Foreword
As this book goes to press, the National Aeronautics and Space Administration (NASA) has passed beyond the half century mark, its longevity a tribute to how essential successive Presidential administrations—and the American people whom they serve—have come to regard its scientific and technological expertise. In that half century, flight has advanced from supersonic to orbital velocities, the jetliner has become the dominant means of intercontinental mobility, astronauts have landed on the Moon, and robotic spacecraft developed by the Agency have explored the remote corners of the solar system and even passed into interstellar space.
Born of a crisis—the chaotic aftermath of the Soviet Union’s space triumph with Sputnik—NASA rose magnificently to the challenge of the emergent space age. Within a decade of NASA’s establishment, teams of astronauts would be planning for the lunar landings, first accomplished with Neil Armstrong’s “one small step” on July 20, 1969. Few events have been so emotionally charged, and none so publicly visible or fraught with import, as his cautious descent from the spindly little Lunar Module Eagle to leave his historic boot-print upon the dusty plain of Tranquillity Base.
In the wake of Apollo, NASA embarked on a series of space initiatives that, if they might have lacked the emotional and attention-getting impact of Apollo, were nevertheless remarkable for their accomplishment and daring. The Space Shuttle, the International Space Station, the Hubble Space Telescope, and various planetary probes, landers, rovers, and flybys speak to the creativity of the Agency, the excellence of its technical personnel, and its dedication to space science and exploration.
But there is another aspect to NASA, one that is too often hidden in an age when the Agency is popularly known as America’s space agency and when its most visible employees are the astronauts who courageously rocket into space, continuing humanity’s quest into the unknown. That hidden aspect is aeronautics: lift-borne flight within the atmosphere, as distinct from the ballistic flight of astronautics, out into space. It is the first “A” in the Agency’s name and the oldest-rooted of the Agency’s technical competencies, dating to the formation, in 1915, of NASA’s lineal predecessor, the National Advisory Committee for Aeronautics (NACA). It was the NACA that largely restored America’s aeronautical primacy in the interwar years after 1918, deriving the airfoil profiles and configuration concepts that defined successive generations of ever-more-capable aircraft as America progressed from the subsonic piston era into the transonic and supersonic jet age. NASA, succeeding the NACA after the shock of Sputnik, took American aeronautics across the hypersonic frontier and onward into the era of composite structures, electronic flight controls, and energy-efficient flight.
This volume, the first of a two-volume set, traces contributions by NASA and the post–Second World War NACA to the field of aeronautics. It was that work that enabled the exploitation of the turbojet and high-speed aerodynamic revolution that led to the gas-turbine-powered jet age that followed, within which we still live. The subjects covered in this first volume are an eclectic mix of surveys, case studies, and biographical examinations ranging across multiple disciplines and technical competencies residing within the National Aeronautics and Space Administration. The topics are indicative of the range of Agency work and the capabilities of its staff. They include:
• the advent of the sharply swept-back wing, which enabled taking fullest advantage of the turbojet revolution and thereby launched the era of high-speed global mass mobility, becoming itself the iconic symbol of the jet age.
• the contributions and influence of Richard T. Whitcomb, a legendary NACA–NASA researcher who gave to aeronautics some of the key methods of reducing drag and improving flight efficiencies in the challenging transonic region, between subsonic and supersonic flight.
• the work of the NACA and NASA in furthering the rotary wing revolution via research programs on a range of rotorcraft from autogiros through helicopters, convertiplanes, ducted fan, tilt wing, and tilt rotor craft.
• how NASA worked from the earliest days of the supersonic revolution to mitigate the shock and disturbing effects of the sonic boom, developing creative test approaches to evaluate boom noise and overpressures, and then methods to alleviate boom formation and impingement, leading to novel aircraft shaping and methods that are today promising to revolutionize the design of transonic and supersonic civil and military aircraft.
• how the NACA and NASA, having mastered the transonic and supersonic regions, took on the challenge of extending lift-borne flight into the hypersonic region and thence into space, using exotic “transatmospheric” vehicles such as the legendary X-15, various lifting bodies, and the Space Shuttle, and extending the frontiers of air-breathing propulsion with the Mach 9+ scramjet-powered X-43.
• the physical problems and challenges that forced NASA and other researchers to study and find pragmatic solutions for such thorny issues as aeroelasticity, oscillatory instabilities forcing development of increasingly sophisticated artificial stability systems, flight simulation for high-performance aerospace vehicles, and aerothermodynamic structural deformation and heating.
• NASA’s role in advancing and maturing computational fluid dynamics (CFD) and applying this new tool to aeronautical research and aerospace vehicle design.
• the exploitation of materials science and development of high-temperature structures to enable design of practical high-speed military and civil aircraft and spacecraft.
• the advent of computerized structural loads prediction, modeling, and simulation, which, like CFD, revolutionized aerospace design practices, enhancing both safety and efficiency.
• NASA’s pioneering of electronic flight control (“fly-by-wire”), from rudimentary testbeds evolved from Apollo-era computer architectures and software, to increasingly sophisticated systems integrating aerodynamic and propulsion controls.
• how the NACA and NASA advanced the gas turbine revolution, producing more efficient engine concepts and technology for application to new generations of military and civilian aircraft.
• how NASA has contributed to the quest for fuel-efficient and environmentally friendly aircraft technology, studying combustion processes, alternative fuels, and pollutant transfer into the upper atmosphere, searching for appropriate technological solutions, and resulting in less polluting, less wasteful, and more efficient aircraft designs.
• the Agency’s work in promoting global environmental good stewardship by applying its scientific and technical competencies to wind and solar energy, resulting in more efficient energy-producing wind turbines and high-altitude solar-powered long-endurance unpiloted aerial vehicles.
The record of NACA–NASA accomplishments in aeronautics demonstrates the value of consistent investment in aeronautical research as a means of maintaining the health and stability of America’s aerospace industrial base. That base has generated an American predominance in both civil and military aeronautics, but one that is far from assured as the Nation enters the second century of winged flight. It is hoped that these studies, offering a glimpse at the inner workings of the Agency and its personnel, will prove of value to the men and women of NASA, to those who benefit across the United States and overseas from their dedicated work, and to students of aeronautics and members of the larger aerospace community. It is to the personnel of NASA, and the NACA before them, that this volume is dedicated, with affection and respect.
Dr. Richard P. Hallion
August 4, 2010