MTA launch event, 2017-03-25

The RRS was pleased to host a launch event at our Mojave Test Area (MTA) for the Girls Academic Leadership Academy (GALA) of L.A. USD on Saturday, March 25, 2017. The event had an excellent turnout.

GALA at the MTA, panorama

GALA students on the MTA observation deck

Longtime member Dave Crisalli was our pyro-op for the event and I was able to serve as his assistant in conducting the launch of twelve alphas and a beta rocket.

Dave Crisalli

Osvaldo and Dave

If anyone else has photos of the event that they’d like to share, please email me:
secretary@rrs.org

Before we got started, we had a safety briefing showing how launch will take place and what to do before, during and after firing. To give an appreciation for the propellants commonly used in amateur rocketry, at a safe distance, we burned a sample of the micrograin.

John Mariano addresses the group

sample micrograin propellant burning

And a composite grain that Larry made for the demonstration

composite grain, before and after

AP composite grain, sample burn

We had 12 alphas and 1 beta for launch. GALA did a great job in painting their rockets. The bright colors not only distinguished one from the other, but they also made finding them downrange by their tailfins in the desert much easier to do. GALA also was wise to number their rockets. We took good notes on the flight times of each (35-38 seconds which is typical). With the wind noise, it wasn’t always possible to hear the faint thump. GALA did well in keeping quiet after launch to hear the thump and figure the direction where it was heard.

GALA rockets ready for launch

alpha launch rails facing out to the gate

GALA ready for launch

alpha launch 03-25-2017

Osvaldo equipped the last of the 12 alphas (all the way to the right in the photo below) with another fin-mounted keychain camera similar to what was done at the November 2016 launch event. Alas, it was not to be, the camera was destroyed and no footage was captured.

12 alphas laying in the rack

The beta was without payload except for the wooden adapter and a plastic Easter egg half as a nose cone. A buzzer and a strobe device was mounted to the beta fins in hopes to be better able to locate the vehicle in the search. Unfortunately, the beta, too was lost. No sound of impact was heard.

alphas and a beta (upside down)

Loading the beta into the rack

RRS beta launch 2017-03-25

Dr. Mitchell Spearrin of UCLA came by the event to tour the MTA as the RRS looks forward to working UCLA on their upcoming projects. Dr. Spearrin brought an Estes Ascender model rocket of his own to test at the MTA with a commercial F-motor. At the end of the GALA rockets, the model rocket was launched. I didn’t get any photos. I believe the winds carried the light rocket pretty far east of the MTA site. I understand that the rocket wasn’t able to be recovered.

Estes Ascender

Several of the alpha rockets launched by GALA were able to be recovered through hard work and sweat. I think of the 12 launches, 7 were recovered? An excellent job by the GALA team in finding and recovering a lot of the hardware.

GALA recovers an alpha

GALA alpha extracted

The RRS wants to thank GALA for their participation and hope they enjoyed the day as we did! We hope to have GALA come back for another event. Also, many thanks to Don Purpurra for contributing his photos of the event. The shots of the alphas and betas he took were incredible!
GALA Academy

If any other schools or groups are interested in participating in one of our build events, please contact our events coordinator, Larry Hoffing:
events@rrs.org

blockhouse view with the launch button gear

Our next RRS meeting will be Friday, April 14, 2017, at the Ken Nakaoka Community Center in Gardena, CA. This will be the last meeting before the RRS symposium which will be held Saturday, April 22nd at the same meeting location in Gardena. We encourage all of our participants to come by the Friday, April 14th meeting in advance of the symposium.

There will be speakers and an exhibition hall with universities and groups from government and private companies in attendance.

the latest RRS symposium flyer

Our latest flyer is linked here for download. Please share and post!
rrs symposium flyer 320

We also have tickets to the symposium being offered through an Eventbrite link given below. The event is free. We encourage everyone who’s interested in coming to sign up as this helps us get a better idea of how many people are coming.
Eventbrite – RRS symposium (free to register)

If I missed anything or if anything is misstated, please contact me:
secretary@rrs.org

ceramic coating on alpha nozzle

The firing report from the November 12th launch at the MTA has already been described in an earlier post, but I wanted to elaborate on one important topic in particular.

The November 12th launch at the MTA offered the chance to test an improved nozzle for the 1-inch RRS standard alpha. The nozzles are the most expensive and difficult parts to machine.

RRS standard alpha nozzle

RRS standard alpha nozzle

The throat in the 4130 steel nozzles is subject to erosion from the zinc/sulfur high temperature combustion gases (2600 F) as the flow is choked before being expanded from the diverging nozzle section. Although the burn duration (~0.8 seconds) is short and the mass of the steel does not heat very quickly, the transient heating is sufficient to soften, melt and ablate the flow path. Each firing results in opening the throat diameter and reducing the thrust. The flow path also becomes very warped with large pockets of the nozzle are removed at the end of the firing. Typically, the nozzle can be re-used one more time with reduced performance before the erosion becomes too severe.

My goal was to combat the erosion that occurs after each micrograin firing and improve the usefulness of the nozzles over multiple firings. I had the interior surfaces of one RRS alpha nozzle coated with a high temperature ceramic coating at Specialized Coatings in Huntington Beach. A link to the company website is given below:
Specialized Coatings

It is this same ceramic coating process that is used in automotive exhaust manifolds and on the piston head surfaces in internal combustion engines. This coating was applied by hand to the smaller 1-inch nozzle for the alpha. Bonding to the 4130 steel was not a problem for this process. The limits of the process were to be tested under the flight conditions of our standard RRS alpha. A photo of the finished nozzle after the coating process before flight is below. The coating was applied primarily to the interior surfaces particularly at the converging and diverging portions of the throat. For better continuity, the coating was applied to the full length of the interior flow path and around to the outer surfaces as well.

RRS alpha nozzle after coating

RRS alpha nozzle after coating

The flight of the alpha was nominal with 3.7 lbs of our typical (80/20, Zn/S) micrograin propellant exiting the nozzle pushing the rocket from the rails. The photo below is of a similar alpha firing just before the one we’re discussing. No visible differences were seen in any of the plumes in all five alphas.

Snapshot - Compton alpha4

Snapshot – Compton alpha4

After immediate recovery of the alpha that same day and extracting the nozzle at the MTA for examination, the results were outstanding. No erosion or degradation of the nozzle was seen at all. In the photo below, it seems that zinc/sulfur residue is caked in the throat which is typical from previous firings. No attempt to clean the nozzle was made as the integrity of the ceramic coating underneath was not certain. Although the throat remained in good shape, any reduction in coating thickness or degradation of the coating properties should be examined.

ceramic coated alpha nozzle after firing

ceramic coated alpha nozzle after firing

I was going to return the flight article back to Specialized Coatings for careful cleaning and a more thorough examination of the interior surfaces at the throat to see how much of the coating was in tact. Unfortunately, this nozzle was lost shortly after returning to the city. My next step will be to recoat another alpha nozzle for a subsequent alpha firing at the next MTA launch event. More data is good and necessary to learn the limits of this process.

Further, after some members at the MTA inspected the nozzle seeing the clear improvement, it was decided to seek pricing for doing more of the society’s alpha nozzles in bulk as this process seems to significantly extend the life of a key part of the rocket. Further alpha firings will be necessary to determine the limits of the process. Also, testing on the RRS standard beta (2″ design) will be another logical step forward.

Many thanks to Specialized Coatings for their assistance in proving a major design improvement to RRS nozzles.
Specialized Coating website – Huntington Beach, CA

Specialized Coatings – Huntington Beach, CA

MTA launch event, 2016-NOV-12

The launch event at the MTA on November 12th was a success. The STEAM students from the Rise Academy in Compton launched four RRS standard 1-inch alpha designs. All were successful and seemed to fly straight.

Rise Academy, Compton, CA – via Facebook

four Compton alphas with Larry's beta

four Compton alphas with Larry’s beta


Larry built the larger 2-inch RRS beta with a simple wooden egg as a nose come mounted to the welded bulkhead.
wooden egg as nose cone on beta

wooden egg as nose cone on beta

Compton alphas on the MTA table ready for launch

Compton alphas on the MTA table ready for launch

The fifth alpha was a design Osvaldo and I put together with the smoke grenade in the payload section as a tracer. The fifth alpha also had a key fob camera module mounted to the midpoint of one of the fins and a ceramic coated nozzle which was very successful. The camera was recovered intact and the ceramic nozzle seemed to work perfectly with no erosion seen in the throat.

the fifth alpha with camera, smoke tracer and ceramic lined nozzle

the fifth alpha with camera, smoke tracer and ceramic lined nozzle

Dave Crisalli was our pyro-op and gave a great safety briefing before we got started. Osvaldo and Dave demonstrated the combustion of the micrograin and composite propellants common to amateur solid rockets.

Dave Crisalli gives MTA safety briefing before launch

Dave Crisalli gives MTA safety briefing before launch


micrograin combustion demonstration at MTA

micrograin combustion demonstration at MTA


Composite propellant sample burn at MTA

Composite propellant sample burn at MTA

The important part was the preparations necessary include checking the range before committing to launch. We had almost still winds all afternoon and high clouds overhead with temperatures being nearly ideal, but we always look and listen before we commit to launch.

Loading Larry's beta in the rails

Loading Larry’s beta in the rails

Larry on range watch before launch

Larry on range watch before launch

arming the alpha for firing

arming the alpha for firing

Richard Garcia stands next to Larry's Beta (for scale)

Richard Garcia stands next to Larry’s Beta (for scale)

Launch was exciting and went smoothly. Everyone did as they should, by counting down then listening for the flight time and the soft “thump” of impact.

Compton in the bunker(2)

Compton in the bunker(2)

Snapshot - Compton alpha4

Snapshot – Compton alpha4

Larry's Beta rocket launch

Larry’s Beta rocket launch

After the launch, the Rise Academy students were a big help in finding their rockets. After listening after each launch for the direction of the thump sound, we had a starting point and direction to start walking. With all the help we had, all five of the alphas were spotted including Osvaldo’s and mine! However, Larry’s beta hasn’t been found yet due to its larger size likely going further downrange. Three of the alphas were extracted from the earth thanks to the hard work and shovels. A great job as most rockets aren’t found so quickly.

Compton alpha found downrange from MTA

Compton alpha found downrange from MTA

Compton alpha extracted by shovels

Compton alpha extracted by shovels

Compton alpha going home

Compton alpha going home

key fob camera survives an alpha flight

key fob camera survives an alpha flight

Compton alphas going home

Compton alphas going home

Many thanks to all that came out to the MTA. Thanks to John Mariano for leading this event. We hope to see everyone come back for another launch day in the Mojave with the RRS.