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. –

MTA Firing Report, 2022-02-12

by Dave Nordling, President, Reaction Research Society

The University of Southern California (USC) Rocket Propulsion Laboratory (RPL) held a static fire test of their third solid motor design in the Earthshaker series. Prior designs resulted in failures and incremental corrections to the design were made for this test. Earthshakiiest was to be the largest impulse motor made by any collegiate team. Osvaldo Tarditti was the pyrotechnic operator in charge.

Earthshakiiest sits ready for static firing at the vertical test stand with sheet metal in place to protect nearby mounting surfaces.

Given the repeated recent failures of USC motor designs, the society required protective barriers installed in the event of another energetic failure. Unfortunately, this would prove to be a wise choice as failure did result right at startup. All personnel were at a safe distance or behind appropriate barriers.

Earthshakiiest motor ruptured at start and burned itself out.
Damage to USC’s test stand was total, The mounting points in the concrete were damaged such that further use is not possible..

The extreme heat from the explosion and fire destroyed the static fire stand, melted portions of the shielding and severely damaged the mounting points such that further use is not possible. USC is working with the RRS to clear and clean up the pad. Many of these tests are very dangerous and can damage our facilities. The society expects all groups to repair, restore or replace any of our assets damaged. A new method of holding future large solid motors is being discussed.

The society thanks our former president, Osvaldo Tarditti, for supporting this event as the pyrotechnic operator in charge and to Bill Inman for also supporting the event on behalf of the society. The operation was conducted safely and much was learned despite the poor outcome. USC will provide details from the testing soon and a path forward,