June 2018 meeting

The RRS held its monthly meeting for June 2018 on Friday the 8th at the Ken Nakaoka Community Center in Gardena. We were well-attended but got a late start on the agenda items. Wilbur Owens came back to see us again and has decided to become a member. Mohammed Daya who has joined the RRS also was able to stop by before the meeting started just to say “hello”. We were also glad to have Sam Austin back in town. Sam is a student at MIT interning at SpaceX this summer. He also paid us a visit both at the MTA on June 2nd and at the meeting tonight to discuss the liquid motor he built. There was lots to talk about at this June meeting between our outreach events and the hot fire testing.

RRS discussing things before the June 2018 meeting starts

A lot to talk about at the June 2018 meeting

[1] The RRS event at the Two-Bit STEAM Circus in Hawthorne was quite a success. The RRS was a bit short-handed, but we have great volunteers that stayed busy the whole time. The air rocket launcher was one of the big hits at the Circus event and we have been invited back for the next event in September. Frank made some improvements to the paper rocket template that is cut, folded and secured with tape to make the narrow tubes with attaching fins that comprise a paper rocket for the pneumatic launchers we have. The build process can be challenging for some, but it always is satisfying to see the finished product fly. The RRS is glad to have these events and we will surely do more.

Here’s some photos that Osvaldo took at the event.

RRS at the Two-Bit Circus STEAM Carnival in Hawthorne, CA. Frank works with kids to make the paper rockets for the RRS air launcher.

The air launcher is made ready to fire a paper rocket.

On a side note to this topic, USC is having a CRASH STEAM Carnival in 2019. We were invited to attend this year’s carnival, but the RRS is shorthanded and couldn’t support. We hope to expand our society to be able to come out for more events across the great city of Los Angeles. We’ll have more information on this event later.

[2] UCLA held their launch event at the MTA on June 2nd. The event was two-fold, it was the final project for the UCLA rocket propulsion class taught by Dr. Spearrin. It was also an opportunity for the UCLA Rocket Project team to static fire their hybrid motor. The event was a success for the class with the winds being nearly calm for most of the day. The small hobby rockets with F-sized motors reached good heights without being carried too far by the winds. Each had an altimeter and a hard-boiled egg as a payload that had to be safely recovered. Most were successful, but others not so much. A full write-up was done on an earlier RRS posting.

RRS MTA launch event – 2018/06/02

As a further note, UCLA was using a Jolly Logic Altimeter 3 model in their hobby rockets. These devices used by UCLA have proven to be very reliable and easy to use. The RRS will acquire some of these to fly in the payload tube of an alpha rocket to see what heights we reach in this micrograin mainstay rocket of our society.

Jolly Logic Altimeter 3 – manufacturer’s site

After UCLA’s static firings of their hybrid motor, the RRS flew an alpha rocket with a parachute system. This is a first in a long time. Osvaldo’s design had a safety switch to engage the battery only when the rocket is loaded to prevent it from getting depleted in waiting for launch. The parachute system also had a pull pin to start the timer circuit when the rocket lifted out of the rails. Osvaldo did bring another prototype of the alpha parachute system to discuss its features at the meeting, but we didn’t have enough time.

Osvaldo’s parachute deployment circuit that fits in a standard alpha rocket

After the June 7 launch event at the MTA, Osvaldo managed to find an RRS standard beta launched by UCLA last year. Although the payload segment sheared off in the extraction process, the nozzle is the precious part that can be cleaned up and reused.

RRS standard beta recovered from the RRS MTA; payload segment was not recovered

Osvaldo was also kind enough to make the adapter piece necessary for testing the RRS standard alpha second-stage solid motor I designed in the horizontal thrust stand at the next event. With this simple doubled-ended adapter that goes in place of the nose cone, the second stage motors once finished can fit into the load cell adapter and the RRS can get thrust measurements. Chris Lujan is working on a sucrose-KN solid grain and Larry Hoffing is working on an AP/HTPB/Aluminum motor grain. I have done the preliminary calculations for both and pressures should be appropriate for the 1.75″ aluminum payload tube. More discussion on this topic in future posts.

RRS alpha second-stage load cell adapter piece for the horizontal thrust stand. It goes in place of the nose cone.

[3] The next RRS build event with the LAPD CSP officers will be with another group of kids in the Jordan Downs housing projects of Watts. We’ll get started next week, 6/15/18, and run six educational sessions on Friday’s and Saturday’s until the launch event at the end of the program at RRS MTA. This will take place on July 7, 2018.

The students will paint and assemble a set of RRS standard alpha rockets. More alpha rockets means more fun for our guests and also more opportunities for our RRS members to try payloads. It’s my hope we can demonstrate another one of Osvaldo’s parachute systems and fly an altimeter chip if we can secure one in time.

Richard Garcia said that he already has an Eggtimer Quark chip which has an altimeter. I had the chance to meet Cris Erving of Eggtimer Rocketry at the last Rocketry Organization of California (ROC) launch event in Lucerne Valley on June 9, 2018. I hope we can get an altimeter payload ready to fly in a standard alpha payload tube by the July 7th launch.

Eggtimer Rocketry

Rocketry Organization of California

[4] The new RRS membership card design has been finished. Many thanks to Bill Janczewski for pulling this together. We have had a few requests for membership cards from members and the RRS has agreed to produce these only on demand.

Jim Gross will be the first recipient of this new style of RRS membership card. This year’s design has the 75th anniversary watermark on it.

The new 75th anniversary RRS membership card

There was some general discussion about the payment of dues. Even as we are growing in membership in our society, the RRS has not been collecting dues on a regular basis. We’re content to primarily use the honor system and gentle reminders to our membership to pay their annual dues of $40 per year or student memberships at $20 per year. It is this small revenue that helps the RRS stay on top of our bills. Student memberships are good as many university projects can require multiple tests at the RRS MTA which is covered with signing the RRS indemnification form and paying membership dues to the RRS.

All membership applications must be sent to the RRS president and approved by the RRS executive council.

Payment of RRS dues ($40) and the added cost of a membership card ($5) can be done by check and through the Paypal donation button we have on the RRS.ORG website. It’s important to make a note on Paypal that you’re paying your Membership Dues. The extra price of $5 for membership cards is pretty small and compensate for the cost of low-volume production as most members may not opt to get one. To those desiring a membership card, please contact the RRS secretary.


For all of our regular membership, I had proposed that the RRS return to using membership cards which were used in the past in the society. Membership cards were issued to all members upon payment and re-payment of their annual dues. This provides a physical mechanism to verify that each member is in good standing with dues paid. The membership cards would have their name and an expiration date that says when annual dues must be paid again.

Although some felt the idea had merit, others felt that we should continue to have the council take the initiative to track payments and remind members to pay their dues as we have been doing. Since members join at different times in the year, this can get complicated but we will rely on members to stay on top of this.

It was a good discussion that also raised issues about what constitutes “active status” in RRS membership and our broader membership policies including corresponding membership for those who live outside of the Los Angeles area but want to remain a part of the RRS in some capacity. It was agreed to revisit this broader topic in the July 2018 meeting as some of our newer members may not be familiar with the past and current membership policies at the RRS.

[5] Sam Austin gave his presentation the Hercules Rocket Engine project at MIT. His liquid rocket propellants are LOX and kerosene. Sam was kind enough to bring his liquid motor that he is finishing. It’s a 500 lbf, 600 psi LOX-kerosene engine with an unlike impinging injector. His stainless steel chamber with a graphite nozzle insert ought to hold up to short burn durations. Everyone was able to inspect the injector, chamber and nozzle parts that Sam made at the MIT machine shop. The delicate work to get a clean injector pattern was impressive. He’ll be water flow testing the injector soon to verify that everything looks right.

The RRS recommended Specialized Coatings, a ceramic coating vendor in Huntington Beach, that we have used with success in the past on alpha and beta nozzles.

Specialized Coatings – Huntington Beach, CA

Sam Austin’s liquid motor nozzle with graphite throat

Sam Austin’s injector assembly for his liquid rocket

Sam is still working on the propellant feed system. He already has a pair of liquid carbon dioxide vessels that are of the right size. After safely removing the original valves and getting the rest of his control plumbing, he will hopefully have what he needs to conduct testing at the RRS MTA or at FAR next month in July 2018.

There were a few questions about different features of Sam’s liquid motor, but overall it looks like it should work. Sam is getting prepared to finish the propellant supply system for a static fire of this rocket motor. With luck, he should be able to get into hot-fire at the RRS MTA or FAR site next month and hopefully before he returns to MIT in the fall. We are glad that Sam has decided to join the RRS as a student member.

The RRS membership had a few suggestions for improvement and a few recommendation for low cost regulators, ball valves and relief valves that have been used in other amateur and professional projects.

[+1] We managed to talk about one bonus topic by showing the video from the vertical static fire of the vehicle-sized solid motor by Jack Oswald and his team at the RRS on Thursday, June 7th. The video clearly shows a nozzle failure after two seconds from start, but it seemed that there may have been grain fracture leading to a partial blockage of the nozzle and then the resulting pressure surge shattered the nozzle. We may upload the video to our YouTube channel once we ask Jack and his team. Hopefully, Osvaldo can extract a few still photos from his footage. I think some of those stills will show an impressive start followed by a change in the flow pattern and abrupt failure with ejecting fireballs of propellant that followed. The RRS works safely and are glad to have our own remote testing site like the MTA to do these larger projects.

Sam’s presentation was very engaging, but we ran out of time before the Community Center closed at 9:00PM. We did not address all of our main agenda items or some of those added at the last minute. We will roll these topics to the July 2018 meeting.

* Osvaldo’s alpha parachute system and the video of its launch on 6/2/2018 at the MTA
* Getting a sign at our first metal gate as you reach the MTA
* Saturday morning seminars for members and how to get those started
+ Richard’s progress with the RRS standard liquid rocket
+ Discussion about the 2019 symposium

+ We did agree to discuss the topic of RRS membership policy and what constitutes being an active member.
+ Also, on the meeting agenda for July 2018 is the quarterly update on the SuperDosa project. I hope to have something ready to present by July 13th.

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

Again, we will have another launch event at the MTA on July 7th with LAPD.

The next monthly meeting will be July 13th at the same place and time (7:30PM).

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.