October 2022 meeting

by Dave Nordling, President, RRS.ORG


The society met at the Compton Airport front office again for our monthly meeting on October 14th. Mike LaGrange joined us by teleconference for the first time. Joel Cool-Panama was welcomed as our newest administrative member.

We first reviewed past events,

  • USC RPL sample grain burns
  • pad anchor modifications
  • restroom progress at the 10/1/22 work event

We spoke of pending events

  • Bill Claybaugh’s new pad, 10/20-10/22
  • Aerospace Corp launch of experimental motor, 10/20
  • next work event, 11/5-11/6, more plumbing
  • USC RPL static fire on 11/12
  • Events subject to change, public calendar soon to come online with the new website

The RRS reported quarterly dividend from Smile.amazon.com

Further concrete repair work is needed. Four of the 28 mounting holes need more work. This will likely be done by the society. We need to determine best way to extract old anchors and patch the holes with sufficient time for curing before redrilling. USC RPL will assist by drilling final anchors once repair work is done. USC has been very helpful in making this important site improvement.

A budget update on restroom with expenses to date and how much to finish. Last estimate showed we’re on target. An update is coming before next month. Our goal is for the restroom to become operational by year’s end.

The society is working hard to help other members to become pyro-ops. More pyro-ops means safer operations and greater flexibility in future events. Frank and Bill Inman have their letters and are working on their applications. The best way to start is being active with society events and apprenticing under experienced and licensed individuals.

RRS has updated their flight waiver with the FAA to 100,000 feet. Some planning and advance notice required. Laminated copy of our waiver and instructions will be put in the Dosa Bldg. Also, launch requirements available from the RRS president.

Patrick Finley of the Collegiate Propulsive Lander Challenge attended. He explained his foundation to encourage propulsive landing technologies among university groups. Five technology prizes. The RRS is a supporter of this initiative. He can be reached at “patrick@landerchallenge.space”

Wolfram Blume has been working on the Gas Guzzler over the summer. Fuel pump and flameholder fixes. Next flight could be in December?

Bill Inman is building the 2nd generation Solar Cat with fellow member Dale Talcott in Nevada. Subscale prototype built in the summer had excellent focus and heating. Next test at MTA could be December, perhaps January.

John Krell’s avionics chips have had some improvements. Now can do 16 channels at over 1 kHz all on a chip fitting in a slim alpha payload tube

First meeting with LACMA by the president and VP on a STEAM project focused on the arts. Further discussions will better define the RRS role. 

2023 Symposium will celebrate our 80th anniversary, tentative date is April 8. Researching locations, food service and potential speakers. Official launch will be in the new year.

New launch rail design proposed for high power rockets using 24-feet of 1515 launch rail and a 1-ton hand-winch to operate. It will be an outdoor fixed asset and supplement existing launch rails. Need to get a materials list and drawings made for a contractor quote.

Larger 60-foot launch rail for liquid rockets is in the planning stages. The RRS has had several entities interested in using such an asset.

We will soon be starting the effort to sort out the old equipment in the north yard, determine the purpose, origin, and dispose or refurbish each item. We must use our space wisely and not store articles without a relevant purpose. Junk will always fill a void.

RRS may be getting a new pair of storage containers and fire-fighting equipment. Council is in discussions and supportive of this site improvement. More details later.

Some at the meeting indicated strong interest in learning how to weld. The RRS is seeking an instructor which may give us training for a nominal fee. More on this next month.

3D printers were discussed near the end of the meeting. Several members have the devices, but design tools are just as important. Google Sketchup, Solidworks and CATIA are options but costs on some can be prohibitive. This would make a fine topic for a future article on RRS.ORG

Nominations for executive council offices will be at the November meeting next month. An election chairman will be appointed who is neither a current office holder or a candidate for office.

Next meeting at Compton Airport front office on 11/11/2022 at 7:30pm.


MTA Launch Event, 2022-05-21

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