MTA launch event, 2018-08-18

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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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.
secretary@rrs.org

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.