From The Mind Of R. T. Jones
HAD YOU BEEN IN THE neighborhood of NASA’s Dryden Flight Research Center at Edwards Air Force Base sometime in the early 1980s, you might have caught a glimpse of an unconventional aircraft cutting the crystal blue Mojave Desert skies. It was bizarre even by local standards—which is saying something, in a place that for decades has seen the fledgling flights of the world’s most advanced planes.
It’s not that the aircraft was particularly speedy; even with its twin jet engines, it didn’t move any faster than a small private plane. Nor did it fly unusually high; again, for the Dryden/Edwards area, an altitude of only about 10,000 feet was nothing compared to, say, the X-15, which had routinely flown all the way to the edge of space. This thing was small, slow, a bit flimsy-looking, and did not even execute any especially thrilling acrobatic maneuvers.
No, the odd thing about this aircraft was its shape—specifically, the wing. You might not even pick it out at first from the ground, depending on your viewing angle. Or you might have thought your initial impression must be mistaken, because an airplane just couldn’t look like that and still be able to fly. But if you kept staring at it, you would have realized that the wing was...crooked, sweeping back toward the tail on one side like other airplanes but jutting forward on the other, as if a normal straight wing had somehow been knocked obliquely off-kilter.
While airplanes come in many shapes and sizes, one attribute they all generally share is symmetry. How could a crazy design with a ridiculously skewed wing like this possibly fly?
Amazingly enough, it did. NASA’s AD-1 experimental aircraft was the brainchild of one of the most creative, unconventional, and influential engineering geniuses of the 20th century: Robert Thomas “R. T.” Jones, a self-taught college dropout whose oblique- wing concept was the culminating inspiration in a remarkable career. His aerodynamic research has touched the lives of every person who’s ever stepped aboard a commercial airliner. Along the way, Jones also found time to help invent an early type of artificial heart, build a new form of telescope, and even develop a new wrinkle on the violin.
Anyone seeking a counterexample to the age-old stereotype of engineers as staid, boring, and hopelessly bland could do no better than R. T. Jones. Born in 1910 in Macon, Missouri, he started out as a farm boy with a passion for building radios and model airplanes. As he wrote in a memoir, he “devoured eagerly” the articles in popular aviation magazines, but also pored—helped no doubt by his innate bent for mathematics—over highly technical reports from the National Advisory Committee for Aeronautics (NACA), the center of cutting-edge aeronautics research in the United States.
After an unsatisfying freshman year at the University of Missouri, he joined up with a local flying circus, lugging gas cans and patching wings in exchange for flying lessons. That gig led to a job at a local airplane company, where he was soon learning from older, experienced engineers working around the clock to build a racing plane for the upcoming 1930 National Air Races.
When the company folded during the Depression, R. T. returned home briefly to bury himself, in his aerodynamics books. But thanks to his father’s work for the local Democratic Party, Jones soon ended up in Washington, D.C., as an elevator operator in the House Office Building. Meanwhile, he continued his self-education in aerodynamics and mathematics at the Library of Congress. The young R. T. mingled not only with influential congressmen (one of whom, David J. Lewis, he tutored in math on the side) but also with some well-known aeronautics experts, including Max Munk, who had worked for NACA and was teaching night classes in aerodynamics for graduate students at a local university. Learning that Jones had read his influential textbook on fluid mechanics, Munk invited him to sit in, deciding that he was qualified even without an undergraduate degree.
Jones proceeded to audit Munk’s classes for the next three years, though still not getting anywhere near an actual degree. He didn’t care: he was learning from a master, and Munk would turn out to be a major influence on his career and ideas. Stanford engineering professor and historian Walter Vincenti observes: “Munk thought in terms of metaphors and analogies and physical terms, and I would guess that R. T.’s natural inclination in that direction was given a bit of a push by his interaction with Munk.”
The work with Munk led Jones directly to the next phase of his career, when Franklin D. Roosevelt’s Public Works Administration opened up a number of government positions in 1934 at NACA’s Langley Aeronautical Laboratory nearby in Virginia. Powerful recommendations from Munk, Congressman Lewis, and Albert Zahm (another mentor Jones had met at the Library of Congress) made Jones a shoo-in. R. T. had now found his professional home, working for the world’s most advanced aviation research organization.
Jones’s timing was impeccable. Civilian aviation was expanding at an increasing pace, with new airlines popping up everywhere and new aircraft being designed and built. The entire future of civilization seemed intimately tied to the progress of aviation, so designing better, safer, and more versatile aircraft was a vital mission. And in the United States at least, that mission belonged to NACA.
Jones had been thrown into the deep end of the pool, but there was no place he’d rather be. He quickly made a name for himself at Langley, working on problems of aircraft stability, control, and wing design. Soon he was writing and publishing the same kind of technical reports and papers he had soaked up as a kid back in Missouri, using the resources of NACA, with its wind tunnels and aircraft, to test and perfect his inspirations. NACA’s work became even more critical with the coming of the Second World War, during which R. T. developed his most important and far-reaching idea: the swept-back wing.
As military aircraft steadily became faster and more powerful, reaching ever closer to the speed of sound, aerodynamic problems multiplied. Flying at trans-sonic speeds (near that of sound) created shock waves that caused pilots to lose control and crash, or even ripped the wings off aircraft. The speed of sound might not really form an invisible and impenetrable “barrier” as some speculated, but passing it seemed to require something more than simple brute engine force.
Jones approached the problem by considering how the shape of a wing affected the airflow around it at different speeds. What would happen, he wondered, if, instead of a straight wing perpendicular to the aircraft fuselage (the classic form every aircraft had followed since the Wright Brothers), each side of the wing were swept back toward the tail of the plane? His calculations indicated that such a wing would indeed greatly reduce the drag—and therefore dampen the shock waves that built up as a plane approached the speed of sound.
It was truly a radical concept. “It came as quite a surprise to us,” Vincenti remembers. “It took us quite a bit of work to understand it. It seems obvious today, but it was such a revolutionary idea at the time that there was some resistance to it, and it took the rest of us quite a while to catch on.” In fact Jones’s superiors at Langley rejected his first paper, arguing that this challenging theory needed further experimental confirmation. The concept of an air-plane with straight wings was just too ingrained in the thinking of even the most advanced engineers. It wouldn’t be the last time that Jones would be ahead of his time.
The war ended before experimental confirmation could be completed, but support for Jones’s ideas soon came from an unexpected source. Even before V-E Day, a special team of scientists had been trailing the advancing Allied forces in Europe, sifting through captured documents, labs, and archives and interviewing German scientists. They discovered that the Germans had already been doing extensive work on the swept-wing concept, notably the famous engineer Adolf Busemann, who had put the idea forward at a scientific conference in Rome in 1935. But Busemann’s work had been largely ignored as too theoretical and outré for serious consideration, and mounting tensions in Europe and the eventual outbreak of war ensured that practically no one outside of Germany had ever heard of it. Some of the new German airplanes introduced late in the war, such as the ME-262 and rocket-powered ME-163, incorporated the swept wing to some degree but made little impact then.
Closer examination of Busemann’s work, along with further experimentation and analysis at Langley, finally brought the aeronautics community around to Jones’s way of thinking. “It was certainly one of the most important discoveries in the history of aerodynamics,” writes aviation historian and aerodynamicist William Sears. It was a classic example of two brilliant minds arriving at the same conclusions completely independently of each other, and Jones and Busemann share equal credit for the discovery, which won R. T. the 1946 Sylvanus Albert Reed Award from the Institute of Aeronautical Sciences.
In 1946 Jones transferred from Langley to NACA’s recently opened Ames Aeronautical Laboratory in Mountain View, California, which is where Vincenti first met him. “I was in charge of the one-by-three-foot supersonic wind tunnel,” he remembers. “R. T. was given an office directly across the hall from me in the wind tunnel building, because we happened to have an empty office there.”
Again, Jones found himself in the right place at the right time. Vincenti and his cadre of young engineers were probing the brand new world of supersonics. “We didn’t know much about supersonic aerodynamics,” recalls Jack Boyd, then a fresh-faced Virginia Tech engineering graduate on his first job. Vincenti agrees: “At that time in supersonic aerodynamics, there was very little to go on. Those of us in my group, we didn’t know anything about it when we began.”
Although Ames was a NACA facility like Langley, the general atmosphere there in those early days tended to be more loose and freewheeling. Supersonics was a wide-open field ripe for invention and discovery, which was precisely where Jones excelled. “All of us were working with R. T.,” says Boyd. “He didn’t like to be a manager, so he didn’t consider anybody working for him. We would throw ideas out about what wing shapes and wing sweeps and profiles would look like, and R. T. would counter with ‘No, that’s crazy,’ or ‘Yeah, that’s fine, why don’t you try it?’ In those days we had the opportunity to do trial and error. So it was very informal.”
Vincenti elaborates: “Our wind tunnel was the only supersonic tunnel available to test such [swept-back] wings at low supersonic speeds. So R. T. and I spent time together laying out models of such wings as they might be incorporated in a supersonic airplane to fly at about Mach 1.5. We would test them and discuss the results and come up with ideas on how to improve them, so we’d make a new model and test it. We went back and forth at that kind of thing for a year or two.”
Still, Jones wasn’t actually a formal member of Vincenti’s group. Or anyone else’s, for that matter. “He was on the NACA payroll, but he was a freelance person; he didn’t report to anyone except maybe the director of the laboratory,” recalls Vincenti. “Everybody knew that R. T. was a rare person and was well-motivated, and the best thing you could do was leave him alone and let him do his thing. The people in charge were smart enough to see what they had and just let him go his way.”
It was the age of X-planes soaring over southern California’s Edwards Air Force Base, flown by ace test pilots such as Chuck Yeager and Scott Cross- field, routinely breaking Mach 1 and stretching the frontiers of flight. The first subsonic jet fighters such as the P¬80 and F-86 soon gave way to supersonic varieties such as the F-100 series, which made practical use of Jones’s ideas of sweepback and high-speed aerodynamics. Meanwhile, up the California coast at Ames, R. T. continued to develop and expand on his swept¬wing theories for supersonic flight, turning out scores of papers that greatly influenced the design and development of the new aircraft. His published work was legendary for the concise and direct character of its arguments. “He made giant leaps,” says Boyd. “I remember reading his first report on the effect of swept-back wings, which was three pages long. He went through all these giant leaps, mental leaps, and expected us to follow them. I never could, quite. After you talked to him, you thought you understood it.”
Other researchers would attempt to “redo” Jones’s work with more intricate and supposedly more sophisticated mathematical proofs, but they would inevitably find themselves unable to escape the elegance of Jones’s unconventional logic. “He was very much an intuitive thinker who thought in physical terms and then used the mathematics to make concrete the ideas that were already in his mind,” explains Vincenti. “He seemed to have a private pipeline to God, somehow.”
From most accounts, it was during the 1950s that Jones hit upon the characteristically unorthodox idea that would become his most famous (or infamous) conception: the oblique wing, which in retrospect seems an almost inevitable evolution of his swept-wing work. If wings swept back by 45, 50, or 60 degrees were so efficient at high speeds, why not sweep them back completely—in other words, put the entire wing on a pivot that could be adjusted for varying flight regimes?
It was typical R. T. Jones. Just when everyone had finally become used to one once-outlandish idea, here he was, again pushing forward into the realm of the absurd. He wasn’t the first to conceive of the idea; again, it had appeared in some of the wartime German research, and an oblique-wing model had undergone some stability tests in the Langley wind tunnels in 1946, although it was rumored that Jones had been the behind-the-scenes motivating force for those experiments. But now the theory of sweepback and supersonic flow had advanced sufficiently (due in no small part to Jones’s work) that the oblique wing could be considered a practical possibility.
Jones certainly realized that some people had trouble with the “unnatural” look of an oblique wing. “Artifacts created by humans show a nearly irresistible tendency for bilateral symmetry,” he noted wryly. But having faced similar resistance to the swept wing, he answered oblique-wing skeptics similarly. “Have you ever seen a bird with an oblique wing?” they would question smugly. To which Jones would reply, “No, but nor do birds fly faster than sound.” He also built and demonstrated a small balsawood oblique-wing glider.
In 1958 wind-tunnel tests at Ames (which, like Langley, became part of NASA at its founding the same year) confirmed that the oblique wing definitely displayed far less drag at high speeds than the (now) conventional sweptback wing, but it remained only an intriguing curiosity. This time Jones would give the world a little more time to catch up, because his restless mind was moving on to something new. In 1963 he once again did something few people expected, switching gears completely to leave Ames and aeronautics and move back east to work for his friend Arthur Kantrowitz at the Avco-Everett Research Laboratory in Massachusetts.
Kantrowitz, a physicist in the same wildly creative mold as Jones, had met R. T. while working at Langley in the 1930s. He went on to become a professor at Cornell University and founded the Avco-Everett lab in 1955 to solve practical scientific problems for America’s defense and space programs. Among these was the development of ablative heat-dissipating nose cones for ICBM warheads and manned spacecraft. Now working with his heart surgeon brother on a new project that called for creative thinking about fluid mechanics, he naturally turned to his former wunderkind NACA colleague. Jones would spend the next seven years working at Avco, helping Kantrowitz develop the intra-aortic balloon pump, a device that has saved the lives of thousands of heart patients. His work on blood flow dynamics also led to the development of one of the world’s first artificial hearts.
Such accomplishments were further proof of Jones’s eclectic interests, all of which he pursued with the same creativity and enthusiasm as he did aerodynamics. Startlingly original, even in his hobbies, Jones met one of his daughter’s needs for a better but prohibitively expensive new violin by deciding that he could probably design and build just as fine an instrument himself. He threw himself into an intensive study of violin construction and acoustics, and after some experimentation managed to construct a rather unconventional instrument with stellar musical qualities, good enough that his daughter later played it in recitals and with symphony orchestras. He went on to build a variety of violins and violas for other players.
When he became interested in astronomy and telescope making, Jones delved just as deeply, creating an innovative type of reflecting telescope with such success that he maintained a profitable sideline of building and selling his designs to amateur astronomers. He also didn’t hesitate to publish the results of both his musical and telescopic hobbies in the professional literature.
“R. T. was very much a broad-gauge thinker who didn’t think only about airplanes,” says Vincenti. “He thought about other things too”—even something as outlandish as teaching birds themselves how to fly. “R. T. had this pet crow called Max, after Max Munk,” Boyd remembers. “He got it as a baby, and it couldn’t land. It would come in for a landing and flare 45° its wings and kind of hit and tumble on the ground. He swore that he taught that bird to land. He would stand there and the bird would come in and flare its wings, and R. T. would do a 14 thing with a stick and make the bird do something different, and finally he learned to flare properly.”
Jones’s love of aerodynamics brought him back to NASA Ames in 1970 to work on various problems of high-speed aircraft design, including revisiting the oblique-wing concept. Once he had developed the idea further through wind-tunnel testing, publishing several more papers, and designing and building small-scale radio-controlled models, the oblique wing was ready to take to the skies. NASA hired Burt Rutan, later famous for his record-shattering airplane designs, to come up with a prototype, which was built by the Ames Industrial Company in Bohemia, New York. The finished airplane, dubbed the NASA AD-1 (Ames Dryden-1), was cheap for an experimental aircraft, costing just under $250,000, and was delivered to NASA Dryden Flight Research Center in February 1979.
Jones’s various papers had shown that the oblique wing could be realized in several different ways. In its purest form, it can be simply a flying wing at an oblique angle, with engines mounted parallel to the flight axis. The wing can also be placed on a normal fuselage and fixed permanently at a particular angle, or center-pivoted to a fuselage, allowing the angle to be changed as desired.
This was the design chosen for the AD-1, since it would allow for tests in various configurations. It could be pivoted in flight from 90 degrees perpendicular to the fuselage—a conventional straight wing—to an alarming 60-de-gree angle. And although the entire oblique-wing concept had been developed for use solely at supersonic speeds, where its advantages would be most marked, the AD-1 wouldn’t be flying anywhere near so fast. It boasted only two small turbojet engines, making it capable of speeds no greater than those of a small private plane, about 180 knots, and altitudes no higher than about 15,000 feet. It was also remarkably tiny, just over 38 feet long with a wingspan of barely over 32 feet. To save weight and ensure mechanical simplicity, a fixed tricycle landing gear was mounted underneath, partially enclosed by the lightweight fiberglass-reinforced plastic fuselage. Fully loaded with its pilot and the small amount of fuel it was able to carry, the AD-1 weighed only about 2,100 pounds.
By the historical standards of Edwards and Dryden, which had witnessed the fastest and most sophisticated airplanes ever created, the AD-1 was humble, but it was perfectly built for its purpose: not to break any records, but to give pilots a chance to explore the actual handling and control characteristics of an oblique wing.
The theory, as usual with Jones’s ideas, was beautiful. But how would it work in the real-world skies over NASA Dryden? On December 21, 1979, NASA pilot Thomas McMurtry took the AD-1 aloft for the first time. Following the scrupulously methodical and carefully incremental canons of flight testing, nothing unusual was at-tempted: McMurtry merely took the craft up and down to show that yes, it could fly. No one was going to try something as radical as pivoting the wing until it was certain that the craft was airworthy.
Slowly and steadily over the following year and a half, repeated flights by McMurtry and another NASA test pilot, Fitz Fulton, put the AD-1 through its paces. By the middle of 1981 they were flying the AD-1 with its wing pivoted at various angles, including at full 60-degree obliquity.
The flight test program essentially confirmed Jones’s ideas. Not only did the oblique wing fly, it did so efficiently and effectively. If it did display some problems with stability at high angles—as Jones had predicted—pilots found these quirks relatively easy to deal with.
Ames test pilot Warren Hall had the opportunity to try out the AD-1 late in the test program. “It really was no big deal for most of us,” he recalls. “It was fun, I got a kick out of it”—particularly flying with the wing at its full 60-degree angle. “There was nothing abrupt. There wasn’t anything that said, hey, this is a bad flying airplane. It was easy to fly. Take off and landing, you just did it, you didn’t think about it. Because you worked your way up from 10 to 60, you learned real quick to go left and right going whichever way you wanted to go, up and down, and there wasn’t any problem at all.” Hall sums up the reaction of most of the AD-1 pilots when he notes, “I would have liked to put it in my pocket and bring it home.”
The AD-1 flew for the last time at the Oshkosh Air Show in August 1982, after providing a wealth of practical data on the application of wing obliquity, and it now resides at the Hiller Aviation Museum in San Carlos, California. The next logical step would have been the construction of a larger, more powerful test aircraft, perhaps even a supersonic one. But this was not to be. “There was a study program for a supersonic version of that airplane which never flew,” says Ilan Kroo, a professor of aeronautics and astronautics at Stanford University. NASA also lost the oblique wing’s chief champion when Jones finally retired from the agency in 1981.
Even in his 70s, Jones was hardly ready to settle down. Although he’d never picked up an actual college diploma—his sole degree was an honorary doctorate bestowed upon him by the University of Colorado in 1971—he became a consulting professor at Stanford, mentoring a new generation of aerodynamicists and continuing to add to his already prodigious list of publications, which included an essential textbook, Wing Theory, in 1990. (An anthology of his collected works, published by NASA in 1976 when he was only 65, was over a thousand pages long and included not only his influential aerodynamics work but also papers on heart-flow dynamics, violin design, and even relativity theory.)
R. T. Jones passed away at the age of 89 in August 1999, shortly after being named to the newly instituted NASA Ames Hall of Fame as one of the most important and influential figures in the research center’s history—merely the latest honor in a long list, including election to the National Academy of Engineering in 1973 and to the National Academy of Sciences in 1981, the same year he had been awarded the Langley Medal of the Smithsonian Institution (following such other aviation luminaries as the Wright Brothers and Charles Lindbergh).
His legacy is visible in the swept wings of every airliner and the current work of every aerodynamicist and aircraft designer—and probably in aircraft still to come. The oblique-wing concept never really went away. Its advantages of decreasing drag at high speeds while greatly reducing fuel consumption have become even more attractive in a 21st- century world struggling to increase energy efficiency.
That objective, coupled with the development of advanced computer flyby-wire systems that can compensate for stability and control problems, may ultimately trump the traditional resistance to the oblique wing’s odd appearance. “There’s always the initial surprise at the asymmetry of the design and the comments that there are no asymmetrical birds,” Kroo observes. But, he notes, “I think for the most part the flying public understands that the FAA has very stringent safety regulations and if it passes those, it’s probably going to be safe enough to fly on. And if they save money because this thing saves fuel, the chances are that this would not be a huge impediment to the airplane.”
The main obstacles to the advent of oblique-wing aircraft are now less psychological than practical. Since the oblique wing is at its heart a design for supersonic flight, currently banned for civilian aviation, companies have little incentive to develop the technology. “Unless you’re talking about supersonic speeds, I don’t think there’s much reason to have an oblique wing,” notes Warren Hall. Kroo agrees: “There have been some studies of trans-sonic oblique-wing airplanes, but the real advantage is supersonic. Because the airplane is quite different, there are many unknowns. It’s always less expensive and lower risk to take an existing design and make small modifications, for example putting winglets on a 737.”
While we may have to wait for a new era of civilian supersonic flight to see an oblique-wing plane carrying paying passengers, a military version may be much closer. The Defense Advanced Research Projects Agency has awarded more than $10 million to Northrop Grumman to develop a concept for an unmanned aerial vehicle (UAV) that would be the purest form of Jones’s idea: an oblique flying wing with an engine pod that would pivot in the flight direction. Called the Switchblade, the craft would be capable of speeds up to Mach 2 and altitudes of about 60,000 feet. So far, the idea hasn’t proceeded farther than some wind-tunnel tests of scale models—as far as is publicly known, no oblique-wing UAVs have yet cruised over Edwards or anywhere else. But it serves as another example of the persistence and pervasiveness of Jones’s innovations.
R. T. Jones’s work will continue to assist everyone who flies, not to mention others who design and build violins, telescopes, artificial hearts, and, of course, aircraft. Kroo compares Jones’s creativity, energy, and unconventional talent for innovation to today’s crop of technological entrepreneurs: “He’s in good company with people like Steve Jobs and others who have gone through an unconventional educational path. I think R. T. would be in lots of interesting startup companies if he were around today.”