Dave Nordling, Secretary, Reaction Research Society
The pioneering theoretical and experimental work that formed the basis for the modern practical liquid rocket was published 100 years ago today.
A Method of Reaching Extreme Altitudes, by Robert Hutchings Goddard (1882-1945), was published by the Smithsonian Institution, on May 26, 1919. Considered the father of American rocketry, Goddard developed the theory of his work while at Princeton University in 1912-1913 with experiments undertaken during 1915-1916 at Clark University.
This 79-page paper described a series of practical experiments using nitrocellulose “smokeless” powder combusted within an enclosed chamber through a de Laval nozzle both in the ambient environment and under vacuum conditions. This paper also included mathematical derivations to develop a theory of rocket action taking in account air resistance and gravity with the goal of determining the minimum initial mass necessary for an ideal rocket to deliver a final mass of one pound to any desired altitude.
In his research, Goddard sought to devise a practical means to send instruments above the range of sounding balloons (about 20 miles) to explore the upper atmosphere. What makes this work fascinating is how much was known at the time of his paper’s publication versus how much was yet to be learned and become common knowledge in our time. Very little was known about the nature of the upper atmosphere in 1919. Yet, the basic concept of a rocket with a restrictive nozzle was known for centuries in the Chinese civilization and later in Europe with the 19th century British Congreve rockets.
In this scientific work, Goddard meticulously lays out his plan of research and the incremental progress he made to verify each of his claims. Most significant is his first conclusion on page 34 that his experiments in air and in vacuum prove that the propulsive force from a rocket is really based on a jet of gas having an extremely high exhaust velocity and is NOT merely an affect of reaction against the air.
Goddard’s work did not receive much funding during his lifetime. His work in rocketry even invited the ignorant criticism of the New York Times and others in the public which had a profound affect on Goddard in his lack of willingness to collaborate even until his death in 1945. In all fairness, it should be noted that the New York Times did see fit to offer an apology to Goddard 24 years after his death and only 50 years ago (in 1969) in the weeks before the Apollo 11 flight that landed the first two men on the moon by a multi-stage rocket operating quite well in the vacuum of space without a media for the vehicle to react against.
Goddard was awarded two patents in 1914, one for a multi-stage rocket and one for a liquid-fuel rocket. Considered an iconic work of 20th century science, all rocketry enthusiasts, students and professionals owe themselves the privilege of reading Dr. Goddard’s 1919 monograph which would lead to the first successful test of a liquid rocket flight in 1923 and the first successful liquid rocket flight on March 16, 1926 in Auburn, Massachusetts.
Goddard’s early discoveries included the determination that fins on a rocket by themselves were not sufficient to stabilize a rocket in flight. Goddard’s inventions included movable vanes to vector the rocket exhaust stream in flight and a gyroscope-based control system to effectively guide a rocket in flight.
Although relatively unappreciated in his home country, Goddard’s work was noticed by the Germans and in years later leading to their own rocket development program leading to the V-2 ballistic missile used to terrifying effect during the latter portion of the Second World War. During the Cold War, the V-2 was the heritage of the first rockets by the first space-faring nations.
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:
Electrical arcs, which can come from electrical equipment or even static discharge
Friction, which can be generated by the sliding contact of materials within the oxygen-enriched environment
Impact of particles or projectiles internal or external to the enriched environment can generate heat
Resonance, which is vibration-induced heating
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.
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.
CONTAMINANTS TO BE REMOVED
Basically, anything that promotes combustion or impact product purity is considered a contaminant. ASTM G93 categorizes contaminants into three types:
Volatile Organic Compounds (VOC)
Hydrocarbon-based greases and oils
Water-based detergents and cutting oils
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.
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.
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.
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.
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?
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.
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:
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.
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:
The RRS held our monthly meeting on April 12, 2019 at the Ken Nakaoka Community Center in Gardena. We had a full agenda with the 2019 RRS symposium just around the corner on Saturday, April 27th.
We first welcomed two new members, Keith Yoerg and Jonathan Martinez. Keith is active with Tomorrow’s Aeronautical Museum (TAM) at the Compton Airport and has given many educational programs to local schools. He’s also a graduate of USC and a former member of their Rocket Propulsion Laboratory (RPL). Jonathan Martinez joins the RRS as a student member from Compton High School. He’s been working at TAM and the RRS hopes to help him in his new project to hot-fire a liquid rocket.
We next talked about the recent launch event with LAPD CSP and Compton Elementary. The “Rockets in the Projects” program is going strong and we were glad to welcome Compton Elementary to our workspace and launchpad in the Mojave Desert.
Under very pleasant weather, we had a good launch event starting with a tour, safety briefing and the kids finally getting a chance to see their rockets fly into the blue sky. Osvaldo had a seventh alpha rocket with a parachute system, but somehow failed to deploy. USC static-fired a six-inch custom solid motor.
After Compton Elementary and LAPD CSP went home, Osvaldo, Frank, Larry and I did a little reconnaissance for the alphas we flew at the event. We were able to find 3 of the original 6 and one more alpha from the past MTA launch event. The higher level winds have been carrying the alphas in a more northerly direction west of the launch rails. For reference, Osvaldo recorded the following coordinates for one of the alphas found: 35* 21′ 16.83″ North, 117* 48′ 50.03″ West.
The 2019 RRS symposium was the next topic. We have over 300 Eventbrite tickets sold at the time of the meeting. The symposium has confirmed a full roster of speakers including AFRL Edwards AFB, Northrop-Grumman, USAF SMC. We decided not to hold the panel discussion this year. The symposium will start at 8:45AM on Saturday, April 27th.
The Ken Nakaoka Community Center in Gardena will allow us to set up the night before (4/26/19) at 7pm until they close at 9pm. There’s a lot of work to be done and we hope all of our membership can come out on Friday and help us with setting up tables and hanging the sign outside.
We also hope all of our membership can help at the symposium on Saturday (4/27/2019) as well. The Ken Nakaoka Community Center opens at 8AM, we will have just a little bit of time to get ready before the event begins at 8:45am with our RRS president, Osvaldo Tarditti, giving the introductory presentation.
The next topic of discussion at the April 2019 meeting was facility improvements at the RRS MTA. The society has decided to invest in upgrading our blockhouse and building a new restroom facility at the site for better creature comfort for the increasing number of guests we’re having each year. Osvaldo has been working up the plans for these two facility improvements and will get bids very soon.
We also hope to solicit donations from the public at the symposium to help the society reach our goals for these facility improvement projects. To anyone wishing to make a monetary donation to the RRS, you can use the “DONATE” button on the RRS.ORG homepage which connects to Paypal. Please leave us a note and accept our thanks. The society is striving to improve our facilities as we prepare to have more events this year.
Osvaldo also told us more about the RRS participating with CALFIRE in their review of the state laws governing amateur rocketry. Members of the Friends of Amateur Rocketry (FAR) organization have also been working with CALFIRE on this important committee. It is the goal of the RRS to inform the public and governing agencies on ways to make the law reasonable, practical and just to the amateur rocketry as we uphold our commitment to public safety. CALFIRE has been very supportive of our hobby and we are building stronger relationships with the State of California and our fellow rocketry organizations.
Discussion on our last topic on the agenda was about the RRS’s participation with the base11 project. We were not able to talk about this subject in much detail as closing time had fast approached. As an educational non-profit group, the RRS has a charter to support university groups. The base11 project is very ambitious in its goal of student-run teams building and flying a liquid rocket to an altitude of 100 km or higher. This multi-year program will be a challenge on many levels both financial and technical. The RRS is happy to support the base11 Space Challenge at the RRS MTA.
The remaining agenda topics will be covered in next month’s meeting including the quarterly progress update on the SuperDosa project and the RRS partnership with Tomorrow’s Aeronautical Museum (TAM).
The RRS is very exciting about the projects we have planned for this summer. Our next monthly meeting will be Friday, May 10th, 2019 at 7:30pm.