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 Work Event, 2022-08-04

By Dave Nordling, President, Reaction Research Society


The society had a small work event at the Mojave Test Area on August 4th, 2022. The purpose was limited to starting the build of a new launch pad foundation for Bill Claybaugh’s upcoming large solid motor powered vehciles. The summer heat and tough soil limited progress but it was useful to gauge what the next steps should be. Launch is scheduled for mid-October.

Joe Dominguez (right) and Bill Claybaugh (left) examine the levelness of the form work.

Many thanks to Rushd Julfiker and Joe Dominguez for volunteering their support to Bill on that day. A new and larger launch pad is designed to support Bill’s larger adjustable launch rail system which will be useful to the larger sizes of future rocket projects at the RRS. New developments will be reported in the near future.


MTA Launch Event, 2021-10-16

by Bill Claybaugh and Dave Nordling, RRS


This firing report will be the first in a series of three articles posted on RRS.ORG. This report will cover the launch event and preparations over many days made by RRS member, Bill Claybaugh. As the attending pyrotechnic operator for this firing event, I have summarized this work for the benefit of our readers with the permission and oversight of Bill.

Bill Claybaugh has been planning to build, load and launch a large 6-inch solid motor for many months and the first attempt had finally come to pass at the RRS Mojave Test Area (MTA) over the span of almost a week starting Tuesday, October 12 and culminating in a launch on Saturday, October 16, 2021. He had studied this project very carefully and built a great many new parts and tools from his home in Colorado. The scope of this project is quite extensive and the larger goal was to enable larger solid motor building by other members of the RRS at the MTA. The 6-inch motor was just the first in what will hopefully be a growing series of similar and larger scale solid motors.

Bill Claybaugh’s description of his six-inch rocket from his Flight Readiness Review presentation.

The predicted performance of this 6-inch single grain motor was 1350 lbf of thrust for a duration of 8.35 seconds which was expected to exceed 70,000 feet; well above the RRS MTA’s standard 50,000 foot altitude waiver. This “P” sized solid motor in this vehicle required an FAA Certificate of Authorization (COA) for this flight on the prescribed dates during daylight hours. The submission of Monte Carlo simulations of the trajectory (splash analysis) were graciously performed by Chuck Rogers (author of the RASAero II software) and a necessary part of the process to verify no significant concerns for impacting nearby populated areas or structures. Also, the FAA Class 3 rocket waiver that was granted would require the launch team to contact the relevant air traffic control 15 minutes in advance of the intended launch for final permission to proceed. A separate article discussing this subject in more detail will be coming soon.

The rocket had two streamers for a recovery system which were intended to be sufficient for easier spotting of the rocket in descent rather than provide a soft landing.

Many members of the society participated in this project over the several days needed to prepare and conduct the mixing, pouring and casting process. RRS members Dave Crisalli and George Garboden lended their time and expertise in solid motor building which led to a stellar finished product on Thursday. Several of Bill’s family and friends attended and supported the preparations for launch.

Bill Claybaugh’s four-finned rocket with an end view of the four-fin 6-inch single-grain motor loaded and ready for the nozzle installation. RRS president, Osvaldo Tarditti, talks with Bill on the morning before launch.
The forward and aft views of the nozzle assembly of the Claybaugh six-inch rocket.
Bill Claybaugh holds his payload system without the fiberglass long-ogive nosecone cover.
Pictures of the different parts of the pneumatic separation system and payload.
Ed Wranoski finishes the mating of the payload on top of the single stage solid motor checking the alignment before preparing to move the rocket to the launch pad.

Given the size of the 6-inch rocket, Bill designed and built a T-slot type of launch rail with a 24-foot length on an aluminum truss structure. The system was designed to be deployed in a green-field site and easily assembled by a small team of people. There were some challenges in getting the design to work but through the combined efforts of those at the site during the afternoon and early evening on Friday, the erecting and loading process was safely completed. Susan and Ed Wranoski both had a lot of great suggestions about getting the right placement of the come-alongs to bring the launcher up to a sufficient angle to secure it by the chains and strap anchors around the pad.

The new launch rail system will be the subject of a separate article coming later on RRS.ORG. Design improvements and substantial changes are being planned such that the next launch event will have an easier time in raising and lowering this important asset for the launching of larger rockets from the MTA.

Testing of the erecting process took place into the early evening by headlights. These operations provided valuable information making launch preparations the following morning far simpler.
Bill Claybaugh, Mike Pohlmiller and Ed Wranoski secured the 6-inch rocket by two bellybands in flyaway railguide system.

During the first launch operations of the rocket, the wireless telemetry wasn’t receiving signals. After restarting the computer and replacing the nosecone, the pyrotechnic charges in the recovery system accidentally fired due to a short. The payload system was removed, inspected and replacement pyrotechnic charges installed. After protecting the terminals from a similar short during final installation of the payload and nosecone, the telemetry system was working and the launch could proceed.

The nosecone being replaced after a quick test of the payload system.
Bill’s 6-inch rocket on the rails and secured for launch.

The launch event coincided with the launch operations of our neighbors’ (FAR). We were in constant communication to assure everyone was under cover at the proper times. The weiather was nearly ideal with very low winds the whole day. After road and air checks were completed, we prepared for launch.

Bill Claybaugh prepares for firing with RRS president, Osvaldo Tarditti, amd others ready to film and photograph the launch.
Still captured from the launch footage showing the rocket clearing the tower.
Last still picture of Bill’s 6-inch rocket before going out of view of the camera.

The initial launch was swift and powerful as the motor ignited and came to full thrust leaving the launch rail. The rocket canted to the northeast opposite the intended direction of the launch rail and the vehicle appeared to corkscrew as the motor burned to its full duration before going out of sight. The recovery system appears to have fired early as one of the streamers and the entire payload module fell back to the northern side of the MTA. The spent rocket motor casing has not yet been recovered. Bill was able to bring back the payload segment for inspection at the MTA while others continued the search for the rocket.

Bill disassembles the recovered payload system after its short descent back to the ground.
Both pyrotechnic separation charges had fired.
The antenna snapped off and was not found.
Recovered flyaway railguides showed signs of recontact from the tail fins from the sharp tears and rips seen. This is a common occurrence with flyaway railguides and they can be refurbished for the next flight.

Based on review of video footage, it appears the sudden turn uprange occurred at around 100 feet and took less than 1/4 second.  The current thinking is that the separation system depressurized, producing the side-thrust that caused the sharp turn after leaving the rail. It is assumed the telemetry loss of signal (LOS) was a result of the antenna snapping off during this sudden turn. LOS occurred at 119 feet and 425 ft/sec. About 0.25 seconds later, the payload can be seen starting to fall away from the rocket which can only occur if the system is depressurized. The payload was recovered about 300 feet from the launch tower and on the ‘new’ azimuth.

After the initiators fire–and both were fired–it would be expected that applying pressure to the quick-disconnect (QD) fitting would:

(1.) NOT result in the four retention pins extending, and,

(2.) would cause venting through the diffusers. 

That is, the burst disk is supposed to be punctured due to the piston driving the hammer through it when the initiators fired and any gas generated in the system is vented past the burst disk and through the diffusers.

The recovered flight hardware instead extended all four pins, did not vent through the diffuser, and did vent through the outlet reserved for the hot initiator gases.  This means that the burst disk was not opened and pressurizing gas was somehow leaking into the hot gas circuit.  The image below of the burst disk shows its condition as found upon opening.

Burst disk valve distorted but not penetrated as designed.


Further disassembly showed that the O-ring seal separating the hot and cold gas circuits around the hammer that penetrates the burst disk appeared damaged from heat. That seal damage was allowing the cold gas to escape into the hot gas circuit and then vent. Further, the O-ring prevented hot gas from getting to the subject O-ring around the piston that drives the hammer through the burst disk was in two pieces and showed clear evidence for melting at the edges. Thus, when the dual-redundant initiators fired, the piston O-ring failed (or had previously failed, although it was undamaged when installed) which allowed hot gas to leak past the piston (which nonetheless hit the burst disk hard enough to dent it but not tear it) and to damage the O-ring separating the hot-gas and cold-gas circuits in the valve. These two damaged O-rings then allowed cold gas to vent via the hot gas circuit, resulting in the payload seperating from the rocket.

Naturally, none of these failures ever occured in previous ground testing.

Wind shear was considered as a cause for the sudden change in vehicle direction witnessed during launch right after clearing the rail. Even in calm wind conditions on the ground, there have been past launch events at the MTA which have had sharp unseen discontinuities in the wind profile causing serious perturbation of the flight path in a rocket flight. This potential cause can not be fully excluded, but it is thought to be unlikely..

The venting of the hot and cold gas _may_ have caused the sudden pitch over as seen in video footage. As of now, this is being carried as a working hypothesis.  However, none of this explains why the initiators apparently fired a few fractions of a second after lift-off.

The telemetry data will soon be downloaded from the ground station to see if there was any indication of the beginning of this sequence of events. Because the ground station showed loss of signal (LOS) at 119 feet, and that LOS appears to have been the result of the antenna snapping off in the course of the sudden pitch change. There might not be any recorded data of the relevant accelerations or rates from the ground station.

This report will be updated as new information becomes available.

Examining the launch rail and supporting cables before the planned lowering.
Former RRS member, Kevin Sagis helps in gradually releasing the come-along chain bringing the heavy launch rail back to horizontal as the rest of the team managed the straps.

In conclusion of that day’s launch event, with the recovered parts from the rocket payload examined and packed for shipment back to Bill’s home, the remaining team worked to carefully lower the launch rail back to horizontal using the reversed process used to successfully and safely raise it. The launch rail support legs were left at the MTA as Bill and Mike Pohlmiller were going to consider a new design approach using the same T-slot backbone. Although there was no evidence of the rocket hanging up on any discontinuity, some repairs of the interconnections between the three segments should allow the combined rail path to be more straight.

The RRS is grateful to the many members and participants we had over those several few days. It was a big success despite some significant challenges and disappointment in the results. The project was designed to be a pathfinder to subsequent large solid motor projects and we expect the next motor build and improved payload system design in the new calendar year, 2022.