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 literatureIdentification 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 verticallyRRS 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.
The latest meeting of the Reaction Research Society was held last Friday, May 13th 2022 and had seventeen attendees.
Screenshot of discussion during the monthly meeting
UPCOMING MTA EVENTS
The meeting began with a discussion of the launch event upcoming at the MTA. Events planned for Saturday, May 21st include:
30 students from a LAPD class launching Baby Bertha model rockets 2 times each
Launch of Wolfram Blume’s Gas Guzzler
Cryogenic testing of Compton Comet tanks
Dimitri has started work on a new set of launch pads to accommodate up to 18 model rockets (which is the number of separate igniters each Cobra firing module can accommodate). The high number of launches we expect to complete this weekend will give us a chance to train members who might be interested in learning how to use the relatively new Cobra Firing System.
Progress on the launch pads Dimitri is building
Wolfram is planning to conduct another launch of his rocket Gas Guzzler, hopefully fixing issues with the parachute system from the last launch. Several members of the Compton Comet team plan to conduct cryogenic shock testing of hardware for their liquid rocket project. Compton Comet team members agreed to send a list of attendees to the RRS President & Treasurer to help confirm that all the members have current membership and waivers on file.
REVIEW OF RECENT MTA EVENTS
We then discussed the recent MTA event where the USCRPL launched a rocket called “Jawbone.” Frank showed a YouTube video that the group made after the launch.
RECAP OF RECENT EXECUTIVE COUNCIL MEETINGS
The RRS Executive Council (EC) met in each of the 4 weeks leading up to the May monthly meeting, and the council provided a brief synopsis of the topics and decisions made in those meetings to the membership. Specifically, one EC meeting included RRS members Richard Dierking and Kent Schwitkis and was focused on emergency preparedness at the MTA, including what infrastructure improvements might be useful from a safety standpoint. Another meeting was attended by Xavier Marshall and focused on modernizing and digitizing the administrative processes of the RRS. The other 2 meetings focused primarily on the new RRS bathroom, and decisions were reached on selecting a contractor as well as construction material (concrete) for the septic tank. The council hopes the septic system will be installed by the end of June, with the bathroom container installed not long thereafter.
Example of a concrete septic tank
DISCUSSION OF MONTHLY MEETING LAYOUT
After several monthly meetings with lengthy presentations, the EC decided to open a discussion with current members on the layout for monthly meetings. The general consensus was that presentations are an appreciated and valued part of the meetings, but that a hard time-limit should be enforced to limit meetings running too late into the night. Many members agreed that 20 minutes is a reasonable limit, and that Q&A periods should be limited as well to avoid lengthy questions that become their own monologues. Most members in attendance agreed that starting the meetings with presentations would be preferable to leaving presentations until the end of each meeting.
PROMOTION OF THE RRS& OTHER ITEMS
Our Vice President Frank Muiccio was asked to give a radio interview as part of a segment on local heroes. The interview will be on AirTalk with Larry Mantle on the local NPR radio station 89.3 KPCC Thursday, May 19th at 11:45 am and can be heard on the radio or streaming on their website. Frank also updated the society on the possibility of an update to the documentary about the RRS youth outreach programs called Rockets in the Projects.
This opened a discussion about the possibility of expanding the classes to potentially include entries in competitions like the TARC challenge. Jerry Fuller mentioned that his local high school in Palos Verdes has had many groups successfully compete in this challenge, and expressed interest in helping connect the RRS with the instructors of that group.
Although Jim Gross was unable to attend the meeting, he sent along information that he wanted the membership to be aware of:
Wanted to let the Society members know there is a 5-day “Cryogenic Engineering & Safety Course” scheduled for 1-5 August 2022 at the Colorado School of Mines. The price is $3,250 per student. This MIGHT be useful for anyone going for a Rockets Class 1 Pyro. Op. License. I’ve never taken it, so I am not sure. More info is available from 1 (305) 972-8847 or www.cryocourses.com or via email at info@cryocourses.com
NEXT MONTHLY MEETING
The next RRS monthly meeting will be held virtually on Friday, June 10th 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.
The Reaction Research Society held its last launch event of the year 2021 at the Mojave Test Area on Friday, December 17th. I was the pyrotechnic operator in charge. This was my first launch event as a Class 1 pyrotechnic operator although none of the activities this day involved a liquid rocket. We had four launches planned for that day. Two from Keith Yoerg, one from Wolfram Blume and one from Dimitri Timohovich. RRS members Wilbur Owens, Xavier Marshall and Bill Inman came to be spectators at this launch event.
Bill Inman at the RRS MTA on 12-17-2021
IMPROVEMENTS TO THE 1515 RAIL LAUNCHER
The first flight of the Hawk in late November revealed a concern about the stability of the 1515 rail launcher with heavier rockets. Although quite heavy in its steel rectangular tube construction, Dimitri and Keith used cinder blocks and sandbags to weigh down the legs of the base. This resulted in damage to several of the sandbags from the exhaust of the M-sized motor from the initial flight.
Flat steel plate with welded boltFlat steel plate added to the 1515 launch rail base for greater anchorage
A flat steel plate with a threaded rod welded to the center was connected to the bottom of the 1515 rail launcher to allow for more weight to the base and allow for more cinder blocks to be added for even more stability. New adjustable feet were added to the existing four threaded holes at the far points of the legs. Eyebolts were also bought to screw into the 3/4-10 holes in the pad to strap the base down if necessary.
The 1515 rail launcher with its new anchor plate held down by cinder blocks.
SECOND FLIGHT OF THE HAWK
The December 17th launch event was primarily for the second flight of Keith Yoerg’s massive 14-foot long, 8-inch diameter Jumbo Dark Star rocket made by Wildman Rocketry with a 98mm Cesaroni N2600 Skidmark motor. The launch was held on Friday to coincide with the anniversary of the Wright Brothers first flight..
The payload tube of the Hawk being prepared for launch on 12/17/2021.
The payload was something very special to the Yoerg family and to American aviation history. The payload was a few squares of cotton fabric from the right wing of the original Wright Flyer aircraft that made aviation history. This cloth was the actual material that flew in 1903.
An authenticated piece of American aviation history flies on the Hawk from the RRS MTA.
A similar piece of the cotton fabric used in the Wright Flyer was sent with the Mars Ingenuity helicopter aboard the Mars 2020 mission being part of the first aircraft flown on a foreign world.
Mars Ingenuity helicopter at Jezero Crater on the surface of the Red Planet in April 2021
It was amazing to fly a similar piece of history at our humble launch site for our members to enjoy on the anniversary of manned flight.
After securing the payload and verifying the recovery systems were in proper working order, the Hawk was taken to the launch pad and erected for flight.
The Hawk slid into the 1515 extrusion rail by its rail buttons.Manually erecting the Hawk took several people to carefully raise and push the stopping pin once the rail was near vertical.Keith checking out the wireless data system.Dimitri connects the igniter circuit into the society’s new Cobra wireless firing system Keith Yoerg and Xavier Marshall of the RRS pose with the Hawk before its second flight on the Wright Brothers anniversary.
Before the countdown, Keith gave a very moving speech with his mother, Janette Davis, present in the observation bunker.
118 years ago today, on the sandy windswept dunes of Kitty Hawk, North Carolina, my Great-Great Granduncles Orville and Wilbur Wright achieved the first powered, heavier-than-air flight of a manned aircraft. A few small pieces of fabric from that historic airplane are ready to take flight again today, from the sands of the Mojave Desert, aboard ”The Hawk” an 8-inch diameter 14-foot fall rocket Honoring Aviation, the Wrights, and Kinetics. In 1903, this fabric reached a max altitude of 10 feet at a max speed of 10 feet per second. Today, that same fabric is expected to reach an altitude of over 7,000 feet with a max speed of 791 feet per second (or Mach 0.7).
We’re now ready to start the countdown.The sky is clear, the road is clear.
Flight 2 of “The Hawk” is launching in 5… 4… 3… 2… 1…
Rail-mounted camera caught a few frames before the N-motor destroyed the lens.
The second flight of the Hawk was close to predictions reaching over 7,800 feet in altitude and 742 feet per second. The Hawk with its drogue and main parachutes working properly was fully recovered. Keith got telemetry data and provided screenshots of the results below.
Telemetry data from the second flight of the Hawk on 12-17-2021
Beckie Timohovich was a big help in the recovery efforts and bringing back the hardware to the launch site. She also makes really good Alaskan caribou chili which we all got to enjoy at lunch in the Dosa Building.
The ratcheting extraction tool for removing alphas from the ground.The Hawk returned safely to the ground with the historical payload intact. Wireless and onboard data was recorded and video footage from the ground and on the vehicle was recorded.
The 1515 rail launcher with its heavier base worked well and did not shift although the straps were singed by the hot exhaust and seemed to be superfluous. The parachute system on the Hawk deployed well and brought the vehicle down in tact. Most importantly, the family heirloom flown as a payload was returned to safekeeping.
The 1515 rail after launching the Hawk. Unfazed and ready for another pounding from Wolfram’s K-sized booster motor
Keith is considering his next flight of the Hawk. One idea is to fly an even larger motor if an O-sized motor will fit in the existing 98mm mount. The goal being to go faster and break the speed of sound and fly even higher. Keith was also pondering adding a second stage to the Hawk. We hope to learn his next plan in the new year as we hope to have another launch event in January 2022.
TWO MICROGRAIN ALPHA ROCKETS
We flew two alpha micrograin rockets. One by Keith Yoerg, one by Dimitri Timohovich. Each had a payload built by John Krell. These were the first zinc-sulfur rockets to be loaded and flown by Keith and Dimitri which although both them have been active members of the society for years, this experience served to initiate them into the RRS.
Dimitri was first to load his blue nose-to-red finned rocket and fire it while Wolfram Blume completed his assembly and preparations for the second flight of the Gas Guzzler two-stage rocket with a water ballasted ramjet upper stage. Keith Yoerg’s alpha with the bright pink nosecone and fins was the second of two alpha flights, Like with the Hawk before it, the RRS used our Cobra wireless firing system with the alpha rockets.
Dimitri Timohovich loads the powdered micrograin into the propellant tube using gentle vibration to release any air pockets.Keith finished with the loading of powdered propellant, installs the nozzle into his alpha.
Keith edited the footage of both alpha flights into one compilation on YouTube. See link below:
John Krell’s Adalogger design custom built for the tight confines and high acceleration of Keith’s RRS standard alpha.Keith prepares to load his alpha into the box rails.Still capture of Keith’s alpha streaking nearly straight up in nearly calm winds that day.Keith Yoerg’s first alpha rocket.
A few days after the MTA launch event, John reported a summary of the results from the two different instrumentation payloads. His emails are paraphrased below.
On 12/17/2021, two Alpha rockets were launched. Both were instrumented with high speed flight computers. Dmitri’s Alpha (blue nosecone) carried an original Alpha Datalogger on it’s third flight and Keith’s Alpha (pink nosecone) carried a newer Adalogger design on it’s second flight.
John Krell had two data logger designs. the original data logger design was flown on Dimitri’s alpha.
The bad news first. The Adalogger SD card socket broke during its first launch. I did not catch this issue prior to this launch. The SD card fell out of its socket during the initial acceleration and no flight data was recorded from Keith’s alpha, The next design update will include a nylon post to prevent SD card ejection. Keith’s Alpha also incorporated a semi-soft shock absorption mounting. It didn’t work as well as planned, but it does show potential with two modifications. Damage to the Adalogger system was minimal and repairable.
9-volt battery mounted in the aluminum nosecone of Dimitri’s RRS alpha.
Dmitri’s Alpha produced significant new data during the burn for a micrograin rocket. The thrust was relatively smooth and constant compared to the previous three Alpha launches that carried flight computers and returned data. Absent were the large acceleration bursts during the burn. (See attached graph)
Acceleration plot of Dimitri’s alpha flight.
Also recorded was the impact. The impact duration was measured at 16 milliseconds. This is the shortest impact duration recorded for an Alpha. A prior impact duration of 18 milliseconds produced a deceleration of 716 G’s. This impact deceleration should exceed that value.
Further analysis of the data is required to determine a value. A picture of Dmitri’s rocket in the ground prior to extraction will be helpful. (Photo was later provided.)
Motor burn duration 0.408 seconds
Maximum Acceleration 103.95 G’s at 0.304 seconds
Maximum Velocity 676 ft/sec, Mach 0.6 based on integrated accelerometer readings
Altitude at Burnout ~138 ft
Maximum Altitude 4,307 ft AGL by barometric readings
Terminal Velocity 463 ft/sec, Mach 0.411 based on barometric readings
My video records of Keith’s Alpha show a shorter burn duration equating to a higher acceleration and velocity. The altitude should also be higher with the shorter down range distance.
Dimitri’s alpha with its red paint at the aft body coming off from the intense heat of the micrograin burn. Dimitri’s rocket was found significantly further downrange than Keith’s but on the same heading
The still pictures at the end furnished the information necessary to estimate the deceleration at impact. Keith’s alpha’s penetration depth of approximately 3 feet 10 inches correlates to a deceleration rate of 680 to 720 G’s in a span of 18 to 20 milliseconds. Dimitri’s Alpha penetrated approximately 3 ft 8 inches into the ground in 16 milliseconds equating to ~900 G deceleration rate. Wow!!!
The main objective was to give all of our active members experience with micrograin rocketry. Although rarely practiced outside of the society, it is considered to be something of a rite of passage and also serves as valid experience with the unlimited category of rocketry. This event gave Dimitri and Keith this experience which will help them as they advance as pyrotechnic operators.
SECOND FLIGHT OF THE GAS GUZZLER RAMJET
Wolfram Blume brought his second build of the Gas Guzzler rocket to the MTA for a December test flight. The same booster section with an Aerotech K-motor was flown. The ramjet was rebuilt and was flying a 3/4 load of water in the gasoline tank to have a representative payload weight including any possible sloshing that might occur.
Wilbur Owens discusses the ramjet operation with Wolfram Blume. This forward view is without the forward cowl. In the background is a graduated cylinder for precisely metering the fuel load into the ramjet.The forward end of the ramjet with its annular cowl and forward spike as it nears final assembly.The Gas Guzzler booster stage design remained the same for this second flight from the MTA.Wolfram holds the lower half of his ramjet ready for final assembly and stacking of the two stages.Wolfram carefully walked the ramjet upper stage to mate with the booster stage already on the launch rail.Wolfram Blume and John Krell examine the Gas Guzzler on the 1515 launch rail before its second flight.The Gas Guzzler sits side-saddled in the 1515 rail launcher to allow proper clearance of the fins.The Gas Guzzler lept straight and clean from the 1515 rails in its booster flight.
From the ground, it was clear that the booster flew straight and stage separation had taken place. The booster parachute ripped loose. The ramjet came down only under its drogue chute and the hard landing damaged the upper stage enough to warrant a complete rebuild.
Clean stage separation was evident, but the booster parachute ripped loose.
Wolfram spent several days after the launch event looking at the remains of Gas Guzzler. A few things are known so far:
The addition of 1.14 kilograms of ballast water did not cause any problems. The two stages – both separately and together – were still stable in flight. Also the stage separation worked.
After separation, the booster came apart at apogee into two pieces. It is an easy fix as a bulkhead blew out and only needs to be better reinforced against the loads. A recent addition of a GPS tracker to the second flight of the booster worked.
The ramjet lost electrical power at apogee. The reason was found and will be repaired. The power failure meant that the GPS tracking stopped at apogee which is a serious problem. Wolfram is considering adding a backup GPS tracker to the ramjet with a separate power supply.
Based on telemetry, the deceleration seen after stage separation gave the drag coefficient (Cd) on the ramjet at 0.25. The accuracy of this calculation is about 10% based on the acceleration readings which is fairly good all things considered.
drag force = Cd * velocity-squared * air-density
The thrust also scales with the square of velocity and that gives the minimum velocity when thrust minus drag exceeds weight to be about 656 feet per second (200 m/sec). This is the minimum velocity which the booster must supply at burnout.
For this flight using the K-motor in the booster, with the water ballast, the maximum velocity was 574 feet per second (175 m/sec). The ramjet reached an apogee of 3,800 feet AGL (above ground level). The booster pushing the ramjet reached an apogee of 3,100 feet AGL. Maximum acceleration under boost phase was 6 G’s. The ramjet was flown without fuel, only an equivalent weight of water instead of gasoline.
The next build of the Gas Guzzler will have a larger booster which will hold an L-sized motor.
In the 12-17-2021 flight, the ramjet’s drogue parachute deployed correctly but the main chute did not. This seems to have been caused by the drogue chute being too small. Rockets with dual-deployment parachute recovery systems typically split the rocket in two places with the drogue ejecting forward and the main ejecting backwards. It is a good, reliable system but it cannot be used in the Gas Guzzler design because you cannot split the ramjet in the middle. Both of the parachutes must deploy from the front. The recovery system design requires the drogue to pull the main out of the ramjet at 1,000 feet. Wolfram developed this system on prior rocket with launches at ROC in Lucerne Valley and it has worked the last three launches. Wolfram is confident that it will work in the next flight of the ramjet, too.
Damaged fragments of the ramjet recovered downrange after the second launch of the Gas Guzzler.
The air flow measured inside the ramjet during the second flight on 12-17-2021 was within the range of an air blower system at Wolfram’s workshop that had considered using to static fire the ramjet with an operational burner. However, he is not comfortable with trying the main burner at his workshop, but testing the flameholder and its igniter is OK. Thus, a static test of a fueled ramjet coupled with an air blower system is being considered.
Going forward, once the ramjet is rebuilt, Wolfram would like to verify the performance of the igniter and flameholder over the full range of the air blower’s speeds in a static fire setup at the MTA. In this testing, he also wants to work on how quickly the flameholder ignites to avoid losing a lot of forward speed after stage separation.
Wolfram will rebuild the ramjet as quickly as possible and could be ready for another launch in February 2022. He would like to do another booster-only flight from the MTA to verify the fixes on that stage. If successful, then the next launch will try a flight with a short ramjet burn using roughly 5 seconds of gasoline fuel.
The society will peer-review the work done so far and find the best way to proceed. Wolfram is still evaluating the data and may have an update to this firing report later.
TESTING OF A GERB AS A LIQUID ROCKET ENGINE IGNITER
Dimitri and I have overseen a few recent liquid rocket engine static fires at the RRS MTA. Although there have not been any ignition problems, we had discussed different approaches to getting a safe and reliable start.
Liquid rocket engines sometimes have problems with achieving reliable ignition. Failure to ignite the cold mixture of propellants due to lack of sufficient energy or outright failure to light can create a serious fire or explosion hazard. One of the simplest approaches is to use a sufficiently energetic pyrotechnic device mounted in the engine throat from the aft side. Visible indication of the igniter firing should be confirmed prior to opening the propellant valves and releasing the stored pressurant gas.
There are a few different pyrotechnic devices that are good for this task such as lances and gerbs. Both require a special license to get. Dimitri, who has such a license and happened to have a couple gerbs that we could try. Lances have been used in prior liquid rocket engine firings and vehicle launches with success.
At this event, we decided to test a gerb to see if it would be appropriate to try in lighting a liquid rocket engine. We secured one to the top of the alpha box rail and fired it to examine the plume,
A gerb is a pyrotechnic device used in firework displays.Simple schematic of a liquid bipropellant rocket engine with an external igniter systemThe gerb was fired to determine if it would make a suitable igniter for a liquid rocket engine.
Our impression of the gerb operation was favorable in terms of its 20-second firing duration, but it seemed that a smaller gerb size might be sufficient. Smaller gerb sizes are available. There is also the long-term consideration of having these available for liquid rocket testing which would require a storage magazine. Other less complicated means should be explored.
IN CLOSING
Several of the attendees stayed behind to clean up the MTA and relax in the Dosa Building. This was the last launch event for our outgoing president, Osvaldo Tarditti, who has faithfully served the society for many years with his time, skills and leadership. We enjoyed the sunset on a mild and nearly calm winded day. It was a fine end to a great day at the MTA and what was our last event of 2021.
