MTA launch event, 2018-06-07

The RRS held another smaller launch event at our private testing facility (MTA) in the Mojave desert on Thursday, June 7, 2018. This was a special event for the RRS members from the former Chaminade High School Rocketry group led by Jack Oswald. They have been working hard on their solid motor design. After a successful test series on a single 6-inch Bates grain, they moved up to a vehicle sized test with multiple six-inch grain modules installed. Dave Crisalli and Osvaldo Tarditti were available to assist in the loading and installation process making ready for testing. The vehicle static fire test was oriented nozzle up with a load cell at the bottom of the frame secured to the vertical test stand at the RRS MTA.

The static fire testing was for a 10,000 lbf-sec flight motor. The motor was expected to perform at 1500 psi, produce over 2+ tons (>4000 lbf) of peak thrust, and burn its 43 lbs of composite BATES grains in approximately 3 seconds.

Osvaldo had video of the firing where we got the still photos below. Osvaldo will bring the video footage to the meeting tomorrow on Friday, 6/8/2018, where everyone can see what may have happened.

Vertical static fire of a solid rocket motor at the RRS MTA, 06-07-2018

The solid motor started okay. The nozzle plume looked good for the first few moments.

Jack’s motor starts off just fine. A nice nozzle plume is evident.

Unfortunately, shortly after start, about 2 seconds into the burn, the pressure climbed substantially to 2300 psi causing a nozzle failure and subsequent burnout.

It looked like something disturbed the flow in the frame just before the huge fireball and the disintegration of the nozzle

After the nozzle failure, the solid motor spews chunks of fiery propellant until it fully burned out.

In the coming months, Jack’s team will make another motor reducing the Kn factor and significantly reinforcing the nozzle design to carry through with their plans of launching a boosted dart to an altitude of 150,000 feet sometime this year. This is still an impressive accomplishment and with some perseverance, success will come. More details to come as things proceed.

During the June 7th event, Osvaldo took some time to search down-range for rockets with his extractor tool. As luck would have it, he found one of the RRS standard beta rockets launched by UCLA in 2017. It was found about 3000 feet downrange which isn’t terribly far away. The winds must have been very favorable to allow the beta to plant itself much closer to the launch site. From the photo, you can see that this RRS beta had a fin-can type of fixture at the tail which is easier to manufacture.

Beta planted 3000 feet downrange from the launch rails, straight west more or less

The convenience of pulling the rocket straight from the ground with the manual winch is tremendous, but the method often shears off the payload tube in the hole. Shoveling does have the advantage of removing most if not all of the parts if one is inclined to spend the hours necessary to dig four feet below the surface. The payload tube from the beta unfortunately was not extracted with the propellant tube. Osvaldo will bring the beta to show everyone at the meeting tomorrow.

Osvaldo lifts the beta rocket from out of the desert floor

We’ll have our monthly meeting (every 2nd Friday of the month) on June 8th at 7:30PM sharp. Please stop in!

MTA launch event, 2018-06-02

The RRS held a launch event at our private Mojave Test Area (MTA) with the students and staff of UCLA on Saturday, June 2, 2018. The event was overseen by our pyro-op, Jim Gross, with me serving as his apprentice. It was a good day for rocket launching despite the 100 degree temperatures that day. The winds were very low and almost still at certain times.

The horizontal thrust stand was fit checked at the RRS MTA concrete slab. All footplate holes aligned with the 1/2″-13 female anchor bolt holes. The load cell blocks mated up to the adapter plates. Concern was raised about the horizontal stability “wagging” of an alpha rocket if it were fired in the adapter as is. Osvaldo started a design to create an extension on the thrust stand which will better retain the rocket from excessive side loading.

RRS horizontal thrust stand passes fit check at the MTA, new primer coating added for rust protection

UCLA was completing a quarterly course in rocketry which featured the hard work of five student teams building their own amateur rocket using commercial F-class motors of different types.

UCLA students pose at the RRS MTA on June 2, 2018

The RRS was able to inspect each one of these model rockets and ask questions of the team members about its construction and the unique aspects used in their payload and vehicle design. Each of the teams ran flight stability tests at the UCLA wind tunnel to validate their design. Each rocket was fired from a rail launcher and a commercial firing circuit under the supervision of the pyro-op.

Six rockets from five teams at UCLA on display in the group photo (6/2/2018)

Before the flights of the student rockets, a test rocket was flown to check the wind speeds. Results showed low winds so the team flights proceeded. The winds at the launch site in the desert were very low throughout most of the day.

UCLA’s demo rocket to test winds before team flights.

UCLA prepares their custom rail launcher for their model rockets

One team attempted a two-stage rocket using a D-class motor in Stage 2. Results from all rockets were largely good. All were recovered and some were able to be relaunched.

UCLA’s Team Sharky prepare their rocket “Bruce” for his maiden voyage.

Each rocket flew an egg as a payload with a parachute recovery system. Each rocket also included a commercial altimeter chip which relayed the results to display on a cellphone application. Altitudes ranged from 1600 to 2400 feet.

UCLA also was static testing a hybrid motor adapted from commercial products to a design of their own. Two vehicle systems were built and alternately tested with replaceable HTPB-based fuel grain modules. UCLA brought a few nitrous oxide tanks to replenish their oxidizer supply. All seemed to go well, but the results were not good enough to proceed with a flight test as originally scheduled.

Dr. Mitchell Spearrin and Jim Gross oversee the hybrid rocket static firing procedure at the RRS MTA, 6/2/2018

UCLA’s Anil Nair prepares the hybrid motor for static firing at the RRS MTA, 6/2/2018

UCLA’s first of three hybrid motor firings, 06-02-2018

Results from first hybrid motor firing left a white residue around the outside of the nozzle

UCLA did buy two of our RRS standard alpha rockets which were custom painted in the blue and gold colors of the UCLA Bruins. At the end of the long day, UCLA opted not to fly their two RRS standard alphas and save them for another flight. The RRS and UCLA discussed flying an altimeter chip in a vented payload tube on the next UCLA flight of the RRS alpha.

Two RRS standard alpha rockets for UCLA

The RRS already had the micrograin propellant mixture ready so we proceeded with a flight test of our own RRS alpha rocket. We had plenty of daylight left in the summer month of June. For those that stayed at the MTA into the late afternoon, the RRS did conduct a first test of a payload recovery system in a standard RRS alpha rocket. This system was built by RRS president, Osvaldo Tarditti.

Jim Gross and Osvaldo Tarditti load an RRS standard alpha with parachute payload into the launch rails

An RRS alpha with its payload being installed.

Instrumented RRS alpha in the launch rack. A manual switch with red flag is used to arm the system before launch. This keeps the battery from depleting while waiting to launch.

The payload timer is started when the rocket lifts out of the launch rails and the pin is pulled out by the yellow wire tied off to the launch rails.

Despite some problems initializing the payload one the first attempt at the launch rack, the rocket was successfully reset, reloaded and flown. The deployment of a parachute from inside an RRS standard alpha rocket’s payload tube with a successful recovery was the only objective of this flight.

In the still winds, the rocket didn’t drift very far from due west and the orange parachute was very visible against the clear blue afternoon skies once it reached lower altitudes. The alpha rocket booster portion was recovered, but the lanyard holding the nosecone and payload segment tore loose on deployment and was not recovered.

Lanyard failure lost the payload and nose with the timer circuit inside, 6/2/2018

Also, the orange parachute did show signs of localized overheating and melting from the 1-gram black powder ejection charge used to deploy the parachute.

scorching of the parachute from the ejection charge; parachute was still effective

The parachute did deploy fully and significantly slowed the descent of the rocket booster. With the low winds, the rocket did not drift very far downrange and was easily recovered 50 feet from the roadside going out west from the MTA

Osvaldo kneels behind his RRS standard alpha parachute system successfully flown at the MTA on 6/2/2018

I took several photos of the assembly and loading process. Osvaldo has promised to explain the full details of his parachute system and deployment timer. The RRS will definitely reattempt parachute recovery with our alphas and hope to fly again at the next event.

As a final step, we make sure to burn off our residual propellants. Jim Gross set this up near the launch pad and used the firing system already in place at the bunker.

Pyro-op Jim Gross prepares to safely dispose of residual micrograin propellant at the RRS MTA

Residual micrograin propellant safely burns up at the end of the day

At the end of the propellant burn-off, the smoke cloud lazily lingered as it rose away from the site. Taking several minutes to do so, this was a very visual reminder of just how favorable the winds were that day.

minutes later, a spent micrograin propellant smoke cloud slowly drifts away in the low winds at the MTA

If there is anything I have missed or misstated, please let me know.

The next monthly meeting is this Friday, June 8th at 7:30PM. Discussion of the UCLA event and our next event with LAPD CSP will certainly be on the agenda.

May 2018 meeting

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.

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