MTA launch event, 2021-01-09

by the Reaction Research Society

The Reaction Research Society held its first launch event of the new year on Saturday, January 9, 2021.  Dave Nordling was the pyro-op in charge.  We had a couple rockets prepared and some maintenance work we wanted to continue.  Dmitri Timohovich brought his whole family to the event and we enjoyed grilled burgers there at the Mojave Test Area.  The January winds were light and cool that day.  It was a good day for launch.

Bill Inman enjoys a burger in the George Dosa Building
Everyone relaxing for a short lunch before getting to launch.

Wolfram Blume brought his two-stage rocket, the Gas Guzzler.  His ramjet upper stage was rebuilt from last year’s unfortunate breakage when dropped during loading on the launch rail last year.  3D-printed plastic parts can sometimes be very brittle and care must be taken.

The 1515 launch rail was put into position with some help from Bill Inman and a few others.  Bill Inman is still working on his solar tracker for his latest iteration of the Scalded Cat.  He made the trip from Carson City to the Mojave Test Area to help others with operations and we were very thankful.

Wolfram was able to mount his booster stage on the rails and carefully erect the launcher.  The booster uses a commercial solid motor, an Aerotech “K” motor.  

Wolfram cleans the 1515 rail at the RRS MTA in preparation for mounting the booster
Wolfram’s booster sits on the launch rail

The ramjet for this first flight was loaded with water to simulate the weight, but would not be fired.  The primary goal was to demonstrate the staging and recovery systems powered only by the booster.  Wolfram went back to the loading area to complete the preparations of the upper stage. During a system checkout, the parachute deployment charge fired.  After some careful examination, the source of the problem seemed to be related to errant software commands.  Wolfram aborted his launch attempt and returned with his rocket stages for further examination back in Los Angeles.  Although the charges could be reloaded, he could not be certain that an early parachute deployment would occur and wreck his vehicle during flight.

The Gas Guzzler upper stage ramjet

Dmitri Timohovich and Waldo Stakes worked on completing the welding of the new steel plate on the vertical test stand. This plate on the vertical test stand was damaged during a test failure many years back and late last year was finally cut out and the space grinded to fit a replacement plate.  Unfortunately, the stick welding system would require a different type of welder and a more powerful source to drop a reliable weld.  The welding of the plate will be reattempted at the next event.

With the grinding complete, the plate is fitted and ready to be welded in place

The second launch of the day would be Dave Nordling’s nitrous oxide hybrid rocket.  This 38mm H-sized commercial hybrid motor kit from Contrails Rocketry (H-222 model) had a modified igniter and was mounted in a new 4-inch body made by Larry Hoffing. The prior launch attempt had issues with severing the nylon plastic filling line so the ignition energy was increased with small bit of composite solid propellant ignited by an electric match.

Several minor problems occurred during launch preparations. The nitrous bottle and manifold filling system was working well but the electrical control box failed during tests.  After some discussion, the defective switch box was removed and we were able to fire and get a clean launch

Dave Nordling leans against the old blockhouse with the second build of the hybrid rocket waiting for launch
The hybrid sits on the 1010 launch rail

We repacked the motor before launch and adjusted the vent tube to be more visible. The filling of the rocket went quickly and smoothly, only about 20 seconds before the white stream of liquid could be seen. The filling was stopped and with a short five-count and the rocket was fired. The rocket came off the rails quickly and it seemed that the modified igniter worked. The big problem was the parachute recovery switch wasn’t turned on before launch. This simple oversight would mean a rebuild would be necessary.

The simplest error can lead to sad results.

The rocket was recovered on the north end of the MTA site. It only seemed to reach about 300 feet of altitude. Unfortunately the ballistic landing broke both stages and the internal motor mounts and a complete rebuild is necessary. The motor case was parts were in tact and so it was extracted and will be reloaded,

The hybrid motor seems to arc to the north against wind.

Beckie Timohovich recorded the hybrid flight on her phone, The rocket seemed to immediately curve to the north off the rails opposite of the wind. It seems that the nylon fill line might be still holding fast despite the added solid propellant charge. The 3/16-inch nylon plastic line being strong enough to hold back the 900 psi nitrous pressure, it also poses a challenge to cut cleanly from the ignition charge. A static firing of the motor will be done next to get a better look at how well the fill line severs and measure the thrust curve directly..

The remnant of the fill line from within the hybrid after firing. The end looks smoothly extruded.

After recovering the hybrid rocket and putting away the equipment, we flew a water rocket for Dmitri’s young son. Although very simple, these things are very fun.

Max Timohovich holds the water rocket fired several times at the end of the afternoon.

The event was a partial success and there is more work to be done on our facilities including adding a new toilet facility at our site and welding in the plate on the vertical test stand. The next hybrid rocket launch may be a couple months away, but Bill Inman may have his next design of his solar heated steam rocket ready for launch af fhe MTA in a few weeks. He had his first successful flight in the Nevada desert just before Christmas. He is getting ready for a flight from the RRS MTA.

Bill Inman has his first successful flight of his solar-powered steam rocket on 12/22/2020

Wolfram seemed confident that he too might be ready to try his first launch of the Gas Guzzler at about that same time. If the next launch event occurs before the next monthly meeting on February 12, 2021, the announcement will come through the society email list.

The sun sets at the RRS MTA after a good day.

January 2021 Virtual Meeting

by Keith Yoerg (RRS Secretary)

The Reaction Research Society’s first meeting of 2021 took place this past Friday, January 8th and was attended by 11 members. Dave Nordling provided a review of the December 2020 event at the MTA, a written account of which can be seen in the post preceding this one.

Screenshot of discussion during the monthly meeting


The first discussion was regarding plans for the upcoming MTA event on Saturday, January 9th. Dimitri (and family), Wolfram, Bill, Waldo, and Dave (as Pyro Op) stated their intentions to attend the launch. Plans include continuing repair and replacement of the bent panel on the vertical launch structure led by Dimitri and Waldo, a launch of Dave’s hybrid rocket, a demonstration flight of Wolfram’s Gas Guzzler, and mention of a grill-out with hamburgers! Expect a launch event update on the results soon.


The discussion continues on improving the restroom facilities at the MTA. While the Executive Committee pursues bids from contractors and other options for a more substantial restroom facility, finding a more immediate replacement for the current pit toilet is a top priority. Digging a new pit toilet should be made much easier by the recent delivery of a CAT backhoe to the Mojave. Due to security concerns, the equipment is being stored at the FAR site in view of their security cameras. Larry and Keith agreed to look into options for cameras that could provide similar security at the MTA.

Backhoe equipment in the desert

While the initial plan was to drag the concrete plinth from the current pit toilet to the new one, a decision was made to proceed with building a new wooden platform to mount the port-a-john instead. Of concern was the seemingly likely outcome of damage to the concrete plinth when trying to place it with the equipment available. Dimitri outlined his idea for the new structure and offered to sketch out a more formal design after reviewing at the MTA at the launch event.


The RRS treasurer offered a reminder for members to pay their dues for 2021, which remain at $40 for full membership and $30 for student membership. As a reminder, the full membership dues will be increasing to $50 in 2022. For questions regarding dues payments, contact the RRS treasurer:

Most of the members on the call got involved in the brainstorming session on how to increase fundraising at the society to cover our insurance and other yearly costs. Xavier proposed putting on a holiday party for the society as a ticketed event, and offered to take charge of scoping out costs and possibilities for the 2021-2022 winter season (when in-person gatherings will hopefully be allowed again). Dimitri discussed the challenges and opportunities involved in listing the MTA site with the Kern County Film Commission as a shoot location. The possibility of holding an auction, either stand-alone or as a part of the yearly symposium was also proposed, and Dimitri offered to put together a draft form letter to submit to companies to solicit donations. Additional items would be donated by members or other involved entities.


A request was made for an update on the status of the 2020 Constitutional Committee, which has been drafting changes to the constitution of the Reaction Research Society. Committee member Frank described that only a few outstanding issues remain, including the definition of active membership, which need to be finalized by the Executive Council before being presented and voted on. The Executive Council intends to meet on this issue soon and present the new constitution to the voting membership in the coming months.

MTA launch event, 2020-12-12

by Dave Nordling, Reaction Research Society

The RRS held it’s last launch event of this difficult but eventful year, 2020. COVID-19 continues to pose a significant threat to the wellbeing of our members and the world at large. One of the advantages of our remote testing site is the ease that our members can socially distance themselves and with masks and proper planning of shared tasks the risk of contagion is easily mitigated. I was the pyro-op in charge for this event. We had three planned launches that would depend on good weather and a work task to repair our vertical test stand.

The winds were strong that day coming into the MTA site from the western route. A lot of sand swirling was a poor omen for the weather that day.

My late arrival found our participants waiting at the gate and with my apologies we entered and began our set up.

Wolfram Blume’s Gas Guzzler was to take it’s first flight today, but he decided to scrub for the day. The winds were a persistent nuisance and prevented launch operations for much of the day, but after 2pm calm winds prevailed. It is difficult to know when the weather will change except that it inevitably does. Wolfram’s first flight will have to wait for the new year,

The Gas Guzzler solid-motor booster stage to the left, the gasoline-fueled ramjet upper stage to the right.


The vertical launch structure at the RRS MTA has had a bent panel from an explosion from a failed test over a decade or more ago. This stretched 1/4” steel panel was significantly bowed away from the others which made mounting very difficult. Replacement panels were made back in October, but today was the day the bent panel would be cut away and the sides grinded to fit the replacement panel.

Dimitri Timohovich was able to cut away the bent panel using a length of aluminum channel clamped to the side for careful alignment of the plasma cutting process.

Dimitri Timohovich cutting away the bent panel from the vertical test stand.
The bent panel removed.

Dmitri brings a lot of mechanical skills and the society is grateful he joined us in helping make improvements to our site. The winds were too high that day for the shield gas flow needed in the welding process. The edges were blended to allow the replacement panel to be fitted accurately within the vertical launch rail using two lengths of unistrut. With careful measurements and the right equipment, Dmitri or Waldo Stakes can stick-weld the replacememt panel in place and keep a reasonable horizontal and vertical positional accuracy with the hole patterns of the plates above and below,

The replacement panel was bolted and held in place for the weld operations to take place at a later date.

The last step after a successful welding of the replacement panel would be applying the spray-on galvanizing paint product to protect the metal from the caustic and harsh desert environment for years to come, The unistrut pieces looked to be handy for future projects so we decided to leave them in place.


Bill Inman and his colleague from Nevada arrived with a third design iteration to his parabolic solar collector heating system for his two-inch steam rocket, This design featured a larger area collector and a launch rail system for his 2-inch SimpleCat steam rocket prototype. The launch rails guide the 2-inch steam rocket vessel at the collector’s focus for heating. At the exhaust end of the rails is the steam release mechanism that was simplified from prior successful designs.

It was dubious if the launch would even be possible that day but Bill’s solar collector system could be deployed from his trailer on our site and at least collect heating data even if the steam rocket wouldn’t fly.

After correcting some initial fit problems, the larger parabolic mirror was deployed.
The new solar collector in work under the early high winds and poor winter sunlight.

Launching was not possible for much of the day so the two groups waited for an opportunity. Bill Inman reviewed with me his steam rocket design and it’s simplified nozzle plug release design, The steam rocket despite its conceptual simplicity has many dangers. The mechanism for controlled release of the 400 degree Fahrenheit pressurized water liquid must be stable, sturdy, reliable and safe to remotely operate, Keeping a safe distance during the planned 3 to 4 hour solar heating cycle is crucial and having the continuous ability to safely scram the system at a safe distance is an absolute must. Bill’s design has a relief valve to avoid vessel over-pressure and relies on defocusing the sun away from the vessel if an abort is necessary, Removing the heat source immediately allows the fluid and vessel to cool if left alone for an hour or more and will ultimately return to ambient temperature once the heat source is removed,

During deployment, the solar collector and mounting frame had several fit problems which were solved at the site. The sun wasn’t consistent that day, but the mechanism held sturdy in the periodic gusting winds. By the end of the day, the collector was not able to generate sufficient heating for the rocket, but the experience in the field was valuable. Bill will be returning in the new year to try again.

Bill Inman at the end of an unsuccessful test at the MTA on 12-12-2020

Bill was disappointed in the results from that day’s activities as this month would have marked the 20th anniversary of his original successful flight of the Scalded Cat from the RRS MTA. I told him to take comfort in the fact that he has come a long way in a short time building three prototype devices in the same number of months. Bill is prolific and dedicated to his goal of being successful. Time should prove the value of patience and persistence.


My patience with the weather was ultimately rewarded as the winds subsided just after 2PM that day. I decided to make the next attempt to launch the larger 3-inch rocket that Larry Hoffing built that is adapted to fit the 16-inch Contrails Rocketry hybrid 38mm motor. A more energetic ignition system able to simultaneously sever the nylon fill line and ignite the combustion of the hybrid solid propellant grain was added and ready since the past July 2020 event. With the cooler temperatures, the solenoid filling valve would likely open according to the pressure gauge on our red supply bottle from Nitrous Supply Inc. in Huntington Beach,

The nitrous oxide hybrid rocket sits on the table in the Dosa Building at the MTA waiting for the winds to subside.

Dmitri Timohovich helped me set up the nitrous oxide bottle and manifold. The two-channel filling and firing circuit needed some labelling to clarify the proper wiring. A new lead-acid 12-volt lawnmower battery was acquired for the society as the previous one finally had to be retired and recycled. The new battery was ready for a launch that would ultimately not happen that day.

The rocket’s recovery system passed checkout as the original internal 9-volt battery installed months earlier was still healthy, The venting tube needed to be realigned with the exit hole to allow the white jet of liquid to be visually indicated when the nitrous volume is fully filled. It is important to detect this at a distance from the blockhouse as it is not safe to examine it more closely.

Fill, drain and firing circuit for a Contrails hybrid rocket motor

The launch would not take place due to a missing push-to-connect fitting to join the fluid filling tube from the rocket back to the nitrous manifold. The schematic above shows the key parts of the system minus the separate vent solenoid that failed on the original manifold, It is always frustrating to be missing one critical item despite days of preparation. After a lot of searching in vain for a single fitting, the container of materials will be better organized in the future and extra 3/16” push-to-connect Prestolok fittings will be ordered to arrive in time for the next launch event.

It was all the more painful to stand at the MTA under nearly calm winds and have to wait for another day. These are the trials and tribulations of rocketry,

Bill Inman and John Krell next to the old blockhouse at the RRS MTA.

At the end of the day, we gathered to discuss the progress or lack thereof that day. We made plans for the next launch event which seems to be best held on January 9th. We were glad for each other’s company and stayed at a safe distance throughout, We’ll return again to the MTA soon.