MTA launch, 2020-01-18

by Dave Nordling, RRS.ORG

The RRS held its first launch event of the new year, 2020, this Saturday, January 18th at the MTA.  As part of the RRS commitment to being more active throughout the year, we have made a specific point to hold an event early in the year.  The weather was perfect. Low winds and slightly cool temperatures made for a great day to launch.

We had a few different projects at this event.  We also used this event as an opportunity to do some minor site improvements including the addition of a pair of standing benches.

New standing benches added to the George Garboden observation bunker at the RRS MTA.

RRS member, Keith Yoerg had a couple of high powered rocket flights.  He had two successful flights before we were told that the FAA waivers that day were cancelled due to adjacent activity at Edwards AFB.  We are thankful for our neighbors at FAR for letting us know, but in the future the RRS should be better informed of such important notices.

Both dual-deploy recovery systems in his rockets worked just fine and the rockets were found and brought back right away.  The telemetry data showed a nearly 4000 foot altitude with a top speed of Mach 0.6 was reached with his I-sized motor, very comparable to the RRS standard alpha. 

Keith prepares his rocket for launch at the MTA

Wolfram and Marianne Blume made their first journey to the RRS MTA from south Orange County. Wolfram had begun his preparations for his first launch of the Gas Guzzler ramjet from our 1515 rail launcher when we got notice that all flights were cancelled that day.  Wolfram is willing to come back at a later date which is in planning.

The Gas Guzzler rocket is a two-stage rocket with a commercial high-powered solid motor and a gasoline fueled ramjet second stage. Wolfram has a lot of systems checks to do before proceeding with the ramjet flight.  This first flight is to be a demonstration of the vehicle booster, staging mechanism and the recovery systems on each stage.  The ramjet will be filled with an equivalent weight of water to keep the vehicle balanced similarly to how it will be in flight.

The RRS has not yet approved the flight of the fueled ramjet flight, but is happy to support the ambitious goals our new member projects like Wolfram’s with system tests. We look forward to seeing how this first flight will go in the near future.

Wolfram Blume prepares his Gas Guzzler ramjet at the MTA

The liquid rocket team at Loyola Marymount University (LMU) came out to visit the vertical test stand at the RRS MTA and discuss many of the important details of liquid rocket operations with our pyro-ops.  LMU is working hard to get into static hot fire testing of their kerosene-LOX rocket motor design by May 2020 at the RRS MTA. 

The RRS is supporting many liquid rocket teams at the MTA for the Base11 competition and in supporting their own university goals.  Making a site visit to the MTA is a good way to conquer the many practical challenges that each team faces in making their systems work.

LMU students sketch out and discuss ideas at the RRS MTA.

The last project attempted at the RRS MTA that day was the commercial hybrid motor that Larry Hoffing and I have integrated into an old 2.5-inch rocket body.  I bought a Contrail Rocketry H222 38mm 16-inch motor kit with a reload pack to get the fill lines and reloadable hybrid fuel grains.  This was an ambitious project to assemble over the end of the year break.

Unfortunately, I was not able to secure a parachute deployment system. Hybrid motors do not have ejection charges so you must have an autonomous system. The Stratologger CF model was recommended, but wouldn’t arrive in time for Saturday’s launch. In any case, the launch would have been cancelled anyway.  I opted to do a simple static fire and mount to the 1010 rail we had deployed.

The H222 motor assembly process was completed per the instructions. The assembly is a very tight fit so a generous use of Krytox and Mobil 1 lubricants is strongly recommended.  In my next build, I may make a pusher tool to make the next assembly easier to do. With the clear vent line strung up through the top of the rocket tube and the fill and igniter lines sticking out through the graphite nozzle, the motor was loaded and ready.

The RRS was kind enough to invest in a nitrous bottle from Nitrous Supply Inc. in
Huntington Beach, CA. The auto racing has a lot of nitrous accessories that work very well for amateur rocketry.  The RRS is grateful to Nitrous Supply for their excellent advice.

The RRS also invested in a solenoid valve manifold from Pratt Hobbies in New York state.  Doug Pratt was great support and provides reliable hardware. It’s important to know your gas bottle connections. CGA 660 type connectors are used in nitrous oxide (N2O) bottles used in the racing industry.  CGA 326 connectors are different and are found on nitrous bottles used in the medical and dental industries.  We opted for CGA 660 type which doesn’t require a medical business license to acquire due to the nitrous oxide being denatured with sulfur dioxide. Harmful to people, harmless to the rocket combustion.

Both the bottle and valve manifold mated well and I tested the 12 VDC solenoids separately using the bare wire leads on my truck battery.  I was going to do a leak check on all fittings and connections, but I forgot my leak check fluid bottles at home.  I was willing to tolerate a little leakage in the outdoor environment after I verified the snug fitting of all parts.

Nitrous oxide bottle with 10 lbm of liquid, complete with fill and vent solenoids.

It was for lack of a proper Parker Prestolok fitting that I was unable to complete the fluid circuit and because of this no static fire at the event would occur.  As I later found out, these fittings are available through Grainger but it would take too long to acquire as they are often not in stock.

The 3/16” OD nylon tubing for my injector is also not very common. Parker Parflex NB-3-046 thick wall tubing can be bought through pneumatic system suppliers who are distributors for Parker Hannifin.  Having a longer length of this 3/16“ OD  tubing would have been ideal.  Instead, I found 100 foot rolls of 1/4” nylon thick wall tubing at Home Depot but I needed to connect between tube sizes.  With a brass  1/8” FNPT coupler (also found at Home Depot) you can adapt between 3/16” and 1/4” fluid lines.  I was missing a pair of 1/4” tube to 1/8” NPT Parker Prestolok connectors to complete the set.

Larry and I will regroup and prepare for the next launch event at the RRS MTA which will be in the next two weeks.  Osvaldo was going to make a special firing box for hybrid rockets with three switches (fill / ignite / vent) and the same key interlock.

The RRS MTA will be hosting USC RPL for their latest solid rocket motor design (1/25/2020) and UCLA for their next liquid rocket motor static hot fire (2/1/2020). 

It was a reasonably successful day and proof that January is a great month for an MTA launch event.  The RRS is grateful to our members who came out to the site to help with assessing site improvements at the MTA which will hopefully begin this year.

MTA launch, 2019-12-07

by Dave Nordling, Secretary, Reaction Research Society


The RRS had our last launch event of the year this Saturday, December 7, 2019, at the Mojave Test Area (MTA). We were hosts again to the Los Angeles Police Department (LAPD) Community Safety Partnership (CSP) and this time with 99th Street Elementary.

The RRS has been reworking some of our rails including our trusted and reliable alpha rail launcher. Months of use had slowly built up uneven layering of zinc-sulfide on the rail surfaces making loading difficult but protecting the steel surfaces from the slow corrosion of the dry salt lake bed just a few miles away. Osvaldo did great work in giving our alpha rail launcher a new lease on life. Thanks also to Russell Hoffing and his kids for helping out with the installation before the event crew arrived.

The refurbished alpha rail launcher is being re-installed on its concrete pad before the 12-07-2019 launch event at the MTA.

The winter seasonal rains have arrived a little early to southern California, but the weather began to clear today just before we started. The winds were very low which was excellent for launching rockets. From the washing action of the rain this week, the loose sand drifted into a vein-like pattern over the harder sand below which gave the ground a slightly “Martian” quality. It was cool but not cold and a great day for a launch.

The 8-inch adjustable rail launcher is still under repair from the failed July 2019 launch. The inner adjustable rail slides are being built from scratch. One of the outer braces was blown off and some of the angle frame pieces are distorted. This will require a lot of rework but we hope to have this launcher back in service soon.

We had a minor problem from the rainwater gathering in the bunker. It wasn’t more than an inch or two deep, but on a cool December morning, it would be a miserable place for our guests. The RRS was grateful to some of the Friends of Amateur Rocketry who let us borrow a small sump pump to pull the standing water out.

Frank Miuccio mans a simple broom to sweep the water towards the small sump pump in the corner. The RRS thanks our neighbors at the Friends of Amateur Rocketry site for their assistance.

We gave the students the standard safety briefing about how to avoid the dangers at the site. We also gave them a live demonstration of how the micrograin zinc and sulfur powder burns in the open showing the brilliant yellow color. Larry Hoffing had also prepared a small sample of solid composite propellant made with ammonium perchlorate and an iron oxide accelerant.

A sample of micrograin propellant lights in a metal cup to show how two simple pure substances can burn so energetically.

Larry Hoffing and his grandsons had a few model rockets to try out at the event. After setting up the launch wire and clamping the smaller 6-foot long 1010 rail to a suitable rigid and weighted base. Winds were very light all day so we had few problems from the elements.

Larry Hoffing and his assistants posing before starting the launch of a few small model rocket motors. The RRS MTA is for rockets of all sizes.

Larry flew a classic Estes model, Big Bertha, which is always a crowd-pleaser. This vintage model design is slowly powered at take-off by a C6-3 commercial motor then gains traction after its fins start working. It has flown to couple hundred feed then at apogee made a nice parachute recovery.

The high-powered fiberglass bodied rocket launched on a 1010 C-rail was boosted by a vintage Flight Systems F6-7 motor, but failed to move vertically up the rail by more than a couple of feet before settling nicely on the launch pad with an impressive 6-inch exhaust flame. It will be back to the drawing board for that model with the possible addition of a more powerful G-sized AP motor or a H-sized hybrid. The students at 99th Street Elementary witnessed the launch, but the biggest part of the event was yet to begin.

Osvaldo holds the finished product, a loaded RRS standard alpha with micrograin propellant. Note the painter’s tape covering the four mounting bolt holes which also minimizes spillage.

The ten RRS standard alpha rockets from the students were already loaded the night before. A last minute addition of another alpha painted by their teacher was included. Osvaldo showed me his latest propellant loading approach that minimizes external powder contamination on the person loading. Using zinc-sulfur is simple, but it has it’s own problems. Many of our spouses and friends are not pleased with the persistent odor of brimstone (raw sulfur) on our clothes upon our return to the city. Osvaldo has known this problem for years and found a simple method of blocking the migrating propellant dust using a simple pillowcase shield. He has also improved the mating funnel and with a steady light bouncing of the propellant tube on a wood block, the propellant tube can be filled with its 3.2 pounds of zinc-sulfur mixture.

Our alpha launch operations were conducted a little differently at this event. Osvaldo did the loading at the rails, while I was manning the launch switch in our observation bunker with everyone else safely under cover. By California law, the person on the launch switch is the pyro-op in charge. With our experienced team doing road and air space checks before each firing, we had a good safe launch and a lot of fun.

Dave Nordling in the bunker waiting for the first alpha to be loaded. Note that nothing is connected until all is loaded and ready.
Osvaldo Tarditti loads an alpha into the rails in preparation for launch.

We had ten alpha rockets plus one extra painted by the teacher for this event. All of them looked really sharp with bright colors easy to spot when recovered from the desert floor. 99th Street Elementary really enjoyed the five weekly classes and were very exciting to have the last class at the Mojave Test Area to see real demonstrations of rocket propellants and the micrograin powder in each of the rockets propelling them into the gray sky one by one.

Ten plus one alphas from 99th Street Elementary loaded and in wait for their time on the launch pad.

Most of the alpha flights were perfect. The flight times were consistent and given the low winds we could hear the whooshing return and the thump on nearly every one to confirm impact.

A nice clean launch of an RRS alpha at the 12-07-2019 event.

We had one particularly troublesome flight which is a rarity with the RRS standard alpha after all of the years spent perfecting that design. The second rocket sputtered and hesitated a lot before taking off slowly from and rails and flopping back to the ground. No obvious cause was found on that rocket, no unusual burn pattern or melting and the propellant tube seemed intact. After inspecting the rocket more thoroughly upon its recovery just a few feet from the launch rail, it was clear that the nozzle mounting screws must not have been installed. No damage was seen to either the propellant tube or the nozzle. The nozzle throat was in tact which indicates it must not have been present to choke the fiery exhaust flow. This also explains the profound lack of thrust, but yet even without a nozzle the micrograin rocket was able to generate enough pressure to lift itself out of the rails. The nozzles often fit very tightly into the propellant tubes which might have been how someone could have failed to notice the missing attachment screws during transport to the launch pad. This is quite an error which will not be repeated.

Anomalous launch of an alpha at the 12-07-2019 event.

We said goodbye to our visitors and prepared to clean up the site. In the winter months, the sun sets quickly so we didn’t have a lot of time to search for the alphas. Frank had a lot of luck finding six of the eleven launched that day. Some of the parts can be reused with a little work.

The Tarditti rocket extractor tool, don’t go downrange without one.
An alpha rocket buried up to its fins in the desert floor.

We’ll surely discuss the results of the launch event at the next RRS monthly meeting which is next Friday, December 13th. Also, we’re already planning the next MTA launch event which will happen in January. We are expecting more launches in this next year, 2020. Thanks for reading!


MTA launch event, 2019-09-21

Larry Hoffing, Events Coordinator, RRS

Photo credits: Osvaldo Tarditti

The Reaction Research Society held another launch event with the LAPD CSP. This event was with the students of Boyle Heights. We had ten standard alphas launched into the blue Mojave sky that day including some model rockets made by Russell Hoffing and my grandson.

A lot of different groups came out for this launch event at the RRS MTA, 09-21-2019

We had students from the CSU Long Beach liquid rocket team come out to make some measurements for sub-system testing that they are planning at the RRS MTA this year.

CSU Long Beach inspects the vertical mounting structure at the RRS MTA
Model rockets in the George Dosa building undergoing preparation for launch
Students from Boyle Heights get their orientation instructions at the RRS MTA
RRS events coordinator, Larry Hoffing; RRS VP, Frank Miuccio and RRS president, Osvaldo Tarditi

Returning RRS member, John Krell, had worked up two prototype instrumentation packages for flights in the ninth and tenth RRS standard alphas on that day. Both rockets were recovered and the results were impressive.

John Krell arms his payload integrated into one of two RRS standard alphas, 09-21-2019
One of John’s prototypes survived the flight and is laid out on the table in the Dosa Bldg.
John Krell examines the recovered SD memory chips to determine the flight profile from the RRS alpha. Over 100 G’s of acceleration at take-off max’d out the sensor!

Materials have been acquired to repair the adjustable rail launcher that was damaged in early August this year. Osvaldo has been busy at work on the repairs. The RRS has several facility improvement projects in the works and we hope to bring this rail launcher back to service soon for larger rockets (4 to 6 inches).

John will hopefully have a full report and an overview of his design. Both Bill Behenna and Brian Johnson are also working on their own instrumentation designs for the RRS standard alpha. With this recent progress, this should help our others members take better data.

Still photo from RRS alpha #3 of 10 launched at the MTA on 09-21-2019.

We’ll discuss more of the results of this event in detail at the next RRS meeting on October 11, 2019. The RRS meets every 2nd Friday at the Ken Nakaoka Community Center in Gardena, California. Stop in and see how things went.