Memorial Tributes: Volume 26
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  • HYLA S. NAPADENSKY (1929-2022)



    HYLA SARANE NAPADENSKY, retired vice president, Napadensky Energetics Inc., died in Madison, Wisconsin, on March 19, 2022, at the age of 92.

    Hyla was born in Chicago, Illinois, on November 12, 1929, the middle daughter of Russian emigrants who moved to Chicago after first settling in Toronto, Ontario. Her precocity and indifference to family and community expectations led her to graduate from high school at age 15. After growing up running the family greeting card store with her older sister during their father’s hospitalizations, she decided to study a field that would lift her out of poverty rather than pursue her early interest in music and art. To this end, she studied math at the University of Chicago, receiving bachelor and master of science degrees in mathematics from the University of Chicago in 1950 and 1952, respectively. She also pursued graduate studies in physics at the University of Chicago and chemical engineering and mechanical engineering at the Illinois Institute of Technology.

    The juxtaposition of her precarious financial position and the intellectual stimulation of her educational environment permeated Hyla’s experiences throughout her educational pursuits. She subsisted on meals of salami or peanut butter while studying under and working alongside Nobel laureates Enrico Fermi (NAS 1945) and Subramanyan Chandrasekhar (NAS 1955), as well as other eminent scientists including Gerard Kuiper (NAS 1950) and her office mate at the Yerkes Observatory of the University of Chicago, Nancy Roman, the first chief of astronomy in NASA’s Office of Space Science.

    Hyla’s first job after receiving her degrees was designing tractor engines for International Harvester, where she worked from 1952 to 1957. Inspired by Enrico Fermi and his lectures at the University of Chicago, she created a program that made use of the accounting department’s new 1950s-era computer to calculate solutions to gearing problems. This may have been the first application of computers to support motor vehicle design.

    In 1957, Hyla moved to the Illinois Institute of Technology’s Research Institute, where she created and led the Explosion Science and Engineering Department. The department consisted of a group of 40 engineers and technicians engaged in various aspects of fire and explosion research and operated two test facilities in Indiana: an explosive test facility near LaPorte and the fire laboratory at Gary. In recognition of her management responsibilities and the continued excellence of her own research studies, she held joint appointments as director of research and senior engineering advisor. Hyla formed her own company, Napadensky Energetics, in 1988 and remained active in her field through leading Academies reports and other efforts until age 88.

    Over the course of her distinguished career Hyla became a recognized authority in the fields of sensitivity of propellants and explosives, as well as weapons vulnerability, which led to her election to the NAE, becoming its eleventh woman member. A pioneer in the study of the sensitivity of explosives to the initiation of detonation by low-velocity impact, she was the first to experimentally reproduce the low-velocity explosion accident environment. Her theories on impact initiation phenomenology and her novel experimental methods enabled the understanding of low-pressure, long-duration detonation initiation mechanisms and spurred considerable research at many laboratories in the United States and around the world. Her seminal work opened many avenues of investigation and has been referenced extensively by other investigators. With the development of large solid rocket motors for space exploration and the first accidental detonation at Cape Canaveral as a result of fallback of an aborted rocket flight, her research activities were dedicated to understanding the detonation of solid propellants by low-speed impact. Her work resulted in analytical and experimental models for understanding initiation mechanisms and predicting conditions for detonation of large, solid rocket motors.

    Hyla applied her deep understanding of these areas to a diverse set of problems. These included studying the effect of explosions on snow load in Greenland, developing regulatory guidelines for the Nuclear Regulatory Commission, working to prevent explosions at offshore oil platforms, and developing safety protocols for airbag manufacturing plants and NASA space shuttles before the Challenger explosion. The impact of her work is indicated by the titles of some of the programs in which she was a principal investigator or project engineer: Safety Criteria for Storage of Detonable Materials; Hazards Analysis Studies of Explosive and Chemical Manufacturing Processes; Explosive Test and Evaluation of Blast Shields for Nuclear Reactors; Investigation of Causes of Accidental Explosions of Munitions on Railroads; Risks to Nuclear Power Plants from Trains and/or Ships Carrying Explosives and Other Hazardous Materials; and Hazards Classification Procedures for In-process Explosives and Propellants: Safe Siting of Petrochemical Plants.

    Among Hyla’s many activities in service to the profession, she served as a lecturer for the International Atomic Energy Agency’s Nuclear Power training courses on the effects of accidents involving flammable or explosive materials that may occur on transportation routes near nuclear power plants. Her work on transportation accidents was the basis for the Nuclear Regulatory Commission’s regulatory guide, Explosions Along Transportation Routes Near Nuclear Power Plants (1975).

    Hyla’s husband Arnold grew up in a family of Romanian immigrants in South America. He came to the United States after political unrest in Venezuela forced the universities to close. Hyla and Arnold met in Chicago during his studies at the Illinois Institute of Technology and in 1956 they traveled to Caracas, Venezuela, so Hyla could meet Arnold’s family and they could get married. The judge performed the ceremony in the inner courtyard of the jail next to his office. Hyla said she always assumed they married but couldn’t be entirely sure, as both the marriage ceremony and marriage license were entirely in Spanish. Hyla and Arnold raised their two daughters in Chicago and Evanston, Illinois.

    In 1994, Hyla and Arnie retired to their home on Lake Superior near Grand Marais, Minnesota. She was known within the community as a “rocket scientist” and mentored many middle school students in the Future Cities Program, led presentations for the local Great Decisions Foreign Policy Association discussion group, joined the volunteer income tax preparers, and volunteered as a board member for various community organizations, including Library Friends, the Education Foundation, the Health Care Foundation, the Cook County Local Energy Project, and WTIP Community Radio.

    Arnie preceded Hyla in death, passing away in 2019. She is survived by daughters Lita (Char Arner) and Yafa (Bob Shannon), two granddaughters, and numerous nieces, nephews, and extended family members in the United States and Israel.