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John Stack

John Stack
John Stack
Credit: NASA

John Stack (1906 – 1972) conceived and led highly successful projects within the NACA and NASA to conquer the formidable barriers to high-speed flight. He is widely regarded as one of the world’s most important aeronautical engineers, having demonstrated superlative technical expertise, leadership qualities, and management capabilities which he brought to bear on critical national programs. As a pioneer and specialist in the field of high-speed aerodynamics, he personally conceived, advocated, and conducted some of the most productive aviation projects ever undertaken by the United States. In conversation and presentations, he seldom failed to get his point across, speaking with an authoritative tone and hand gestures.

Stack was born in Lowell, Massachusetts, and during his high school years developed a keen interest in non-aeronautical activities such as motorcycle racing and amateur radio broadcasting. He entered the Massachusetts Institute of Technology in the fall of 1924 to study architectural engineering. It was not until he returned home the following summer that his father found, to his great surprise, that John had actually been studying aeronautical engineering. He was awarded a degree in aeronautical engineering in 1928, and joined the Langley Memorial Aeronautical Laboratory staff in July as a junior aeronautical engineer. He recalled that the Chief of Aerodynamics, Elton Miller, took him on a tour of the Langley wind tunnels and flight hangar, asking Stack where he wanted to work. Stack replied “The Variable Density Tunnel,” upon which Miller replied “Good — because that’s where I had already decided to send you!”

During his 11 years at the Variable Density Tunnel, he worked on the design of the 11-Inch High-Speed Tunnel, the first of Langley’s high-speed tunnels, and participated in the development of the early NACA supersonic tunnels such as the 24-Inch High-Speed Tunnel. These tunnels pioneered the acquisition of supersonic data in the early 1930s. The breadth of his contributions included analyses of aerodynamic data and the development of specialized flow visualization equipment that permitted researchers to visualize shock waves emanating from aircraft at supersonic speeds.

By 1939, he had already become recognized within the international aeronautical community as one of the world’s leading specialists, and was put in charge of the 8-Foot High-Speed Tunnel and all the high-speed wind tunnels at Langley. In 1942, he became Chief of a new Langley Compressibility Research Division that focused on high-speed flight; and in 1944, he was the first Langley staff member to be chosen to deliver the prestigious Wright Brothers Lecture sponsored by the Institute of Aeronautical Sciences. His career continued to advance; and in 1947, he was promoted to Assistant Chief of Research at Langley, followed in 1952 by appointment as Langley’s Assistant Director, a position he held until transferring to NASA Headquarters in 1961.

As a member of the NACA, Stack conceived and conducted many high-speed research projects, including exploration of high-speed propellers. However, he is most renowned for his contributions as a driving force and team leader behind two of the most important projects ever undertaken by the NACA. The challenge to aerodynamicists had been the lack of capability to obtain accurate data from wind tunnels of the day at transonic conditions, because of interference effects of tunnel walls. Stack led teams devoted to identifying approaches to resolve this issue, including the possible use of research aircraft and modified wind-tunnel configurations. His strong-willed advocacy and leadership for the conception and development of the rocket-powered Bell X-1 research airplane was critical to that program’s success. The X-1 was the first aircraft to exceed the speed of sound in level flight — a milestone in aviation history. That exceptional achievement was followed by his support and enthusiasm during the conception and development of slotted walls in wind tunnels to enable testing at transonic speeds. His efforts at NASA included leadership in the beginning of the U. S. National Supersonic Transport Program, and the development of the variable-sweep-wing concept that was successfully applied to the F-111, F-14 and B-1 airplanes.

Stack was also a strong supporter of international cooperative programs between NASA and European NATO countries within the Mutual Weapons Defense Program. This activity included numerous NASA studies of European aircraft and aeronautical concepts, including flutter studies of the Italian G.91 fighter and wind-tunnel tests of the proposed British arrow-winged, variable-sweep Swallow supersonic transport configuration. Langley wind-tunnel and flight-research activities also helped to ensure the success of revolutionary aircraft such as the Vertical/Short Takeoff Landing (V/STOL) AV-8 fighter, now flown by the U.S. Marine Corps.

In recognition of his extraordinary achievements, he was a member of the three-person team that received the esteemed Collier Trophy in 1947 for their pioneering research in supersonic flight and leadership in the X-1 program. That achievement was also recognized by the Air Force Association’s Field of Science Award for 1948. He won the Collier Trophy again in 1951, for the conception and practical application of the slotted-wall wind tunnel. In 1952, he received the Sylvanus Albert Reed Award and the Medal of the Society of Engineers awarded by Sweden. He was also awarded the Wright Brothers Memorial Trophy of the National Aeronautic Association in 1962.

Stack was emphatically disappointed and frustrated by the de-emphasis of aeronautics that occurred within NASA during the early days of the space program. He was even tepid in his support for the highly successful North American X-15 rocket-powered hypersonic research airplane and its tie-in to the space program. He decided to retire from NASA in 1962, after serving a year as Director of Aeronautical Research at NASA Headquarters in Washington. He then became Vice President of Engineering at the Republic Aircraft Corporation, which later consolidated with Fairchild Industries. He retired from Fairchild in 1971.

John Stack married Helen Sturtevant in 1928, and had a daughter, Martha, and a son, John “Pete” Stack. Pete Stack also spent his career working for NASA at Langley, becoming a well-known expert in instrumentation and measurement systems during a 40-year career.

During his life, Stack had always relished competition — especially in sporting events — which he enthusiastically joined during his early NACA days at Langley. He was very active in intra-organizational contests, including softball and bowling. Along with several other Langley staffers, including Engineer-in-Charge H. J. E. Reid, he entered virtually every shooting competition in the area. He was also deeply involved with horses, fox-hunting, horse shows, and thoroughbred breeding and racing.

John Stack, a legend in aerospace history, died on June 18, 1972 (Father’s Day) when he fell while riding a horse.