The RRS held its monthly meeting for September 2018 this Friday, the 14th, at the Ken Nakaoka Community Center. We were displaced from our usual meeting room, but got the upstairs room F with the window view which was pretty nice. We were well attended, but got a very late start. Meetings begin at 7:30pm. There were several little events at the meeting which did not make the agenda.
Alastair Martin, Bill Behenna and Richard Garcia at the September 2018 meeting of the RRS
The RRS was glad to welcome new student member, Bailey Cislowski. We had a short little social event at the end of the meeting which was a nice way to end the week.
Bailey Cislowski and RRS VP, Frank Miuccio
Also, the RRS was glad to re-welcome new members Wilbur Owens and Xavier Marshall. Wilbur had his first rite of passage in the RRS by taking his first standard alpha rocket. He’s looking forward to filling it with micrograin at the next launch event on October 27th. It will be one of many to come!
Xavier Marshall and Wilbur Owens; Wilbur gets his first RRS alpha
Xavier invited the RRS to come tour the Experimental Aircraft Association’s local chapter at the Compton Airport. The EAA holds regular events including educational events with local kids.
Experimental Aircraft Association, Spirit of 96
Contact information for the local chapter of the Experimental Aircraft Association in Compton
RRS member Alastair Martin is active with the Mars Society which just completed their 21st annual International Mars Society convention at the Pasadena Convention Center. If Alastair can oblige at our next RRS meeting, I have asked him to give the RRS a report on his experiences at the event.
Mars Society – home page
Besides film-making and photography, another one of Alastair’s talents is screen-printing on shirts. I recently had the RRS logo added to this bright-yellow shirt that I bought to better survive the hot Mojave desert climate of the RRS MTA. These bright-yellow “Ultra-Club” cool & dry shirts can be bought on Amazon in a variety of sizes besides the “XL” that I wear.
The RRS logo proudly worn on a fall afternoon
I recently purchased a fly-away rail guide from Additive Aerospace. This company specializes in model rocketry parts including this simple clamp-on device that obviates the need for mounting rail buttons on the smaller rockets.
Additive Aerospace – fly-away rail guides
Additive Aerospace was nice enough to customize their standard 38mm design to fit the slightly smaller (1.25″ diameter) RRS standard alpha propellant tube. The fit check was perfect and the next step will be to attempt to launch an alpha from the 80-20 rail launcher we have.
Flyaway rail guide customized for an RRS standard alpha micrograin rocket is a good fit (and held closed by my hand).
Flyaway rail guide has two pairs of rail buttons to hold the rocket on the launch rail.
The flyaway rail guide is spring-loaded to open once the rocket travels up and off the launch rail, then simply falls away as the rocket speeds off
1.5-inch 80-20 aluminum rail extrusion, rail buttons are guided down this path on the rocket’s way up and away
12-foot aluminum 80-20 rail launcher, RRS MTA bunker in the background
Osvaldo completed the cylinder piece of the ballistic evaluation motor (BEM) assembly that I designed for testing the burn rate of solid propellant samples. I forgot to bring the graphite nozzle pucks that Richard Garcia made for the assembly. Once the gaskets are fitted and the pressure transducer is checked out, we can begin to prepare 4-inch long samples of propellant into the 3/4-inch PVC tubes for which the BEM was designed to fire. This will be a useful tool in characterizing the AP/HTPB/Aluminum solid propellant batches that will be used in the prototypes of the SuperDosa project. Larry has already made a small batch of the RRS standard recipe solid propellant. Some of these first grains may be used in the propellant burn demonstration at the next RRS MTA launch event.
RRS BEM cylinder sits on top of the bottom plate, top plate in the background
Thanks to Osvaldo again for his help with the two-stage alpha rocket that I designed. In this prototype, the payload tube was made longer for the possibility of a parachute recovery system for the upper stage. The 1-1/4″ PVC pipe was machined down to 1.600″ OD to fit inside of the standard alpha’s aluminum payload tube. The steel nozzle design, although simpler to make, may prove to be excessively heavy and throw off the mass balance of the rocket. The graphite nozzle design with its split retaining ring may be the better choice. More work is needed before attempting to fly this prototype design including completing the inter-stage timer circuit for deploying the in-line second stage motor in flight.
Two-stage RRS alpha rocket; second stage with a small AP/HTPB/Aluminum solid grain motor
Since August, Osvaldo has made some progress in testing the load cell that will be used in the horizontal thrust stand. The bottle jack he used was tapped with an analog pressure gauge and the compression load into the load cell can be accurately measured. Despite some seal leakage problems with the older bottle jack, the results he and Matteo gathered from his data acquisition unit showed our S-type load cell matches the calibration sheet fairly well.
Load cell compression testing rig using a pressure gauge and a bottle jack
Finally, we got to some of the originally scheduled agenda topics:
Frank Miuccio gave an overview of the next educational event that had its first event of the series held today at Weigand Elementary school. This is the latest in the series of events we’ve had with the LAPD CSP program. The final event will the launch of the alpha rockets at the RRS MTA on October 27, 2018. Dave Crisalli will be our pyro-op at the event.
Osvaldo, Larry and Frank listen at the September 2018 meeting
We didn’t have another launch event planned yet for this year, but it’s always possible.
Richard Garcia gave a brief overview of his successful hot-fire test of his 1000-lbf kerosene-LOX motor on August 18, 2018. His pintle injector with an ablative chamber insert worked very well despite a leaking fitting at the LOX port. Some of the equipment did not work completely as hoped, but the overall test produced a stable thrust profile and clean cut-off. Richard put a lot of work into this first design which helps pave the way to the RRS standard liquid rocket project which will remain a regular topic with the RRS moving forward.
Richard Garcia after presenting his liquid rocket testing results; a proud day
Richard then moved into the details of integrating a liquid motor into a rocket body. Using commonly available parts and a few simply made connecting pieces, a simple but effective liquid rocket design can be made with a modest budget easily affordable to universities and individuals. This is still a work in progress, but the RRS is committed to bringing this project to fruition. We look forward to the next engine build which will likely be in a series of builds that will ultimately lead to the RRS standard liquid rocket design.
Richard’s Solidworks model showing both propellant and pressurant tanks plumbed into the rocket body
We had a very short discussion about the RRS expanding our roster of pyro-ops. Chris Kobel of ROC presented at our August meeting and gave a lot of practical advise on this subject.
Many of our next member “class” including myself have already written their rocket resumes to describe their experience with rocketry and have begun soliciting licensed pyro-ops for recommendation letters which is not a task to be taken lightly. Beyond the RRS regular and lifetime membership, the Rocketry Organization of California (ROC) was willing to help RRS members learn and earn their recommendation letters by attending and participating at events at ROC. The Friends of Amateur Rocketry (FAR) have also been very helpful to those of us who are aspiring to be new pyro-ops. The rocketry community is a small one and it is good to have the support of like-minded organizations to keep the membership across all societies safe, strong and active.
ROC holds monthly events on the 2nd Saturday of each month. I have been working on organizing a group of RRS members to go out to the next ROC event to get to know our smoke-and-fire sisters and brothers.
Rocketry Organization of California – Roctober event on Oct 13-14, 2018
To all of our membership interested in making this trip to the Lucerne Valley on October 13th, contact the RRS secretary. If we have a good number of people interested, we can make this a worthwhile trip. This trip would be on the Saturday immediately following the RRS meeting on that Friday night (Oct 12th). ROC will be holding an event with school kids, but if the RRS members bring their rocket resumes we may be able to have a conversation with the ROC leadership and get some advice and training. If we get a few members to ride out, I’ll contact ROC to let them know we’re coming. Please let me know by Friday, September 28th.
Next meeting of the RRS will be October 12th, which is always the 2nd Friday of the month. The quarterly update for the SuperDosa project will be part of the agenda as well as several items we did not cover in our agenda. All RRS members are welcome to make suggestions for discussion topics at future meetings. For those wanting to add topics, please let me know. I will post the preliminary agenda topics at the 1st of the next month on the RRS website Forum page.
As always, please keep your email and contact information up to date with the society. We’re glad to see so many new members and returning members. Even if you can’t make it to Gardena on a regular basis, just send us a line to say “hello” and tell us how you’re doing.