FREDRIC F. EHRICH (1928-2023)

BY ALAN H. EPSTEIN

FREDRIC FRANKLIN EHRICH, a world leader in aircraft engine engineering, especially rotor dynamics, died in Dedham, Massachusetts, on Aug. 17, 2023. He was 94 years old.

Fred began his professional career in the early 1950s, as jet engines were emerging from their infancy. He started at Westinghouse but moved to General Electric (GE) in 1957, where he oversaw the engineering development of the T64 aircraft engine and later became a leader in tackling the vexing problems of rotor dynamics. Upon retiring from GE in 1994, he joined MIT as a senior lecturer in its Gas Turbine Laboratory and spent the next two decades teaching and mentoring students. Fred combined the hard-nosed drive of an industry engineer with the heart of a scholar. He solved problems important to products and then wrote scholarly treatises encapsulating the physics of lessons learned. Along the way he authored over 50 technical papers, “The Jet Engine” in the Encyclopedia Britannica, and he served as the founding editor of the Journal of Vibration and Acoustics. His book, Handbook of Rotordynamics (McGraw-Hill, 1992), is a landmark in the field. He also lectured widely around the world.

Fred was born to William and Yetta Ehrich in New York City on Dec. 17, 1928. This was exactly 25 years after the Wright Brothers’ first flight, a coincidence Fred later considered auspicious. He grew up on the then-ungentrified east side of Manhattan, which was a melting pot of immigrant ethnicities and cultures. As a child he took great advantage of the educational opportunities in NYC, including its libraries and public schools. Fred entered MIT at the age of 15 and graduated three years later with a degree in mechanical engineering. He was then awarded a graduate fellowship by the Dutch government to study at the Technical University of Delft. There he met several Holocaust survivors, including a cousin. This motivated him to cut his studies short in early 1948 and volunteer for the Haganah, the Israeli army. He trained in Marseilles and then sailed on the Pan York, a converted freighter carrying refugees and Holocaust survivors to Israel. On arrival, he joined a unit of English-speaking volunteers and served as a combat engineer, helping to open the road to Jerusalem during the siege. When hostilities ceased in 1949, Fred returned to MIT, where he earned M.S. and Ph.D. degrees in mechanical engineering, graduating in 1951.

Fred’s first job was with the Westinghouse Aircraft Gas Turbine Division in Philadelphia, where he quickly rose to supervisor of the analysis and mechanical development section. Later, he was assigned as resident liaison to Rolls-Royce Derby, sailing in September of 1955 for England with Joan (Collier), his bride of two days. They returned to the United States in 1956 to Westinghouse’s Kansas City, Missouri, operation. Westinghouse Aircraft Engine Division was then in sharp decline and consolidating its engineering and manufacturing functions.

In 1957, Fred joined the GE Aircraft Engine Division in Lynn, Massachusetts, and the Ehrichs settled close by in Marblehead. For the next 37 years, Fred and GE prospered. He had many roles there, including leading the design and development of the T64 turboshaft in the early 1960s. This engine powered several large helicopters and fixed-wing military aircraft. It is still in service. Subsequently, Fred focused on technology development. He led the development efforts on components and engine demonstrators that were the precursors to the T700/CT7 and F404/414 engine families. The T700 powers more helicopters than any other engine today. The F404 engine and its F414 derivative power many of the world’s fighter aircraft, both U.S. and foreign. Thousands of these engines have been produced and production continues. These designs can be traced back to Fred’s work on the GE12 and YJ101 demonstrator engines in the late 1960s and early 1970s.

In the 1980s, Fred focused on rotor dynamics. Gas turbines generate thrust and work by spinning rows of airfoils at high speed. The higher the speed, the more work can be done by each row and thus the lighter the engine. But the vibrational modes of structure are excited by the rotation and by interactions with the aerodynamics. The resulting vibrations and geometric distortions have been endemic problems in the history of jet engines. They have proven challenging to diagnose and difficult to remedy. Fred’s papers combined rigorous modelling with physical insight. They deepened our understanding and suggested practical solutions, making a significant impact across the industry.

Fred’s contributions to the literature date to the early 1950s. The papers in the 1950s and early 1960s ranged over many of the then-important challenges emerging in jet engines, including boundary layers and secondary flows, acoustic resonance and noise, and diffuser and combustion instabilities. Common across these disparate areas was his rigorous analytical approach. A paper Fred co-authored with colleagues at GE and MIT won the Melville Medal from the American Society of Mechanical Engineers (ASME) in 2003 for the best paper in ASME Transactions during the previous two years. An ASME fellow, Fred served as the chair of ASME’s Design Engineering Division.

Fred enjoyed a rich life away from work and delighted in time spent with family. He was active in community affairs and service, and as an MIT alumnus counseling prospective students. Together with Joan, he enjoyed art, music, theater, gardening, hiking, swimming, and adventurous travel. He and Joan lived in a house overlooking the water and were enthusiastic small boat sailors, sailing from Marblehead Harbor. Fred was predeceased by Joan, his wife of 66 years. He leaves his three children and their spouses: Diane Ehrich and Martin Cohen; Elliot Ehrich and Nancy Donovan; and Naomi Ehrich Leonard and Tim Leonard; and six grandchildren.

Fred was an effective and enthusiastic teacher. One of the points that came across clearly was embodied in his statement, “All gas turbines have rotor dynamic problems.” Well, he should know; he was the engineer people approached to fix the problems.