A Tribute to Mr. George Dosa

by David Crisalli, Reaction Research Society


Some time in October of 1966, I had hitched a ride and gone down to an RRS meeting in Gardena. I was 13 and still in the 8th grade. At that meeting, I met Mr. Dosa for the first time. I met several other RRS members that evening, but Mr. Dosa was the most memorable. He was warmly welcoming, very enthusiastic about rocketry as a field of study, and also excited about having new students like me join the Society. 

As I attended more meetings and began to get involved in designing and building rockets, Mr. Dosa was always ready to offer help of all kinds from the loan of technical documents to the manufacturing of parts on the lathe and other tools he had in his garage. I spent many an enjoyable hour with him making steel nozzles, aluminum adapters, and fiberglass nose cones.

At one particular meeting in 1967, Mr. Richard Butterfield showed a 16 mm film of a hydrogen peroxide liquid mono-propellant rocket built and launched by RRS members David Elliot and Lee Rosenthal some 15 years before. I was completely captivated as I watched the two high school students in the film machine parts, fabricate sheet metal components, static test a liquid rocket motor in Mint Canyon, and then successfully launch the rocket in the Mojave Desert. Mr. Dosa saw my interest and enthusiasm and talked to me at some length about liquid rockets after the film. Then he asked if I would like to see the one he was working on. I jumped at the chance. 

The RRS meetings in those years were held in an old, small, wooden building on an isolated piece of property owned by a division of Pratt & Whitney in Gardena. It was really a shed but the RRS had been given permission to hold its monthly evening meetings there and store some of its equipment there. On the same piece of property, some 50 or so feet away, was a slightly larger wooden structure. Although larger, it was more of an empty garage and was not as suitable for meetings as the smaller building. When I told Mr. Dosa I would love to see the liquid rocket he was working on, he led me out of the meeting building and across the dark space between the buildings. It was probable nearly 10 PM by this time and there were no lights in the areas around either building. 

As Mr. Dosa opened the door into the very dark second building, he told me to wait there until he could turn on the light. “The light” was a single low wattage bulb hanging on a wire from the high ceiling. When the light came on, even in that dim glow from a single bulb, what I saw took my breath away. There, lying horizontally on a plywood table, was a bi-propellant liquid fueled rocket with the upper half of the skin removed. All of the tanks, plumbing, bulkheads, stringers, and longerons were precisely made and beautifully assembled. The rocket was more than 15 feet long and about eight inches in diameter. It was designed, Mr. Dosa explained, to run on 90% hydrogen peroxide and ethyl alcohol. I marveled as each piece of the structure and propellant plumbing was explained to me. The design was also unique in that Mr. Dosa had made the fuselage octagonal rather than round. This left him “corners” inside the rocket skin that he had used to run plumbing and wiring. The beautifully made fiberglass nose cone and boat tail were both round and the structure smoothly transitioned from octagonal to round at both ends. Mr. Dosa, a master at many fabrication techniques, had fashioned incredibly precise sheet aluminum sections that perfectly mated with the octagonal structure on one end and the perfectly round nose and boat tail on the other.

I could have stayed and talked to Mr. Dosa for hours, but it was very late now and my ride was leaving. Needless to say, I was completely stunned by what I had seen that evening and over the next several months and years, I must have made quite a pest of myself often keeping Mr. Dosa on the phone for long periods asking questions and listening to his patient explanations. From our first meeting in 1966 until I left for the Naval Academy in 1972, I met and worked with Mr. Dosa at RRS meetings and at rocket firings in the desert many, many times. Each and every time, it was a great joy to see him, talk to him, and learn from him. 

When I left for the Navy in the summer of 1972, “George” as he now had me call him, told me that he had been in the U.S. Navy during World War 2. He had met his lovely wife, Ann, overseas and brought her back home after the war. He wished me the best of luck in the Navy and asked me to stop by and see him whenever I got back to southern California.

After being gone for 18 years, I did find my way back to an RRS meeting and renewed my old acquaintance with George. In the intervening almost two decades, he had changed very little and was still as welcoming, enthusiastic, and as patient an instructor as ever. In the early 1990’s, I volunteered to restart publication of the long dormant RRS News. George was more than a little excited as he was always a huge proponent of documenting all of the projects that RRS members undertook. We began a very enjoyable and several year collaboration writing, editing, and publishing the RRS News more or less, once a quarter. 

During that same time frame, a few members of the RRS and I had started teaching a solid propellant class. As part of that class, several of us had written a course handbook. At the beginning of that course book, Niels Anderson and I had written a dedication to George because of his long, tireless mentoring of so many students and RRS members over the years. I include it here because I believe it captures the essence of who George was within the Society…


“Since the days of Dr. Robert Goddard, the United States has always had its share of rocket enthusiasts and experimentalists. In 1943, even before the end of the Second World War, the young students who founded the Reaction Research Society were hard at work experimenting with propulsion systems. As the “Space Age” dawned, the imaginations of millions were fired with the possibility of flight beyond the atmosphere of Earth. But to members of the many amateur rocketry groups forming during those days, flights of the imagination were not enough. Those with the interest, drive, and courage to try, designed and built fantastic rockets that exploded out of their launch towers on towering pillars of fire and smoke. These were not cardboard models with minuscule motors producing ounces of thrust. These were thundering metal machines, many feet long, producing thousands of pounds of thrust, and flying into the clear desert skies at unbelievable speeds. 

It was a great time of advancement, adventure, and experimentation. Some of those who built these great, unforgiving machines also became the mentors for hundreds of others who followed. These special few not only pursued their own projects, but stopped to share what they had learned with others. Guiding, advising, encouraging, they were tireless in their belief that there was much to be learned in the pursuit of amateur rocketry and they helped all who came and asked. Amateur rocketry, as a whole, owes a debt of gratitude to the few who trained and directed those of us too young and full of wild enthusiasm for our own good. They taught us many things, fed our enthusiasm for learning, encouraged us through failures, and kept us safe all the while with their knowledge and experience. 

This course is dedicated to one such man, Mr. George Dosa. George has been an active rocket propulsion experimentalist for many years. In many ways, he can truly be considered one of the founding fathers of experimental rocketry. George Dosa was the state of California’s first licensed solid propellant rocket pyrotechnic operator. He has been the back-bone of the Reaction Research Society for the last 38 years and still serves today as the Director of Research for the RRS. 

George has dedicated his life to the continuance, advancement and testing of experimental rocket propulsion systems. He represents the very essence of the golden years of experimental rocketry and has crusaded to preserve the right of new experimenters to follow this fascinating and technical hobby. Giving generously of his own time, he has contributed greatly to the education and encouragement of others. As a consequence, the Reaction Research Society would like to thank George by dedicating this first in a series of amateur rocketry propulsion classes to him personally and to his efforts in behalf of amateur rocketry over the years. ” 

Niels Anderson and David Crisalli, March 1996


George told me once that he had been born 30 years too early…he would have liked to have been that much younger when the age of rocketry began to blossom in the 1950’s and 1960’s. From my standpoint, George was born at exactly the right time. Had he been born later, we might not have met and worked together as we did. George lived for nearly a century and all through that time he was a kind, patient, and enthusiastic teacher, a gentle man with dreams of exploring the heavens. I will miss him greatly and I will say farewell (for now) with an old nautical expression….I wish you fair winds and a following sea, George. In a twinkling of God’s eye, we will meet again.

Most sincerely, 

David E. Crisalli, August 2019


David Crisalli is a lifetime member and former President of the RRS. He also is the owner of Polaris, Inc. in Simi Valley, California, a rocket propulsion testing and consulting company.

June 2019 meeting

Dave Nordling, Secretary, Reaction Research Society


The RRS held its monthly meeting on Friday, June 14, 2019, at the Ken Nakaoka Community Center in Gardena, CA. We had several discussion topics on the agenda, but we had a last minute confirmation of a special guest. Terry Price, a nationally recognized expert in composite materials, gave the society an overview of composites used in many industries including aerospace.

Terry Price, retired consultant and formerly of Cerritos College and the Center for Composites Training
Terry describes the processes involved in composite manufacture. Our special guest (seated left) was Dennis Lord, President of the Experimental Aircraft Association, Chapter 96, at the Compton-Woodley Airport.
Terry answers questions from our membership, Drew Cortopassi, Steve Majdali and Larry Hoffing.

Terry’s presentation lasted for nearly the entire meeting, but no one seemed to mind. It’s a fascinating subject with many applications. Those specific to rocketry would be composite over-wrapped pressure vessels and tubular composite air-frames.

RRS treasurer, Chris Lujan, and RRS vice president, Frank Miuccio, engrossed in the presentation by Terry Price.

Another one of our guests at the meeting was Dennis Lord who is president of the Experimental Aircraft Association, Chapter 96 (EAA 96). Dennis came to help promote the EAA and let us know that the National Transportation Safety Board (NTSB) was going to make a presentation at their meeting on Saturday, June 15th. The EAA meets every 3rd Saturday of each month.

At the very end of the meeting, Osvaldo did bring up a few topics, mainly about the past Mojave Test Area event we had with UCLA on June 1st, and the next event we’re planning with LAPD CSP on July 13th. The RRS has had some issues with the MTA site being left untidy by our guests. The RRS would like to remind our visitors to please pick up their trash before they depart.

Our concrete test pad with male anchor bolts protruding. The RRS is thinking of making a cleaner simpler interface at this part of our testing site.

Also, the use of male anchor bolts, which are commonly available at hardware stores like Home Depot, while convenient to the builder make for a terrible tripping hazard as these bolts remain planted for years. As we are getting more users at the MTA site, the number of irregular protruding bolts is growing and becoming irksome. The best solution is to work with the RRS before making changes to our concrete and using female anchor bolts which may require ordering in advance. The RRS has discussed making a common ground interface for all users to adapt their horizontal thrust stands. Although some of our past users may have to redrill their bolt patterns in their equipment, in the long run, it will be simpler and better for all. There will be more on this subject in the coming months as the RRS is pursuing several renovation projects to improve the MTA.

Frank Miuccio spoke about the latest class with LAPD CSP called Operation Progress with the students of Watts.  The first classes started in June and the class will finish with the launch event at the MTA on July 13th.

The latest event with the RRS, Operation Progress in Watts
The kids begin the paper rocket part of the class.
Paper rockets being launched from the lawn on the school grounds.

One of the last topics before we adjourned late on that evening was a new payload being made by returning RRS member, John Krell. Nearly all of our RRS standard alphas, flown by the dozens several times a year, fly with empty payload tubes. There has been much conjecture on the apogee height and burnout velocity of an RRS standard alpha micrograin rocket. Best estimates are that they are subsonic and may be reaching heights of nearly one mile. To answer these questions, a simple payload to measure barometric pressure and record the acceleration of the swift alpha.

John Krell describes the avionics payload he’s been working on to fly in an RRS standard alpha rocket.

John’s prototype is only at the breadboard stage, but he has identified the right parts for the first flight prototype using an Arduino Nano microprocessor and a 100G rated accelerometer as best estimates of the RRS alpha acceleration are at least 50G’s.

A closeup view of the prototype payload consisting of a barometer, accelerometer, and microcomputer for data acquisition.

Our next meeting will be July 12, 2019. We will discuss the topics we couldn’t cover this month including the RRS liquid rocket projects and the RRS social media improvements including adding a better calendar feature for the growing number of events we’re having.

Our next launch event at the MTA will be July 13th with the LAPD CSP.


Oxygen Cleaning: A Validated Process Is Critical For Safety

David Escobar, Director of Engineering at Metso Automation


Industrial oxygen is used for many purposes: in a basic oxygen furnace for making steel, water pollution countermeasures, including sewage treatment, habitability and superfund site rehabilitation, and chemical processes such as production of vinyl chloride, nitric acid, epoxyethane and hydrogen peroxide. It is also used for medical treatment, life support in harsh environments and industrial gasses for welding and other processes.

The production of oxygen has risen from approximately 470 billion cubic feet in 1991 to over 1.5 trillion cubic feet in the U.S. and more than 4 trillion cubic feet globally in 2014.

Oxygen is the most common oxidizing gas and is, of course, highly reactive. When dealing with an oxygen-enriched environment, it is important to control the sources of ignition. Ignition can be caused by many things, among them:

  1. Electrical arcs, which can come from electrical equipment or even static discharge
  2. Friction, which can be generated by the sliding contact of materials within the oxygen-enriched environment
  3. Impact of particles or projectiles internal or external to the enriched environment can generate heat
  4. Resonance, which is vibration-induced heating
  5. Heat of compression (HoC) is the most common cause of explosion due to contamination. Heating is caused by the adiabatic compression of a fluid; this is often called auto-ignition.

Auto-ignition is the phenomenon of spontaneous ignition of a fuel source due to the heat generated by the sudden compression of a gas or HoC. When a valve in a high-pressure or high-velocity oxygen flow is opened or closed quickly, the kinetic energy is converted to increased temperature and potential energy in the form of increased pressure. If the temperature generated by the compression exceeds the temperature needed to ignite non-metallic seals or even the pipe itself, the result is a spontaneously explosion or auto-ignition. When this happens in oxygen systems, the effect can be devastating.

A fire in a process plant

Because the HoC is substantial and can generate thousands of degrees of temperature even at moderate pressure ratios, oxygen systems are designed to limit the pressure drops to control HoC and limit temperature within the autoignition temperatures of the system components.

Thus, it is absolutely essential that contaminants, which can introduce lower auto-ignition temperatures than even the non-metallic seats and seals, be removed from any oxygen system. Any method that achieves the desired cleanliness level is acceptable. CGA 4.4 and the recently issued MSS-SP-138 provide excellent recommendations for cleaning processes.

Oxygen Cleaning A Validated Process is Critical for Safety 2
A technician moves hardware in a clean room using proper protective equipment

CONTAMINANTS TO BE REMOVED

Basically, anything that promotes combustion or impact product purity is considered a contaminant. ASTM G93 categorizes contaminants into three types:

Organics

  • Volatile Organic Compounds (VOC)
  • Hydrocarbon-based greases and oils

Inorganics

  • Nitrates
  • Phosphates
  • Water-based detergents and cutting oils
  • Acids/solvents

Particulate

  • Particles, lint and fibers
  • Dust – Weld slag, etc.

Specifications vary on cleanliness level, methods and validation, and include how much residue is acceptable, what method of cleaning can be used and what kind of inspection must be conducted.

CLEANING METHODS

Mechanical cleaning is used to remove scale, coatings, paint, weld slag and other solid contaminants and can include grit or ice blasting, wire brushing and grinding.

Aqueous cleaning can be with hot water and steam cleaning or alkaline cleaning. Hot water and steam cleaning is effective against water-soluble contaminants, and is normally used with detergent. Alkaline cleaning uses caustic salt in water to create a highly alkaline solution. It is effective against hydrocarbon oils, grease and waxes, and generally is enhanced by agitation and/or jet spraying. Typically this is used for industrial parts washers. This process is greatly enhanced by ultrasonic agitation, but the solvent residue must be removed as well.

Semi-aqueous cleaning uses hydrocarbon solvent and water emulsion, which is effective for removing heavy contaminants from parts like heavy grease wax or hard to remove soils. Emulsion may require agitation to maintain the mixture, and parts must be rinsed before the emulsion can dry. Otherwise, contaminants may re-deposit on the part that was cleaned.

Acid cleaning varies substantially based on the acid used.

  • Hydrochloric acid is used to remove scale, rust and oxides. and to strip platings (chrome, zinc, cadmium, etc.) and other coatings
  • Chromic and nitric acid are used to for passivating, deoxidizing, brightening and removing alkaline residues in addition to cutting oils
  • Phosphoric removes oxides, light rust and fluxes

Acids must be removed completely from the part prior to drying and, depending on the acid strength, may need a neutralizing process.

Solvents can be used without water dilution or emulsion. Alcohol is a common solvent often used to revisit areas of concern identified by black (UV) light inspection. Solvents like alcohol evaporate completely, leaving no residue.

Vapor degreasing is a process in which a solvent is heated until it vaporizes, while the part is maintained at a lower temperature. The solvent then condenses and dissolves contaminants. The part must be oriented so that the condensed solvent can drain from the part by gravity. This method is very effective for inaccessible areas on parts but requires a contained environment for the part during the process.

Any combination of cleaning methods that achieve the desired cleanliness level is acceptable.

INSPECTION METHODS

Visual inspection can be direct, including white light, which is effective in detecting contamination down to 500 mg per square meter. UV (black) light visual inspection identifies contaminants that fluoresce and is effective in detecting contamination down to 40 mg per square meter.

Indirect visual inspection is done in two ways: wipe test and solvent filtering. A wipe test can identify contaminants in locations that have no direct line of sight. Typically, both white light and UV light are used on the wipe cloth, and are effective in detecting contamination down to 30 mg per square meter. Solvent filtering rinses the inaccessible area in solvent, which is then filtered to capture contaminants. The filter is then visually inspected and can detect 100 ml per square foot of low residue solvent and it also uses white and UV light.

Oxygen Cleaning A Validated Process is Critical for Safety 3
White light inspection of cleaned surfaces

Quantitative inspection is done by evaporating the solvent used for cleaning and obtaining the weight of the remaining effluent. Acceptable levels of residue vary according to user requirements.

ADDITIONAL CONSIDERATIONS

Clean room: This provides a designated location where the environment limits dust airborne particles, where clean tools and clean assembly and test equipment can be stored. It can also provide controlled lighting for visual inspections.

Clean test equipment: Pressure test equipment contains contaminants in hoses and pumps. If a test machine cannot be dedicated for clean testing, give special consideration to cleaning of test equipment or alternate testing with clean gas.

Packaging: After cleaning, give specific instructions on how to package the product to preserve cleanliness in shipping and subsequent storage. Consider the role of desiccant as a possible contaminant. Use compatible products or control desiccant to prevent contamination. Consider the addition of actuation and accessories to the valve. Can the actuator be installed and set up without violating the protection? If the protection is compromised, are there procedural steps to identify and remediate any contamination?

SUMMARY

Oxygen cleaning is used to remove contaminants that can significantly reduce the temperature of auto-ignition. There are many methods for doing the actual cleaning. CGA 4.4 and the recently issued MSS-SP-138 provide excellent recommendations, but any method that achieves the desired cleanliness level is acceptable. It is important to know what level of cleanliness your standard process produces. Process validation using a quantitative measurement allows the supplier to have confidence in process quality when using qualitative inspections for production work.


Editor’s Note: The following article was posted on April 20, 2015 in Valve Magazine.com. It is reprinted here for the Reaction Research Society (RRS) with permission from the author and Valve Magazine. The information here is very useful in amateur rocketry and is intended to make our readers aware of the importance of a proper oxygen cleaning process for lines and valves. High purity oxidizers must be handled with care and cleanliness is of paramount importance. The RRS would like to thank David Escobar of Metso Automation and Judy Tibbs, Director of Education at the Valve Manufacturers Association and Editor in Chief of VALVE Magazine.

David Escobar is director of engineering at Metso Automation. Reach him at david.escobar@metso.com.

CGA refers to the Compressed Gas Association. Founded in 1913, the CGA is an organization dedicated to the development and promotion of safety standards in the industrial, medical and food industry. The CGA is comprised of over 110 member companies worldwide working together through the committee system to create technical specifications, safety standards and educational materials; to cooperate with governmental agencies in formulating responsible regulations and standards; and to promote compliance with these regulations and standards in the workplace.

For more information, go to the CGA website:

www.cganet.com

MSS refers to the Manufacturers Standardization Society of the Valve and Fittings Industry. Standard practices (SP) documents are available related to many applications including the standardized practice of oxygen cleaning (ANSI/MSS SP-138). ANSI or the American National Standards Institute has adopted the standard for oxygen cleaning of valves and fittings.

https://webstore.ansi.org/Standards/MSS/ANSIMSSSP1382014

ASTM stands for the American Society for Testing and Materials. It is now an international organization known simply as “ASTM International” with its headquarters in West Conshohocken, Pennsylvania. ASTM publishes voluntary consensus technical standards including ASTM G-93 for the Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments.

For more information, go to the ASTM International website:

astm.org