By James Schultz
In one of the most famous radio broadcasts ever aired, a series of news bulletins purported to follow the progress of an alien invasion of American soil. Debuting on Halloween, 1938, the Orson Welles adaptation of British writer H.G. Wells’ science fiction novel War of the Worlds caused a sensation when as many as a million listeners became convinced the dramatization was real. In urban areas, panicked crowds gathered, while in the countryside, entire families fled their homes – both fearing they would be targets of an imminent, apocalyptic Martian attack.
Faster than a speeding bullet - Taken aloft under the wing of a B-52, the X-15 rocket powered aircraft was flown from 1959 to 1968, helping to investigate all aspects of manned hypersonic flight. While setting unofficial speed (4,520 mph) and altitude records (354,200 feet) the X-15 contributed to the development of NASA’s human spaceflight programs.
Roughly 40 years later, a lonely bleat from high above Earth’s surface would herald another sort of invasion. Only this time fiction would give way to fact: a basketball-sized sphere known as Sputnik ominously announced the Soviet Union’s claim on what would be eventually dubbed “the high frontier.” In the race to space, the United States had been trumped by its chief geopolitical rival and likely mortal enemy. “Conjure the scene from ‘The Wizard of Oz’: the wicked witch flies over the Emerald City spelling out ‘Surrender Dorothy,’ and all the terrified citizens rush to the wizard to find out what it means,” wrote Neil Armstrong biographer and Auburn history professor Dr. James R. Hansen in his book Engineer in Charge. “In an exaggerated way, this gives some idea of how the Sputnik crisis and the resulting American space program triggered [public feeling].”
How could the wizards of aeronautical science respond? Although researchers had been experimenting with rockets for well over a decade – with many suborbital launches taking place on the state of Virginia’s isolated Eastern Shore – none had yet lofted a satellite to orbit. And no one had demonstrated any American airplane equivalent that could seamlessly make the difficult leap from atmosphere to vacuum.
Then-president Dwight Eisenhower reacted to Sputnik by signing the National Aeronautics and Space Act in late July 1958. Roughly two months later, on Oct. 1, 1958, the National Aeronautics and Space Administration, NASA for short, opened its doors. It was no accident that aeronautics came first in the title. “Anyone launching a rocket knows you have to account for passage through the atmosphere. On reentry you also have to deal with frictional heating,” said Dr. Jaiwon Shin, associate administrator for NASA’s Aeronautics Research Mission Directorate. “So the study of aeronautics and its applications to spacecraft design, materials and structures was and remains essential. That holds true whether we’re talking about Earth or other planets with different atmospheres.”
Adding space studies to the professional portfolios of those who began their careers working for NASA’s predecessor agency the National Advisory Committee for Aeronautics, referred to by insiders as “the NACA,” (unlike NASA, each letter of the NACA acronym was pronounced separately) would prove a natural progression. The American space program would essentially be invented by dozens of young devotees who matured into methodical engineers and aerodynamicists; the intellectual heirs to Orville and Wilbur Wright’s tradition of painstaking experimentation and refinement.
First the NACA and then NASA would provide the experimental capabilities and facilities that would be used in the development of practically every domestically produced commercial transport and military aircraft in the past 50 years. NACA experts would generate databases and technical reports to advance fundamental knowledge in such areas as airfoil design, aircraft handling and compressible aerodynamics, even as the national spotlight would illuminate NASA’s new role in space exploration and travel.
Richard Whitcomb, developer of the transonic area rule, supercritical wing and winglets, which transformed military and civilian aircraft design.
“NASA’s strength has been the identification of big problems; the ability to focus on what’s critical and identify the real bottlenecks,” said Dr. Tom Crouch, senior curator for aeronautics at the Smithsonian’s National Air and Space Museum and biographer of the Wright brothers. “Then its people offer up directions for solutions. It’s hard to think of any airplane flying today nationally or internationally where the NACA or NASA hasn’t made a contribution.”
The NACA, like NASA, bowed onto the world stage during a time of geopolitical unrest. Just before World War I, support for federally sponsored aeronautics studies was lukewarm. Military conflict would prove persuasive, as elaborated in Engineer in Charge by historian James Hansen:
Suddenly, or so it seemed to those who assumed innovation would require centuries and not decades, flight was an imperative in both the military and civilian worlds. Flight equaled commerce, and money. No longer the sole province of daredevils and hardy adventurers, flight would quickly become a serious business – literally.
The United States needed aircraft that wouldn’t shake themselves to pieces while aloft, reliable controls that wouldn’t fail even under duress, wings that would slide efficiently through an often turbulent atmosphere, and engines that, while powerful, would sip fuel rather than gulp it.
Rickety wouldn’t work. Slow would be shunned. And don’t forget to have a working prototype completed by next Tuesday, at the latest.
The Aeronautical Trifecta
H. Julian Allen, NASA Ames Research Center Director from 1965 to 1969, developer of the “Blunt Body Theory” of aerodynamics that led to the design of ablative heat shields protecting Mercury, Gemini and Apollo astronauts as their space capsules re-entered Earth’s atmosphere.
No matter the timetable, pushing the aeronautics envelope was no easy task. Identifying potential issues and challenges was an important first step; the NACA made a series of vital theoretical contributions, furthering the understanding of the ways wings, engines and fuselages responded both independently and as an integrated system under a wide variety of flight conditions.
NASA’s predecessor agency also designed and built a number of wind tunnels, places where small models and large aircraft prototypes alike were tested and evaluated as airspeeds were changed and atmospheric conditions were fine-tuned.
Despite experimental advances vetted by flight tests, vexing problems remained. Chief among them was how to enable airplanes to fly faster while not burning enormous amounts of fuel. Enter NACA/NASA researcher Richard Whitcomb, who would see ways over some of the biggest hurdles confronting military and commercial aviation. Although inspired by studies done by other aeronautics scientists domestically and abroad, Whitcomb nonetheless demonstrated an unmatched individual ingenuity that would lead to the creation of three crucial innovations: the area rule, the supercritical wing and winglets. All would eventually be widely and routinely deployed on aircraft.
“Dick Whitcomb’s achievements really stand out: one every decade for 30 years, from the 1950s through the 1970s,” said the Smithsonian’s Crouch. “He’s probably the most significant aerodynamicist working in the last 50 years. Whitcomb’s intellectual fingerprints are on virtually every commercial aircraft flying today.”
In December 2007, several hundred attendees commemorated the 104th anniversary of the Wrights’ first powered flight, honoring Whitcomb’s achievements at the Wright Brothers National Memorial in Kitty Hawk, N.C. Whitcomb’s efforts would be recognized as on par with other aerospace pioneers, men and women such as Orville and Wilbur Wright, Charles Lindbergh, Amelia Earhart, John Glenn and Neil Armstrong, all of whom were lauded for their contributions to flight science and technology.
Whitcomb’s first innovation – and, in the eyes of many, his most important – was discovery of what would be called the area rule. As writer Lane Wallace noted in her article “The Whitcomb Area Rule: NACA Aerodynamics Research and Innovation,” Whitcomb’s knowledge of airflow behavior was enhanced by study of the unusual shock waves he encountered during experiments in one of the NACA’s wind tunnels over a period of seven years. Without such exposure, it is doubtful Whitcomb would have gleaned information sufficient to understand the causes of the air drag that made travel at or over the speed of sound so difficult to achieve without huge propellant expenditures.
Whitcomb discovered if the fuselage of an airplane was narrowed to resemble the shape of an old-fashioned Coke bottle, drag would be substantially reduced and speed significantly increased – but without the need of additional engine power. As noted by historian Dr. Michael Gorn in his book Expanding the Envelope, Whitcomb, in describing the advance, remarked that “The basic idea was as simple as giving the air someplace to go so it wouldn’t push back on the wing. It was as simple as putting wings on a Coke bottle.” Although quickly adopted by the military for supersonic fighter aircraft, the area rule’s true legacy was that it made commercial subsonic jet travel practical by making it affordable. Applied to jetliner design, the area rule enabled efficient fuel consumption even at high subsonic speeds.
If the area rule was Whitcomb’s major accomplishment of the 1950s, his supercritical wing revolutionized the design of 1960s-era jets. The key was the development of a swept-back wing airfoil that delayed the onset of aerodynamic drag, increasing the fuel efficiency of aircraft flying close to the speed of sound.
Side by side -The F-8 Digital Fly-By-Wire (left) and F-8 Supercritical Wing experimental aircraft in flight.
Again, historian Gorn:
In the 1970s Whitcomb’s third major advance was winglets, vertical wing tips that reduced yet another source of drag to further improve aerodynamic efficiency. Many airliners and private jets now sport wingtips that are angled up for better fuel performance.
“Whitcomb’s work was huge in terms of its impact on commercial aviation,” said independent scholar Dr. Robert Ferguson, who is writing NASA’s First Day, a history of NASA aeronautics research that begins shortly after World War II and continues through the present. “Whitcomb was ahead of the curve, in terms of bringing all the elements together. We’re literally flying on Whitcomb’s wings.”
An Innovation Portfolio
For NASA, the transition from the “A” to the “S” in its acronym was vividly demonstrated by the development, in partnership with the Navy and Air Force, of the X-15 experimental aircraft (such craft are known within NASA as “X-vehicles”). Between 1959 and 1968 the X-15 made 199 flights, setting an altitude record of 354,200 feet (67 miles) on Aug. 22, 1963 and a speed record of Mach 6.7 (4,520 mph) on Oct. 3, 1967.
The X-15 program set benchmarks for hypersonic aircraft performance, stability and control, high-temperature materials, shock interaction and aerodynamic heating. It marked the first use of a human-rated throttleable rocket engine, the first reaction control system for attitude control in space and development of the first practical full-pressure suit to protect pilots in space. Knowledge gained from X-15 flights contributed to all four American manned spaceflight programs: Mercury, Gemini, Apollo and the space shuttle.
“The X-vehicle research pushed us into flight regimes that we hadn’t fully explored,” said Shin of NASA’s Aeronautics Research Mission Directorate (ARMD). “We continue to learn about those regimes, at very high speeds where the demands on aircraft are severe. The data that we’ve collected are helping with the design of vehicles that could one day revolutionize flight.”
Iconic image - NASA research pilot Bill Dana watching NASA’s NB-52B cruise overhead after a research flight in the HL-10 lifting body (left). The HL-10 was flown at NASA’s Dryden Flight Research Center from 1966 to 1975 to study and validate the concept of safely maneuvering and landing a low lift-over-drag vehicle designed for reentry from space. John Reeves is at the lifting body’s cockpit.
NASA’s X-vehicle programs are still going strong. One is the X-51 effort, a joint venture with the Air Force and the Defense Advanced Research Projects Agency to develop a supersonic combustion ramjet, or scramjet, aircraft intended to fly at Mach 4.5 to 6.5. Engine tests on the ground successfully achieved a thrust equivalent of Mach 5.0 in 2007. The first test flights, each lasting at least five minutes, are scheduled for 2009.
“The recent hypersonics work NASA has done is impressive. It’s a terribly difficult theoretical and practical problem,” said Ferguson. “It’s the kind of basic research that challenges scientists and engineers, and really pushes some fundamental areas, like high-temperature aerodynamics, fluid dynamics and systems integration.”
Another X-vehicle project, the X-48B, is a partnership that includes aircraft manufacturer Boeing and the Air Force. Its airframe resembles a flying wing, but differs in that the wing blends smoothly into a wide, flat, tailless fuselage, providing additional lift with less drag than a traditional cylindrical fuselage, thus burning less fuel at cruise speed. Because the engines can be mounted on the top, there also is potential for significant noise reduction on the ground.
NASA’s innovations portfolio isn’t limited to the X-vehicle programs. Glass cockpits, pioneered in ground simulators and demonstration flights in NASA’s Boeing 737 “flying laboratory,” replaced electromechanical dials and gauges with full-color, multifunction, electronic, flat-panel displays on which pilots can select a variety of easy-to-read graphical views of key flight indicators. This concept quickly became commonplace on commercial, business and military aircraft and eventually on the space shuttle, beginning with the shuttle Atlantis’ total technology update in the late 1990s.
From 1976 through 1981, NASA, the Army and the Navy developed the first tilt-rotor vehicle – the Bell XV-15 – which demonstrated the ability to hover like a helicopter but could then rotate its engines and rotors to achieve forward flight like a fixed-wing aircraft. That program led directly to development of the U.S. Marine Corps and U.S. Air Force V-22 Osprey.
The 1980s saw a flurry of NASA aeronautical developments, including:
• Stall-resistant wing research that has influenced wing designs on modern general-aviation aircraft to improve stall-departure characteristics;
• On-board windshear-detection systems to alert pilots of the imminent approach of hazardous weather. NASA researched the fundamentals to understand the dangers to craft, crew and passengers, then helped develop sensors to detect it;
Let’s get vertical - Vertical research flight of the unique XV-15 tilt-rotor aircraft at the NASA Dryden Flight Research Center (1980-1981).
• The UH-60 Airloads Program, jointly sponsored with the Army, to obtain comprehensive, accurate, documented data over the complete operating limits of the UH-60 rotor system so the helicopter community could increase its understanding of rotor behavior, refine and validate analysis tools and design improved rotorcraft,termed the “gold standard” in rotorcraft data; and
• Air-traffic-management automation research, using computers and specialty software to gather information from many sources, including radar systems, flight plans and weather reports, to identify and predict where slowdowns may occur because of airspace congestion.
Another key research area came about as the result of the crash of a commuter flight in 1994, where super-cooled large droplet (SLD) icing was suspected as a primary cause. At that time, little was known about the exact process whereby large droplets freeze on wings and how ice accumulates under SLD conditions. So NASA undertook close collaborations with colleagues in the national and international icing community and those with expertise in such fields as atmospheric characterization, ice-accretion physics and computer simulation. Subsequently, the SLD research initiative led to much greater understanding of how such conditions arise and how pilots and planes can avoid them.
Over the Horizon
An executive order signed by President George W. Bush on Dec. 20, 2006, underscored the importance of ongoing federal support for aeronautics research. The National Aeronautics Research and Development Policy calls continued progress in “the science of flight … essential to America’s economic success and the protection of America’s security interests at home and around the globe.”
For its part, NASA continued to push the aeronautical-research envelope in the first decade of a new century. In addition to wind tunnels and flight research facilities that comprise its Aeronautics Test Program, NASA focused on three other areas of enterprise:
• Fundamental Aeronautics, addressing noise, emissions and future-vehicles performance challenges, from low to high speeds;
• Aviation Safety, concentrating on improving the intrinsic safety of current and future aircraft in an increasingly complex and more automated airspace system; and
• Airspace Systems, focusing on methods and means to increase the capacity, efficiency and flexibility of the nation’s airspace system.
“All of our aeronautics research has at its core service to the nation,” said ARMD associate administrator Shin. “What we’re doing should ultimately benefit American citizens, whether it’s safer and cleaner skies or next-generation air travel. But to make those advances you first have to understand the basics. That’s why aeronautics research is so important.”
One essential aeronautics-related initiative in which NASA is participating is known as NextGen, short for the Next Generation Air Transportation System. The NextGen goal is nothing less than a comprehensive overhaul of the nation’s air system to accommodate a doubling or even tripling of current capacity by the year 2025. Coordinating participants’ efforts is the Joint Planning and Development Office, or JPDO, whose mandate it is to oversee the contributions of federal agencies like NASA, the Federal Aviation Administration, the White House Office of Science and Technology Policy and the Departments of Commerce, Defense, Homeland Security and Transportation. Also involved are local governments, regional authorities, commercial air carriers and private-sector firms, all of whom are helping to define NextGen parameters.
Sleek design - The fifth flight of Boeing’s sub-scale X-48B Blended Wing Body aircraft over the edge of Rogers Dry Lake at Edwards Air Force Base, Calif. on Aug. 14, 2007.
Aiding in the effort is NASA-created software to help air-traffic control systems become vastly more efficient, rapidly generating thousands of aircraft trajectories that will enable smooth, minute-by-minute air traffic flows at the national level.
Beyond NextGen, NASA is also examining how future aircraft could be retooled to become safer, quieter and more environmentally friendly. For example, in the case of noise reduction, by leveraging computer simulations and wind tunnel and flight tests, NASA researchers have participated in the development of engine nozzle chevrons that use an asymmetrical-scallops design to reduce noise in both the passenger cabin and on the ground.
NASA has also led the Synthetic Vision System (SVS) initiative, which makes use of flat-screen displays to provide real-time, clear-daylight views to pilots regardless of the weather or hour of the day. Visual information is culled from onboard sensors, inputs from a derivative of the Global Positioning System and topographical databases that are subsequently analyzed and processed by computer. An SVS derivative, commonly called the Enhanced Vision System, has been certified on Gulfstream business jets and is expected to come online with other commercial aircraft in the near future.
In addition, NASA’s specialists in computational fluid dynamics, or CFD, have made huge strides in matching computer-based, aeronautical design-and-modeling code to the strictures and imperatives of real-world flight.
When a history of 21st century aeronautics is written, one of its themes may well be the integration of airplanes, airports and air travelers into a highly connected, highly responsive, aerospace ecosystem. Within such a system, each element immediately responds to and interacts with the other. Although vital, passenger safety and comfort aren’t the only considerations; also critical are environmental health (including little or no pollution from emissions, engine noise or aircraft manufacture), energy efficiency, in-flight self-repair and active anticipation and avoidance of severe weather.
Ultimately, aeronautical lessons learned by NASA terrestrially may be applied off-world. If one day, as some hope, there are “planetary planes” traversing extraterrestrial skies and navigating through less-than-hospitable aerodynamic conditions, their success will be due to the aeronautical research being conducted today.
One hundred years hence, even as NASA or its successor looks back on a second century of flight, a new generation of aeronautical-science wizards may be confronting challenges difficult to presently visualize. That would seem appropriate, given that powered flight itself was once seen as an outlandish preoccupation suitable for cranks and dreamers. No more; NASA’s most enduring aeronautical legacy may be that the impossible was made only difficult and the difficult made all but inevitable. History, as always, will be the ultimate judge.
J.R. Wilson also contributed to this article.