Tag Archives: Baby Bertha

MTA Launch Event, 2022-05-21

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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

MTA Launch Event, 2021-09-26

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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, 2021-02-20

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by Dave Nordling, Reaction Research Society

The Reaction Research Society held another launch event at the Mojave Test Area (MTA) on February 20, 2021. The weather was not cooperative for much of this day with wind gusts well beyond acceptable limits for launch (> 25 MPH). Our neighbor, Dave Crisalli and his Polaris Propulsion team, were using the Dosa Building as he had construction activities planned but were cancelled for that day. The RRS and Polaris Propulsion were glad to share the Dosa Building as we both made good use of the day.

The three planned objectives (weather permitting) for this MTA launch event were:

  • Build a new pit toilet restroom just north of the original site.
  • Conduct Solar Cat operations at the MTA
  • Conduct model rocket launches from Keith Yoerg’s new wire launcher array

THE ALL-SOLAR POWERED SOLAR CAT PROJECT

Bill Inman and his colleague, John Wells, made the long journey to the MTA from Nevada. Bill had made further improvements to the launching system and solar collector powering the Solar Cat steam rocket. He was able to and a remote tracking motor and drive system to further automate his solar concentrator, but several minor problems in setup prevented a launch that day.

Bill Inman and John Wells examine and prepare the solar collector system from the trailer at the east side of our MTA.
Photovoltaic panel mounted to the front of the collector to power the tracker.
Bill Inman and John Wells set up the latest iteration of the Solar Cat steam rocket from just west of the alpha and beta launch rails

Bill is striving to use an entirely solar powered system including a photovoltaic power system for his auxiliary functions. Because of the east to west passage of the sun through the sky, the steam rocket must be launched in a northerly direction. This is possible if done from the northern or western edges of our launch site.

Although the winds were excessive throughout most of the day, Bill could still conduct some assembly testing and even conduct steam rocket heating operations while keeping the rocket secure on the ground. Launch would only be attempted if the winds lowered in that time. Sadly, much of the day passed in correcting minor problems and system tests. The system proved ready but insufficient sunlight remained that day and launch would have to be conducted from the MTA at the next opportunity.

BUILDING A NEW PIT TOILET AT THE MTA

The society has been examining many improvements to our Mojave Test Area which has stood for over 65 years. The site has been improved over the many years but time has taken its toll and renovations are needed.

The top priority selected by our membership and visitors was the restroom facilities. Our short term plan was to build a second pit toilet while we work on plans for a more luxurious option in the longer term. This effort is viewed as a stopgap solution which will serve our society for at least a few years. Dmitri Timohovich and Wilbur Owens contributed greatly to this effort. With the many people we had at the site, we were able to start and complete the project with time to spare that day.

Our starting point for the project.
Wilbur operates the backhoe to get the trench dug for the sonotube. While Dmitri completes the wooden deck for the new pit toilet,
The precarious job of installing the sonotube once the pit is at the proper depth.
After getting sonotube vertical, the rest of the pit was filled with a few bucket loads of dirt and a few of us with shovels.
The new restroom deck gets placed and aligned with the new sonotube.
The toilet booth is removed from the original concrete platform. Our president, Osvaldo Tarditti, pauses a moment to consider how much crap our society has taken from our visitors and members alike,
The toilet booth is placed on the new platform, but first some further trimming of the sonotube must be done,
RRS secretary, Keith Yoerg, and RRS member, Dave Nordling, stand at the original concrete platform now filled flush to the surface with dirt. The task is nearly complete.
Once firmly affixed to the new platform, the toilet booth was fit checked by Dmitri Timohovich. He is signalling that our pit toilet is now ready for business.

The pit toilet project was a success thanks to both our members providing their physical and material labor and the careful planning and coordination that took place starting in this new year. This improvement project will be only one of several to come. We hope to make our remote testing site both more functional but also a bit more comfortable to all who visit us after many hours drive from the city.

LAUNCHING ROCKETS FROM A NEW MULTI-WIRE RAIL STRUCTURE

With the last hours of the day upon us, the winds had subsided to a more reasonable speed. Keith Yoerg had a few model rockets prepared for launch with commercial motors. He had also built a multi-wire launcher which is a convenient way to display and launch several small vehicles successively.

Max Timohovich (left) views the Baby Bertha and the Big Bertha rockets as they sit on the launch rail made from PVC pipe and fittings.

Second thing introduced at this MTA launch event was a four channel launch box built by Dmitri Timohovich. With a clean wood finish and a rugged latched case, this box proved its function well with the launch of three model rockets that day.

The new launch box was tested at the 2/20.2021 MTA launch event

After some glitches with the electric matches, Keith was able to launch and recover the Baby Bertha (A8-3) and the Big Bertha (A8-3) rockets. We got excellent footage of these classic model rocket types. The last of the three launches was the slightly larger Star Orbiter (E16-6) which left the rails cleanly and the recovery system deployed without issue. Although the winds had subsided sufficiently at ground level, the higher level winds carried the Star Orbiter for a long horizontal trek west well beyond the property line, After some searching, the Star Orbiter was lost to the desert hoping to be recovered

Baby Bertha leaps off the wire rail with its tiny A8-3 motor,
Big Bertha comes back under its parachute landing just to my left. This great video can be seen on the RRS Instagram account.
The last photo of the Star Orbiter as it sits on the pad before the wind carried it far to the west.

IN CLOSING

The team cleaned up the area and put away the gear at sunset. We talked about setting the next launch date in March 2021. We hope to have a new date set soon, likely after March 12th.