MTA Launch Event, 2022-04-23

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

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 –


MTA firing report, 2022-03-12

by Dave Nordling, President, Reaction Research Society


The Reaction Research Society held a members only event on March 12th. I was the pyrotechnic operator in charge, We used the event to make some facility changes, launch a set of model rockets to prepare for school events coming soon and conduct the second and last destructive burst test of a fired steam vessel. All were successful.

The society has needed more storage space at the MTA and was glad to receive a donated 40-foot container. We are very grateful to member, Dimitri Timohovich, for making that possible including transporting to the pads in the north yard. We hope to add shelving and reorganize our gear soon.

New storage space at the MTA.

The vertical test stand is in need of some refurbishment. After USC’s last failed solid motor test, the anchor bolts will have to be removed and the concrete patched as necessary. A new mounting design is being discussed and USC is willing to provide labor and support to the cleanup activities. Measurements of the entire floor plan were made to make a drawing for easier planning of future tests. The vertical test stand has stood for many years and will be ready for many more.

Our pad is well worn and in need of some work.

We took some time to examine the area where our new restroom facility will be placed in the south of the MTA. Seeing the placement of the septic system is an important next step in expanding our facility.

Future site of the RRS MTA restroom facility.

Bill Inman ran his second burst test of a retired 20-lb propane container. He rebuilt the “mailbox” sheet metal shroud and found another propane fired burner. Mechanical cables to remotely pull the vent valve open or pull away the heat source were tested and ready. With 4 gallons of water filling the closed vessel laying on its side and the burner lit and running, the vessel was run to failure at 1260 psig. This was higher than the prior 1135 psig burst of the first tank on 1.15.2022 and both well above the proof pressure of 900 psig for these commercial product vessels for cold liquid storage.

Bill Inman prepares his second test article for burst testing.
Similar setup as before with the relief valve for safety
Bill cleans up and insoects his equipment after a successful burst.

A video camera recorded the pressure gauge as the heating took place. Total run time was roughly the same at 45 minutes. Bill safely monitored and recorded the time and rising pressure readings with binoculars from the safety of our blockhouse. Footage was reviewed to confirm the last reading before burst (1260 psig). A second video camera was positioned north of the test article and recorded some of fragments flying away. Collateral damage was less on this second test and it will be the last one of its kind. With two data points, a conservative limit can be set and Bill’s steam rocket tests will use an ample factor of safety.

PVC launch rails for wire launching model rockets.

After the area was clear and the major fragments gathered, we brought out one of our PVC rail launchers which will be used in forthcoming launch events. We had a few model rockets to fly and the winds were light making recovery less of a hike.

The Estes Generic E2X takes flight with a solid recovery.
Keith Yoerg celebrates another flight and recovery of the Charlie Horse.

It was nice to have an easy and fun time at the MTA. We barbecued a few burgers and ate well that sunny day with cool temperaturess. We plan to be back again for more maintenance operations and another school launch event.

For questiions, contact the RRS secretary or president,