by Dave Nordling, President, Reaction Research Society
The University of Southern California (USC) Rocket Propulsion Laboratory (RPL) held a static fire test of their third solid motor design in the Earthshaker series. Prior designs resulted in failures and incremental corrections to the design were made for this test. Earthshakiiest was to be the largest impulse motor made by any collegiate team. Osvaldo Tarditti was the pyrotechnic operator in charge.
Earthshakiiest sits ready for static firing at the vertical test stand with sheet metal in place to protect nearby mounting surfaces.
Given the repeated recent failures of USC motor designs, the society required protective barriers installed in the event of another energetic failure. Unfortunately, this would prove to be a wise choice as failure did result right at startup. All personnel were at a safe distance or behind appropriate barriers.
Earthshakiiest motor ruptured at start and burned itself out.Damage to USC’s test stand was total, The mounting points in the concrete were damaged such that further use is not possible..
The extreme heat from the explosion and fire destroyed the static fire stand, melted portions of the shielding and severely damaged the mounting points such that further use is not possible. USC is working with the RRS to clear and clean up the pad. Many of these tests are very dangerous and can damage our facilities. The society expects all groups to repair, restore or replace any of our assets damaged. A new method of holding future large solid motors is being discussed.
The society thanks our former president, Osvaldo Tarditti, for supporting this event as the pyrotechnic operator in charge and to Bill Inman for also supporting the event on behalf of the society. The operation was conducted safely and much was learned despite the poor outcome. USC will provide details from the testing soon and a path forward,
by Dave Nordling, President, Reaction Research Society
UCLA Rocket Project conducted a static fire test series at the Mojave Test Area on February 5, 2022. i was the pyrotechnic operator in charge for the event. Bill Inman of the RRS was also present as my apprentice in overseeing operations leading to hot-fire that day. UCLA returned with improved launch control and instrumentation boxes. They also invested in plastic tube mounting fixtures for cleaner routing of their low pressure plastic pneumatic lines.
New launch control and instrumentation boxes.Cryogenic liquid cylinder mobile cart used to place the vessel behind the vertical test stand frame
UCLA had three liquid engines prepared for testing which was a very aggressive goal. Some problems occurred in ethanol fuel tanking operation which resulted in a minor spill. Ethanol is volatile and very flammable, but dissipates quickly and doesn’t pose a lasting hazard or contaminant.
The issue was partially with the procedure lacking precise metering of a prescribed volume and part with a lack of coordination between the teams. Fuel loading is not considered one of the more challenging tasks but even simple items can cause serious problems if the team fails to keep their focus, The RRS has recommended UCLA reconsider and revise their procedures as needed but also to take a wider view of what operations are in place and who is doing what, where and when. Coordination is a full time job requiring diligent leadership and responsible participants,
Ethanol fuel transferred to the propellant tank by a low-pressure gas supply while the tared vessel is wieghed on a scale.
The first engine in the series was a modified version of a prior impinging injector used in last year’s flight. The team was able to complete propellant loading and retreat back to the blockhouse for pressurization operations. All proceeded well until the last part of the countdown.
Ignition failure scrubbed the first firing attempt as the F-sized rocket motor lit but propelled itself downrange pneumatically under excessive pressure built up enough to eject the fixture off the engine before the team could commit to firing. Per UCLA’s procedures, the spotter correctly indicated ”no fire” which caused the launch team to safely abort the sequence. The team held on the release of the pressurant and opted to remotely relieve the system as allowed in their plumbing design after the umbilicals were released. As there was no remote means of draining the LOX, the pneumstically actuated vent was left open to allow the LOX to boil out and with sufficient time elapsed the team was able to approach.
View of the clamshell fixture holding the igniter before the first attempt on the first motor,
The 3D-printed clamp-on fixture that held the igniter was examined and reassembled. The decision was made to drill large vent holes in the plastic two-piece clamshell which would help in the next firing attempt. Unfortunately, the second firing attempt failed to achieve ignition. This time, the spotter did see and hear the F-sized hobby motor fire but the igniter was not energetic enough to light the initial propellant streams. The LOX and ethanol streamed from the engine during the blowdown period and quickly evaporated without fire or explosion. This is a potential failure mode that all liquid hot-fires must plan for. Ethanol and liquid oxygen do not contaminate the area and are quickly dissipated but a chilled pre-mixture of fuel and oxidizer is quite dangerous.
The modified igniter holding fixture with added vent holes.UCLA removing the first engine and associated vehicle systems mounted to their vertical frame.Facility connections being made as the mobile test stand is put in place.
Duringn the hardware switch, we had some discussion about different methods of ignition including automotive diesel glowplug systems and high-voltage stungun transformer cells all powered by 12-volt battery or capacitor-based small power sources, Both would require significant development and only a test with cryogenic propellant would be a fair test of these devices. UCLA had some interest in exploring these options but it would have to wait to the next academic year.
I discussed UCLA’s methods of scrubbing their test and recommended they put in a safer means of draining their LOX and ethanol in future operations. This will be discussed before subsequent tests at the MTA.
UCLA has had good results from pyrotechnic igniters using cut-down lances, but these are not easy to acquire as they are ATF-regulated. UCLA decided to try hobby rocket motors which had problems in this first engine test series. The only option forward was to continue using the vented fixture fitted for F-motors and a hope a prior ignition failure did not occur.
With the mobile test stand in place, the second engine tested was the injector design that will fly on UCLA’s rocket. It is the same one used lsst year which worked well. The first injector was unable to be tested that day due to ignition problems and UCLA’s decision to proceed with the second engine as their backup. Time was becoming short as the late afternoon arrived and UCLA had to switch over to their mobile testing rig which would hold the second and third engines when tested.
Second engine being put into the mobile stand,Preparations for the second engine hot-fire run out to sunset,UCLA in the blockhouse for final checks before firing
Liquid oxygen quantities in the cylinder ran low and full oxidizer tank load wasn’t possible for what would be the last test of the day. After finishing the LOX tanking, UCLA retreated to the blockhouse for final checks before second firing. No igniter problems were seen with this second engine, but it was a possibility given the recent problems with the first test series.
Hot-fire of the second engine by UCLA.
The hot-fire went to nearly full duration but the burn likely finished fuel rich. Some buzzing was evident so UCLA will review the data to see if the same instability seen in prior firings was present. It didn’t seem to be damaging and if the performance is still sufficient UCLA should have at least one good engine to fly in May when they try to surpass the university-built liquid rocket altitude record.
UCLA posed for a photo after the hot-fire and just before the lengthy teardown in the cold hours of the evening.
The third engine was left for a later test date. UCLA is considering another hot-fire series but only after a full review of the data from February 5th.
My thanks to fellow RRS member, Bill Inman, for making the long drive from Carson City, Nevada to support this test.
Also, a big thanks to Eric Beckner of Friends of Amateur Rocketry for staying late and handling the return of the liquid oxygen cylinder.
The RRS is glad to support university teams with our unique facilities at the Mojave Test Area (MTA). Contact the society at ”president@rrs.org” for those interested in similar projects.
The latest meeting of the Reaction Research Society took place by teleconference on Friday, December 10th and had twelve attendees.
Screenshot of discussion during the monthly meeting
RECAP OF KEITH YOERG’S NOVEMBER LAUNCH OF “THE HAWK”
Keith kicked off the meeting with a recap of the first launch of his rocket “The Hawk” an 8-inch diameter 14-foot tall rocket that was flown from the RRS Mojave Test Area on November 28th. The rocket utilized the 1515 rail launcher which was secured in place to one of the concrete pads using sandbags and tie-downs. The motor was a 98mm Cesaroni M1790 Skidmark which features sparks in the trail.
First launch of Keith Yoerg’s rocket “The Hawk”
Keith shared some slow-motion video of the flight captured with a GoPro camera and other data from the flight, including a 3D flight path. The rocket reached an altitude of 4,846 feet as measured by the barometer on the onboard AltusMetrum Telemega flight computer, and was successfully recovered with only minimal damage to the body tube. The rocket is in the process of being prepared for another launch on December 17th to coincide with the anniversary of the Wright Brothers first flight.
Map of the flight path with barometric altitudes in red and GPS in blue. The GPS appears less reliable on this flight.
RESULTS OF THE 2022RRS EXECUTIVE COUNCIL ELECTIONS
Election chairman Drew Cortopassi presented the results of the 2022 executive council elections. The RRS Executive Council for 2022 is as follows:
President: David Nordling Vice President: Frank Miuccio Secretary: Keith Yoerg Treasurer: Larry Hoffing
The society members in attendance congratulated the incoming new president and other incumbent officers and expressed their gratitude to outgoing president Osvaldo Tarditti for his stewardship of the organization. Osvaldo noted that the future of the group looks bright, and promised to send anyone who asks him a question a photo of him fishing.
USC SOLID ROCKET GRAINS STATIC FIRING
Osvaldo and Dimitri provided a recap of the lengthy solid rocket motor testing campaign that USC conducted at the MTA from December 4-5. On Saturday the 4th, the team worked through the night until around 2 am to be able to complete their goal of firing 20 separate grains of solid fuel by 2:45 pm on Sunday the 5th. The only reported mishap was that the U-Haul the USC team rented broke down just after leaving the dirt road to the MTA, which Dimitri suspected was because they had been using the battery from it to fire the rocket motors.
While the campaign was an ambitious one, the repetitious nature allowed them to get some of the younger students involved who wouldn’t normally be able to take part in on a day when only one motor is being fired. It was remarked that having more young members with hands-on experience is very good for the future of their program and the continuity of knowledge after the upperclassmen graduate. Dimitri mentioned that additional work will be needed to fill in the area of ground blasted away by all the recent USC solid rocket static firings – which has been affectionately named the “Trojan Trench.”
On the same weekend, a team at the FAR launch site launched their “Genesis” rocket – a hypergolic liquid propellant rocket that has been in development since the early 1980’s. Several RRS members had worked on the rocket at various times during its design and fabrication process. Unfortunately, the parachute system did not work and the tanks ruptured on the landing causing a small fire that self-extinguished but was visible from the MTA.
A THANK-YOU FOR DIMITRI’S RECENT WORK AT THE MTA
Our outgoing president, Osvaldo Tarditti, took a moment to extend a special thank you to RRS member Dimitri Timohovich for all of the recent work he has done in improving the facilities we have available at the MTA. Not only did he take the lead in the recent blockhouse roof repair which included several trips up to the site for the initial build, cutting the edges, and installing the tar paper, but he also donated four propane bottles for the society to use in the heaters and BBQ up at the Dosa Building.
The old blockhouse with a new roof.
In addition, Dimitri has agreed to take on the bulk of the work in building out the interior of the containerized bathroom. Three concrete pads have been poured at the MTA to accommodate this 20-foot high cube container as well as another one adjacent to it.
Future site of the RRS containerized restroom facility.
Osvaldo has procured most of the fixtures for the interior and plans to drop them off at Dimitri’s house – where the container will be delivered so that he can work on it more easily. Dimitri gave a tentative timeline of mid-January 2022 for when the container may be ready for transport out to the MTA.
PLANNING FOR MTA EVENT ON DECEMBER 17
Keith discussed his plans for a second launch of “The Hawk” on Friday, December 17th – this time on a Cesaroni N2600 motor. In addition, Dimitri has an RRS Standard Alpha rocket constructed and ready for launch and Osvaldo agreed to prepare one for Keith to get experience with the Zinc-Sulphur rockets. Dimitri volunteered to bring food for the group – award winning caribou chili made from meat they hunted, dressed, and prepped themselves in Alaska.
CALIFORNIA’S NEWEST ROCKETS CLASS 1 PYROTECHNICS OPERATOR
RRS member Dave Nordling informed the group that he recently learned that he passed his Class 1 Rockets Pyrotechnic Operator’s License exam. Congratulations Dave!
Office of the State Fire Marshall (OSFM) governs the licensing of pyrotechnic operators in California.
With additional members continuing to work towards earning their licenses, we can make sure that the RRS is able to accommodate a wide range of rocketry testing and schedule requests.
NEXT MONTHLY MEETING
As a reminder – yearly membership dues are due January 1st. Please click on the yellow “Donate” button on the right panel of this website to pay online via PayPal, or mail a check to the society post office box in Los Angeles.
Reaction Research Society; P. O. Box 90933; Los Angeles, California, 90009-0933
The next RRS monthly meeting will be held virtually on Friday, January 14th at 7:30 pm pacific time. Current members will receive an invite via e-mail the week of the meeting. Non-members (or members who have not received recent invites) can request an invitation by sending an email to:
secretary@rrs.org
Please check your spam folders and add secretary@rrs.org to your email whitelist to make sure you are receiving the meeting invitation.
