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.


MTA Launch Event, 2021-09-26


by Keith Yoerg, Reaction Research Society Secretary


The RRS Mojave Test Area (MTA) hosted a launch event and work party on Sunday, September 26th. The USC Rocket Propulsion Lab (USCRPL) had arrived a few days earlier to prepare for a static firing of their 8″ diameter solid rocket motor named “Earthshaker II” which took place on the 26th. Several RRS members also answered the “Yoerg Challenge” to launch model rockets, and Dimitri was out with his water rockets. On the work side of things the Dosa building was re-organized, a security camera was installed, and a discussion began on how best to replace the aging roof on the blockhouse.

USCRPL 8″ SOLID ROCKET STATIC TEST

USCRPL had their setup ready for a static test of their 8″ solid rocket motor in the late afternoon, which was secured below the vertical test stand. Unfortunately, shortly after coming up to full power the motor exploded. All personnel were at a safe distance in the bunker and no one was injured. RRS President and Pyrotechnic Operator in charge Osvaldo approached the site once it was safe and extinguished the resulting flames.

Still shot from a video of the USCRPL motor explosion
Pyrotechnic Operator Osvaldo bringing a fire extinguisher to the lingering fires

All requests to use the RRS MTA must be made to the RRS president and reviewed by the executive council.  For any questions about this test series or any future test series, please contact the RRS president.

president@rrs.org

YOERG CHALLENGE MODEL ROCKET LAUNCHES

Many RRS members had model rockets on hand to answer the “Yoerg Challenge” and launch at the MTA site. Dimitri and his son Max launched a “Helios” and “Dazzler” on C6-3 motors. Keith launched a “Baby Bertha” on a B6-4 and a “Big Bertha” on a B6-2. Dave Nordling launched a “Baby Bertha” on an A motor. Bill Inman & Jon Wells also launched model rocket kits, and John Krell launched a model kit on a G motor. (I will endeavor to do a better job of recording the rockets & motors that everyone uses at these launches for more specific reports in the future).

Keith Yoerg, Bill Inman (on the launch box), Waldo Stakes and Diana Castillo wait as the countdown progresses.

We did not have the new wireless Cobra firing system at the MTA site during this event, so we used the 4-pad controller that Dimitri built earlier this year. The controller split its time between this low-power launch pad and the water rockets which Dimitri had set up on the underground blockhouse.

Several of the model rockets ready to launch on the PVC launch pad built by Keith Yoerg

I will also mention that prior to these launches, we enjoyed a nice potluck BBQ of brats, (homegrown) potato salad, chips, beans, and corn. Several members contributed food which was expertly prepared by Becky. We’ve been doing this more often and seem to keep getting better at it every time!

WORK PARTY TASKS

In addition to the more exciting “fiery” aspects of the day, RRS members also completed a lot of routine maintenance at the MTA site. We completed several general organization tasks in the Dosa Building and the storage containers, and a security camera was installed on the Dosa Building. There was also a lengthy and robust conversation about methods to replace the aging blockhouse roof, which has been high on the the society’s list of desired site improvements for several years.

Keith Yoerg and Jon Wells discuss options for repairing the old blockhouse roof.
Security camera installed on the Dosa Building

MTA Launch Event, 2021-08-28


by Dave Nordling, Reaction Research Society


The RRS Mojave Test Area (MTA) was used by the student group, Michigan Aeronautical Science Association (MASA) of the University of Michigan at Ann Arbor.  Given the remoteness of the RRS MTA and the great distance that the Michigan team was willing to travel, MASA had planned an extended test campaign to use the site for their cold flow and ultimately hot-fire their RP-1/LOX 2,550 lbf liquid rocket engine.  Originally planned for a week, the team arrived on Monday, August 16th, and continued to use the MTA site through August 28th.  In the end, Michigan faculty called the end of the MASA test series as the new semester was starting and many materials needed to be returned before MASA left southern California.

The MASA logo on the back door of the mobile trailler.
Initial checks of the mobile propellant supply trailer. Over the road travel loosened a lot of plumbing joints.

MASA is a new student group to the society and had very ambitious goals in what they wanted to accomplish in the planned test series.  Typically, the RRS will work with new universities and new clients over a period of many months before agreeing to a first test series at the MTA on a weekend campaign.  Proper planning is an essential requirement for success and the RRS must become thoroughly familiar and comfortable with all planned use of the MTA site.  Like with all attendees to the MTA, indemnification waivers were required from all attendees including spectators.  MASA limited their staff to only essential personnel and ran a day and night shift to both safeguard their equipment through the night and provide continuous support to prepare for the next day’s events.  The team was able to find rented housing accommodations in the local areas of California City and Ridgecrest.

Nate Campbell verified valve functions in conjunction with the mobile control trailler.
The MASA control room was well equipped and was able to safely and remotely conduct test operations.
More leak checks under the rising moonlight and electric lamps at the RRS MTA.

MASA has had a couple years of experience with their propellant flow systems in laboratory tests at the university and was willing to hold several meetings with RRS members sharing their full test procedures and schematics, and answer questions posed by RRS pyrotechnic operators in advance of their arrival.  The MASA fluid systems had many appropriate safety features and used high quality valves and parts.  MASA has developed a control system that uses motorized needle valves in place of a pressure reducing regulator for independent propellant tank pressure controls.  MASA had conducted many tests of this system and held several tests to confirm proper operation in the early steps of their MTA campaign.

The MASA liquid rocket engine, RP-1 and LOX, rated for 4300 lbf thrust but the hot-fire goals of this campaign was 2550 lbf.

MASA’s system designs also had some problems with the nitrogen compressor (booster) system being unable to operate due to a regulator failure. The team was able to bypass the unit, but it limited the top pressure of the blowdown tests to the bottle pressure (2000 psi). A few changes were necessary for vent line routing to improve operational safety. Remote pressurization operations were safely executed but proceeded very slowly and thus a great degree of boiloff in the LN2 limited run time.

The composite overwrapped pressure vessel (COPV) originally was intended for compressed natural gas service in ground vehicles. These vessels have a good safety record in demanding applications and are often used in de-rated aerospace applications.
The MASA team made several changes to their vent line routing for improved safety.

The event was successful in some respects that it gave the students a practical understanding of how to conduct test operations under desert conditions.  It also revealed some of the shortcomings in their plumbing design (leaks) which they were able to fix well enough to get to cold flow with cryogenic LN2 and water on the last day of testing (when this report is dated).  The cold flow tests provided useful data in their control algorithm which will be useful to the next series of tests.  MASA also gained experience in safe cryogenic tanking and operations with these hazardous fluids.

MASA team proceeded into LN2 tanking of their oxidizer propellant tank for the cold flow test through their engine and plumbing.

Logistics was a big challenge for the MASA team due to errors in their communication with local suppliers.  Nitrogen and helium gas bottles were significantly delayed and cryogenic liquid nitrogen cylinders also were very late to arrive at the MTA.  Some of these problems can be easily mitigated for the next test campaign now that relationships have been better established. While MASA was disappointed with some of the outcomes from the test series, they are interested in returning to the RRS MTA in the latter part of this calendar year.  This follow-on test series will be discussed at length in the coming months.

A gang of nitrogen bottles sit chained togeither in a pressurant feed manifold.

The society was similarly challenged in supporting this MASA campaign.   The society is grateful to everyone who assisted at the MTA (Osvaldo Tarditti, Waldo Stakes, Bill Inman and myself) or those who gave their comments and concerns (Larry Hoffing, Jim Gross).  Several members spent multiple days at the MTA both during the week and on weekends.   The RRS provided the necessary oversight during the hazardous portions of the testing campaign which was particularly difficult to schedule during weekdays.  The MASA team was very open and disciplined in their interactions with the society.  The RRS was also glad for the University of Michigan’s support and communications throughout this event.

It was a challenging event which was made possible by the contributions of many RRS members over many days.  Frequent communication between MASA faculty and the RRS was a firm requirement on all days of this tenacious campaign and the MASA team provided daily briefings on their progress.

The MASA team showed tremendous dedication and perseverance sex shop over this extended campaign in the summer heat of the Mojave deset.
Cold flow testing complete with pressurized LN2 through the oxidizer path and water through the fuel path.

This testing campaign and current RRS policies will be discussed at the next monthly meeting, 9/10/2021.  Pursuant to our mission statement, the society is glad to support projects of this kind to universities capable of conducting safe experiments at our unique testing site and to those who are willing and able to provide the society with sufficient advance notice to review their reports, schematics and inspect their hardware.  This campaign is firm proof that we will need more licensed pyro-ops and more members available to support any similarly extended test series in the future if they are accepted by the council.  By building and enforcing a consistent and fair policy for all new and prior clients, the RRS can better operate to the benefit of everyone.

All requests to use the RRS MTA must be made to the RRS president and reviewed by the executive council.  For any questions about this test series or any future test series, please contact the RRS president.

president@rrs.org




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