Tag Archives: boosted dart

Launch Event, 2023-04-22

Posted on by

by Bill Claybaugh, RRS.ORG

Editor’s Note:

RRS member, Bill Claybaugh, built and launched his second 6-inch rocket from the RRS Mojave Test Area on Saturday, April 22, 2023. Target apogee was 69,000 feet. Winds were very low that day. Jim Gross was the pyrotechnic operator in charge for the launch event. Dimitri Timohovich and Rushd Julfiker assisted with the efforts. Bill launched from a 24-foot aluminum channel type launch rail using a pair of belly-bands that disconnected from the vehicle after clearing the end of the rail. The following is Bill’s update report on the flight as of July 1, 2023.

Flight 2 – Six Inch Rocket

Fight II Flight Report

Introduction

Something fairly violent happen to this vehicle at about 3.4 seconds into flight: onboard data and ground video indicate the rocket pitched at least 30 degrees while traveling at about Mach 2.2 at around 4100 feet above ground level (AGL).

Recovered hardware indicates the vehicle broke up under these conditions.  The parachute compartment, which was attached to the top of the motor by four ¼-20 fasteners, was torn away by fracture at all four fasteners (the fasteners remained attached to the motor). The payload, which was attached to the parachute compartment via four 0.250” diameter pneumatic separation system pins, remained attached—indeed, it was recovered with the separation system still functional and still latched to the top of the parachute compartment.

Bill Claybaugh with his second 6-inch rocket before launch.

Video shows a sudden pitch at about 3.4 seconds after first vehicle motion.  The onboard data (which records the initial part of the breakup because the computer was located in the payload section) shows that the gyro tilt went from about 5 degrees to 50 degrees over 0.08 seconds.  Measured longitudinal acceleration went from the previous around 26 g’s to 34 g’s in 0.05 seconds, and after returning to around 24 g’s for 0.15 seconds, to -12.7 g’s (the sensor floor) for 0.03 seconds, before recovering to -9 g’s for 0.01 seconds followed by loss of power. (See Chart 1.)

Chart 1: Acceleration and Tilt

Video shows the vehicle recovering from this pitch maneuver and continuing on a near vertical ascent though burnout at a video-based about nine seconds after first motion.

Flight

Following failure of the AlClO (Aluminum / Potassium Perchlorate) based head end initiator to successfully ignite the rocket (AlClO based initiators have had this issue previously, AlClO appears to be too energetic for this application, tending to blow the secondary ignition materials out the back of the rocket and on to the ground rather than igniting the grain) a jury-rigged rear end ignitor was substituted and the rocket successfully lifted off about 0.25 seconds after flames first appeared around the vehicle base.

Onboard data shows the vehicle ascending at about 88 degrees from horizontal to about 50 feet altitude when a lazy “S” turn (first to the northeast, then back to the southwest) is visible in the video and data. This turn starts about the time the belly-bands can be seen on video falling away from the vehicle.

Following this maneuver, the vehicle returns to near vertical flight to the Southwest, turning, with perturbations, from about 88 degrees tilt to an 86-degree gyro tilt over the next two-plus seconds.  Acceleration steadily builds from an initial 18.6 g’s to a maximum of 27.3 g’s at 2.53 seconds; this acceleration broadly follows the curve expected from the combination of the thrust curve, drag, and the lessening weight of the vehicle as propellant is consumed, however, the measured acceleration is much higher than expected based on static tests and flight simulations.

Telemetry reported Loss of Signal (LOS) at 2.7 seconds and at an (accelerometer-based) 2313 feet altitude and 2440 ft/sec velocity.

Measured onboard acceleration suddenly jumps from a base around 26.5 g’s at 3.18 seconds to 32.8 g’s at 3.21 seconds; measured onboard acceleration stays above 30g’g for the next 0.06 seconds, peaking at 34.7 g’s at 3.21 seconds and followed by a return to around 24 g’s for 0.15 seconds and a sudden drop to -12.7 g’s (the sensor floor) from 3.42 to 3.44 seconds and a final reading of -9.3 g’s followed by loss of power to the on-board computer.

Onboard data shows the gyro tilt angle moving from around 5 degrees at 3.37 seconds to 50.6 degrees at 3.45 seconds, followed by loss of power.

Video over this period show the vehicle suddenly turning through an apparent (visual) 30 degrees or so before pitching back to a near vertical ascent.

Analysis

A less energetic initiator is required for this vehicle; a development program will be initiated to achieve both a more reliable and a gentler ignition in future.

Figutr 1: Recovered Nozzle

Following flight, a single sliver of graphite was found on the ground about 150 feet from the launch tower.  This piece of graphite was exactly the correct shape to fit at the very rear of the graphite throat insert where that insert blends into the titanium nozzle extension. 

Recovered nozzle hardware showed that about 1-inch of the rear of the nozzle insert was missing (see Image 1); assuming the two pieces of the insert found inside the rocket were broken by impact forces, it follows that around one inch at the rear of the insert failed prior to impact. This failure would have induced a flow discontinuity in the rocket’s exhaust which thrust vector could account for the sudden pitch at 3.4 seconds into flight. The vehicle’s return to near vertical ascent appears to be due to aerodynamic assisted dampening of the perturbation, based on the tilt data from the earlier–possibly belly-band related–slow spiral of the vehicle.

Note that the recovered nozzle shows plating of Aluminum Oxide onto the ZrO coated Titanium nozzle extension above the end of the graphite nozzle extension but not in the area originally covered by the graphite insert.  This suggests the insert was present during startup (when Aluminum Oxide would be expected to condense on the nozzle extension surface) and the loss of the about 1-inch of the bottom of the graphite nozzle insert must have occurred later.

Analysis indicates that thermal stress cannot have been the cause of the loss of the back of the nozzle insert: maximum thermal stress occurs at the throat and reaches no more than 60% of the tensile strength of the graphite.  Careful measurement shows that the break occurred at the location of the joint between the titanium nozzle extension and the aluminum nozzle support structure, it thus appears that a (possibly heating related) stress concentration at that location was the probable cause of the graphite failure.

Loss of telemetry at 2.7 seconds appears to be a consequence of the GPS and transmitter antenna assembly failing mechanically; the flight computer was recovered with a clean break at the antenna PCB board.  This suggests the need for more robust support of these parts of the payload.

Breakup of the vehicle began about 3.41 seconds after launch.  The recovered pieces indicate separation of the parachute compartment from the motor was due to the upper part of the vehicle being pulled longitudinally forward, away from the (thrusting) rocket motor; further, the fracture pattern indicates an abrupt failure rather than a slightly slower swaging of the metal.  Based on the acceleration data indicating at least four hundredths of a second of significant negative g’s just before loss of power, coupled with gyro data showing the payload being thrown through an about 45 degree turn over the last 0.08 seconds of data, we can guess that the mechanical failure was a consequence of rather than the cause of the sudden turn of the vehicle.

Figure 2: Booster, post-impact

Actions

Development of a gentler and more consistent initiator is required; an effort focused on BKNO3/V (Potassium Nitrate with Boron held in a Viton matrix) has been started.

The vehicle nozzle has been redesigned to use a single piece titanium throat insert support structure and nozzle extension.  The angle of the joint between the graphite insert and the titanium shell has been increased to the conventional 5 degrees (the flight nozzle used a 3-degree angle that may have been too thin at the very end of the throat insert).

Heat paint testing of the Titanium nozzle extension on the flight nozzle indicated a maximum heat soak temperature of about 800° degrees Fahrenheit on the outside surface; this suggests a maximum outside wall temperature during operation of about one-half the paint-indicated heat-soaked temperature. Since these temperatures are well below the maximum working temperature of 6Al4V Titanium under these loads, the new nozzle is designed to allow for greater heating of the shell.

Analysis based on assuming a maximum Titanium temperature during operation of about 400° F indicates a maximum possible temperature of about 1140° degrees at the ZrO / Titanium interface and about 2800 °F at the inside surface of the Graphite insert, implying a maximum surface temperature at the nozzle throat of about 4350 °F.  A similar analysis indicates a maximum possible temperature at the inside surface of the nozzle exit of about 3300° F.

The high temperature RTV layer between the graphite insert and the ZrO layer was originally 0.005” in thickness in two sections separated by a 0.030” cork layer (a total of 0.010” of RTV); it thus should have had sufficient space, after pyrolysis of that layer, to accommodate the estimated 0.0024” thermal expansion of the Graphite Nozzle Insert.

The payload internal fiberglass support structure for the flight computer failed both at the base and at the antennae.  This structure will be redesigned in aluminum so as to provide still more robust support to the flight computer assembly.  Making this change will reduce the sensitivity of the GPS antenna and will absorb some of the transmitted energy from the telemetry antenna (the reason for going with fiberglass previously).  The effects of lower sensitivity will have to documented once that hardware is available and assembled.

The measured inflight acceleration is significantly higher than that expected from static testing and modeling of the flight trajectory; however, the burn time indicated from multiple videos is about that expected from motor modeling and the previous static test.

Analysis of the cause of the apparently higher than expected thrust has proven inconclusive.  A grain crack or void (possibly associated with the energetic AlClO initiator) would usually be expected to grow until the motor case failed.  The slightly higher than modeled initial grain area (see the report from the first flight of this vehicle for a discussion) is too small (at 0.86%) to account for the higher initial thrust (123% of the expected level). A static test motor is being prepared to try and resolve this question.

Strengthening the joint between the motor and the parachute compartment is relatively easy; additional fasteners and a thicker section to the joint should reduce the probability of a failure similar to that which occurred on this flight.  Alternatively, the motor tube could be extended by six inches to avoid having a separate parachute compartment altogether, albeit with some induced operational inconvenience when placing the initiator into the forward bulkhead.

Summary

Partial nozzle failure appears to be the main concern with this vehicle design; a secondary issue is strengthening internal components and some joints to better survive the extremely harsh conditions encountered on this flight. Finally, a cause for the apparently higher initial thrust will be sought via static testing of a new motor, which will also confirm the new nozzle design.

October 2018 meeting

Posted on by

The RRS met for our monthly meeting on Friday, October 12, 2018, at the Ken Nakaoka Community Center in Gardena. As usual, we got started by calling the meeting to order and reading the treasury report. We had a big agenda but covered most of the topics.

[X1]
Richard Garcia wasn’t able to join us at the October meeting. He wanted to report that he has made some design improvements to the RRS standard liquid rocket. He’s finished upgrading his engine design code to be able to analyze a blowdown engine (pressure-fed from the tanks). He also will soon have drawings for a thrust chamber design.

With some luck, I hope he’ll be back into testing at the MTA sometime soon next year.

[X2]
Electro Tech Machining (ETM) in Long Beach, California, specializes in graphite stock, graphite parts and Electrical Discharge Machining (EDM). They are experts and have been a loyal supporter of amateur rocketry groups such as UCLA and USC. The Reaction Research Society is happy to endorse them as they have been a great support to our society member’s projects as well.

Electro Tech Machining – Long Beach, contact information

Contact Cathy Braunsdorf at Electro Tech Machining.

Electro Tech Machining
2000 W. Gaylord Avenue
Long Beach, CA, 90813
(562) 436-9281

Electro Tech Machining in Long Beach, the graphite specialists

Electrical Discharge Machining (EDM) – Wikipedia article

I stopped in this week to pick up some round stock for making more graphite nozzle pucks for the ballastic evaluation motor (BEM) that is nearing completion. Graphite makes an excellent high temperature material for nozzle throats or any low ablation surfaces. We have used graphite inserts into reclaimed alpha and beta nozzles over the years at the RRS. Our society members have used graphite throats in their larger solid motor tested at the RRS MTA back in June 2018.

Plastic nozzle puck used for scale against the graphite round stock acquired by the RRS from Electro Tech Machining in Long Beach, CA

Moving into the meeting agenda, we shifted the order a little, but I have kept the numbering the same:

[1]
The latest educational event at Weigand Elementary school in Watts is going very well. The LAPD CSP program continues to help sponsor the event and we get great excitement from the kids. This Friday was the fifth of six educational events where they get to assemble the empty rockets. Osvaldo, Larry and Frank were on hand to help with the build process. The kids are really enjoying the process of learning and painting the team rockets will done in the last session before going out to launch at the RRS’s private testing site, the Mojave Test Area (MTA).

Two of our young participants show their assembled RRS alpha rocket at Weigand Elementary, Frank Miuccio in the background at the right

[2]
The next launch event at the RRS MTA will be the final step in the RRS’s educational program for Weigand Elementary school. We have this scheduled for October 27th and we hope to have cooler weather than in prior events now that the summer has passed. We have nine alphas from Weigand Elementary and three more alphas from our new membership, Wilbur Owens, Xavier Marshall and Michael Lunny.

Xavier Marshall looks over his first RRS alpha, welcome to the club!

[3]
I gave my quarterly briefing on the SuperDosa project at the October meeting. This time, I organized my thoughts and ideas into a presentation to give the RRS a general overview of the project and where we are so far.

Largely, I wanted to reiterate the project’s overall goals to many of the new members who have joined the RRS since the project’s inception in January 2017. The RRS intends to retake the amateur rocketry altitude record and in the process reopen our ability to make larger solid rocket motors and expand our reach both in our own community and literally with payloads ultimately flying above the atmosphere.

SuperDosa quarterly report, Oct-2018

I also acknowledged the recent progress of some of our new members formerly of the Chaminade Rocketry Club. Also, USC had a launch attempt with their Traveller III rocket, part of their Spaceshot Initiative. Unfortunately, instrumentation was not functioning but the flight looked to be nearly perfect. I hope USC will come present their recent accomplishments at a future RRS meeting.

Materials acquisition and some discussion about how to proceed with the propellant burn rate testing were the highlights of the discussion. More progress needs to be made in a few areas for completing the first prototype:

(a) Complete the design of all parts for the first prototype (6-inch booster)

(b) Begin prototyping instrumented dart payloads to practice flying and recovering these while getting good data. Making these devices work under the tight and unforgiving conditions that they must.

(c) More work in parachute recovery

(d) Estimating friction heat loads and heat mitigation strategies for the payload

Much of this prototyping work can be done at the MTA by flying smaller subscale vehicles and testing subsystems to prove they can work. More importantly, these tests give the society practice for the large vehicle testing which will reclaim the altitude record for the RRS.

The response to the SuperDosa project’s progress was very constructive and many new ideas were offered. I’m thankful to Frank, Steve Majdali, Larry, Osvaldo, Bill Behenna, Drew and Xavier for their inputs. I have taken notes and given actions to other members who are willing to help advance key areas of the project. Unfortunately, this topic was to be the last of the evening as my presentation easily exceeded the 20 minutes I intended.

The next quarterly report for the SuperDosa project will be January 11, 2019, and I hope to report a great deal of progress.

[4]
We had a last minute addition to the agenda, with Steve Majdali talking about black powder rockets and some very nice black powder rocket making tools he acquired while on travel. Black powder rockets are a classic form of amateur rocketry and involve many techniques that are broadly useful in other areas such as composite grain motors.

Steve Majdali shows the RRS his metal spindle for a cored grain type of 3-inch black powder rocket

Steve gave us a lot of great information specific to black powder making, pressing and a wealth of other practical information. Based on this new avenue of research, I felt the RRS would benefit more if Steve discussed this topic in more length in a stand-alone article soon to be published here on the RRS.ORG website.

[5]
The RRS has been in contact with the Additive Rocket Corporation (ARC) of San Diego. They are a startup company in San Diego with the goal of making high performance rocket motors using their novel design methodologies and 3D metal printing equipment. Discussions are still underway and thus there wasn’t much to tell. ARC was an exhibitor at the 75th anniversary symposium this year in April.

Additive Rocket Corporation (ARC) of San Diego at the 75th anniversary RRS symposium

[6]
In my discussions with ARC, they were kind enough to offer to 3D print a simple small liquid rocket chamber I designed. Prices are not cheap, but this futuristic manufacturing technique offers a great deal of complexity that is not easily nor cheaply replicated by traditional means. I have been in discussions with ARC and hope to have more to present at the next RRS meeting.

125 lbf thrust chamber design, uncooled; prototype for the RRS standard liquid project

[7]
Alastair Martin could not join us at October’s meeting. I was going to have him discuss the current topics of interest at the recent 21st Annual Mars Society Convention held this summer. Alastair is very involved with the Mars Society and the RRS.

Alastair will be at the November RRS meeting so we’ll put this topic on the next agenda.

[8]
New RRS members, Wilbur Owens and Xavier Marshall, are active with the Experimental Aircraft Association, chapter #96, at the Compton Airport in the Los Angeles area. EAA-96 is a like-minded group of enthusiasts centered on experimental aircraft. The EAA-96 has hangar space and a range of machining tools offered to their members.

Experimental Aircraft Association, Spirit of 96

Xavier had mentioned at the last meeting that the EAA would love to host a visit by the RRS. Accepting the EAA’s invitation, the RRS has scheduled a visit to the EAA in Compton on November 3rd at 10:00AM. The EAA will give an hour tour of their facilities and projects. We hope to foster a strong relationship between the EAA and the RRS.

Talk with Xavier Marshall, Wilbur Owens, the RRS president, vice president or secretary for details.

Experimental Aircraft Association (EAA) hangar
1017 W. Alondra Blvd.
Compton, CA, 90220
(310) 612-2751

One of the key points of discussion at this visit will be to discuss how the RRS and EAA can help each other or participant in joint projects. The RRS is interested in using the EAA hangar facilities if they are available. Annual membership at the EAA is $40 to the EAA national society and $40 more to the local chapter at the Compton Airport. As I understand but must confirm, with EAA-96 chapter membership, RRS membership can have access to the machining tools for building rocketry parts for those of us without facilities in our own homes.

Xavier had also mentioned that hangar storage was often very cost-effective which could be a service that the RRS could use as we look to expand our shop capabilities to our membership.

EAA Chapter 96 hangar, Compton Airport

The EAA hangar is just straight east and not very far from our regular meeting location in Gardena at the Ken Nakaoka Community Center just north of Artesia Blvd. (CA-Hwy 91). The address is above.

[9]
Osvaldo’s recent successful design of an alpha parachute recovery system was not able to be covered. We may expand this topic into a fully illustrated RRS.ORG article if we can not get this topic on next month’s agenda. This has been a quiet success and definitely worthy of exhibition to our membership.

[10]
Jerry Fuller of Aerospace Corporation had indicated interest in building and testing a larger subscale prototype of his liquid-infused hybrid motor grain. Aerospace had earlier this year successfully demonstrated a smaller prototype in flight at the RRS MTA. In choosing the next larger design, he has selected a common model rocketry size (98 mm) just under 4-inches which will allow him to use commercially available rocket body parts. Jerry is active with our friends at Rocketry Organization of California (ROC).

At this time, he is still working on the design until resources can be allocated. The RRS has invited him to present his results and the new prototype he has in mind. The RRS is happy to support private groups with a testing area and a community of amateur enthusiasts happy to assist.

[11]
The RRS had discussed having a small group of our membership go out to the next ROC event which is held the 2nd Saturday of the month. Unfortunately, neither I nor Drew were able to go this month. With the Friday night rains falling on the city, it might not bode well for the event at the Lucerne Valley as they must operate on the dry lake bed.

We are looking to coming out to the November ROC event in the Lucerne Valley and hope we can bring other RRS memmbers with us. In particular, some of our members are interested in getting more practical experience through the NAR or Tripoli prefect at ROC. Moreover, some of the RRS membership is seeking experience and support as we acquire letters of recommendation for the California pyro-op licensing in rocketry.

[12]
Saturday seminars have not yet been scheduled, but the RRS is still committed to offering an extended time period for fuller discussions by invited speakers.

[+] RRS member, Jim French, is a speaker of which we would be very excited to have. Jim was a development engineer at the famed Santa Susanna Field Laboratory here in Los Angeles during the development of the reliable and powerful H-1 engine and the injector for the massive F-1 engine. Later, he worked at TRW on the reliable, hypergolic fueled, Apollo Descent engine at TRW at their San Juan Capistrano testing site (now defunct). His book, “Firing a Rocket Engine” is available on Amazon and it is a great read.

Amazon.com – James A. French, Firing a Rocket Engine

[+] Reaction Research Society founder, George James, is another speaker we have been wanting to have. His founding work with his other organization, the Rocket Research Institute (RRI) was a great topic he covered only briefly at the 75th anniversary symposium in April.

[+] Rocketdyne retiree and materials expert, John Halczuk, is another potential speaker on the subject of his extensive research of the V-2 rocket. He gave an excellent talk last year at California State University in Northridge, on history of the V-2’s development and deployment. The V-2 guided many design decisions still used in modern rocketry today in both the United States and particularly in the former Soviet Union.

We were not able to discuss this topic in detail, but more information will be forthcoming, hopefully in the form of an announcement of our first Saturday seminar at the Ken Nakaoka Community Center on a Saturday morning.

[13]
The next RRS symposium date in 2019 will be set soon. Based on the powerful success of the 2018 event, the RRS has decided to further the tradition one more year. We hope to have an even better mixture of universities, private companies and government agencies.

Date to be announced in November, the RRS will hold the 2019 symposium at the Ken Nakaoka Community Center in Gardena

There was no time to formally raise the subject, but it was decided by the council members present at the October meeting that the 2019 RRS symposium date will be formally set by an offline discussion and the date officially announced at the next RRS meeting on November 9, 2018.

[IN CLOSING]
The next meeting of the RRS will be November 9th at the Ken Nakaoka Community Center in Gardena.

We will most certainly discuss the results of the MTA launch event scheduled for Saturday, October 27, 2018. I will build the agenda starting at the end of the month. Please contact the RRS secretary for ideas and information on meeting topics.

secretary@rrs.org

As per our constitution, the RRS will hold its annual nominations of officers for the next calendar year 2019 at the November 9, 2018 meeting. Voting by the administrative membership will take place thereafter and managed by our election chairman. Results will be announced at the next meeting on December 14, 2018.

Thank you for reading.

—- —-

July 2018 meeting

Posted on by

The RRS held its monthly meeting on July 13, 2018 at the Ken Nakaoka Community Center in Gardena. We got a late start (7:45pm), but we were very well attended. New member, Wilbur Owens, brought a friend of his from the Compton Aviation Museum. The RRS accepted a new student member, Bill Behenna. We also had two newcomers from Caltech stop by who were interested in joining the society.

Our July 2018 meeting gets started

We welcomed our newcomers and started our meeting with a very full agenda. Frank brought a new air launcher device he built which operates by a hand piston. We didn’t have time to discuss it but Frank is adding more teaching tools to our educational program to show how much fun even simple rocketry can be.

Frank’s hand pump air rocket launcher

We went a little out of order from the agenda, but we managed to cover all topics in this meeting that ran very late.

[1]
The first topic of the agenda was to confirm to everyone that the next launch event at the MTA will be on July 21st. We will host a new group of students completing the RRS educational program. This is another fine group of students from the Watts area and we are grateful to the LAPD CSP program for their continued support of this recurring and successful project. Frank and Larry noted that we will try to get this event started earlier to attempt to avoid the scorching heat of mid-day.

Also, we had a discussion about how to improve the society communications in the wake of a last minute unforeseen change of schedule for a launch event. This was an exceptional case and unlikely to happen again soon, but it did highlight an important aspect of RRS operations which is communicating with our membership. It is very, very important that all active members have their emails with the RRS secretary as the duty to send out the mass email falls to me. There are two ways that the RRS secretary communicates to our active membership:

    (1) the email list for meeting agenda notices

I have been building this email list and maintaining it, but I know that I am missing some interested parties. The communication between our membership is still important. Please be kind to other members and pass on the notices and encourage everyone not receiving their emails to let me know to make the proper inclusions. This is a constant work in progress and I am thankful to those who help make this happen.

    (2) posting of all launch event dates is on the RRS website

I regularly update the launch date information under the “Forum” section of the RRS website under the “Launches” tab. Modifications to the RRS.ORG website were discussed as a means to make a clearer way for anyone to see if we are “GO” or “NO-GO” before the launch event. I’m not sure what Chris Lujan has in mind, but we will discuss this issue further as time goes on. Effective communication to our membership is important. The use of other social media platforms like Twitter or Facebook were suggested, but it is not clear how widely used these platforms are with our membership that spans many generations of technology adoption.

[2]
The second topic from the agenda was my proposal for the RRS to acquire a road sign. This has been approved by the society and the cost is not unreasonable. Placement of a simple sign at the first gate leading into the RRS’s private testing site, the Mojave Test Area (MTA), will make it easier for newcomers to be sure they are going directly to our site adjacent to the Friends of Amateur Rocketry (FAR).

RRS sign at the MTA entrance

The RRS does have a great sign built on top of a metal arch right at the entrance to the MTA built by member, George Garboden, but the society felt a second smaller sign (24 inches tall by 36 inches wide) at the first gate would be another helpful feature to show newcomers the way in.

Proposed road sign for outside the first gate to the RRS MTA

Placement of the sign will be about 10 feet behind the barbed wire fence about 6 feet to the left of our larger metal gate. This should assure good visibility to those reaching this fork in the road.

We had a substantial discussion about the sign content. The results of this discussion are in the sample posted from the website. We also had a substantial discussion about mounting of the sign and the desire to have a solid structure that can withstand years of the gusting winds of the Mojave. The sign quality chosen was of the highest quality to assure a long life under the corrosive effects of Koehn Dry Lake. Richard has suggested that the sign include the RRS logo which I will look into with the vendor. The RRS has given the authority to proceed on this task.

Further to this subject, Richard Garcia has suggested the sign be accompanied by some kind of metal sculpture representing a rocket. This would nicely complement the sign, but this is a topic beyond the original scope of the meeting. In times past, George Dosa had a large metal pipe embedded vertically into the dirt which used to have fins on it like a rocket reaching the end of its ballistic flight. I think the pipe is still there but the fin decorations have been long removed.

[3]
The subject of Saturday seminars was only briefly discussed at the July meeting. In past meetings, the RRS has had special presentations made by invited guests. These are very enjoyable to our membership, but they do often run long and consume a lot of meeting time. To be more effective in our meetings, it was recommended that for lengthy presentations, the society ought to schedule a special meeting for our membership on a Saturday morning at the Ken Nakaoka Community Center in Gardena. This way, those of us with day jobs can come to the center before the heat of the day and enjoy the presentations at our leisure. The RRS has identified several potential candidates for these “Saturday seminars”, but thus far, the first session has yet to be scheduled. We will revisit this topic in later meetings. Our vice-president, Frank Miuccio, will be the point of contact on this topic going forward. Updates on this topic will be posted on this website.

[4]
The RRS director of research, Richard Garcia, discussed his progress with the RRS standard liquid rocket. This has been garnering a lot of enthusiasm as many universities have been pursuing similar goals.

RRS director of research, Richard Garcia, explains his liquid rocket prototype at the 75th anniversary symposium

The RRS has decades of experience in building these powerful but simplified launchers, but in recent times our activity in this area has been slight. Richard has made a lot of the key drawings, but is still working to finalize the dimensions and proceed with construction. The RRS membership at the meeting had the chance to review his current drawings and make suggestions. Richard will proceed with completing the design and drawings and with the RRS support begin with selection of suppliers, machinists and construction.

Richard’s rocket will use the RRS 15×15 rail launcher that we have at the MTA. The 16-foot rail length should be sufficient to guide the rocket to a stable initial flight. Further aerodynamic study will be needed to finalize the design. Preliminary pictures and features of the design will be discussed in future posts.

[5]
The next topic was the subject of pyrotechnic operators and the RRS’s mission to qualify more members as licensed pyro-op’s to expand our ability to conduct events and improve the knowledge of our membership in this important aspect of safety in operations. What we do can be very hazardous, but with the attention to detail and commitment to safety that we have shown over the decades of our history, we are blessed to not have ever had a fatality and very likely to continue this tradition long into the future.

The RRS has identified a few members including myself who are committed to starting the process of becoming a pyro-op with the California State Fire Marshal’s office. The first step is making a request to the Cal State Fire Marshal for their latest package of information which includes a PDF copy of the latest laws and regulations that every pyro-op is expected to know.

California State Fire Marshall rules on fireworks also governs amateur rocketry

In parallel, the RRS is creating a standard package of information for members that include these state provided materials and other resource materials deemed useful by the RRS to properly educate any current or aspiring pyro-op.

The second step in the process is getting five letters of recommendation from licensed pyro-ops of the same class or above the class level you are applying for. The first level of licensing is Rocket Class 3 which is what our new pyro-ops will seek. The final step is paying your exam fees to the state of California, sitting for the exam, passing the exam and getting your license information from the state. It is very important that our membership strive to keep their state license current and not let it lapse. The RRS is indebted to our pyro-ops for making a big part of what we do possible and safe.

Letters of recommendation require a licensed pyro-op to vouch for your abilities to conduct safe operations and a demonstrate sufficient knowledge and competence in all relevant areas for rocketry all in a signed document sent to the state of California. It is not an easy thing to ask of someone who doesn’t know you well. It is not uncommon and very reasonable for many pyro-ops to refuse a request for a letter of recommendation. It is the requester’s sole duty to prove themselves to each licensed pyro-op that they are worthy of their endorsement.

In the past, the RRS had many pyro-ops and by attending MTA events and participating in meetings and other society events, RRS pyro-ops would get to know you and could more easily vouch for your skills to the state. Osvaldo has been successful in securing his letters of recommendation and sending his application to the state. He is now waiting for instructions on when to sit for his examination. This is a process that can take months.

I have also been fortunate to secure letters of recommendation from licensed pyro-ops, but I am still in the process of qualifying in the eyes of other pyro-ops I have asked for their endorsement. It was suggested that the new class of RRS pyro-ops combine our efforts and share our resources. It was also suggested that we ask some licensed pyro-ops to make a presentation at an RRS meeting or special event as a way of educating us in the practical knowledge that they have gained as a pyro-op. Perhaps through these sessions, more of our members can get the letters of recommendation necessary to begin the process.

Dave Nordling assists in the loading of an RRS alpha into the rails under the instruction of pyro-op, Dave Crisalli

It is my intent to encourage the RRS to adopt a more unified approach to gaining this knowledge either by seminar or by apprenticeships that could be offered by other rocketry groups such as Rocketry Organization of California (ROC). I took the action to approach ROC and other amateur rocketry groups about sending a set of our aspiring pyro-op members to a launch event or special training session in the hope to achieve wider endorsement and help build the RRS roster of pyro-ops.

[6]
As required since the start of the SuperDosa project, I presented my quarterly update.

To remind everyone what the SuperDosa project is, it is the society’s desire to retake the amateur rocketry altitude record lost in 2004 to CXST. At a height of 380,576 feet (116 km), this is a daunting challenge, but we have a substantial amount of knowledge and experience from our past members to drawn upon. Many boosted dart designs, similar to the SuperLoki or Viper III, are capable of reaching this altitude range above the von Karman line of 328,083 feet and 4 inches (100 km).

Boosted Dart – Viper IIIa

We have decided to begin a long process to build a boosted dart type of rocket and launch it from Spaceport America or Blackrock to retake the amateur rocketry altitude record by aiming for 400,000 feet (121.92 km). This will take several attempts and perhaps a few different designs, but eventually we will succeed.

For comparison, USC recently set an altitude record for a university built rocket of 144,000 feet (43.89 km).

Some of our newest RRS members just recently fired a full-scale solid motor at the MTA with the aim of reaching 150,000 feet (45.71 km).

The vehicle that succeeds in meeting this challenge and restoring the RRS title will be named after long-time member and a mentor to many in the RRS, George Dosa. George was the first licensed pyro-op in California for rocketry and wrote large portions of the rules governing our hobby. George is still active with the society and we are showing our gratitude by using his name for this project.

SuperDosa-mockup (2)

George Dosa at the 75th RRS symposium in April 2018, third from left

Substantial progress has been made by Larry Hoffing in making sample batches of the RRS standard recipe, although I understand he had to make some deviations to the mixture due to lack of particular chemicals necessary for plasticizing and release from the mold. Addition of accelerants such as iron oxide is not necessarily part of the RRS standard mixture, but it has been used in other mixtures to increase burn rate with good results. The RRS is in the process of re-establishing suppliers for the key materials such as the HTPB binder and the ammonium perchlorate and aluminum powder of different sieve sizes.

Substantial progress has been made with some of our new members and their booster design which was unsuccessfully tested on June 7, 2018 at the MTA. The mixing procedure and some of the equipment necessary for casting larger grains will surely be useful in this sustained effort to build motor of this size. Part of the issue was poor subscale testing to get burn rate data.

The RRS is working on completing a ballistic evaluation motor (BEM) to attain proper propellant curve data which should benefit all society projects using the same solid mixture. I have not had any luck with the getting our top and bottom plate assemblies yet, but I hope my machinist will be available soon to complete all parts well before the next quarterly update.

RRS ballistic evaluation motor design concept

Some of the parts are ready. Richard Garcia was kind enough to turn out the initial set of nozzle pucks of variable throat sizes. I have the fasteners and gasket materials which need to be cut for the seals. The RRS has a 5000 psig pressure transducer and some of the fittings, but we need a short length of clean stainless steel tubing to make the pressure connection. We have a data acquisition unit, but the wiring harnesses needed to be made to route back to the blockhouse.

Chris Lujan has recommended that instead of bringing someone’s personal laptop we get a simple computer like a Raspberry Pi unit to do the data crunching and output the results. The desert environment can be very damaging and it would only take a simple computer to manage the data and output the results. Chris will work on this hardware and software aspect of the data acquisition and processing.

RRS BEM graphite nozzle pucks, courtesy of Richard Garcia

More progress on the SuperDosa progress will be presented in October at the next quarterly report.

[7]
The next topic of discussion was led by Alastair Martin. Alastair is a very active member of the RRS and the Mars Society. He is a filmmaker and producer and brings many talents to the society.

Alastair Martin records elements of Richard Garcia’s rocket candy propellant manufacturing process at the RRS MTA, 4/7/2018

Alastair discussed the necessity of the RRS embracing a larger social media presence. The benefits are that the RRS can reach a wider audience, particularly in the younger demographics. Alastair recommended that the RRS open an Instagram account and do work on improving our Facebook page that is already online. Although there are other social media platforms, it was these two services that he has the most success in his businesses.

The use of Instagram can make the society better able to show the world a glimpse of our activities from a select group of our active membership. Instagram is useful for conveniently and frequently posting photos and short videos and is virtually instantaneous. This nicely complements the website we currently use. The RRS approved the opening of an Instagram account.

Once you have the Instagram smartphone app loaded, you can find us at our Instagram ID which is our full name without spaces:
Reactionresearchsociety

Our society treasurer, Chris Lujan, generated the account and he will be primarily responsible for the RRS Instagram account. The executive council, director of research and events coordinator will be the first members to have permission to post photos to the RRS Instagram feed. The RRS will consider allowing other trusted members to post on our new Instagram account as we go on.

Reaction Research Society on Instagram

The RRS has a Facebook page. I think it is our vice-president Frank Miuccio, that maintains this site. The RRS will strive to post more often on Facebook which is widely used by many people worldwide.

RRS on Facebook

As secretary, I will continue to maintain our world-wide web site, RRS.ORG as our primary means of advertising ourselves and posting updates to activities.

[8]
After some debate and discussion, the RRS has decided to proceed with holding the 2019 RRS symposium in April next year. Although it is a substantial commitment of resources and money by the society, the 2017 and our 75th anniversary symposium were successively larger hits with our public audience. We will strive to improve our symposium based on the lessons we’ve learned and use the momentum of enthusiasm built from two very successful events. However, it was agreed that after the 2019 RRS symposium, the society will not hold another for two years. Our commitment to what will be the 2021 symposium will be pending until the year before.

The 2019 RRS symposium is coming in April.

With this decision, setting the date and starting our long process of contacting industry, academia and government speakers will begin. There will be more discussed on this topic in future meetings. We are excited to confirm another symposium and hope to make this event even better than before.

[9]
The agenda had originally stated that our next launch event at the MTA with LAPD CSP will be Saturday, July 21st. We circled back to this topic reminding everyone that the safety briefing will be conducted at 10:30 AM and the launch event will proceed at 11:00 AM. It is the goal to have all eight of the standard alphas assembled by the students launched before the heat of the noon-day sun rises. We want to encourage our membership and invited guests to this event to arrive very early which for me means leaving Los Angeles at least before 7:00 AM. Dave Crisalli will be our pyro-op for this event and I have volunteered to be his apprentice unless one of our other pyro-ops in training would like to do so.

[10]
I had an agenda item to discuss future events at the MTA including one possible event with a BBC program in the UK. This may occur in October 2018 and discussions are still in work. The RRS will likely hold another educational event with the LAPD CSP in the fall which may be able to coincide. Larry had made contact with the Girl Scouts of Orange County who were seeking the RRS to participate in a regional STEM event. All of these projects will also be discussed further at the next meeting in August 2018 as more information comes in.

[11]
Osvaldo gave our meeting audience a demonstrate of his new method of loading micrograin propellant (without the propellant of course). For some background, the RRS standard alpha is a common platform in our society events. They are particularly common with our educational classes that we hold regularly. Based on the micrograin propellant invented by our founder, George James, this simple mixture of zinc and sulfur powders presents a challenge in loading. The coupler is installed with an O-ring seal at the head end. The 3-foot long, 1.25-inch DOM steel tube with four welded sheet metal fins and holes drilled for installing the nozzle is basically an open tube closed at one end.

alpha bulkhead loaded and bolted in

RRS standard alpha configured for propellant loading; nozzle is installed at the end of loading

The 80% zinc and 20% sulfur by weight propellants are premixed by tumbling and is loaded into the propellant tube by hand. Entrapped air is a frustrating factor in getting a tight packing of the propellant into the tube. As the powder falls to the bottom, the air can not completely get out of the way and empty pockets form. These pockets can be released by simple mechanical tapping or gently bouncing the tube vertically on a wooden block. In the finite volume of the propellant tube, entrapped air is a waste of space that could be filled with the mass of propellant. The loaded weight of the alpha subtracted from the empty weight of the alpha propellant tube at the start is the only real gauge of how well packed the propellant is.

Many methods of compaction and casting of the micrograin propellant to achieve higher densities have been tried over the RRS history. Some of these have had success, most did not. This topic is a long subject which can be researched and summarized in a separate article if there is sufficient interest. For now, only the simple method of manually loading the premixed powder will be discussed.

The common method used today is to pour in the propellant mixture one cup at a time and bounce the bottom of the tube on a wooden beam. Vibration devices do work, but they tend to work too well in that the zinc and sulfur being of different densities start to separate which is very undesirable. This method of one cup at a time is slow, but effective.

a cupful of micrograin propellant drawn from the tumbling mixing drum

traditional loading method that carefully removes trapped air by periodic mechanical tapping is very slow and very messy

When the RRS started to run more launch events with schools, loading a dozen or more propellant tubes started to take a great deal of time including coming to the MTA on the night before. Osvaldo who is the main person doing this loading sought a faster but effective means to loading.

He tried a few experimental practices including drawing a vacuum at the bottom of the tube with a special fitting and using a lowered piston on a string approach, both of which were flawed and not that successful.

His most recent method has proven to be very effective and quick. He gets a length of tiny brass tubing and loosely affixes a round cardboard disk. With this cardboard disk inserted into the mouth of the tube and a proper funnel attached, the full propellant load of the alpha can be loaded directly into the funnel.

Rapid micrograin loading by small brass tube and cardboard disk

By allowing the weight of the full propellant load to lower itself into the tube on top of the cardboard disk, the disk serves as a seal to divert any entrapped air beneath up through the hole in the brass tube. The air below the solid powder mass has a route to escape through the hollow tube up the center. With this technique the whole propellant load can drop into the tube in one motion, leaving the cardboard disk at the bottom. The brass tube easily pulls out from the cardboard disk and out of the propellant tube now loaded with the micrograin propellant.

tube and cardboard disk aligned in the funnel in the mouth of an empty RRS alpha propellant tube

Illustration of rapid method of loading micrograin propellant

This technique eliminates the barrier of the air below trying to move past the falling mass of powder and results in a reasonably dense packing of the propellant all done in one shot.

Osvaldo Tarditti and his rapid method of micrograin loading; note the very small but long brass tubing and the extra large funnel to hold the full ~4 lb load of micrograin propellant

I took photos of Osvaldo’s process at the last launch event with UCLA on June 2, 2018. The pictures and illustrations I have posted of the technique that has been successfully demonstrated at the MTA are hopefully clear enough to show the principle.

[12]
This was intended to the first topic, but Osvaldo circled back it at the end. Osvaldo successfully flew a parachute system in an RRS alpha. This is a feat that I don’t think has been in done in a very, very long time. Most of our alpha rockets come back ballistically and require back-breaking extraction by shoveling out of the hard-packed dry lake bed. It has been a general goal of the RRS to encourage more payloads to be flown in the RRS standard alphas as we do a lot of these flights. It has been a goal of mine to eventually fly a parachute system in the tight confines of the alpha’s payload tube. Osvaldo developed a pull switch that activates a timer chip inside to delay the firing of a small powder charge that ejects the parachute by means of a rising piston. This was discussed in the details of the same launch event with UCLA on June 2, 2018.

Osvaldo stands behind his RRS standard alpha parachute system successfully flown at the MTA on 6/2/2018

We did not have a lot of time to show all of the parts, but Osvaldo did mention that he will fly his parachute system again at the July 21, 2018 launch event with a modified timer design and break-wire system that is more compact. I may get Osvaldo to write a full detailed article on this subject in a future posting to come. This parachute system if proven to be repeatably effective may become a standard part of our RRS launch events with schools, but we must consider the added costs of producing them with standard costs we already charge for our RRS standard alpha. This is a really good topic and I’m sure we’ll be talking more about this in August.

[BONUS]
Richard Garcia treated us to a short video made by Microcosm back in 2001 with their experimental launch vehicle that did engine test at the RRS MTA. This dual-engine liquid rocket had thrust vector actuators and went through a successful hot-firing in the video.

Microcosm’s Scorpius-S-RM-20k vehicle test at the RRS MTA in 2001

The video showed the later rocket flight. We may post this on the RRS YouTube channel for everyone to see. It was a nice way to conclude our meeting with a rocket firing and flight.

[IN CLOSING]
We adjourned the meeting very late (well past 10:00 PM) which is only possible due to the kindness of our hosts at the Ken Nakaoka Community Center which closes at 9:00 PM. We are very grateful to them, but the RRS must strive to be more effective in our meetings to start on time and finish on time.

If there are any topics for next month’s meeting, please contact the RRS and make your suggestion. In the August meeting, we will likely discuss the July 21st launch and lessons learned from that event. We also have other events planned for this fall.

The next RRS meeting will be August 10th.

If there is anything I have missed or misstated, please let me know.
secretary@rrs.org