MTA launch, 2020-03-01

by Dave Nordling, RRS.ORG


The RRS held a launch event on Sunday, March 1st, 2020, at the Mojave Test Area.  It was a brisk morning with steady winds that occasionally slowed enough for a safe launch.

This launch event was originally for a university static fire and a few member projects.  The university had to reschedule but we had sufficient interest from our own projects so we held the event.

View from behind the RRS MTA large test stand, 2020-03-01

The weather was a concern with passing storms and rain predicted earlier in the week.  But as often happens, the weather shifted for the better on launch day with winds staying low enough to launch most of our projects.

Wolfram’s booster sits on its stand in the Dosa Building

Wolfram has been working for a few years on his Gas Guzzler ramjet rocket. He is just now entering the first system flight tests to demonstrate the staging and recovery systems.  He filled his ramjet with water in place of the gasoline to have a representative weight.

The Gas GUzzler booster stage on the 1515 rails, loaded and ready
Both stages of the Gas Guzzler sit on the 1515 rails as Wolfram inspects the fit between them

Wolfram was able to load his booster on to the 1515 rails with good alignment. His upper stage had some alignment problems due to using a different prototype for this initial flight.  After some examinations on the pad, he pulled his rocket stages back to the Dosa building for internal adjustments to assure a clean fit between the booster and upper stage.

Kieth Yoerg’s rocket, Charlie Horse is made ready for flight from the 1010 rail
Charlie Horse rises on the black plume of a Smoky Sam high-powered motor.

The next launch was Keith Yoerg’s high powered rocket, Charlie Horse.  He used an I-350 Smoky Sam motor and had a dual-deployment system with a GPS tracker built in.  The flight was smooth off the rails but the trajectory data seemed to show a steady wind pushing west to east. He reached an apogee of around 4000 feet. Recovery wasn’t a problem as his rocket landed just a hundred yards east of the RRS MTA.

Wolfram stands with his ramjet upper stage and its broken cowl piece. Some rework will be required.

Wolfram returned his rocket to the pad but accidentally dropped the second stage breaking a piece of the ramjet plastic cowl on the concrete below.  With this significant disruption of the aerodynamic surface, he was forced to abort the flight and rework this part.  He was also going to check some of the other parts in his assembly for this long-awaited first flight.  It’s important to not rush a project and wait until all is ready for a successful flight.

Osvaldo and Larry check the payload packaging of the hybrid rocket one last time
The hybrid motor is installed and ready for today’s launch.

The next flight was to be the hybrid rocket that Larry, Osvaldo and I have been working. The Contrails H222 motor was safely loaded from last month and after some improvements to the vehicle body for better parachute recovery functions, we felt we were ready.

The winds were still favorable so we proceeded with clearing the area and making our electrical connections back to the old blockhouse.  With just a handful of people and the lightweight vehicle, the old blockhouse was sufficient for our operations that day.

The RRS nitrous oxide bottle ready to fill our hybrid rocket motor

The nitrous bottle was refilled from the prior week and the manifold was plumbed to the vehicle tank.  With the opening of the nitrous bottle, remote operations could begin.  The time of tanking the small 38mm H-motor tank was not precisely known, but was not expected to take very long given basic calculations of the available flow rate.  As expected, the tank volume primed within 15-20 seconds.  We waited a full minute as we were initially unsure of whether the full volume was filled with liquid.  After spotting a jet of liquid escaping from the vehicle body vent, we were assured that the hybrid motor was ready to be ignited. 

Osvaldo conducted the firing operation after a short five-count. The resistor and Pyrodex charge ignited after a slight delay for the resistor to heat up sufficiently. The motor seemed to reach full thrust quickly and leave the rail as expected from the thrust curves from this commercial motor.

Kieth Yoerg’s onboard camera takes a test photo of me loading the hybrid motor on the 1010 rail

The vehicle was spotted tumbling after leaving the rails leading us to believe the rocket was not properly balanced.  More detailed calculations would have been beneficial, but from initial estimates and the heavier recovery system in the extended rocket body, it was believed the rocket would be stable enough.

Examination of Osvaldo’s high speed camera footage from the hybrid flight revealed the reason for the vehicle tumbling.  Some of the frames show that the nitrous fill line remained attached to the rocket during launch and even after clearing the rails. The fill line did snap loose in the flight at some point, but it was supposed to completely sever at ignition.  This imparted a significant torque to the vehicle leading to a tumbling and short trajectory back to ground.

Note the nylon filling line is still attached as the rocket leaves the rails
Just a little later in the high speed footage the fill line and igniter cable start to come out, but the rocket is already knocked off course.
Both the fill line and cables are free of the rocket while the nitrous still flows over the fuel grain and the motor is lit.

Worse, in my rush to get the hybrid loaded on the rails and made ready for filling operations, I forgot to arm the recovery system.  This is a classic mistake and one that I could have easily avoided. 

At least, the other issues with the flight limited the distance the rocket travelled.  The rocket was recovered just north of the 1010 launch rail still within the bounds of the MTA.  The rocket landed on its nose breaking it and significant body tube damage was sustained. After disassembling the hybrid motor from the body, we opted to scrap the rocket body and rebuild a new one for the next flight.  The fill and fire operations were successful and the equipment we built worked fine.

The first hybrid rocket destroyed in flight. A new rocket build will start soon.
The spent hybrid fuel grain extracted from the Controls H222 motor tube.

The Contrails H222 motor parts survived well. We were able to easily remove the motor assembly and disassembled the parts for inspection. The graphite nozzle showed very little ablation and will be reused.  None of the parts had heat damage.  The fuel grain didn’t exhibit much ablation as compared to the other unburned grains we had. The burn duration in flight seemed to be similar to what is shown on the thrust curve, but this should be reviewed against the flight footage.

More review of the flight footage will be necessary to better understand how the hybrid motor operated. We are considering changing the ignition method to use an electric match and maybe a shape charge that would better ignite the hybrid motor.

We are considering building a static testing rig for the hybrid motor to verify some changes we intend to try with the ignition.  There will be more on this subject in later reports.

Larry holds his experimental solid motor, a simple end burner to test his mixture
Larry suspends his motor from an old steel rod from our modular rail system still under repair

Larry Hoffing had built a custom composite solid rocket motor using a spent casing from a commercial solid motor. This simple end-burner grain also had a custom-made nozzle.  Larry had suspended his experimental motor a length of metal piping threaded on our large adjustable box rails that is still undergoing refurbishment.

Still image from Larry’s motor firing, rapid overpressurization just after ignition

Unfortunately, Larry’s motor design was not successful and rapidly overpressurized scattering both end caps and propellant grain fragments across the desert floor.  No fires resulted from this static firing failure and no serious damage was done to nearby structures used for this demonstration.

Larry’s motor case ripped at both ends, back to the drawing board

The last launch attempt was Keith Yoerg’s smaller model rockets using the tiny B and C motors.  The winds became stronger as the day progressed and by that time sustained wind levels were too high for any launch particularly for such a small vehicle.  These rockets would be saved for a later event and Keith began examining his Charlie Horse rocket and its camera footage.

Kieth’s model rocket launcher being brought back to the Dosa Building as high winds prevented further launches that day.
Tiny desert flowers bloom in the spring at the RRS MTA

It was a good day for the RRS to have a launch event exclusively for our member projects. We plan to hold more of these events for both universities and our membership very soon.


MTA launch, 2020-02-22

by Dave Nordling, RRS.ORG


The Reaction Research Society (RRS) held a launch and static fire event for three UCLA teams and one of our own RRS teams at the Mojave Test Area (MTA) on Saturday, 2/22/2020. Poor weather was a persistent threat from the day before with light rains coming and going from the early morning hours and even throughout the launch day. Winds calmed just enough for a successful rail launch of UCLA’s solid rocket motor. Fortune favors the bold and this proverb did not disappoint our participants that day at the MTA.

Rain clouds still filled the skies on a very calm morning. Preparations began for UCLA’s solid rocket motor launch from our rail.

With the liquid and hybrid rockets, Osvaldo Tarditti, our RRS president was our pyro-op in charge. I served as his apprentice for this event as part of building my experience for becoming a pyrotechnic operator 1st Class. This was the second of two apprenticeships I have served under two first class pyrotechnic operators. Osvaldo gave our safety briefing to all of our attendees that day before beginning the scheduled events.

UCLA gathers around to hear our safety briefing. Most have been to the RRS MTA before but we give the briefing each time to reinforce good practices.

UCLA had three projects ready for flight or static-fire at the MTA. The first was the solid motor driven rocket built by the UCLA Project Prometheus team. They were using a commercial K-sized motor with a vehicle equipped with a downward-facing camera built into the lower body.

UCLA’s Project Prometheus built a rail-launched rocket with a commercial solid motor.
The Gerald Ticonderocket in the color scheme of a common wooden pencil.

Elizabeth, the UCLA team leader for this solid rocket project assisted me with the launch preparations. The rail launched rocket worked perfectly and the recovery system operation was visually confirmed as it descended to the west of our launch site.

My 2-1/2 inch rocket with a commercial H-222 hybrid motor from Contrails Rocketry. The body has been extended for better packaging.
The motor has been successfully loaded into the body tube complete with retainer. All that remains is to complete the recovery system packaging and find our next opportunity to launch.

Larry, Osvaldo and I have made progress on improving the 2-1/2 inch rocket with a commercial H-sized hybrid motor. Larry made an extension on the payload tube to fit all of the recovery system more easily. We have the Contrails H222 motor fully integrated and ready for loading.

The RRS reloaded and refurbished our nitrous bottle and valve manifold, but we didn’t get to loading operations.

Our nitrous bottle was refurbished and reloaded for the testing and we successfully conducted a valve test of the manifold that verified that our control box works well. We were reworking the black powder charge and repacking the parachute when the weather shifted and the winds picked up.

Weather changes quickly in the desert. Our smaller rocket missed our window for launch that day.

The weather was perfect 15 minutes earlier with the launch of UCLA’s solid motor, but at the time we were discussing launch of our hybrid motor it became clear the weather would be getting worse and winds too strong for launch of a smaller rocket such as ours. Since the RRS will be returning to the MTA site on Sunday, March 1. We figured we would do some minor improvements to the payload packaging and try again when we are fully confident and hopefully with better weather for the flight.

The hybrid motor is secured to the RRS I-beam. This is one of the very first assets of the society which predates our arrival to this MTA site.
UCLA hybrid rocket team making load cell adjustments on their thrust stand before hot-fire.

UCLA’s hybrid rocket team under the same name, Project Prometheus, sought to static fire a commercial M-sized hybrid motor as part of getting ready for a flight later this semester. They secured their test stand vertically to our historical I-beam location which was the original article from even before the RRS moved to the current MTA site in 1955. The RRS was glad to assist UCLA in securing to this location and making ready for nitrous oxide fill operations then ignition for static fire measurements.

Hot-fire of the hybrid motor took place around 5pm which by all appearances was a success. The motor case was intact and post-flight assessments looked promising, but an error in data acquisition resulted in no thrust measurements being recorded despite successes in pre-test checkout. UCLA is considering re-attempting this testing at the RRS MTA very soon.

UCLA working on their liquid rocket’s pressurant system.

The last of the three projects would be the static fire of the liquid rocket for Project Ares. The liquid rocket team mounted their hardware to the vertical test stand simultaneously as the hybrid rocket team mounted to the I-beam thrust stand. Both teams worked hard to be ready before the other but in the end, the liquid rocket took longer to be ready.

This would be a second attempt to static fire their liquid rocket system from 2/1/2020 at the RRS MTA. UCLA had been finding and fixing leaks in their pressurization system in the weeks leading before this test.

Making some preliminary checks before commencing liquid oxygen tanking of the rocket.

They proved their fixes before departing to the RRS MTA, but again ran into problems with leakage in the pressurant system. After several more repairs and discussion with the team and pyro-op in charge, the decision was made to proceed. All other systems had passed checks and the leak rates measured were consistent and would only reduce the burn time while assuring safe engine hot-fire.

UCLA begins the final operations following their proven checklist.

Around 5:30pm in the last light of that long day, UCLA’s liquid rocket was proven in a brilliant, steady and powerful hot-fire of their ethanol-LOX propellant liquid rocket. It was an exciting time which showed reasonable thrust results that led UCLA to conclude that the testing that day was sufficient to proceed with flight vehicle integration operations for their motor.

UCLA’s static fire on 02/22/2020 was steady and well controlled.
All initial inspections of the liquid motor looked good. Preliminary review of the data was encouraging and will be useful in grounding their vehicle performance predictions.
In the last rays of daylight, all three UCLA teams pose with their project’s pride at the RRS MTA vertical test stand.

UCLA did a great job of cleaning up at the site. They also returned the LOX dewar back to the nearby Friends of Amateur Rocketry site. We’re thankful to everyone who made this day a triple success. Our next launch event is scheduled for March 1st. We’ll also discuss this and our other recent MTA events at the next RRS meeting on March 13, 2020.


MTA launch, 2020-02-01

by Dave Nordling, RRS.ORG

The RRS met at the Mojave Test Area for our third launch event of the year in successive weeks. We were glad to host UCLA’s Project Ares for another static fire test of their liquid rocket.  The team has worked hard to improve their design from last year and had just presented their Critical Design Review (CDR) to peer review.

UCLA completes their on-campus CDR for the latest design of Project Ares
UCLA stands in their lab getting ready for the next hot-fire

The second project for the day was to be my hybrid rocket that I have built with Larry Hoffing.  The commercial H222 model from Contrails Rocketry is built into an old 2.5-inch rocket body that Larry had on hand.  I had some missing fluid connectors at the last attempt and it was my hope that this next attempt with the motor successfully loaded and a parachute recovery system in place, this would be the first hybrid launch from the RRS MTA in many years.

Larry Hoffing measures out a small powder load for the parachute deployment

Osvaldo had made a two-channel switchbox using an extension cord for controlling the nitrous oxide fill and drain solenoid valves.  The unit worked very well in system checks and we were to use our existing firing box for ignition.

Osvaldo cycles the solenoids using our new fluid flow control box

After a successful leak check of the manifold under pressure, we had a serious mishap with the nitrous bottle during a solenoid valve test resulting in loss of our stored oxidizer propellant. We surveyed the situation with our pyro-op and realized our error. With some minor repairs to the manifold, replacing a gauge and recharging the nitrous bottle, the fluid system will be restored.

Dave Crisalli, our pyro-op in charge at the RRS, talks with UCLA as they are setting up

Larry and I proceeded to complete the parachute recovery system to verify all systems are present and functioning.  I chose a MissileWorks RRC2+ dual-deployment system for parachute recovery using only the drogue chute circuit and all settings in default mode.  We also had an old Jolly Logic altimeter chip as a backup for the system.  All electronics passed inspection and we began a packaging check after securing the vent line stub.  At the end of checks, we felt the payload space was too tight and with our launch attempt already scrubbed we sought to make some improvements to the recovery system.

Parachute deployment for the hybrid rocket
Laying out the parachute with a Nomex cloth for heat protection from the powder charge

The RRS hybrid rocket launch will have to wait for the next launch event. We’ll make some improvements and hopefully have success soon.

The remainder of the day was spent overseeing UCLA’s next attempt with their ethanol/LOX liquid rocket. The team has had modest success with their prior hotfire in November but was looking to demonstrate further improvements.

Anneliese Peterson of UCLA installs the relief valves into the propellant feed system
Dave Crisalli discusses progress with UCLA’s design from within the safety of the George Garboden observation bunker

UCLA discovered and repaired several leaks in their pressurant connections. They also successfully purged their propellant tanks and had reached the decision point whether to proceed with LOX loading.

Based on a thorough discussion by the team and with our pyro-op in charge, UCLA opted not to proceed with hot-fire preparations and will make further corrections to their rocket systems before returning to the RRS MTA in the coming weeks.

UCLA showed great teamwork and maturity in their decision on how to best proceed. A future hot-fire date hasn’t been set yet, but the RRS is ready to support. 

It wasn’t a great day for hot-firing but many felt something important was learned that day at the RRS MTA. We will likely be back again sometime this month.  Wolfram Blume may be ready to conduct his first system test flight by then and Larry and I certainly will be ready to try again with our hybrid.  UCLA will also likely return this month.  The next launch event with LAPD CSP will be coming in March. 

In all cases, groups wanting to use the RRS MTA must contact the RRS president and submit a standard record form. We require a minimum of three weeks notice to consider all requests.

Our next meeting will be 2/14/2020 as the second Friday falls on Valentine’s Day this year.  We will surely discuss the MTA events since our last meeting including this one.

Thanks to everyone who came out and made this a great day.