Pilots of new, certificated airplanes (production test pilots) or of newly designed, incompletely tested airplanes (experimental test pilots).
Before its first flight, every new airplane is at least partly an unknown quantity. Performance test pilots must have the skills needed to verify the handling and performance of an airplane just off the production line. Experimental test pilots must have the education and the skills required for the first flight and for the gradual extension of the flight envelope of an experimental aircraft, while being alert and prepared for unknown and unexpected engine problems and departures from controlled flight.
On a plane’s first flight, a performance test pilot verifies the proper performance of the engine and all flight controls and cockpit instrumentation. However, extensive tests of flap or spoiler operation are commonly left for later flights; retractable gear may or may not be retracted for the first flight. Typically, the airplane is not quite trimmed for hands-off straight and level flight and some adjustments will have to be made when the airplane is back on the ground. The stall warning device will probably have to be adjusted to provide the proper advance notice. The engine will also be new and probably running hotter than when well broken-in.
Then the production test pilot must verify that all aspects of an aircraft’s various systems are working properly and that it satisfies certification requirements in takeoff, climb, and cruise performance, as well as safe low-speed and stall behavior. This requires an intimate engineering knowledge of the aircraft as well as an ability to hold a given airspeed extremely accurately, with acute observational and communication skills.
Because of the popularity of homebuilt aircraft in the United States, many pilots become production test pilots in the early phases of the required test period. Although they are not required to pass any special tests or attend test pilot schools, they should thoroughly prepare themselves for the task and be even more alert to possible difficulties with instrumentation and the power plant. Possible performance ranges for homebuilt aircraft range from tens of knots in ultralights to hundreds of knots in turbine-powered designs. If the builder has designed the aircraft or made significant deviations from a proven design, the test pilot is really an experimental test pilot.
The testing of experimental planes can be much more interesting, more glamorous, and more dangerous than performance testing. These test pilots have been responsible for testing and verifying all the major advances in aircraft performance in every decade of powered flight, from craft capable of speeds tens of miles per hour to thousands of miles per hour, from open-cockpit to blind flying, from propeller-powered to jet- and rocket-powered, and from kite-based biplanes to the space shuttle. Although ground simulators can do a good job of preparing the experimental test pilot for the handling and performance characteristics of an experimental aircraft, a great deal of knowledge, skill, courage, and levelheadedness is still required in advancing the frontiers of flight.
America’s first flight test sites appeared near the end of World War I: the Army Air Force’s McCook Field in Dayton, Ohio, and, in 1918, the Naval Air Test Center at Patuxent, Maryland. In recognition of the increasing speeds and complexity of aircraft, specialized, formal test pilot schools appeared in 1943 in Great Britain (the Empire Test Pilots’ School) and in 1945 in the United States (the Naval Test Pilot School at Patuxent and the most famous, the United States Air Force Test Pilot School at Edwards Air Force Base on the dry lake bed near Palmdale, California).
Eddie Allen trained at England’s famed center of advanced flight research and flight testing at Farnborough, Hampshire, in 1917, going on to become a test pilot for more than a dozen civilian and military groups and the acknowledged dean of American test pilots. He died in 1943 while trying to save a burning prototype of the Boeing B-29 bomber.
Jimmy Collins was a freelance test pilot during the difficult Depression years when work, especially good-paying work, was very hard to find. He specialized in zero-lift terminal velocity (precisely vertical) dives, which the Navy required for its planes at that time. Also a gifted writer, his description of the physical sensations in pushing over into straight-down flight makes for chilling reading even today. Collins perished in the pull-out from his last such dive, in Grumman’s last biplane fighter, the XF3F-1.
Charles A. Lindbergh, barnstormer, top-of-his-class Army fighter pilot, and an experienced airmail pilot, participated in the design of his Ryan monoplane, the Spirit of St. Louis, in 1927, made carefully planned local and transcontinental test flights, and then flew it from New York to Paris to win the Orteig Prize. He thereby became America’s best-known aviator, stimulating the growth of aviation in America as never before and never since. As a civilian test pilot during World War II, he tested fighter aircraft and developed methods for increasing their combat range.
Jimmy Doolittle presaged today’s engineer/test pilot, earning a masters degree (1924) and then a doctorate in aeronautics (1925) from the prestigious Massachusetts Institute of Technology. Beginning as an Army Air Force test pilot, he became famous for a string of achievements. He was a race pilot in the 1920’s and a test and demonstration pilot for the prewar Curtiss Hawk fighter. He participated in the development and test flying of the first gyroscope-based flight instruments and radio navigation aids that permitted totally blind flying from takeoff to landing, and developed and led a very early raid (1942) against Japan following the attack on Pearl Harbor in 1941; the squadron flew Army Air Force B-26 bombers from a carrier deck. He was elected an Honorary Fellow of the newly formed Society of Experimental Test Pilots (SETP) in 1957.
Charles E. “Chuck” Yeager, a World War II fighter pilot and an “intuitive engineer,” completed a flight test pilot training program after the war and was chosen for the attempt to break the fabled sound barrier in the experimental research Bell X-1 rocket plane. In October, 1947, he did just that, producing the first sonic booms for the expectant, worried flight test personnel on the ground, becoming a legend in his own time, much as had Lindbergh and Doolittle.
Scott Crossfield, one of the founding members of SETP, was the first pilot to exceed Mach 2 (twice the speed of sound) in the rocket-powered Douglas D-558-2 in 1953, and made the first flights of the rocket-powered, hypersonic (Mach 6) North American X-15 in 1955.
Initially, test pilots used a knee pad to record their observations and then filled out a more detailed flight report after landing. By the late 1940’s, especially for the X planes, research aircraft carried full on-board data acquisition instrumentation, which was eagerly read out upon landing. Contemporary automated telemetry systems relay acquired flight parameters to the ground as they are changing, allowing test flight engineers to immediately tell the test pilot where to take the next test point, and when to quit. Variable-stability aircraft such as the Bell X-22A (as modified by Calspan Corporation) can accurately reproduce the handling and performance of many other aircraft.
Test pilots have led the way to the solution of many deadly aeronautical traps. Perhaps the first to be encountered and at least partially solved was the tail spin: easily recovered from in some trainers if the center of gravity is not too far to the rear, but potentially deadly in heavy and fast aircraft. The next problem was flutter, which is an aeroelastic phenomenon in which aerodynamic forces generate an excitation at a natural frequency of the structure, such as a flapping flag in a strong wind; this is most likely for the ailerons and other control surfaces, but the usual result is a lost airplane. By the 1940’s, the mysteries of “compressibility” were costing many lives as research and fighter aircraft went into unrecoverable dives. Up to perhaps Mach 0.3, the air can simply speed up and change its direction in response to the pressure differences around an airplane, but around Mach 0.6, 0.7, or 0.8, some air will reach the speed of sound because an increase in speed of the air over the wing is the way lift is generated. The point at which this occurs is called the critical Mach number and, soon after it is exceeded, shock waves perpendicular to the surface are generated where the air is abruptly slowed back down to subsonic speed. These superthin shock waves cause the air to separate, much like a low-speed stall, and render control surfaces ineffective; they also tend to oscillate in the fore-aft direction, producing control surface “buzz.” Inertia or roll coupling was the next big problem, once the problems of supersonic flight had been overcome. Everyday hypersonic flight is the next frontier, and experimental test pilots will be expected to lead the way.
Test pilot flying has not been entirely a man’s job. America’s Jacqueline Cochran, Germany’s Hanna Reitsch, and Great Britain’s Joan Hughes have all been elected Honorary Fellows in SETP.
Armstrong, Don. I Flew Them First: A Test Pilot’s Story. Mesa, Ariz.: Champlin Fighter Museum Press, 1994. The author was a test pilot for the Royal Canadian Air Force and four U.S. manufacturers, Curtiss, Douglas, Goodyear, and Grumman. Askue, Vaughan. Flight Testing Homebuilt Aircraft. Ames: Iowa State University Press, 1992. The author presents vital information to help the pilot of a homebuilt airplane prepare and implement a professional test flight program and envelope expansion. Doolittle, James H., with Carroll V. Glines. I Could Never Be So Lucky Again. New York: Bantam Books, 1991. Born in 1896, Jimmy Doolittle became perhaps America’s greatest pilot hero. He was a celebrated aerobatic and race pilot. A pioneering test pilot/engineer, he made precision measurements of the loads on aircraft and pioneered blind (instrument) flying. He organized and led the first attack on the Japanese mainland after the devastating attack on Pearl Harbor in December of 1941. This is his story, well told. Hallion, Richard P. Test Pilots: The Frontiersmen of Flight. Rev. ed. Washington, D.C.: Smithsonian Institution Press, 1988. Premier aviation historian Hallion presents an authoritative, insightful description of the progress in aircraft design and performance along with the test pilots who forged the way through myriad problems, from the 1910’s to Voyager and the space shuttle. Hoover, R. A., with Mark Shaw. Forever Flying. New York: Pocket Books, 1996. Jimmy Doolittle called Bob Hoover the “greatest stick-and-rudder pilot who ever lived.” He was a barnstormer, decorated World War II fighter pilot, and an experimental test pilot in the early jet era when the X planes were trying to break through the sound barrier. Millions of people have seen him perform precision aerobatics in the P-51 Mustang and in a civilian twin-engine aircraft. Yeager, Chuck, and Leo Janos. Yeager: An Autobiography. New York: Bantam Books, 1985. Chuck Yeager, the first to fly faster than the speed of sound, tells of his growing up and learning to hunt in West Virginia, his learning to fly in 1942, flying combat in World War II, and test flying afterward.
Aerospace industry, U.S.
Airline industry, U.S.
Charles A. Lindbergh
Navy pilots, U.S.
Pilots and copilots