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W. Hewitt Phillips

W. Hewitt Phillips
W. Hewitt Phillips
Credit: NASA

William H. “Hewitt” Phillips (1918 – 2009) was a major contributor to advances in the aeronautical and space programs of the NACA and NASA. He was exceptionally broad in his knowledge and expertise of the various fields required for aerospace vehicles and technology. His accomplishments included solutions to critical issues and problems associated with the flight dynamics and control of aircraft and spacecraft; and the design, construction, and implementation of unique research facilities. During a remarkable 58-year career at Langley, he personally conducted or led highly-successful research efforts on vehicles ranging from propeller-driven airplanes of World War II to manned space vehicles of today. 

Phillips was born in Port Sunlight, England, and came to the United States with his parents at the age of 2. He was educated in the Belmont, Massachusetts, public school system. He developed an intense interest in model aviation as a child, and enthusiastically built models and joined model clubs. His interest in model activities remained a trait throughout his personal life and career. After graduating from high school in 1935, he enrolled at MIT where he studied aeronautical engineering, earning his bachelor’s degree in 1939 and his master’s degree in 1940.

After working a summer job in industry at Pratt and Whitney Aircraft in 1939, he concluded that industry’s deadlines and lack of time for in-depth analysis was not his vision of a career. During his year of graduate study, he took the Civil Service exam for a junior aeronautical engineer, excited by the possibility of being hired by the NACA. According to Phillips, the exam was exceptionally hard, because the exam questions had been submitted by none other than Eastman Jacobs, the most noted aerodynamicist at Langley. Nonetheless, Phillips passed the exam and was hired by the NACA, reporting to Langley in July 1940.

He was assigned to the Flight Research Division, which was managed by legendary NACA researchers “Gus” Crowley and Floyd Thompson. His first efforts were within the Flight Research Maneuvers section headed by Robert Gilruth. The environment at Langley in flight research was extremely hectic, with critical wartime projects and high-priority prototype aircraft coming to the lab in seemingly endless streams for NACA studies. An arrangement had been made with the military to supply the NACA with the third airplane off of the production line of every new military airplane produced, for evaluations and problem-solving. As a result, Phillips was immediately involved in assessing the stability, control, and flying qualities of a large number of U.S. military aircraft, including evaluations of the famous F4U Corsair and the P-40 Warhawk fighters. He also conducted flying-quality evaluations of the British Hawker Hurricane and Supermarine Spitfire fighters. In 1943, he participated in Navy flight evaluations of the first captured Japanese Mitsubishi Zero, results of which provided critical guidance on how to counter the aircraft in air-to-air engagements.

Phillips augmented his experimental flight-test studies with extensive analytical studies of aircraft dynamics and concepts to minimize the required pilot’s control forces, which became unacceptably high during high-speed maneuvers. This research ultimately led to Gilruth’s idea for an all-moving horizontal tail, demonstrated in flight with the Curtiss XP-42 airplane. The technology would pay off after the war when military aircraft reached supersonic speeds. The concept was applied to the X-1 research aircraft and, subsequently, all modern supersonic fighters including today’s Air Force F-22 and Navy F/A-18. 

One of the most famous contributions by Phillips was his identification and analysis of a potentially dangerous dynamic flight phenomenon called “roll coupling.” He first noted the phenomenon during Langley free-fall tests of a model of the X-1, when the model exhibited violent oscillations and accelerations in pitch during rolling maneuvers. Phillips derived the relevant equations to describe and predict the problem, which became known as “inertial coupling.” The coupling problem subsequently arose again during early flight tests of the F-100 fighter, the X-3 research airplane, and other slender configurations. In his memoirs, Phillips commented that he received far more recognition from his pioneering report on inertial coupling than for any other work he accomplished in his NACA and NASA career at Langley.

Phillips led numerous other important research activities of the NACA following the war. One important challenge facing the NACA was how to obtain transonic aerodynamic data, since wind tunnels of the time were not properly designed for test conditions near the speed of sound. He was in charge of supervising the design of equipment and conducting flight tests, using Langley’s wing-flow concept of acquiring transonic data by mounting small model components on the wing of a P-51 aircraft, and measuring data on the model when the local flow became transonic. He also studied the causes and cures of pilot-induced oscillations, some of which had led to catastrophic failures of aircraft. In addition, Phillips conceived and planned flight tests to define atmospheric turbulence, and developed systems for gust alleviation. 

When NASA was born to advance the nation’s capabilities in space technology, he focused his efforts on the manned space program and supervised research on space rendezvous, navigation, and lunar landing. During the early days of the space program, before Project Mercury, he conceived and patented an innovative winged entry vehicle with fold-out wings that was tested in several Langley wind tunnels with promising results. Reviews of the concept were held for the Space Task Group, that had responsibility for selecting the spacecraft configuration; but the urgency of the project demanded a simpler approach such as the capsule ultimately adopted for flight. 

Under his leadership, his division developed piloted simulators used by the astronauts for critical training that helped ensure the success of the Gemini and Apollo missions. He personally conceived and successfully advocated for the famous 200-foot-high Langley Lunar Landing Facility that was used for training astronauts prior to the first moon landing. He later provided analysis and consultation during the development and operations of the Space Shuttle. Although his prime interests had shifted from aeronautics to space during his NASA years, Phillips’ unique expertise and experience were widely recognized, and he was requested by other agencies to participate in accident investigations of civil and military aircraft.

During his career, he led efforts in the design and application of multiple aerospace simulators used to train pilots and astronauts, as well as to conduct fundamental research for aerospace vehicles. An important example of a NASA simulator conceived by his division is the Langley Differential Maneuvering Simulator, a facility that was heavily used in the 1970s and 1980s, during the developments of the F-14 and F-15 fighters for studies of flight dynamics and control during air combat.

Phillips retired from NASA in February 1979; but continued his scientific interests at Langley as a Distinguished Research Associate, exploring concepts for airfoils, propellers, and solar-powered aircraft. He even had an opportunity to operate a wind tunnel for the first time in his career, and relished the experience. In his memoirs, he recalled that the only other experience he had in a wind tunnel was upon arrival at Langley in 1940, when his group was conducting tests in the Langley Full-Scale Tunnel of a Fairchild XR2K-1 parasol-wing airplane. During the project, someone was required to sit in the cockpit and move controls as needed. As a junior engineer, he was nominated. With the wind blowing past the open cockpit at 100 mph on a bitterly cold day in November, he never forgot the unpleasant experience.

Phillips received numerous awards during his career, including the Institute for Aeronautical Sciences’ Lawrence Sperry Award of 1944. This famous award, now given by the American Institute of Aeronautics and Astronautics (AIAA), honors notable contributions made by a young person, age 35 are under, to the advancement of aeronautics or astronautics. Phillips also received the NASA Distinguished Service Medal and the President’s Award for Distinguished Federal Civilian Service in 1979.

In 1947, Phillips married Viola Ohler, who was the head of the Editorial Office at Langley following the transfer of Pearl Young to the NACA Aircraft Engine Research Laboratory. They were married for 49 years and had three children: Frederick, Robert, and Alice.

William Hewitt Phillips passed away at his home on June 27, 2009, at the age of 91.