Category Archives: Firing Report

MTA Launch Event, 2022-05-21

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by Frank Miuccio, Vice President, Reaction Research Society

The RRS held a launch event at our private testing site, the Mojave Test Area (MTA) on Saturday, May 21, 2022. Larry Hoffing was the pyrotechnic operator in charge. Temperatures were still mild and below 90 Fahrenheit. Winds were very slight for the entire event,

The main event was the launch of a number of student built model rocket kits using commercial motors. The second planned event was a member project, the two-stage Gas Guzzler ramjet, by Wolfram Blume. The third event was a cryogenic liquid tanking test at the vertical test standt of a portion of the Compton Comet liquid rocket overseen by Dave Nordling and Waldo Stakes.

Students prepare to hear the safety briefing after their arrival at the RRS MTA

The RRS teamed up with Boyle Heights YMCA and taught the students about rocketry over several weeks before the launch event. These students were the ones involved with the YMCA’s robotic program. We had 22 students come out to the MTA. During this launch day, we launched 23 Baby Bertha rockets all built from kits and custom painted by the students.

Students and mentors observe the safety briefing and propellant burn demonstration.

These rockets were launched first with smaller A8-3 engines. The students then retrieved their rockets and went into the Dosa Building and reassembled the parachutes for their next launch. The next launch was done with a larger C6-5 engine. All went well for the day.

Larry Hoffing and Frank Miuccio prepare the new launch racks for the Boyle Heights flights.

We were able to use the new launch racks built by Dimitri Timohovich which gave us the capability to set up 18 rockets at a time which was our channel limit of our Cobra launch system. We have made a great investment with this safe and convenient product and more of our pyrotechnic operators are getting trained in its use thanks to Keith Yoerg.

The Boyle Heights YMCA wants to continue doing classes with the RRS. The students had a great experience.

Boyle Heights students observe the launch of their rockets from the observation bunker.

The second event of that day was Wolfram Blume’s next attempt to launch the Gas Guzzler for its second flight. Significant design improvements were made. This very ambitious project is the result of a lot of complex design and 3D-printed parts which must fit correctly into their respective assemblies. Unfortunately, a critical fit problem with the nose piece prevented Wolfram from completing the build despite some on-the-spot adjustments. He postponed the flight to conduct minor repairs back at his home workshop. Wolfram plans to return to the MTA on June 4th at our next launch event with the UCLA Capstone Project.

The gasoline fueled ramjet upper stage and solid motor powered booster sit ready for inspection.
L-sized high-powered motor to the left, ramjet second stage to the right.

The third operation at the MTA was a cryogenic liquid tanking test. The Compton Comet is a large liquid rocket being built by students and former students of Compton College. Led by Dave Nordling and Waldo Stakes, it is a project supported by the RRS and each person on the team is a member of the society. The Compton Comet describes both the vehicle which will be built and flown by the student members of the society and the team, itself. The ethanol/LOX vehicle uses a surplus 1500 lbf thrust chamber from an RM6000-4-1 engine once used to power the Bell X-1. The project is still in the latter parts of the design phase and important component testing is essential before committing more resources to construction. Bill Inman assisted with some of the operations that day.

Waldo Stakes (sleeveless, to the right) explains the goals of the cryogenic testing.
Schematic of a cryogenic liquid cylinder from Chart Industries literature
Identification of the parts on a cryogenic liquid cylinder, medium-pressure unit, Chart Industries

The Compton Comet uses a pair of surplus stainless steel oxygen aircraft tanks. With the two tanks joined in series, a cold shock test with liquid nitrogen was done to verify their integrity after some minor welding was done. These tanks are decades old but have passed hydrotesting and visual inspection at the welded connections. These operations gave the student members hands-on experience with the safe transfer of cryogenic liquids. The society has acquired personnel protective equipment (PPE) such as polycarbonate faceshields, long elbow-length gloves and long cryogenic aprons to help future projects.

LN2 cryogenic liquid cylinder and vacuum jacketed transfer hose connected to the dual propellant tanks supported vertically
RRS members Drake Pearson and Aarington Mitchell, observe the start of cryogenic liquid loading wearing their PPE. All others stand back.

RRS member Diana Castillo recorded the time of each event and observations of the team as the tanking test progressed. The cryogenic liquid loading in uninsulated tanks is a slow process that loses much liquid to boiling. Eventually liquid nitrogen does accumulate in a tank if sufficient flow and capacity is available. The tank was vented at the top throughout the testing. A cryogenic rated relief valve to be used later in the full static fire was also present.

Filling from the top tank, the lower tank never reached full. The design is being reconsidered.

The second objective of this test was to demonstrate the pilot-operated solenoid valves intended for use as the main propellant valves of the vehicle. One of these high-pressure rated, normally-closed angle valves was connected at the bottom of this dual-tank setup. Cryogenic temperatures have been known to cause failures in electrical equipment. After attempting to fill the lower tank and having a significant amount of liquid nitrogen sitting at the inlet, the solenoid valve was well chilled for this functional test.

End view of the 2-prong Bendix (Amphenol) electrical connector.
Unable to get a suitable two-prong plug to the MIL-SPEC interface, the connector wires inside were used to manually actuate the 24 VDC 1Amp valve.

Before cryogenic loading, the valve was tested at ambient conditions using a pair of 12 VDC gel cells strapped in series to get the full 24 VDC needed to actuate the pilot solenoid. The circuit was switched by manually connecting the positive terminal by alligator clips. The distinct popping sound of the core stem moving inside was easily heard and very repeatable.

With the valve fully chilled after 40 minutes elapsed, the valve was tested again and functioned reliably. This is an important validation of the solenoid working in a relevant environment. The angle valve’s internal spring is very large and will require significant inlet pressure (150 psi?) to open. It was decided to leave the tanks vented at all times during this initial cryogenic liquid filling operation and leave a flow test for later. There were no signs of leakage from the valve outlet which was also a good result.

The Compton Comet project team recorded and discussed their findings. Leaving the tank vented, the liquid nitrogen boiled away in the warm afternoon. The remaining members enjoyed some time in the Dosa Building eating grilled burgers and hot dogs made by Waldo Stakes. Dimitri was able to reinforce the metal support legs of this donated propane gas grill to continue its service to the society.

The society cleared the areas and stored our gear. The next MTA event will be June 4th with the UCLA Senior Capstone Project. Wolfram Blume will return to fly the Gas Guzzler for a second flight. Dave Nordling will be the pyro-op in charge. Any other member projects are welcome and they should contact the RRS president to schedule them.

president@rrs. org

MTA Launch Event, 2022-04-23

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by Jim Gross, Reaction Research Society

Excellent artwork generated by USC RPL for the launch.
Group photo on the night before.

The USC RPL group had a large number of experienced seniors graduating this year.  The pandemic had minimized activity over the past two years, so the group had many new students with little experience in conducting firings.  Many of the experienced students were graduating so the purpose of this project was to teach the lower classmates how to conduct the firing preparations.

The Jawbone 6-inch rocket sits on the launch rail at the RRS MTA

I was the Pyrotechnic Operator (Pyro Op) in charge and arrived at the MTA at 0822-hours and shown the work done so far.  The vehicle was on the launcher but the igniter was not yet installed.  USC RPL had two 3-bag igniters prepared in fueling area.  One was attached to their traditional dowel road but the spare was not.  

Custom built igntier for the solid motor.
Spare charges

The Pyro Op gave the safety briefing covering both rocket and environmental hazards at 0900-hours to the 79 participants.  The predicted time to impact if the recovery system failed was 89-seconds.  Everyone then got under cover in the bunker and final instrumentation checks were conducted.  The igniter was inserted at 0913-hours and the vehicle launched at approximately 0922-hours.  The ignition was prompt and the flight looked normal.  Telemetry was lost during the flight.

High angle view from the north of the launch of Jawbone.

Some interesting facts about Jawbone:  The predicted altitude was about 34,000-feet.  It used their older propellant.  It was reported the motor had about 40-lbs of propellant.  This contrasted with the 100+ pounds that was reported on the Standard Record Form (SRF).  The igniter had a total of 33-grams of igniter composition of which 24-grams was powder and the rest was strips of propellant.  The igniter composition was the same AP/HTPB propellant as the motor.  The free volume of the motor was reported to be 114-cubic inches. The outer diameter was 6-inches.

Jawbone was recovered late in the afternoon.  The data recording system was working and to be downloaded and analyzed when the team returned to USC.

Further details on the event were provided by Jeremy Struhl of USC RPL:

USCRPL successfully launched and recovered Jawbone on Saturday, April 23rd, 2022. The vehicle reached an apogee of 41,300 feet above ground level (AGL), a maximum speed of Mach 1.717, and a peak acceleration of 7.266 G’s.

Infrared camera view of the Jawbone launch from the RRS MTA, 04/23/2022

Jawbone saw multiple new systems in avionics and recovery. First, the avionics unit on Jawbone received a number of upgrades. First flown on CTRL+V, USC RPL’s custom pancake-style PCB stack conforms around the nosecone deployment CO2 canister, allowing more space in the nosecone. The system featured a new custom battery charging and management PCB to prolong pad standby time. Additionally, this was our first flight of the Lightspeed Rangefinder, an in-house designed and built tracking unit that used four ground stations positioned around the launch site to triangulate the position of Jawbone following its flight. This positional data proved valuable during the post-flight recovery of the vehicle.

Fish-eye lens view of deployment at 41,000 feet
Another view of the spent booster stage.
View from within the booster during deploymemt, nosecone in view

The Jawbone recovery system featured a next-generation design with improvements from the prior rocket ”CTRL+V “ dual deployment recovery system used in that flight. Using a connector and extension wire running along the forward shock cord segment, USC RPL’s custom avionics unit attempted to control the active deployment of the main parachute when the vehicle reached a decent altitude of approximately 5,000 feet. Unfortunately, the recovery system experienced a partial failure resulting in the main parachute failing to open. The drogue parachute was still successfully deployed, so the vehicle was recovered intact. The main parachute, which was constrained using a Tender Descender, was never deployed due to unexpected loads during nosecone deployment disconnecting the cable attached to the Tender Descender.

MTA Firing Event, 2022-04-02

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by Dave Nordling, President, Reaction Research Society

The RRS held a launch event at the Mojave Test Area on Saturday, 4/2/2022. Larry Hoffing was our pyrotechnic operator in charge. It was a very pleasant day with low winds for most of the day.

The sign arch welcomes people to the Mojave Test Area

It was also the first time in a long time that all four members of the executive council were present at the same event. We took the opportunity to capture the moment in a photograph.

The executive council for 2022; Keith Yoerg (secretary), Dave Nordling (president), Larry Hoffing (treasurer), Frank Miuccio (vice president)

The primary project for that day was the launch of 15 Baby Bertha rockets made by the students of Nickerson Gardens over the six-week educational program the society held with the support of LAPD CSP. The rockets give the students a tangible sense of accomplishment and seeing them in flight from the MTA gives them good memories of what hard work can do.

The newest armada of Baby Bertha’s ready for flight.
Students wait in the Dosa Building before the launch.
The launch rails made ready for the event.

There was an RRS standard alpha made for this occassion which flew at the end. It was prepared by our experienced pyro-op, Larry Hoffing, and made an impressive finish to this school event.

Larry Hoffing (right) trains his colleague in the assembly and loading of a micrograin alpha rocket.
Larry Hoffing oversees the launch rail with Keith Yoerg for an alpha launch.

Secondarily, we had a few members of the USC RPL team out at our site to begin repairs of the concrete pad area used in their static fire tests. Removal of the male anchor bolts in USC’s custom mounting pattern were finally distorted too much to be useful. They were a frequent tripping hazard and their removal was a blessing.

USC RPL cinducts repairs of the vertical test stand pad.
USC RPL team at work making improvements at the MTA.

Also, the USC RPL team made several contributions to improving the MTA site with earthwork, brush clearance, and just good old fashioned hard work. We’re grateful to them coming out to help keep the site in good shape,

Earthwork in progress to backfill the erosion.
View from the blockhouse of the Peregrine rocket ready for launch.

The last portion of the day was spent launching a few more model and high-power rockets before the winds became too high. We used the time to plan our next event and rearranged our materials in our new storage container.

Our next monthly meeting is Friday, April 8th. Contact the RRS secretary for information.

secretary@rrs.org –