David W. Rabenhorst, 87; 'Superflywheel' Inventor

David Warren Rabenhorst, an inventor who made significant contributions to early missile and satellite technologies and who advanced the development of flywheels for energy storage, died of cancer July 19 at Montgomery General Hospital. He was 87.

Mr. Rabenhorst, an engineer at the Johns Hopkins University Applied Physics Laboratory for 33 years, created the "superflywheel" in 1968 for use in powering commuter cars, computers and shipboard systems.

"Flywheels are a common fact of life that we rarely notice," an APL article explained. "Every automobile had one to help smooth out the power delivered by its several discrete cylinders. Flywheels store power as their speed is increased, and release power as they slow down."

Mr. Rabenhorst's superflywheel was made of newly developed filamentary material, rather than conventional steel, and was lighter and able to store more energy. It could also accelerate to very high speeds without breaking into damaging chunks.

During his time at APL, Mr. Rabenhorst contributed to the Terrier missile program and played a key role in the successful launching of the early Transit navigation satellites. He also worked on the production of the world's first electronic helicopter.

Mr. Rabenhorst, whose background was in aeronautical and mechanical engineering, produced more than 22 patents. For his work at APL, which included at least 10 patents, he received the Master Inventor Award in 2007, the first year the honor was bestowed.

A Washington native, Mr. Rabenhorst graduated from McKinley Technical High School and received a bachelor's degree in aeronautics engineering from Catholic University. He lived in Silver Spring.

Mr. Rabenhorst, who retired in 1981 from the APL, had spent the past 21 years volunteering at Montgomery General Hospital and installing Lifeline medical alert systems in the Leisure World community in Silver Spring.

The Kiwanis Club of Leisure World recognized Mr. Rabenhorst as Citizen of the Year in 1993.

Mr. Rabenhorst, who sang baritone and bass, participated in many vocal groups including barbershop quartets, men's chorales and church choirs. He was in demand as a soloist at weddings, funerals and other occasions.

He was a member of the Inter-Faith Chapel at Leisure World, where he sang in the choir and was chairman of the deacon board.

A golfer, he had three holes in one and a number of team championships to his credit.

Survivors include his wife of 66 years, Mary Margaret "Peggy" Rabenhorst of Silver Spring; three children, Daniel Wayne Rabenhorst of Ashton, Barbara Rabenhorst Potts of Fort Washington and David Alan Rabenhorst of Woodcliff Lake, N.J.; five grandchildren; and six great-grandchildren.