December 2016 meeting

The RRS held our last monthly meeting of 2016, this Friday, December 9th, at our usual meeting location at the Gardena Recreational Center. We were well attended but started at 8:10pm due to traffic causing problems for some.

The launch event at the MTA of November 12th with the Compton magnate school, Rise Academy, was a very successful event.
4 alphas, 1 alpha from Osvaldo/Dave, 1 beta from Larry. Osvaldo brought the recovered keychain camera footage that was taken. The quality was quite good considering the small device and the rough environment of the alpha launch. The green plume of the smoke grenade was quite clear. I showed some of my video footage of four of the five launches.

RRS to establish a point of contact with the mayor of Compton to help promote more RRS events. The RRS alpha build events are becoming more popular and this is great. A flyer for the RRS alpha build event is in the works. Certificates of completion for the RRS alpha build events will be a good thing to give at the completion of the event. The RRS alpha build event instructive presentation slides are still in work.

SuperDosa project has progressed slightly. To the visitors and new members in attendance I gave the original October 2016 briefing to reaffirm the purpose of the project to reclaim the amateur altitude record for the RRS. Our starting basis for design has been the SuperLoki. Chris Lujan helped me solve a problem with OpenRocket for the flight simulation. Propellant sample testing is the next step. I acquired a pressure transducer that will be useful for the ballistic evaluation motor tests for burn rate calculations. The design of the BEM is in work. The next meeting for the SuperDosa project will take place before year’s end.

The RRS has been the recipient of a manual hydrotest pump generously donated by Rice Hydro Inc., of Carson City, NV. We are very grateful to Rice Hydro and hope to give a good demonstration of this device in use as we proof tanks and tubing assemblies in the near future.

Rice Hydro Inc – Carson City, NV

The RRS made contact with Apogee Astronautics who owns a few SuperLoki launchers. Osvaldo and I met with the owner, Robert Kleinberger, who was passing through Los Angeles last month on business. The RRS has asked Robert to make a short presentation about sounding rockets and the SuperLoki. Although Robert wasn’t able to present at the December meeting tonight, we hope he’ll be able to send a presentation for next month’s meeting.

Three students from the UCLA Rocket Club came to the meeting, Hayden, Justin and Aaron; Dr. Mitch Spearrin is their co=advisor along with Dr. Richard Wirz who is on sabbatical. UCLA has been testing and flying hybrids (paraffin with nitrous oxide). UCLA is looking to build and fly a liquid rocket. We’re thankful to have UCLA come out tonight and hope to do projects with them in the future.

UCLA Rocket Project (URP)

Oliver and Mark were showing their model rocket, with a H-motor. They had built and tested an excellent dual-deployment parachute system. Also, they generously donated a 4 and 6 inch PVC electrical conduit pipe material for the RRS which may be used for a mockup at the upcoming RRS symposium in April 2017.

The RRS held annual elections for the Executive Council. Election results for 2017 were as follows.
President = Osvaldo Tarditti
Vice President = Frank Miuccio
Secretary = Dave Nordling
Treasurer = Chris Lujan

Osvaldo summarized the MTA activities for this year which included three junior high school launch events, 2 from Hermosa, 1 from Compton done in 2016. USC held static fire tests at the MTA.

The Mars City Design organization was discussed again. Three to five prototype projects useful in Mars habitats will be built at the MTA as a field test of concepts. Concrete 3D printing is a key technology to be demonstrated. The habitat will have real people living inside for the demonstration, if successful, the space can be used for camps and science field trips.

John Glenn passed away this month. The RRS encourages individuals to contribute to the Astronaut Scholarship fund that was started by him and the rest of the Mercury 7 astronauts. Also, this month is the 100th anniversary of Robert H. Goddard’s seminal paper “A Method of Reaching Extreme Altitudes” that was submitted to the Smithsonian for publication.

We ran out of time quickly as we had many topics. Some will be brought up in our next meeting. The meeting adjourned at 9:36pm.

Let me know if there’s any additions or corrections to make. I put this summary together as soon as I got home.
Our next meeting will be January 13, 2017 in our usual location at the Gardena Recreational Center.

Molten Metal Works – intro course

I just completed the introduction to welding class at Molten Metal Works in Glendale this Sunday, Dec. 4th. It was a 6-hour class taught by Thea and Eric covering the basics. It was a good hands-on experience learning to use a MIG welder.

MMW instructors, Eric and Thea

MMW instructors, Eric and Thea

For someone who has never welded before, it was good basic instruction. We learned the DASH basics and how to operate the welder. I enjoyed it a lot and hope to take the TIG basics class next. I thank Frank for recommending the place and I thank Thea and Eric for their patient instruction. Welding is fun!

learning to weld at MMW in Glendale

learning to weld at MMW in Glendale

Their website explains in more detail the requirements of the class and the facilities available. They offer memberships to use their facilities both on an hourly basis and by monthly subscription. It’s a good place with lots of artists and craftsman using the space. I plan to come back.
Molten Metal Works

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.