The UCLA Project Prometheus held a static fire event at the RRS MTA for two of their latest designs of their liquid rocket engine. The pyrotechnic operator in charge was Osvaldo Tarditti with Dimitri Timohovich and myself as apprentices for these two static fire operations. This was a liquid ethanol and oxygen engine of the same 1500 lbf design used in prior years. There was a change in the injector pattern and a new ablative liner was used in the first of two engines.
UCLA had come to the MTA on the prior afternoon to begin their setup with plans to be ready for the first of two hotfires when the pyrotechnic operator was to arrive that day. UCLA was in fact ready and after a short review of all plumbing and changes made since last year’s testing followed by the basic safety briefing to all attendees the tanking operations began.
During the pandemic, UCLA had a long pause without access to their laboratory. This time allowed the team to collaborate remotely and consider improving their testing rig which was deployed at the MTA for the first time.
The first engine hotfire had a few delays from the igniter failing to light in the last seconds of the count. The count was recycled with the same result. After the avionics team corrected the problem and the oxidizer supply was replenished, UCLA returned to their countdown and had a generally successful hotfire. The test ran the whole duration but the chamber internal wall ablative liner seemed to not be sufficient and a breach of the chamber jacket was seen.
After purging the engine and safing the ground test system, UCLA waited for the engine to cool. Photos were taken of the post-test conditions and we all took a break for lunch before swapping engines for the second of two planned tests.
The second engine had the old ablative liner material and went full duration without any obvious trouble. Also, the second engine used a small solid motor on a 3D-printed clamp-on mount which worked well. Similarly the engine was purged and allowed to cool before its removal for inspection back at the university. UCLA will likely examine the igniter firing circuit and system before their next engine firing or flight.
The team was very proud of the progress made and the data gathered will be very useful in anchoring their next flight vehicle’s performance. UCLA intends to surpass 30,000 feet with this next flight to claim the FAR-MARS prize. UCLA is still the current record holder at 22,000 feet from last year’s flight. Vehicle dry weight reductions in this year’s design and minor improvements to other vehicle systems could make the difference in claiming the prize.
The old blockhouse had it’s roof replaced two weeks ago thanks to Dimitri Timohovich and other RRS members who lended a hand. Trimming of the roof beams was finished and the blockhouse was used for the first time with UCLA’s liquid rocket static fire.
As UCLA was packing up to depart the MTA, we used the time to build another wire launcher rail for model rockets in upcoming school events with LAPD CSP. Dimitri and his son, Max, launched a few volleys of some water rockets using a special system using an air compressor and solenoid firing box built for remote charging of nitrous oxide based hybrid motors. The system worked well and it was great fun.
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.
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.
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).
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.
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.
The RRS held a launch event at our Mojave Test Area (MTA) on April 10, 2021, the day after our monthly meeting. COVID-19 still remains a threat so everyone continued to observe protective protocols – masks & physical distancing. For the first time in months, we had a day with great weather for launching rockets and we made the most of it! We had low-power, high-power, and experimental solid rocket launches, another launch of Bill Inman’s Solar Cat, the maiden voyage of Wolfram Blume’s Gas Guzzler, and a static fire of Larry Hoffing’s solid power motors. Osvaldo Tarditti was our pyrotechnic operator in charge.
CTRL+V (USC RPL)
Preparation for the first launch of the day: CTRL+V actually began the day before launch with motor integration and other preparation work taking place at the MTA site. On the morning of the launch, the team from the USCRPL installed the rocket on the launch rail, which was then raised into place south of the MTA’s vertical test stand. Wires running from the rail were staked to poles and hammered into the ground to provide additional stability for the rail. Several launch crew members can be seen prepping the rocket above, and a still image of the launch of the rocket can be seen below.
The rocket flew on a 6″ experimental rocket motor. A specific procedure was followed prior to launch, under the supervision of the pyro op, which included radio go/no-go call outs from several teams including tracking, avionics, and even a drone that took footage of the launch! All spectators and crew were in the bunker during takeoff at 11:04 am – ignition was prompt and rocket left the rail quickly and cleanly. The initial telemetry reported by the team indicated an altitude of over 11 km. Several members then went off on the daunting task of recovering the rocket from wherever it landed.
The next flight of the day came from BPS.space with the rocket Lumineer. This launch was conducted from one of the pads just west of the vertical test stand. The flight took place around 1:20 pm on a commercial Cessaroni “N” motor and was livestreamed to a reported 9,000 viewers on YouTube. The rocket utilized a “fly-away” rail guide to provide stability and eliminate the drag of rail buttons, which can be seen still in the process of falling from the rocket in the image below. The target altitude was 10 km, but telemetry was lost shortly after takeoff so the actual peak altitude was unclear after launch, and the rocket was not recovered for some time.
GAS GUZZLER (Wolfram Blume)
Wolfram Blume has been diligently making the pilgrimage to the MTA events over the last several months and the weather has been uncooperative for his chances of launching, but that finally changed in April! The maiden voyage of the GasGuzzler took place from the pad just west of the vertical test stand. This flight was conducted to answer several questions about staging during the flight – so the ram jet second stage was flown empty and only the first stage, commercial solid rocket motor was used to power the rocket. A slow-motion (10% full speed) video of the launch can be seen here.
The ascent of the rocket was smooth, validating the rigidity of the rocket’s design and the stability when empty. The data from onboard altimeters confirmed that the ram air entering the 2nd stage was enough to separate the 2 stages immediately (0.1 second) after motor burnout which occurred at 1,440 ft. The parachute for the booster stage deployed successfully and that stage was recovered without damage. The ram jet, upper stage utilizes a dual-deployment of a drogue parachute at apogee and main parachute at 1,000 ft above the ground. While each of these deployments were successful, the main parachute did not pull out of the deployment bag so the stage landed hard and damaged a few parts. Fortunately, the 2nd stage is not the final parts intended for the full flight of both stages so there will not be delays to the project to rebuild. Wolfram collected lots of useful data and plans to add a GPS tracker and other upgrades before his next flight. We all hope the weather remains in his (and all of our) favor!
CHARLIE HORSE (Keith Yoerg)
Up next was the 12th flight of Keith Yoerg’s rocket Charlie Horse. This was the first flight test of the LoRa GPS tracking boards discussed in previous reports. There are several difficulties with getting the units setup properly, not least of which being the frequent firmware updates required to pair the board with the mobile phone app (2 updates in as many months). Powering up the boards the night before would have helped eliminate these struggles, but a successful launch was still completed, a slow-motion (10% full-speed) video of the launch can be seen here, which was on a commercial Cessaroni I280-Smokey Sam motor.
One issue still to be resolved with the LoRa trackers is a setting within the Meshtastic mobile application which trades off tracking range for the speed at which new information packets are sent. The “medium” setting was used on this flight but for rocket flights it may be advantageous to reduce the range (which is purported to be up to 10 miles) in favor of more frequent location updates. More testing will be done on future flights in hopes of developing a cheap, simple GPS tracking available for rockets flying at the RRS.
SOLAR CAT (Bill Inman)
Bill Inman’s solar-heated steam-powered Solar Cat rocket took to the skies around 4:31 pm. While the weather was perfect for most of the projects, the light overcast that can be seen in the pictures above proved problematic for the solar heating required for the best flight. In addition by launch time, the solar collector was at its westernmost limit so no more heating was possible. At launch the water temp was 370 F and was at 130 psi.
The flight reached 41 mph speed and achieved a 60 ft altitude. While this was an improvement on the first Solar Cat launch at the MTA, with additional heating there could be even more impressive stats. While he can’t control the clouds, Bill hopes to arrive at the MTA site the night before a launch in the future to increase the chances of getting off a good test and launch before reaching our western limit of travel for the solar collector.
THE YOERG CHALLENGE (Dimitri Timohovich & Keith Yoerg)
With this being Dimitri’s last MTA event before leaving to Alaska for the summer, some other RRS members need to step up to the plate to keep the “Yoerg Challenge” alive. I have put out the call for more RRS members to build low-power rockets to fly at the MTA, and have left my 5-pad PVC launcher at the site for future launches. IT’S CHEAP, IT’S FUN, IT’S A CHALLENGE (and everyone is a winner)! What’s not to love? So get out there and build some model rockets!
The entrants this month included Keith’s Big Bertha, Baby Bertha, and Hi-Flyer XL rockets and Dimitri’s Space Crater – which carried eggs in honor of Easter this month. Fortunately, Dimitri’s wife had the foresight to hard-boil the eggs because his rocket took the “Crater” part of its name a bit too seriously (the remains are shown above). A few of Keith’s flights before the GoPro battery died can be seen here.
SOLID MOTOR TEST FIRE (Larry Hoffing)
Larry Hoffing had some experimental solid rocket motors ready to test fire, but with all the other activity going on at the site he took the time to install a new “No Smoking” sign on the covered propellant loading area (shown below). Once things were a little less active, Larry was able to affix the motors and perform a test-fire. While the burns were long, they did not produce much thrust and need to be improved upon before use in a rocket.
In addition to everything detailed above, one of the USC RPL members flew a high power rocket to earn her Level 1 certification with the National Association of Rocketry, and Dimitri flew his water rockets with his son.
This was by far the most active event at the MTA in the past year and was an exciting day for anyone who likes to see rockets fly! Our next launch date has not been decided upon, but we hope to have an event in May to continue hosting at least one event per month at the site.