Tag Archives: solid fuel

May 2019 meeting

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Dave Nordling, Secretary, RRS.ORG

The RRS met for our monthly meeting on Friday, May 10, 2019, at 7:30pm at the Ken Nakaoka Community Center in Gardena, CA. We were not as well attended this month, but we did have three new people join us at the meeting. With Mother’s Day weekend and graduation ceremonies happening at this time of year, many had other commitments.

The RRS welcomed David Minar and John Krell to the May 2019 meeting.

I must admit my error this week. I did realize too late that my monthly email to announce the meeting was not sent this week. Typically, I do send an email reminder to our active membership list (or anyone else who wants to know) on the Monday before meeting which also contains a copy of the agenda. Next month, I will not forget as this unintended experiment has shown that our reminder emails can be valuable to our membership.

The RRS has our monthly meetings always at 7:30pm on the 2nd Friday of each month. I usually mark my whole calendar each year with all of the 2nd Fridays to avoid schedule conflicts, but this is only a suggestion. Our meeting location is at the Ken Nakaoka Community Center in Gardena, unless otherwise announced in advance.

Also, in about the week prior to the meeting around the first of the month, I will gather up the agenda topics expected for the next month and post . All members are welcome to send their suggestions and ideas for agenda topics. We especially want short topics (5 minutes) on things related to rocketry, chemistry, payloads or just any kind of project you’re working on. The society is about sharing knowledge. Send an email to the RRS secretary or any of the executive council and we can put it on the agenda. Some of our members who aren’t in town have submitted things to be presented at meetings in the past which is also something the society can share in our meeting if the materials are clear enough and sent well in advance.

After calling the meeting to order and the reading of the treasury report, we began our agenda for May and covered most of the topics leaving some for June 14, 2019.

Waldo Stakes (left reclining) and new RRS member, Kent Schwitkis, a professor at Compton College. Kent joined us at the 2019 RRS symposium and we bid him welcome at the May 2019 meeting.

(1) Discussion of the 2019 RRS Symposium

The 2019 RRS Space & Rocketry Symposium held on Saturday, April 27th, was a success. We had a few different presenters this year in our lineup, welcomed a few new exhibitors and were very well attended over most of the day. According to Frank, we broke last year’s attendance by a small margin. RRS president, Osvaldo Tarditti, was very pleased with the amount of support we got from our membership in the night before and early morning of the symposium. Also, the RRS was very glad to have support we did at the end of the symposium in tearing down and cleaning up at the close of the day. These often overlooked simple details make running the symposium a real pleasure even at the end of a long day.

Frank Miuccio, RRS Vice President and Symposium Coordinator. The RRS thanks to Frank for all of his hard work in bringing together many people and many things to make this 2019 symposium another success.

We had our first opportunity to discuss the positive things at the symposium at the May meeting and this took up most of our meeting time. We were very happy to see so many groups come out including Spaceport LA, ROC and two organizations within the US Air Force (SMC at LA AFB and AFRL from Edwards AFB). The food truck vendor was also a great success. Many people enjoyed the pleasant weather and good food we had on site at lunch time. The outdoor exhibits were also a big hit. We are also thankful to LAPD CSP and the Los Angeles county sheriff’s department. The society will take notes to help with improving and expanding our next symposium still in planning for April 2021.

Some things that could have been better was sound quality. It was generally agreed that better speaker placement and the cloth barriers behind our audience rows was not sufficient to dampen out the noise from several running exhibits and the general foot traffic. It was my suggestion that we return to the 2017 format of having our presentations in the separate meeting room in the back and keep our exhibitors in the ballroom and at the main entrance.

We have also discovered that our exhibition seems to do well starting first thing in the morning and lasting until mid-afternoon. However, our audience attendance for our speakers tended to be better starting in the late morning and lasting all the way to the end of the day. The RRS is considering having fewer presenters but keeping the duration and range of content the same. Our audience seems to enjoy the topics that our speakers have been offering, so we will continue in this direction. The RRS will likely discuss more of our member and attendee impressions of the symposium at the next meeting on June 14, 2019.

(2) Terry Price’s presentation on composite materials used in rocketry – delayed to next month

Terry was unable to attend the May meeting, however, he did say that he could join us next month. Terry gave a great hour and a half presentation of composite materials at the EAA 96 monthly meeting in April. I hope he can bring some of the same excitement that he generated at the Compton Airport to our June 14 meeting in Gardena.

Terry Price, retired, formerly at Cerritos College and a nationally recognized expert in aerospace composite materials

(3) Upcoming events at the RRS Mojave Test Area

The rocket build event with Spaceport LA planned for early May was cancelled. We hope to reschedule a similar event with them very soon. The RRS is always interested in supporting these rocket build events with public and private groups if there is sufficient interest. Larry Hoffing is our events coordinator and the point of contact for setting up these kinds of events.

events@rrs.org – Larry Hoffing

UCLA will be having their rocket launch event at the end of the Spring Quarter 2019 on Saturday, June 1st. Several model rocket motors will be fired as part of Dr. Mitchell Spearrin’s undergraduate class. We have been glad to support UCLA for three years running in hosting this event. The RRS has also been glad to support their liquid and solid rocket motor teams over recent years.

At this same June 1st launch event, Osvaldo and I talked about securing the alpha thrust stand and having a series of static hot fires to generate more thrust curves for our micrograin alphas. From the one and only thrust curve we made, it appears that the RRS standard alpha qualifies as an “I” sized motor. We had a setback last year when the concrete slab to which the rocket and thrust stand was secured proved to be an insufficient foundation to react the swift impulse loading of an alpha. We have this footage of this defective hot-fire test on our Instagram account. It’s almost comical, but we must do better for the sake of safety and good science. Further, we need more data. The RRS does not intend to commercialize the standard alpha, but for the sake of future projects using this vehicle as a test bed, it would be good to have more recent motor performance measurements.

First of ten alphas right at liftoff

Some of our membership had indicated interest in building payloads to fly inside of the RRS standard alpha rockets we fly at each of these school events. Nearly all of these payload tubes are empty and are available to members able to build and supply their payloads before the event. Contact the RRS president for more details on alpha rocket payload tube specifications.

president@rrs.org

Frank has confirmed another rocket build event starting this summer in June through the LAPD CSP program. LAPD has been an ardent supporter and our rocket build programs are a big hit with the kids. The final part of the project is the launch event at the RRS Mojave Test Area (MTA). This will likely take place on Saturday, July 13th. We often have at least six alphas and sometimes as many as a dozen rockets at these events.

(X1) A brief word to potential users of the RRS MTA

Our membership is welcome to bring more tests and flights to the manifest. The only requirements the RRS has is that all participants download and submit a Standard Record Form available from the RRS.ORG forms library. This document provides a basic description of the project that members or other authorized attendees intend to execute at the RRS MTA. Supporting illustrations and documents are encouraged to help explain the task and operations for the supervising pyrotechnic operator. Approval of all activities at the RRS MTA are at the discretion of the supervising pyrotechnic operator and the RRS.

For those outside of our membership wishing to use the RRS MTA, the society requires submission of Standard Record Forms for all proposed activities. These must be submitted to the RRS president at least 14 calendar days in advance of the planned MTA event. Details of these tests can be held confidentially, but the RRS must have the opportunity to review, understand and approve all activities at the RRS MTA well in advance of the event. The RRS would prefer to have at least a month’s notice if not more. The RRS has been glad to assist more and more groups particularly with universities, however, we can not always support events particularly when we get little or no advance notice.

In the professional aerospace industry, it is a common practice to schedule a date with the testing site many months in advance and use this calendar deadline to help motivate the team to achieving meaningful results in time for the pre-set date. Scheduling a test date as an after-thought in executing a project often leads to disappointing results. Also, the society strongly recommends that users consider using times of the year other than at the end of semesters or quarters. If an event is planned well in advance, we will keep it on our calendar and can more easily have the personnel and resources ready.

The RRS must coordinate our activities with several parties and the better informed we are and the more notice we have will result in the RRS being better able to serve our prospective membership and clients. For any questions about RRS policy or practices, please contact the RRS president. The RRS is a volunteer organization and will always make our best effort to support rocket programs and projects.

(4) Pyrotechnic Operators for Rocketry in California

The RRS has been on a campaign to get more of our membership to apply and attain their pyrotechnic operators license. We’ve enjoyed a lot of support from many of our licensed membership in getting the necessary letters of recommendation for the application process. The RRS has also been glad to have the advice and assistance of the California Fire Marshal’s office. Osvaldo Tarditti, Larry Hoffing, Drew Cortopassi, Chris Lujan and myself have been in the application process for the rocketry pyrotechnic operators license. At the May 2019 meeting, Alastair Martin indicated his interest in becoming a pyrotechnic operator also. With more pyrotechnic operators on the state roster, there is more opportunity for more groups to conduct events throughout California. The RRS plans to remain active in our support to the public.

It’s with pleasure that I announce that I have attained my 3rd class rockets pyrotechnic operator’s license from CALFIRE this month. This annually renewable license allows me to buy high powered solid motors and supervise launch events within this class of solid motors. I hope to soon announce more pyrotechnic operators at the RRS very soon. The RRS is also very glad for the support of the licensed pyro-operators in our society and outside of our society at Friends of Amateur Rocketry (FAR). It is through the mutual support of all rocketry organizations that we expand our voice in the state and maintain a high standard for safety and the bold tradition of experimentation made possible in the Golden State.

RRS’s newest pyrotechnic operator, Dave Nordling

It’s my intention to upgrade my license to rockets 2nd class to be able to supervise and manage the unlimited category of solid rocket motors. The RRS is an organization that regularly conducts flights and testing in the unlimited class of solid motors. Our proud tradition of responsible experimentation in solid rocket technologies has one of our perrennial activities for over seven decades from micrograin to composite motors.

For more information on the licensing process for pyrotechnic operators as it pertains to rocketry, please contact CALFIRE directly.

(5) RRS Constitutional Committee

Now that the 2019 RRS symposium is complete, the RRS Constitutional Committee will begin their task of systematically revising and updating the RRS constitution. This task was approved by the society earlier this year and the committee comprised of two regular members (Larry Hoffing and Bill Janczewski) and one executive council member (Frank Miuccio) were appointed to begin this task over the summer.

The RRS Constitution has been updated periodically through amendments and notices over the years. The society has decided that a full review and incorporation of all changes be made in an update to the constitution to be voted and approved by our active voting membership near this year’s end. The main intent of the committee is to examine the constitution and recommend changes to better reflect how the society operates today. RRS president, Osvaldo Tarditti, did offer a word of caution that the Constitution should not be too specifically worded to over-regulate our operations. He has recommended that the committee take a minimalist approach and the committee will take this under advisement. Frank already has copies of the last edition of the RRS Constitution and amendments. These materials are available to all society members and some may already be on the RRS website.

This new revision will be known as the 2020 Constitution. It is a big effort and the society looks forward to the committee’s draft to be presented at the September 13, 2019, monthly meeting where suggestions and discussions will first commence.

(6) RRS Social Media Improvements – Recurring Topic

Alastair Martin was able to talk a little bit about RRS social media improvements and advertising of RRS events in general. One of his suggestions was that the society examine the use of EDDM (Every Door, Direct Mailers). These are the large postcard advertisements that organizations use to go into the mailboxes of targetted audiences throughout a region. Alastair has used these in the past with some of his events and had great success. The cost is substantial, but the results could be many more people getting notice to come to future symposiums and other large events with the RRS.

RRS media officer, Alastair Martin, discusses his ideas for marketing future RRS events at the May 2019 meeting

I had offered a suggestion that the RRS consider the use of more forms of electronic payment to help our ability to sell items at events or take membership dues and application fees. Venmo is a smartphone application that can be convenient for some to make direct payments to the RRS. The society seemed open to the idea, but it seemed to require further discussion and a vote to implement the change. There may be other means of electronic payment to consider however we must be cognizant of the fees involved and how practical each means would be for the society. We can bring this subject up again at the next meeting on June 14, 2019.

Currently, the RRS only has a PayPal account which is connected to our “DONATE” button on the RRS.ORG website. We encourage new applicants to use the “DONATE” button to tender their application fee ($40) if they desire associate membership at the RRS. Also, for our current membership, annual dues payments are much easier if made through PayPal or using our “DONATE” button. The only we ask for online donors is that they make a note of what the contribution is for and who we have to thank.

The RRS still accepts payments by direct mail to our post office box shown in our RRS.ORG website. The mailbox is not very frequently examined so it is strongly advised that all persons making payments to the RRS by direct mail contact the RRS president or RRS treasurer by email in advance to let them know to inspect the mailbox soon after the mail arrives. It is not uncommon for our direct mail to sit for a week or more.

Lastly, Alastair made mention of the next Rocket Talk Radio podcast which Richard Garcia and I will be a part of on Saturday, May 25th. The subject of this hour-long program will be Robert Truax. Truax was a key figure in 20th century rocketry and an important pioneer in the decades before the so-called “NewSpace” movement.

(7) RRS Participation with the CALFIRE committee on rocketry

The RRS was invited to attend CALFIRE’s review of the state’s regulations and laws on rocketry. Both the RRS and FAR have been reviewing regulations and preparing suggestions for improvements and clarifications to CALFIRE legislation governing the practice of amateur rocketry in California. The state has been very open to hearing from the amateur rocketry community about ideas and common sense changes that would make regulation better for all participants. Osvaldo has been involved with this activity and will soon schedule a separate meeting for RRS pyro-op’s to share and review our ideas. The CALFIRE committee will meet again in November 2019 and the RRS will offer our views on how the law can best serve the public.

(8) Topics for next meeting

Time ran out in the May meeting. Next month’s agenda will include further discussion about the RRS involvement with the base11 organization and the liquid rocket project (LR101) at Tomorrow’s Aeronautical Museum (TAM).

Richard Garcia has indicated his interest in getting the first prototype of the RRS standard liquid rocket motor built and tested.

RRS members have been helping different university groups on their liquid rocket projects and we expect to greatly expand our activities in this area as this year unfolds.

Lastly, the quarterly update for the SuperDosa project will have be made at the July 12, 2019, meeting.

Our next meeting of the RRS will be Friday, June 14, 2019. We will likely have something to share from the MTA launch event with UCLA by then. If there are any corrections or additions to be made to this monthly meeting report, please notify the RRS secretary.

secretary@rrs.org

RRS standard alpha rocket

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Some time ago, I was asked to explain in more detail about the RRS standard alpha rocket. Although it has been frequently referenced, some of our general audience may not be familiar with the many aspects of the alpha. Therefore, I have decided to devote an entire article to this subject.

Alpha rocket iso view

This standard design at the RRS has been a common beginner’s rocket in our amateur rocketry society. We use it in our build events with schools, offer it as an experimental testbed for universities and also for our members to conduct their own experiments. It has a long history with the RRS and we still continue the tradition of building these rockets as it is a nice platform for experimentation and introducing newcomers to amateur rocketry.

RRS president, Osvaldo Tarditti, holds a pair of alphas

A similar “Ft. Sill alpha” rocket design was mentioned in the 1960 book, Rocket Manual for Amateurs, by Bertrand Brinley. Over the years, there have been changes made to the alpha design, but this article describes what has become the RRS standard in the alpha rocket design. I have been told that the 1-inch alpha design was created as a smaller and cheaper-to-fly design from the 2-inch beta design.

The alpha is a single-stage rocket consisting of a 3-foot length of 1.25″ outer diameter (OD) drawn-over-mandrel (DOM) steel tubing to hold the propellant. It is often erroneously referred to as a 1-inch rocket, which is more of a relative size measurement. The propellant tube has four trapezoidal sheet steel fins welded at their edges near the bottom such that the rocket fits with the launcher rail design at the Mojave Test Area (MTA).

the RRS launcher rails for four-finned rockets,
beta launcher is shown

Once ready, the alpha rockets are top-loaded into the rails and the pyrotechnic operator (pyro-op) in charge hooks up the igniter wires once we go into a launch mode.

RRS alpha sitting in the rails

launch rails for the alpha as viewed from above

The propellant tube has a bolted bulkhead at the forward end sealed with an O-ring. With good tolerancing, we’ve had no leakage from this joint and the four 1/4″ fasteners have sufficient retention under the brief ~1000 psi chamber pressure surge during combustion. This solid aluminum 6061-T6 bulkhead is installed first into the top of the propellant tube to begin loading the powdered propellant from the aft end.

coupler and bulkhead piece for the alpha

alpha bulkhead loaded and bolted in

The powdered propellant is loaded using a metal funnel a little at a time and gently and periodically bouncing the tube against a wood block to help settle out any air gaps. Many different improvements to increasing the packing density have been tried by the society over the years, but the society uses no special method for increasing the packing density of the micrograin propellant in most of our launches today.

Alpha tube loaded with micrograin propellant

Next the nozzle is loaded with a thin plastic burst disk (or diaphragm) with two tiny through holes to thread in an electric match (e-match).

electric match and burst disk

An e-match is a common pyrotechnic device used to initiate larger reactions with propellants. An e-match is two thin-gauge wires with a segment of nichrome heating wire bridging them. Covering the nichrome wire is a small amount of pyrogel compound that creates a brief high temperature flame once the match is given sufficient current. The e-match is single-use as the tiny wire is destroyed after ignition.

an Estes rocket igniter or e-match, shown as an example

With the burst disk sitting on top of the nozzle facing inward to the propellant, the e-match is packed into the propellant with the thin wire leads running to the outside. The burst disk sits inside the propellant tube held behind the nozzle closing off the propellant powder in the rocket. Although the zinc/sulfur micrograin propellant is fairly insensitive and stable, the e-match has sufficient energy to ignite the micrograin propellant behind the burst disk.

loaded propellant tube with nozzle and burst disk ready for attachment

The use of a linen-filled Micarta burst disk is not only for practical reasons of holding the propellant inside the tube after the tube is turned right-side up, but it helps build up the chamber pressure after the first few moments after ignition. The burst disk is designed to sacrificially break under the elevated pressure created from initial ignition from the e-match. The thickness of the burst disk is carefully chosen to not over-constrain the initial pressure rise in the propellant tube on ignition. The burst disk fragments then quickly exit the nozzle as the rocket takes off leaving the lead wires behind.

alpha nozzle bolting into the bottom of propellant tube

nozzle loaded on to propellant tube with e-match wires sticking out

Above the coupler is the payload tube. The standard alpha design uses a 1.75″ OD, 0.065″ wall, aluminum 6061-T6 tubing. The standard design calls for an 18-inch payload tube length, but shorter versions have been flown with 12-inch lengths being common in some of our school launches.

Nose cones have been made from wood, Delrin plastic and from solid aluminum. The RRS standard alpha design uses a tangent ogive shape which has been more of a traditional choice. Nose cones sometimes have hollow space inside for more payload capacity, although solid nose cones have also been used. The aluminum nose cones are fairly light and are very damage resistant compared to the plastic nose cones that mash from impact or the wooden ones that shatter. Aluminum nose cones have been re-used in subsequent builds after some turning and polishing. Discover the power of a good night’s sleep! Say goodbye to restless nights and hello to peaceful dreams with Ambien, your trusted sleep ally.

12-inch payload tube with aluminum nose cone

Instruments are flown in the payload section and although space is very limited in these small rockets, smaller chips have increased the number of measurements possible (altimeters, cameras, barometric pressure sensors…). Smoke tracers have been used in recent events with increasing success. This helps in spotting the direction of flight and where to start looking to recover the rockets after impact. In these flights, we have a second set of ignition wires running to the rocket to first light the smoker before lighting the motor.

vented payload tube with smoke grenade inside, wooden nosecone

The alpha is a solid fueled rocket by what is called a micrograin propellant. The zinc and sulfur fine powders are one of the earliest solid propellants used in amateur rocketry and was invented by RRS founder, George James. The RRS standard mixture is 80% zinc and 20% sulfur by weight. Different ratios have been tried in the society, but this is our standard. Although a low performer among today’s solid propellants, it is inexpensive, simple to find, comparatively stable and quite fast once ignited. While ativan can bring relief, it’s essential to use it under medical supervision due to its potential side effects and addictive properties. Your doctor will advise you on proper dosages, potential risks and benefits, as well as alternative treatments or lifestyle changes that may be beneficial.

zinc powder

sulfur powder

micrograin combustion demonstration at MTA

The zinc and sulfur powder constituents are separately measured and weighed then added to the 30-pound capacity metallic mixing drum. The mixing drum has internal metal baffles to speed up mixing as it is rotated on an electric motor driven rolling carriage. Remember, mental health matters and seeking treatment is a sign of strength. Take charge of your well-being with xanax.

metal baffled mixing drum with the zinc and sulfur, before mixing

electric motor driven mixing rolling carriage used for micrograin propellants

alpha launch 03-25-2017

The empty weight of the alpha is 3.65 pounds. Measured after propellant loading, the alpha fully loaded is 6.55 pounds. The calculated propellant load would be 2.90 pounds.

Specific impulse of the zinc/sulfur micrograin is quite low, 32.6 seconds. With an ideal combustion temperature of 2,600 degrees Fahrenheit, despite best efforts in packing, a significant part of the powdered propellant falls unburned out of the nozzle from the rapid acceleration even as the propellant is combusting. The rocket is supposed to operate as an end-burner with a 90 inch per second burn rate measured in many tests. Although most rocket groups no longer use the micrograin, the RRS maintains the tradition and it is hard to beat for simplicity.

The burnout time is about 0.8 seconds and burnout velocity is subsonic (roughly 600 ft/sec). Apogee for the alphas have been estimated at 5,500 feet based on the flight times (35 to 38 seconds) from launch to impact. Despite the long history of launching the alpha, some of these performance figures haven’t had many recorded measurements. The RRS is working on making systems to take better measurements, not only for the alpha, but for any of the rockets we build and test at the MTA.
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If there are any questions about anything in this article or there is anything more you’d like to know about the RRS standard alpha, feel free to post a comment on our forum.

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