Tag Archives: thrust stand

MTA launch event, 2018-08-18

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The RRS had a small event at our private Mojave Test Area (MTA) on August 18, 2018, to allow Richard Garcia to test his liquid rocket motor. Richard built a pressure-fed, 1000-lbf kerosene-LOX motor including all of the static fire test stand equipment and control valves.

desert morning at the MTA

Richard Garcia reviews his list in the MTA blockhouse

Switch panel and electrical cabling

Richard had spent a good part of Friday and early Saturday getting his test stand mounted and ready. He had made arrangements to share the contents of a liquid oxygen dewar to supply the oxidizer he needed for his test with other RRS member, Sam Austin. Sam was also preparing to fire his liquid rocket motor at the Friends of Amateur Rocketry (FAR) site just south of the RRS MTA on this same day. Arriving early in the morning, I was glad to help Richard with the final preparations at the RRS MTA to start the initial checkouts and ultimately a successful hot-fire test.

Richard checks the wiring and pneumatic line connections

Richard’s 1000 lbf kerosene/LOX motor was designed for a chamber pressure of 300 psig and used a pintle-type of injector with an ablative lined chamber and graphite nozzle.

Richard Garcia tests both flow paths of his pintle injector in water flow

Ablative liner, G10, sits inside the combustion chamber of Richard Garcia’s 1000 lbf kerosene-LOX liquid rocket motor

Graphite nozzle within the chamber assembly of 1000 lbf kerosene-LOX motor

He brought his motor hardware to the January 2018 meeting, but now it was finally time to prove his design with a hot-fire test.

Richard shows his liquid rocket motor at the January 2018 meeting

Richard’s test used a high pressure nitrogen bottle to pressurize his propellant tanks, the left one for liquid oxygen (LOX) and the right one for kerosene. This regulated inert gas source also provided pneumatic pressure for the propellant valve actuators.

Richard’s static fire tanks and equipment mounted and ready for test, 2018-08-18

The top half of the thrust stand with the tanks and valves is fixed to the structure. The engine is suspended below and is secured to a plate which was mounted to an S-type load cell. These devices are an affordable means of measuring both compressive and tensile forces by the internal strain gauges built into them.

An S-type load cell used for thrust measurements in the static fire equipment

Caution was taken to keep the motor clean during handling and installation by caps on the ports and closing off the nozzle with aluminum foil.

View of Richard’s 1000-lbf motor from below; aluminum foil covering the nozzle exit to prevent foreign object debris (FOD) in the injector

With the validation testing complete and all valves are working, fuel was loaded, then preparations to load the cryogenic liquid oxygen (photo courtesy of Rick Maschek of FAR)

Careful review of the firing procedure before getting down to testing

Preparing for LOX transfer (photo courtesy of Rick Maschek of FAR)

All propellants loaded, everyone in the blockhouse, running the final checks before starting the countdown (photo courtesy of Rick Maschek of FAR)

The view from the blockhouse, a nice clean start of the liquid motor (photo courtesy of Rick Maschek of FAR)

Another view of the rocket firing from Richard’s tripod-mounted camera, 2018-08-18

A few seconds later with the dust kicking up from the motor firing, 2018-08-18

Closeup view of the rocket firing from a small mounted camera; it blew over from the firing but capture this image

Most of the testing seemed to work well. The motor had a clean start and stable run time for the full 5 seconds duration that Richard had predicted. Post-test inspection showed the engine to be in very good condition.

A view from up the nozzle after hot-fire; all looks good

Surface of the 1-inch thick steel plate was melted from the impinging plume; perhaps we’ll mount the next engine a bit higher

Tank pressure measurements were able to be recorded, however the thrust and chamber pressure (Pc) measurements were corrupted. Richard is working on downloading the hot-fire video to be posted on the RRS YouTube channel.

Soon he’ll disassemble the injector and chamber to see if the motor can be fired again. This was a great success for the RRS and we hope this to be the start of several liquid motor hot-fire tests as the RRS continues to improve on this powerful type of rocket.

Richard Garcia stands next to his 1000-lbf kerosene-LOX liquid rocket motor at the RRS MTA, 2018-08-18

I hope that Richard will be able to present his results at the next RRS monthly meeting on the 2nd Friday of the month. The next RRS meeting will be Friday, September 14, 2018 at the Ken Nakaoka Community Center in Gardena, California.

The RRS would also like to thank Mark Holthaus and Rick Maschek of FAR for their assistance on this test.

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May 2018 meeting

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The RRS held our monthly meeting on May 11, 2018 at the Ken Nakaoka Community Center. We were well attended, but got a late start. After the reading of the treasury report, we started with the discussion of the agenda items. We were happy to be visited by Wilbur and Mel Owens and Harry Reid of the Compton area. They heard of our work with schools and have interest in rocketry projects. We hope to form some kind of partnership to help support like-minded Los Angeles area groups.

RRS president, Osvaldo Tarditti starts the May 2018 meeting

May 2018 meeting of the RRS gets underway

First on the agenda was discussing the results of the 75th anniversary symposium. We had a lot of great feedback and built a lot of good relationships with industry, universities, schools and private groups at the all-day event. We also discussed some of the lessons learned from the symposium and what worked well and what could have been done better. The RRS is very grateful to the many people who supported the RRS in making this event possible. The discussion then turned to discuss if the RRS will hold a 2019 symposium around the same time next year. After some initial discussion, the vote was postponed to next month’s meeting.

Discussion of the 2018 RRS symposium

Second on the agenda was the upcoming launch event at the MTA on June 2nd with UCLA. UCLA will launch 10 of their commercial rocket motors as the final part of the quarterly class that Dr. Spearrin has with his students. The RRS is glad to host the event and we also plan on launching at least two of our standard alpha rockets at the event.

Alpha rocket iso view

Also, the RRS horizontal thrust stand is nearly complete as Osvaldo and I confirmed the fit of the final load cell parts to the frame. Osvaldo brought the frame and I brought the load cell to the meeting. Everything looks ready to go for final fit up on the concrete pad at the MTA at the June 2nd launch event. Having the ability to make actual thrust curve measurements on the RRS standard alpha rockets will be very valuable to better understand the performance of this classic rocket. Much of what is known of the flight characteristics is based on old knowledge which could be somewhat theoretical. Getting new data will be a step in the right direction to reducing uncertainty.

RRS horizontal thrust stand sits on a dolly at the May 2018 meeting

payload tube adapter, S-type load cell and thrust stand adapter; fit check is complete

After some discussion of scheduling other possible launch events at the RRS MTA with Cal Poly Pomona and USC, we moved on to the next agenda item.

The third topic on the agenda was about the next educational event that the RRS will support with our partners in the LAPD CSP program. This summer program will be with Operation Progress in Watts. The first session will kick off on June 15th and the final launch event is planned for July 7, 2018.

Operation Progress – Los Angeles

The fourth topic on the agenda was regarding the RRS pyrotechnic operators manual that I am compiling for the society. The RRS uses licensed pyro-ops at our events and we are on a mission to expand our roster to better support the growing activities at the MTA. Osvaldo, Richard and I have begun the process of getting endorsement letters from our fellow pyro-ops and when our applications to the state of California’s Fire Marshall office are complete and received, we will take and pass the exam to become licensed. Having a society manual to capture this knowledge is not only useful to train new pyro-ops but it is beneficial for all of our society to have simple access to this important information.

RRS pyro-op manual and training guide

The fifth topic on the agenda was a discussion of RRS payloads. I have been pushing our society membership to think about and design payloads for the many RRS standard alpha rockets we launch. Although the payload tubes are very small (1.60″ inner diameter), there are many opportunities for flying ever-shrinking sensors in these payload volumes.

Larry brought a few commercially available sensor packages that he hopes to fly in beta rockets. Some of these devices are simple and powerful which have been used in high-powered model rocketry with a lot of success. Payloads such as these will certainly work well in RRS rockets as well. Beta rockets tend to be expensive, so it would be nice to have those that fit inside the alpha payload tubes (1.600″ OD or about 1-1/8″ square).

most payloads are too big for the alpha payload tubes; force-fitting doesn’t help

Example of pre-fabricated instrumentation package; clean, simple, but often too big

I have designed an in-line second stage for an RRS standard alpha. Osvaldo was kind enough to machine the interstage and second stage pieces that I described in last month’s meeting post. The second stage would have a solid motor poured into a PVC casing that fits within the standard alpha aluminum payload tube. The pieces fit very well together which is very encouraging. I took the interstage part home with me to integrate the umbilical port and wiring and work up the delay timer for the upper stage igniter.

RRS standard alpha interstage and second stage motor casing

The final topic on the agenda was an idea that Osvaldo had for more educational program at the RRS. The RRS has gotten to know many fine speakers in areas of professional and amateur rocketry. In the past, we have invited speakers at our meetings, but we often don’t have an appropriate amount of time to listen and discuss these topics at length. The idea put forth is that the RRS would hold Saturday morning presentations to our interested membership. The idea was well received and approved by the society. A list of speakers is being built and Osvaldo will try to schedule the first presentation in what we hope will become a long series. More details will be coming in future announcements.

One last topic wedged in as we were finishing was that the RRS will be attending the Two-Bit Circus event in Hawthorne, California, next Saturday, May 19, 2018. The Two-Bit Circus is a high-tech STEAM-based amusement park that started in downtown Los Angeles and is growing to include more areas of the city. The RRS is glad to be a part of it. The link to the event is below.

Two Bit Circus – Hawthorne 19-MAY-2018

The RRS will have a booth at the Two-Bit Circus and will be bringing our air launcher for small paper rockets. Frank built a new air launcher that’s a little cheaper, but just as powerful and fun to try. The RRS will have it available for demonstration near the basketball courts at the event.

Frank’s T-shaped air launcher

The RRS meeting concluded late at 9:25pm. We are grateful to the Ken Nakaoka Community Center for letting us stay beyond the 9pm closing time of the center. The RRS must try to begin our meetings on time so we can finish on time.

If there is anything I have missed or misstated, please let me know.
secretary@rrs.org

The next monthly meeting of the RRS will be June 8, 2018. Please join us.

MTA launch event, 2018-04-07

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The RRS held a launch event with the students of Florence Joyner Elementary School at the MTA on April 7th, 2018. This event was the final step in the five-week RRS program that started in February thanks to the support of the Los Angeles Police Department’s (LAPD) Community Safety Partnership (CSP). The students got a tour of the RRS Mojave Test Area where both amateurs and professionals can test rockets in the open space of the Mojave Desert.

Students from Flo Jo Elementary at the RRS MTA

As always, we gave a safety briefing to the students to the hazards of the desert and our testing site. Dave Crisalli was our pyro-op for the event and gave an excellent background of the exciting work we do at the RRS.

Dave Crisalli addresses the students and officers as Frank Miuccio looks on

Safety briefing inside of the George Dosa building at the RRS MTA

The tour also included a live demonstration of burning the micrograin zinc/sulfur powders in the open air. The bright yellowish flame is a vivid demonstration of the combustion process.

Live demonstration of micrograin propellant at the MTA

We also demonstrated the burning of a more common solid propellant, an ammonium perchlorate, HTPB and aluminum powder composite grain. The same constituents used in the Space Shuttle’s solid rocket boosters (SRB’s). Thanks to Larry Hoffing for making the sample grain for the test.

Sample of a composite solid propellant grain just before the demonstration.

The Flo Jo elementary class built 10 RRS standard alphas for the event. Each painted uniquely by each of the teams.

Standard alpha rockets from Flo Jo Elementary

Once everyone had the safety briefing and completed the tour, we proceed to send everyone to our safety bunker as Dave Crisalli and I loaded each rocket into our rail launcher.

Dave Crisalli and Dave Nordling load an alpha into the launching rack

Each of the rockets flew straight and fast from the rails and did not disappoint the class seeing their hard work fly off the rails in a huge yellow cloud.

wide-angle still shot from Osvaldo’s high-speed camera, 2018-04-07

An RRS alpha rocket takes off, view from the bunker

After the clean launch of all of the rockets, the kids and the LAPD ventured out to the desert to try to find each of their rockets. Flag poles were made for the occasion to mark the locations so that they could be extracted later by shovel. 7 out of 10 rockets were found and two older rockets from previous events were also found and marked. It is tough to find each rocket in the desert scrub, but with the hard work of the students it’s good to recover at least some of the parts as they can be reused with some work.

After launch, the students and their mentors march to the desert to search for their rockets

The kids were very organized and had a great time. After taking a group photo at the gate, they returned to the city. The RRS was glad to host them and hope they can come back soon. Also, thanks to the LAPD CSP program for being supporters of this project to give this experience to the hard-working students of Watts.

Flo Jo Elementary and LAPD CSP pose before the RRS MTA sign

The RRS membership stayed behind to try a few experiments. The first test was trying to finish the foot plate welds on the horizontal thrust stand I have made for static testing alpha rockets motors of similar size with S-type load cell donated to the RRS by Interface Force Inc.

Interface Inc. – Precision Load Cells

The construction of the horizontal thrust stand is nearly complete, but unfortunately the desert winds made welding of the plates impossible. This steel frame will firmly hold alpha-sized rockets for static fire testing when bolted down to concrete slab in front of the old blockhouse. As a historical note, it was a young Dave Crisalli that helped pour this slab in the late 1960’s.

Osvaldo prepares to weld the foot plates of the horizontal thrust frame at the MTA

Scribe marks were made on the plates and the assembly was taken back to the city to be completed later. Many thanks to Jim Shirley of Shirley Design and Custom Fabrication in Huntington Beach for finishing the structural welds. The integration of the load cell and final mounting to the concrete slab will take place at the next launch event where the RRS hopes to measure the thrust and impulse bit of our standard alpha rockets.

The RRS horizontal thrust stand frame is complete and ready for mounting at the MTA

Richard Garcia built his own vertical test frame to support a small steel engine case he made for a rocket-candy grain.

Richard mounts his frame to the MTA structure for his experiment.

Rocket-candy is a simple mixture of potassium nitrate and sugar. Under moderate heat, the sugar caramelizes to form a viscous but firm mixture that suspends the oxidizer and can be packed in to the paper tube cases.

Richard “cooks” the sugar and potassium nitrate under low heat of the electric hot plate.

Richard’s work was documented by RRS member, Alastair Martin, who is working on a larger documentary of the RRS classes and our members’ experimental work at the society.

Alastair Martin films the tools and process of Richard Garcia’s rocket candy production

Once the motor grains had set, they were test fired to verify the quality of the mixture. The second motor grain was loaded in the steel rocket tube mounted to the vertical stand. Results were not spectacular as the end-burner grain design didn’t create much pressure. More testing will be done to improve performance, but the steel case and nozzle were undamaged.

Richard Garcia’s steel motor case and nozzle, just before loading the motor grain

Richard’s sugar rocket motor fires securely from the vertical mounted stand

One of the newest tools invented by our president, Osvaldo Tarditti, is a new ratcheting tool that pulls the rocket straight from the ground by a simple portable frame that can be angled to get the rocket to come out straight. The tool must be operated by two people to pull the rocket body straight from the ground. The tool was successfully demonstrated and nine rockets were pulled from the ground without any of the back-breaking work of shoveling. This is an excellent advancement for the society and will be very handy in the future.

Osvaldo’s newest invention, the Rockextractor

As this is the first launch event of this 75th anniversary year of the society those of us that were at the MTA at the end of the day took a group photo by the old I-beam which has been a part of the RRS since our earliest days of rocket testing. You can see the I-beam by itself in many of the old society photos. At the new MTA site, it is an integral part of our larger test structure that has seen hundreds of uses and still going strong.

Frank Miuccio, Alastair Martin, Dave Nordling, Richard Garcia and Osvaldo Tarditti pose by the iconic RRS I-beam

The RRS will be having their next monthly meeting on Friday, April 13th. The RRS 75th anniversary symposium is also happening on Saturday, April 21st. Please come out as it will be a great occasion with speakers and exhibitors from industry, universities and other amateur rocketry groups.