and procuring equipment to get the club off the ground
David, the president of the team, has some previous rocket experience with both high power and liquid rockets – including a 9.5 kN pintle injector rocket engine. The team is currently building their own fiberglass, high power rocket from scratch which they plan to fly on a commercial, CTI 75mm solid rocket rocket motor. This scratch build is not only helping them build out their workspace to do filament winding and carbon fiber layups – they also intend to fly a 3D printed avionics bay with an avionics board designed from scratch. They hope to use the lessons learned from this project to inform work on future, more complicated projects.
The Clarkson University team solicited advice and opinions on their plans for a liquid bi-propellant LOX/Ethanol rocket. The design is currently in its early stages but the specifications are to have 500 lbf thrust, with a fuel-centered pintle injector. They predict that with a 15-second burn time they could build a rocket that would reach an apogee of 35,000 ft. Several RRS members gave their opinions on this design and other challenges involved with starting a fledgling club from scratch. I know many of the members are excited to see what these students will do!
WIRELESS LAUNCH CONTROLLERS
We decided to do a short recap of our recent discussions and presentations from vendors of wireless launch controllers. Dimitri offered to let us use his Cobra system when he returns to California in July, and there was talk of attempting to launch 16 low-power kits at the same time to further test/prove the efficacy and safety of the controllers. RRS members seemed generally impressed with the presentation from Cobra last month, but concern was raised that it’s not a necessary expense. There was a bit of a debate about whether laying and coiling several hundred feet of igniter wire is triple-digit changes the calculation, but Osvaldo has graciously offered to be the cable spooler for any project that requests it.
MTA PERMANENT BATHROOM STATUS UPDATE
The Executive Council updated the membership on progress with the permanent bathroom. After a meeting in Downey earlier this month, it was agreed that RRS member Wilbur would build the container in the LA area and then transport it out to concrete pads which will need to be built at the MTA site (along with a septic solution). The first step of this process has been completed – and the RRS has placed a down payment on a 20 foot “high-cube” shipping container to be used for the bathroom. A schematic of the container is shown below.
The current plan is still to build 2 of these 20-foot containers. Water will be supplied by a well and stored in a tank installed on top of the bathroom or a nearby storage container. The bathroom facility is planned to be located southeast of the Dosa building, alongside the existing storage containers.
NEXT MONTHLY MEETING
The next RRS monthly meeting will be held virtually on Friday, July 9th at 7:30 pm pacific time. Current members will receive an invite via e-mail the week of the meeting. Non-members (or members who have not received recent invites) can request an invitation by sending an email to:
The latest meeting of the Reaction Research Society took place this past Friday, May 14th and had 20 attendees – including a guest presenter and a project update from the Compton Comet team, which is composed of RRS members. We kicked off the meeting saying vitrual hello’s and catching up on personal updates.
UPCOMING EVENTS AT THE MTA
The group kicked off society business by planning for upcoming MTA events later this month. Wolfram Blume is continuing progress on the Gas Guzzler, but windy forecasts continue to limit his ability to do further launch testing. Osvaldo and Wolfram planned to visit the MTA on May 16th to do a practice setup for a future static firing and some housekeeping tasks at the property.
Osvaldo also informed the membership about an active day planned for Saturday, May 29th with groups from UCLA planning to do another static firing of their hybrid motor and a liquid rocket launch to 33,000 ft. and a team of students firing model rockets. Several additional RRS members expressed interest in attending this event.
GUEST PRESENTATION – COBRA FIRING SYSTEMS
Scott Smith, the founder of Cobra Firing Systems was our guest presenter for this month, continuing our recent discussions on wireless launch controllers. Scott has been in the pyrotechnics industry for 10 years, and developed Cobra into a 25-person company with roughly 14,000 customers around the word. They have worked with Mythbusters, Disney, and the US Military to name a few.
RRS member questions for Scott focused on safety, in particular the risk of misfires and adding a physical shunt to the system. The data is encrypted, includes checksums, and is built around a US-based company Synapse, which has allowed the company to avoid any reports of accidental misfiring due to stray wireless signals. Cobra firing boxes are modular in nature and allow for what the company calls a “slat” – which allows for a cap to be used as a physical, mechanical shunt on the system.
MEMBER PRESENTATION – COMPTON COMET
RRS student members Manuel Marques, Aarington Mitchell, and Tre Willingham presented on the status of their project the “Compton Comet” which is being built at the Compton Airport under the guidance of RRS members Waldo Stakes and Dave Nordling.
The rocket is a 75% ethanol & liquid oxygen bi-propellant rocket with a regeneratively-cooled engine. The engine is a surplus XLR-11 which should produce roughly 1,500-lbf of thrust, and was originally used in a group of 4 to power the Bell-X1 (the first aircraft to break the sound barrier). The rocket is estimated to reach an altitude of 20,000 km and will use a 2-parachute dual deployment recovery system.
THE FUTURE OF IN-PERSON RRS EVENTS
Members discussed the likelihood of in-person RRS events like the Symposium and meetings at the Gardena Community Center in 2021. It mentioned that the Symposium typically takes between 90 to 120 days to prepare, and it would be unlikely that the RRS would host one before spring 2022. There was a bit more of an optimistic outlook on the monthly meetings with a tentative goal set for a return to the Community Center in August (pending COVID restrictions).
MTA PERMANENT BATHROOM STATUS UPDATE
Designs and plans for the permanent bathroom structure at the MTA have been the main focus of the ongoing, twice-monthly meetings of the RRS Executive Council. Frank updated the membership on the current status of the project, which has gone through several iterations. Currently, RRS member Wilbur is working with professional drafters to get precise designs on paper – including model numbers for things like toilets and water heaters. A precise, written design will help the society get a final product that matches expectations.
The current plan is to build 2 or 3, 20-foot containers with 2 bathrooms each or 1 bathroom and 1 shower. These will be transported to the MTA and installed on concrete plinths which drain to a concrete septic tank and leach field. Water will be supplied by a well and stored in a tank installed on top of the bathroom or a nearby storage container. The bathroom facility is planned to be located southeast of the Dosa building, alongside the existing storage containers.
RRS BY LAWS
The RRS Executive Council has reviewed the recommended changes to the By Laws provided by the 2020 constitutional committee. Following are the By Laws as agreed to by the 2021 RRS Executive Council:
LAUNCHING & STRUCTURES
Richard Dierking raised a question regarding the new structure being built on the Polaris land adjacent to the RRS site, and whether it must be considered an occupied structure during launch testing at the RRS site. This prompted a lively debate about the nuances of the regulatory framework around rocket activities in the Mojave desert, with several members voicing their opinions.
Safety of all personnel must be the #1 priority during activities at the MTA & communication between between the RRS, FAR, and Polaris is the best way to ensure that. Concurrent operations at adjacent properties are avoided when possible, and the RRS maintains relationships with our neighbors so that the Pyrotechnic Operator in charge is in contact with & can ensure the safety of personnel at adjacent property when operations overlap.
NEXT MONTHLY MEETING
The next RRS monthly meeting will be held virtually on Friday, June 11th at 7:30 pm pacific time. Current members will receive an invite via e-mail the week of the meeting. Non-members (or members who have not received recent invites) can request an invitation by sending an email to:
The RRS held a launch event at our Mojave Test Area (MTA) on March 20, 2021, the spring equinox. COVID-19 still remains a threat so everyone had to observe protective protocols. We had a lot of wind that day making launch impractical, but we still were able to get many things done that day including another static fire of a hybrid motor, some system checkouts of the Gas Guzzler and a possible flight of the Solar Cat steam rocket. Osvaldo Tarditti was our pyrotechnic operator in charge. Also joining us that day was fellow Rockets 2nd Class pyrotechnic operator and RRS member, Jim Gross,
MOBILE TRAILER CLEANUP
Mike Gottlieb was a lifetime member of the RRS who passed away over 2 years ago. Years prior, he had acquired a surplus mobile trailer from the former Rockwell International company which was left to reside at the RRS MTA. By permission from his surviving family, this single-axle, climate controlled trailer has been donated to the society. The trailer was opened by the RRS president and the interior inspected by our members present at our March 2021 launch event.
For now, the space will be used for light storage until more space can be acquired elsewhere. We used the time to reorganize the contents of our storage trailer. We hope to renovate this new mobile trailer soon and restore its climate control systems which will be convenient in the summer months.
PUBLIC ADDRESS SYSTEM AT THE MTA
During the cleaning and reorganization of our storage space, we pulled out the public address equipment we had. The 12 VDC battery powered system including loud speaker and microphones worked well in a test from the old blockhouse. The society has talked about having a more distributed system around the main areas of the site. This will require some further equipment purchases, but for now we have a core system to start from. The goal is to make coordination of our events easier to do when we have large groups of people at the MTA again. Further still, we’d like to coordinate launch timing better with our neighboring amateur rocketry group (FAR) to our south.
NEW RESTROOM FACILITY
As discussed at the March 2021 monthly meeting, the society is going forward with building a new restroom facility with flushing toilets. This will be a big convenience to our visitors and members alike. The executive council has received bids and plans for the restroom and is working with suppliers to find the best solution given our budget. We are grateful to our generous benefactor and the many people who supported this project with their time and skills. More progress should be made soon as we would like to deploy this facility before the hot summer months arrive this year.
FIRST FLIGHT OF THE SOLAR CATFROM THE MTA
Bill Inman and new member Jonathan Wells returned to the MTA for another attempt to launch the solar powered steam rocket, the Solar Cat. He has been making many adjustments and had his first launch near his home in Carson City. Today would be his first launch of his Solar Cat from the MTA.
Bill was able to work out minor problems on his trailer mounted systems last month and was fully ready to use his solar heating and tracking system for the hours necessary to reach launching temperatures of the stored water load in his steam rocket.
Bill has had some minor problems with the release system which led to a unintended release of the rocket. No one was injured but it did cost him several useful hours for insolation (heating). His second attempt was only a partial heat load but sufficient to conduct the first (technically second) flight at the MTA. Keith Yoerg managed to capture the short flight in the late afternoon. It’s a bit comical to watch given how short the flight was, but it is a significant milestone in getting this non-traditional form of liquid propulsion to work. We look forward to the advancements, Bill will make for future flights from the MTA.
REBUILD AND SYSTEMS CHECK OF THE GAS GUZZLER
Wolfram Blume had made several improvements since his last flight attempt of his two-stage ramjet-solid motor rocket. He was able to correct software issues but also made physical feature changes to his booster. Wind speeds were excessive for much of the day, so he used his time at the MTA for fit checks while on the 1515 rail launcher.
Wolfram was able to conduct his tests making use of the 1515 rail launcher. He left in the afternoon after completing his tests and will return for our next launch event planned for April 10. 2021.
WIRELESS FIRE CONTROL AT THE MTA
Wireless fire control is a remote means of conducting launch without stringing long wire connections. This has been a controversial subject at the RRS with some of our members actively supporting using these systems and others being skeptical about their safety.
Richard Dierking mentioned the Wilson F/X wireless firing system which has been used at the Rocketry Organization of California (ROC) and at the Friends of Amateur Rocketry (FAR) site. Fellow RRS member, Dmitri Timohovich, has used Cobra Firing Systems for pyrotechnic events in the movie business with success. He brought one of these systems to demonstrate at the MTA with test bulbs. The 64-bit encryption in this system vastly reduces the possibility of stray signals causing an unintended firing.
A decision was made at the March 2021 meeting to proceed with care by testing one of these wireless fire control systems with only low-power simple model rockets. We also thought meeting with a sales representative or technical advisor from a wireless fire control system manufacturer to explain the safety of these systems to the society would be an excellent idea. Some of our members have had a negative experience with these systems with unintentionally firing. Older wireless fire control systems have had safety issues. Safety in operations with pyrotechnics of any kind is of paramount importance.
The RRS plans to educate themselves further about wireless firing system technology before making any further policy decisions. It is agreed that every pyro-op in charge at the event has the final say about what systems are and are not allowed at the event. The best course of action for any project leader is to discuss all aspects of their test or launch with the pyro-op in charge well in advance of the event at the MTA.
STATIC FIRING OF THE HYBRID MOTOR
The last two firings of the Contrails H222 38mm 16-inch hybrid motor left some questions about how reliable the ignition of the motor is. From both prior flights, it was evident that quick severance of the nylon plastic fill line at the launch command was not happening. Altitude was very low from such a powerful motor according to the curve. Since the last flight damaged the rocket body beyond repair, the next firing was intended to watch the startup sequence in careful detail under static conditions.
The motor survived in tact from the last short flight, The nozzle, spent grain and floating injector were shoved forward from the impact, but all parts were able to be removed, cleaned and reassembled for another firing with the last of my three fuel grains from the kit.
The static test firing was done on the vertical test stand using a simple wooden fixture and 1/2-inch fasteners. The fixture was built quickly and unfortunately not perfectly. We had to fire the motor upside-down which is not representative of how the engine flies.
The igniter used in the 3-20-2021 test used an electric match as was done in the second test. The kit comes with an electric resistor. In the first test, this was insufficient to get ignition and sever the fill line. Second firing used an electric match and a fragment of composite propellant. This achieved ignition but the fill line wasn’t fully severed. The third attempt used a similar load with a bit more composite propellant. The idea was to produce an ignition flame hot and fast enough to soften and sever the pressurized nylon fill line, With the escaping oxidizer liquid, the combustion should be enhanced and help sever the line. In practice, this doesn’t seem to occur quickly enough,
In the hybrid firing that day, the igniter fired and some chuffing from the nozzle was seen but the combustion was not sustained and the oxidizer supply emptied. The motor will be disassembled and inspected to see if all the composite propellant was consumed or if the nitrous oxide dispersed the pack before the full burn could finish.
MORE WATER ROCKETS
Dmitri upgraded his water rocket launch system to fire multiple rockets. He had a remote firing box which made it very easy to set up. The winds were too strong for any high altitude flights, but the modest water rockets were plenty of fun.
The Yoerg Challenge started as a simple request to those attending our meeting on March 12, 2021 before the launch event: build as many model rockets from as many people as possible and launch them from the multi-wire launcher array that Keith built last month. Dmitri and I both answered the challenge for the event, Although many of our members have built many model rockets since they were kids, some of have not. For those experienced and inexperienced, the Yoerg Challenge was issued. More rockets at each successive event inspires others to build more rockets and more ambitious rocket builds. The RRS is for all forms of reaction propulsion even with a simple model kit.
At the end of the day, Keith and Dmitri launched their model rockets using small “A” sized motors to keep their altitudes low and avoid being carried far downrange with the high winds. I decided not to fly my first model as I left early that day. We hope others will build and bring theirs at our next event.
Next launch event will be April 10, 2021, with USC and member projects.