Memorial Tributes: Volume 26
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  • Michael Maloney
  • Steven Koff
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  • BERNARD L. KOFF (1927-2021)



    BERNARD LOUIS KOFF, a pioneer in the advancement of gas turbine engines and their technologies, and former executive vice president of engineering and technology at Pratt & Whitney Aircraft Engines, died November 2, 2021.

    Ben, as he was generally called, was born in Huntington, Long Island, New York, on March 24, 1927, the only child of William and Ida Koff. At an early age, he became enthralled with machinery while helping his father maintain tractors and other equipment on the family farm. He became proficient at rebuilding engines on the family Fordson tractor and modifying farm equipment to increase operational life. Growing up near both the Grumman and Republic Aircraft Companies, he watched and was fascinated by the P-47 Thunderbolt and F4 Wildcat fighter planes that flew overhead. His high school civics class thesis was about becoming an aeronautical engineer, and in 1944 he joined the Army Air Force and worked on the first deployment of radio signal flight control.

    Following World War II, Ben was accepted into the engineering school at Clarkson University, where he was first exposed to gas turbine engine design technology. The university engineering laboratory had a WWII Junkers Jumo turbojet engine that powered the twin engine Messerschmitt 262 fighter aircraft used for instruction of early jet engines. He was fascinated by the compressor design and use of aluminum airfoils riveted to turbine disks.

    Ben excelled at his studies and received his BS in mechanical engineering (cum laude) from Clarkson in 1951 and his MS, also in mechanical engineering, from New York State University in 1958. He also received an honorary doctor of science from Clarkson in 1993 and was recognized with the Golden Knight Award as a Most Distinguished Alumnus.

    On March 30, 1952, Ben married Sonia Gordon, and they were happily married for 57 years until Sonia’s passing in 2009.

    Ben joined General Electric Company in 1958 and quickly made significant contributions in the area of gas turbine compressor design for the J93 Supersonic engine. He introduced the first midspan shrouded blade at GE and increased the blade chords to improve stall margin and durability. This compressor later became the prototype for the GE1, TF39, CF6-6, CF6-50, and CF6-80 series of engines using the same aerodynamic design.

    Ben went on to design a family of compressors for commercial and military engines derived from the J93 and started a new generation of compressors using higher stage loading to reduce the number of stages and improve durability. Innovative configurations such as a new ring drum rotor construction were developed, patented, and used in the CF6 family of engines. He created lightweight ring drum rotors used in all CF6 engines and derivatives, and in the GE1 compressor derived from the 11-stage J93 compressor that added three stages to produce a 14-stage compressor, which was used for the TF39 and CF6 engines by adding two more stages. The 14-stage compressor was reintroduced when boosters were added to limit the compressor discharge temperature to 1200°F in the CF6-50 and others. These numerous innovative engineering accomplishments greatly improved durability and reduced fuel consumption, resulting in significant competitive advantage for General Electric’s aircraft engines.

    Ben joined Pratt & Whitney Aircraft Engines in 1980 as senior vice president of engineering in the Government Engine Business, responsible for directing the design, development, and manufacture of military engines. He led the design and development of the F100-PW-220 and F100-PW-229 engines for F-15 and F-16 frontline fighters, and the Advanced Turbine Engine Gas Generator (ATEGG) PW5000 demonstrator engine that transitioned into the F119 supercruise engine and F135 for Lockheed’s F-22 and F-35 stealth fighters, respectively. These highly successful engines propelled Pratt & Whitney into the dominant market share position for fighter aircraft engines, a position the company still enjoys.

    Extending and exploiting Pratt & Whitney’s lead in materials and coatings development and application, Ben was directly responsible for creating and leading high temperature turbine blade and vane cooling technologies using film and convection cooling, combined with single crystal materials and advanced thermal barrier coatings, to increase turbine temperature by an astounding 500°F. Such technology development was paramount for achieving unprecedented 4000 Tactical Air Command cycles in the F100-PW-220, and allowed Ben to select a simple engine cycle configuration for the F119 and F135 engines that would operate with the highest turbine temperatures, winning sole source deployment in the F-22 and F-35 fighter aircraft.

    Ben also created and directed numerous technology advances in fans, compressors, combustors, turbines, jet nozzles, electronic controls, and stealth configurations. The F100-PW-220 was the first engine to incorporate a digital electronic engine control (DEEC), replacing the hydromechanical unit used in the F-16 and F-15. Coordinating with the Air Force, Ben visited Congress to create and endorse the Integrated High-Performance Turbine Engine Technology (IHPTET) Program, creating $1.5B for the American aircraft engine industry to increase the power of the gas turbine engine.

    In 1990 Ben was promoted to executive vice president of engineering and technology at Pratt & Whitney Aircraft Engines, with responsibility for leading the design, development, and manufacture of commercial and military aircraft and rocket engines—the entire P&W product line. He continued to direct the state-of-the-art advancement of high temperature turbine technologies used in the F135 engine for the F-35 Joint Strike Fighter and in P&W/Air Force technology programs. He worked with the Air Force and Navy to define and implement technology programs for both current and new engines.

    He also directed the initial design of the PW4084 turbofan engine for the Boeing 777 aircraft, including the design of hollow diffusion-bonded titanium fan blades, a key enabling technology. Additionally, he directed the design and development of the high bypass (12:1) Advanced Ducted Propulsor (ADP) geared turbofan engine (1992), demonstrating the highest turbofan propulsive efficiency ever recorded. This fan drive geared system was the demonstrator and precursor of the geared turbofan (GTF) engine that is now used throughout Pratt & Whitney’s new commercial engines. The GTF engine provides a 20 percent fuel burn reduction, and as of 2022 there were more than 1,300 of these engines in use.

    He served on numerous government committees and the Air Force Scientific Advisory Board. For the National Academies he was appointed to the Committee on Air Force/Department of Defense Aerospace Propulsion (2005–06), Aeronautics and Space Engineering Board (1992–96), and Committee on Requirements for Testing Facilities and Computational Capabilities at the Arnold Engineering Development Center (1991–92).

    Ben’s honors and awards are among the highest the aerospace industry can bestow. They include the 2012 SAE Cliff Garrett Award, 1993 SAE Franklin Kolk Award, 1992 ASME/AIAA/SAE Daniel Guggenheim Medal, 1991 AIAA & SAE Littlewood Lecture Award, 1990 AIAA Reed Aeronautics Award, 1989 AIAA Engineer of the Year, 1988 Air Force Association Theodore von Karman Award, 1988 ASME Tom Sawyer Award, 1988 P&W George Mead Medal, 1984 AIAA Air Breathing Propulsion Award, and 1970 GE Perry T. Egbert Award.

    He was elected to the National Academy of Engineering in 1988 and designated an ASME fellow and honorary member as well as a fellow of the AIAA and SAE. Ben Rich (NAE 1981), former president of Lockheed Skunk Works who nominated Mr. Koff for NAE membership, said: “Ben Koff is without question the most outstanding gas turbine jet engine designer since the inventors Whittle and von Ohain created jet propulsion.”

    Ben stayed active his entire life mentoring his family in the hobbies he loved, including dividend stock investing, shotgun shooting, precision rifle and pistol shooting, ballroom dancing, tennis, bicycling, motorcycling, making and flying model airplanes, and making general repairs.

    Ben is survived by his children Cheryl Bernstein, Steven Koff, and Laurie Troy, six grandchildren, and four great-grandchildren.