****Chapter 5**
**The Whitcomb Area Rule:****NACA Aerodynamics Research and Innovation**

**by Lane E. Wallace**
**

As the 1940s came to a close, military aircraft manufacturers in theUnited States faced a disturbing problem. The Bell X-1 had broken the so-called"sound barrier," and both the Air Force and the Navy were looking for nextgeneration aircraft that could operate at supersonic speeds. But preliminarytests of models indicated that even the best designs put forth by industryengineers were not going to be able to achieve that goal. A sharp increasein drag at speeds approaching Mach One was proving too much for the limited-powerjet engines of the day to overcome.

The solution to this frustrating impasse was found by Richard T Whitcomb,a young aerodynamicist at the National Advisory Committee for Aeronautics(NACA) Langley Research Center in Hampton, Virginia. His development ofthe "area rule" revolutionized how engineers looked at high-speed dragand impacted the design of virtually every transonic and supersonic aircraftever built. In recognition of its far-reaching impact, Whitcomb's arearule was awarded the 1954 Collier Trophy.

Yet it is not just the significance of the concept that makes the discoveryand application of the area rule interesting. The story of its developmentprovides insights on how innovations are "discovered" and how, even ata time when research projects were growing bigger and more complex in scope,a single, creative individual could still play a critical role in the developmentof new technology. In addition, while the area rule concept was appliedalmost universally to supersonic aircraft designs, that "success" alsoillustrates some of the factors that influence whether industry appliesa given technology, regardless of its inherent worth.

**
**The Transonic Drag Problem and the Area Rule**
**

Researchers in the Langley Research Center's wind tunnels had begunworking with transonic airflows and the problem of transonic drag (at speedsapproaching and surpassing the speed of sound) even before the end of WorldWar II. In 1943, John Stack, head of Langley's Eight-Foot High-Speed Tunnelbranch, obtained approval to increase the power in the tunnel from 8,000horsepower to 16,000 horsepower. The upgrade, completed in the spring of1945, allowed researchers to produce reliable airflow data in the tunnelfor speeds up to Mach .95. 1

One of the researchers working with Stack in the Eight-Foot High-SpeedTunnel was a young engineer named Richard Whitcomb. Whitcomb had been fascinatedwith airplanes and aerodynamics since he was a young boy, building andtesting airplane models

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135
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**136 THE WHITCOMB AREA RULE: NACA AERODYNAMICS RESEARCH AND INNOVATION**
****NACA/NASA Langley engineer Richard T. Whitcomb was awarded the 1954Collier Trophy for his development of the "area rule, " an innovation thatrevolutionized the design of virtually every transonic and supersonic aircraftever built. Here Whitcomb inspects a research model in the 8-Foot TransonicTunnel at Langley. (NASA photo no. LAL 89118).****

made out of balsa wood. He was hired by the Langley Research Centerin 1943, aft receiving an engineering degree from the Worcester PolytechnicInstitute. The Langley managers initially wanted him to work in the FlightInstrument Division, but Whitcomb stubbornly insisted that he wanted towork in aerodynamics. Fortunately, he was granted his preference and wasassigned to Stack in the 8-foot wind tunnel.

Initially, Whitcomb was assigned the task of performing test monitoringfor other researchers. But for an eager young engineer, the key to advancementwas to "run the tests and keep your eyes open, your ears open," Whitcombrecalled. "I kept coming to Gene (Draley, Stack's replacement as head ofthe 8-foot tunnel) and saying maybe it ought to be done this way. Let'stry this. And somewhere along the way, Gene says 'OK, go try it,' and that'swhere I got started." 2

By july 1948, Whitcomb had developed a reputation as "someone who hadideas" 3 and was starting to pursuehis own research experiments. He proposed a series of wind tunnel testsin the repowered 8-Foot High-Speed Tunnel for a variety of swept wing andfuselage combinations. He hoped the tests would uncover a configurationwith significantly lower

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drag at transonic speeds. The tests were run in late 1949 and 1950,but the results were both perplexing and discouraging. None of the combinationshad much effect on reducing the drag of the models as they approached MachOne.4 Clearly, the researchers neededto know more about the behavior of airflow in the transonic region in orderto figure out what was causing such a stubborn drag problem. Unfortunately,this data was difficult to obtain. Even the upgraded eight-foot wind tunnelat Langley could only reach speeds of .95 Mach.

Because of the limitations of the available wind tunnels, researchersin the mid-1940s had resorted to several "stopgap" methods to try to learnmore about transonic airflow. One series of experiments involved droppinginstrumented test missiles from a B-29 Superfortress. Test airfoils werealso mounted on the wing of a P-51 Mustang fighter plane that was thenput into a high-speed dive. With this configuration, the airplane's speedremained subsonic but the airflow over the portion of the wing holdingthe test airfoil surpassed the speed of sound. A third approach used rocketmodels launched from Wallops Island, a remote beach location across thebay from the Langley Research Center.

All three methods had their drawbacks, however. The falling-body andwing-flow techniques offered less precise data than that obtained in awind tunnel. The rocket tests produced more precise data, but they were"100 times as expensive as a wind tunnel test" and could only explore asingle parameter at a time. Furthermore, the Schlieren photographs thatillustrated the shock wave patterns of high-speed airflow could only beobtained in a wind tunnel.5

Consequently, it was not until Stack and his team of engineers, whichincluded Whitcomb, developed a "slotted-throat" modification for the 8-footwind tunnel in 1950 that transonic flows could be thoroughly explored.6The slotted-throat modification prevented the choking that had limitedthe speeds in the test section of the tunnel and allowed the air to gothrough the speed of sound. For the first time, researchers had a toolto investigate precisely what airflow did in that speed range and whatmight be causing the puzzling drag they had observed.

Actually, the slotted throat wind tunnel was only one of the tools Whitcomband his associates used to investigate transonic airflows. But once thatwas in place, they could then employ other existing research tools to lookat what the airflow was doing. In late 1951, Whitcomb tested a swept-backwing-fuselage combination in the now-transonic Eight-Foot High-Speed Tunnel.7Tuft surveys, which used small pieces of yarn taped onto airfoil and fuselagesections, were conducted to look at airflow disturbances. Coverings withpressure-sensitive openings were put on model sections to determine thevelocity of the air over particular areas, and Schlieren photographs wereused to look at the shock wave characteristics of the model at transonicspeeds.8

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138 THE WHITCOMB AREA RULE: NACA AERODYNAMICS RESEARCH AND INNOVATION
**

The results, especially those revealed by the Schlieren photographs,showed that the shock waves created as the airflow approached the speedof sound were different and bigger than anticipated. Undoubtedly, it wasthe losses from these unexpected shock patterns that was causing the sharpincrease in drag at transonic speeds. But the question of what was causingthe shockwaves still had to be answered before researchers could try tofind a way to combat the phenomenon.

Several weeks later, a world renowned German aerodynamicist named Dr.Adolf Busemann, who had come to work at Langley after World War II, gavea technical symposium on transonic airflows. In a vivid analogy, Busemanndescribed the stream tubes of air flowing over an aircraft at transonicspeeds as pipes, meaning that their diameter remained constant. At subsonicspeeds, by comparison, the stream tubes of air flowing over a surface wouldchange shape, become narrower as their speed increased. This phenomenonwas the converse, in a sense, of a well-known aerodynamic principle calledBernoulli's theorem, which stated that as the area of an airflow was madenarrower, the speed of the air would increase. This principle was behindthe design of venturis,9 as well asthe configuration of Langley's wind tunnels, which were "necked down" inthe test sections to generate higher speeds.10

But at the speed of sound, Busemarm explained, Bernoulli's theorem didnot apply. The size of the stream tubes remained constant. In working withthis kind of flow, therefore, the Langley engineers had to look at themselvesas "pipefitters." Busemann's pipefitting metaphor caught the attentionof Whitcomb, who was in the symposium audience. Soon after that Whitcombwas, quite literally, sitting with his feet up on his desk one day, contemplatingthe unusual shock waves he had encountered in the transonic wind tunnel.He thought of Busemann's analogy of pipes flowing over a wing-body shapeand suddenly, as he described it later, a light went on.

The shock waves were larger than anticipated, he realized, because thestream tubes did not get narrower or change shape, meaning that any localincrease in area or drag would affect the entire configuration in all directions,and for a greater distance. More importantly, that meant that in tryingto reduce the drag, he could not look at the wing and fuselage as separateentities. He had to look at the entire cross-sectional area of the designand try to keep it as smooth a curve as possible as it increased and decreasedaround the fuselage, wing and tail. In an instant of clarity and inspiration,he had discovered the area rule.

In practical terms, the area rule concept meant that something had tobe done in order to compensate for the dramatic increase in cross-sectionalarea where the wing joined the fuselage. The simplest solution was to indentthe fuselage in that area, creating what engineers of the time describedas a "Coke bottle" or "Marilyn Monroe" shaped design. The indentation wouldneed to be greatest at the point where the wing was the thickest, and couldbe gradually reduced as the wing became thinner toward its trailing edge.If narrowing the fuselage was impossible, as was the case in several designsthat applied the area rule concept, the fuselage behind or in front ofthe wing needed to be expanded to make the change in crosssectional areafrom the nose of the aircraft to its tail less dramatic.11

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FROM ENGINEERING SCIENCE TO BIG SCIENCE 139

**The Pieces of the Puzzle: Creative Innovation**
**

Although the pieces may have come together in a flash of insight, therewere actually several important elements and processes that contributedto Whitcomb's discovery. Whitcomb had developed a reputation as somethingof a "Wunderkind" at Langley because of his unique combination of knowledgeand intuition about airflows; a combination that undoubtedly contributedto his discovery of the area rule. 12The intuition may have been a gift, but his knowledge of airflow behaviorwas certainly enhanced by his seven years of experience working with Langley's8-foot wind tunnel.

The discovery of the area rule concept was also dependent on the previousinvention of the slotted-throat tunnel design. Without that piece of technology,Whitcomb could not have gathered the information necessary to understandthe causes of transonic drag. In fact, the very existence of the wind tunnelsat Langley was a critical factor in allowing a new approach in design tosurface and be tested. If the information had to be obtained through anelaborate, expensive flight test program, fewer ideas could have been investigated,and Whitcomb might not have had the opportunity to test his innovativetheory.

****At Wallops Station, in tidewater Maryland, in 1953,Langleys Pilotless Aircraft Research Division (PARD) tested rocket-poweredmodels of the delta-winged Convair F-102 before, (left) and after (right)modification to take advantage of Whitcomb's "area rule. " (NASA Photo)**.**

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**140 THE WHITCOMB AREA RULE: NACA AERODYNAMICS RESEARCH AND INNOVATION**

In addition, the projects conducted at Langley were still fairly small,individual research efforts that allowed for experimentation. This kindof atmosphere, while not entirely unique among government-funded facilitiesin the early 1950s, was becoming more unusual. At one time, individualor small-group research efforts had characterized many research laboratories.But the exponential growth of technology and complex technological researchduring World War II began to change that. The Manhattan Project, responsiblefor the development of the atom bomb, symbolized for many a significantshift in technological research from small, independent projects conductedby single laboratories to large, complex research programs involving manypeople, broad resources and funding, and multiple disciplines.13

In a bigger and more complex research environment, with approvals anddecisions dependent on higher-level program managers, Whitcomb might nothave had the latitude or opportunity to develop and test the area ruleconcept. But the NACA Langley environment offered a middle ground betweena small, independent laboratory and a large research program. Whitcombhad expensive technological tools at his disposal, such as the slotted-throatwind tunnel, but he still had the independence and flexibility to developand test a radical new concept on his own.14

Whitcomb was also assisted by the informal management environment andthe orientation toward experimental research at the Langley Research Center,both of which were conducive to individual innovation. As John Becker explainedin his case histories of four NACA programs,

> *Management (at Langley) assumed that research ideas wouldemerge from an alert staff at all levels.... On a problem of major proportionssuch as transonic facilities, any scheme for research that survived peerdiscussions and gained section and division approvals was likely to beimplemented ... and very little (paperwork) was required in the simpleNACA system. Occasional chats with his division chief or department head,or a brief verbal report at the monthly department meeting were about allthat was required of the NACA project engineer.*15

This kind of environment was particularly well-suited to an introspectivethinker like Whitcomb. Managers knew he was a talented aerodynamicist,and they were wise enough to keep his paperwork to a minimum and give himthe space and freedom to think, experiment, and explore.16

Langley's orientation toward hands-on, experimental research was a significantfactor in Whitcomb's discovery, as well. As opposed to research centersthat focused more on theoretical research, Langley encouraged exploratoryexperiments such as the wind tunnel tests Whitcomb devised to investigatewing-body combinations and airflow at transonic speeds. The breakthroughon the transonic wind tunnel itself, in fact, was a result of a researcherasking himself, "I wonder what would happen if I turned up the power?"That simple question "I wonder what would happen if. . ." instigated numerousexperiments at Langley that , in turn, led to significant discoveries.17

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FROM ENGINEERING SCIENCE TO BIG SCIENCE 141
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This curiosity-driven, experimental approach was especially significantin discovering the area rule, because there was no available theory toexplain the unusual drag encountered at transonic speeds. Researchers hadto come up with a creative way of reaching beyond the known, and the exploratoryexperiments conducted by Whitcomb and others yielded the data that allowedhim to understand the cause of the transonic drag and shockwave phenomena.Conducting hands-on experiments with an aircraft model in a wind tunnelalso helped Whitcomb "see" the airflow behavior in a way mathematical formulaswould not have.

Still, these factors only provided the tools and environment that madeWhitcomb's discovery possible. The breakthrough still required the insightof a creative mind; a mind able to "see" the problem and able to step backfrom accepted rules of design to contemplate a solution based on an entirelynew approach. The process by which Whitcomb was able to do that offersinsight itself as to how scientific or technological innovation occurs.

Science and technology are often viewed as fields completely divorcedfrom any of the arts. Common phrases that distinguish something as "a science,not an art" and describe "the scientific method" as a way to discern anunassailable truth indicate our collective view of science as a rational,logical, linear, mathematical and precise process. Yet since almost thebeginning of time, artistic vision has played a critical role in the advancementof technology and science. Undoubtedly, even the first cave dweller toinvent the wheel first had a picture in his or her mind of what the devicewould look like.

Albert Colquhoun, a British architect, asserted that even scientificlaws are "constructs of the human mind," valid only as long as events donot prove them wrong, and applied to a solution of a design problem onlyafter a designer develops a vision of the solution in his head.18This artistic vision becomes even more important when a scientist or engineerneeds to go beyond the leading edge of knowledge, where existing theoriescease to explain events. At this point, a designer's imagination is criticalinenvisioning potential new solutions. As one analyst of technological developmentsaid, "The inventor needs the intuition of the metaphor maker, some ofthe insight of Newton, the imagination of the poet, and perhaps a touchof the irrational obsession of the schizophrenic."19

Whitcomb was not the only person to look at the problem of transonicdrag. As early as 1944, German aerodynamacist Dietrich Kuchemann had designeda tapered fuselage fighter plane that was dubbed the "Kuchemann Coke Bottle"by American intelligence personnel. Kuchemann's design was not aimed atsmoothing the curve of the cross sectional area to displace the air lessviolently, however. He had simply observed the direction of air flow overa swept-wing design and was trying to design a fuselage that would followthe contours of that flow.20

Whitcomb's area rule was also, in retrospect, said to be implicit ina doctoral thesis on supersonic flow by Wallace D. Hayes, published in1947. But the mathematical formulas employed by Hayes, as well as severalother researchers working on the general problem of transonic and supersonicair flows, did not lead their creators to the necessary flash of inspirationthat crystallized the area rule for Whitcomb. Why didn't they see whatWhitcomb did? The answer, in part, may lie in the precise fact that theywere working with mathematical formulas, instead of visual images. Theanswer may have been imbedded in the numbers in front of them, but theycouldn't see it.

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**142 THE WHITCOMB AREA RULE: NACA AERODYNAMICS RESEARCH AND INNOVATION**

What led to Whitcomb's insight was his talent to see and work with visualmetaphora skill described by Aristotle as a "sign of genius" and an importanttool for seeing things from a fresh perspective, or discovering new truthsabout existing objects or ideas.21In his history of American technological progress, Thomas Hughes also stressedthe importance of visual metaphors in developing innovative ideas, notingthat "although they are articulated verbally, the metaphors of inventorshave often been visual or spatial. Inventors, like many scientists, includingAlbert Einstein, Niels Bohr, and Werner Heisenberg, show themselves adeptat manipulating visual, or nonverbal, images." 22

When Adolf Busemarm used his "pipefitting" metaphor to describe thebehavior of transonic air flow, Whitcomb painted a vivid picture in hismind of air "pipes" flowing over an aircraft. He then incorporated intothat image the other information he had obtained through his experimentswith transonic air flow. Suddenly, he "saw" what was causing the unusualshock waves and what could be done to combat the problem.

In order to see a solution that went beyond existing theory, however,Whitcomb also had to be willing to break free from accepted rules, or paradigms,of aerodynamics.23 In the late nineteenthcentury, Ernst Mach had shown that a bullet-shaped body produced less dragin flight than any other design. This accepted "paradigm" of aircraft designled to the basic fuselage shape employed by transports, World War II fighterplanes, and even the Bell X-1 rocket plane. It was also still the acceptedrule of thumb as engineers began to design the first turbojet-powered supersonicaircraft. The assumption that a bullet-shaped fuselage was the most efficientaerodynamic shape, however, led researchers to look elsewhere for elementsthat could be modified to reduce the drag of aircraft at transonic speeds.To see the solution that Whitcomb envisioned indenting the fuselage inthe area of the wing to reduce the dramatic changes in the aircraft's overallcross-sectional area from nose to tail required going against a "truth"that had worked and had been accepted for over fifty years.

The same paradigm that had helped advance aircraft design for half acentury became, ironically, one of the barriers that kept researchers fromadvancing aircraft design beyond subsonic flight. Why was Whitcomb ableto step back and consider an approach that broke this accepted rule? Forone thing, the circumstances required it. Kuhn noted that "the failureof existing rules is the prelude to a search for new ones."24Certainly, the stubborn problem of transonic drag presented Whitcomb witha situation where existing theories and rules were not working.

Secondly, Kuhn observed that "almost always, the men who achieve ...fundamental inventions of a new paradigm have been either very young orvery new to the field whose paradigm they change ."25When he came up with the area rule concept, Whitcomb was only 30 yearsold. Possibly, the fact that he had not spent twenty years designing bullet-shapedfuselages contributed to Whitcomb's ability to conceive of a differentdesign. He was also something of an introspective thinker and individualisticresearcher, which may have made him more able to contemplate a "fringe"idea that broke from his peer group's assumptions. In any event, Whitcombwas willing to step back from accepted truths and

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FROM ENGINEERING SCIENCE TO BIG SCIENCE 143
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simply look at what his data was showing him; paint a visual pictureof it in his mind and see not what he expected to see, but what was reallythere.

While this may seem a simple and obvious solution to outsiders withforty years of hindsight, Whitcomb's ability to break free of the designdoctrines that dominated aeronautics in his day was, in fact, a uniqueand remarkable ability that truly set him apart from many others in hisfield. Once someone comes up with an answer, it often seems obvious. Butthe researchers struggling with transonic drag were not aware they werecaught in a paradigm that did not work. They were focused on trying tocut a workable path through a dense forest they knew as real and immutable.Whitcomb's genius was his ability to see that the problem was not the path,but the forest itself.

**
**From Idea to Application**
**

When Whitcomb presented his concept of the area rule to some of hiscolleagues at Langley, he encountered skepticism. After all, it was a radicalapproach to aircraft design. But division chief John Stack still allowedWhitcomb to present the idea at the next technical seminar. And listeningto Whitcomb's presentation, this time, was Adolf Busemann, whose staturein the aerodynamics community was such that his opinion carried a greatdeal of weight. Busemann, whose visual pipefitting metaphor had providedthe catalyst to Whitcomb's discovery, understood what Whitcomb had seen.He told the others present that Whitcomb's idea was "brilliant." The skepticismamong some of the others, including Stack, remained. But the support fromBusemann was enough to get Whitcomb the go-ahead to test his theory.26

Throughout the first quarter of 1952, Whitcomb conducted a series ofexperiments using various area-rule based wing-body configurations in Langley's8-Foot High-Speed Tunnel. As he expected, indenting the fuselage in thearea of the wing did, indeed, significantly reduce the amount of drag attransonic speeds. In fact, Whitcomb found that "indenting the body reducedthe drag-rise increments associated with the unswept and delta wings byapproximately 60 percent near the speed of sound," virtually eliminatingthe drag rise created by having to put wings on a smooth, cylindrical shapedbody.27

In a simple world, this validation of Whitcomb's theory would have beensufficient for the principle to be applied to all new industry designs.All that would have been necessary would have been to notify the aircraftmanufacturers that a better design approach had been developed. The worldis not that simple, however, and the inherent worth of an innovation israrely enough for it to be incorporated into commercial products. As LouisB.C. Fong, director of the Office of Technology Utilization at NASA (NationalAeronautics and Space Administration) commented in 1963, "In this age ofautomation, there is nothing automatic about the transfer of knowledgeor the application of an idea or invention to practical use ... there isresistance to new ideas and new technologies; part psychological, partpractical ... and often economic."28

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**144 THE WHITCOMB AREA RULE: NACA AERODYNAMICS RESEARCH AND INNOVATION**

NACA or NASA engineers tend to measure the success of a new idea ortechnology strictly in terms of technical objectives met. Industry, onthe other hand, measures innovative success in terms of profit dollarsgenerated within a specified payback period.29Consequently, a new approach or technology, even if it is technically "better,"may be rejected by industry if its use involves extra costs for the manufacturer.These costs can be in retooling for a new design, replacing machinery,or even in retraining employees or changing the traditional ideas and approachesof its engineers. All of these factors can produce resistance to a newidea or technology within a company, and overcoming that resistance canbe a difficult process.30

There are a couple of situations in which new technology may be rapidlyassimilated into commercial products, however. One is if it can be incorporatedwith minimal extra cost, and a second is if it solves a problem that amanufacturer needs to solve.31 WhenWhitcomb developed his area rule, there was a manufacturer in each of thesesituations, and that fact played a significant role in the speed with whichhis innovation began to impact the design of new aircraft.

While Whitcomb was conceiving and testing his area rule concept, theConvair Division of General Dynamics was developing what it hoped wouldbe the company's first supersonic aircraft. The Convair F102 "Delta Dagger"was designed to be a long-range interceptor, with delta wings and the mostpowerful turbojet engine available at that time, the Pratt & WhitneyJ-57. Early test results of an F-102 model in Langley's 8-Foot High-SpeedTunnel, however, seemed to indicate that the design's transonic drag mightbe too high for the aircraft to surpass Mach One.

The NACA had immediately classified any information pertaining to thearea rule, as it had the research on the slotted throat wind tunnel thatallowed the area rule to be developed. In 1952, the United States was engagedin heated and high-stakes competition for military superiority with theSoviet Union, and NACA realized the importance of transonic research indeveloping superior military aircraft. Although the classification wasnecessary, it made dissemination of information about the area rule moredifficult. Fortunately, NACA's history of successful technology transferefforts had been less a product of published writings than the variouslevels of informal NACA-industry cooperation and researcher-to-engineerdiscussions.32 The area rule wouldprove no exception.

In mid-August 1952, a group of Convair engineers were at Langley toobserve the performance of the F102 model in the Eight-Foot High-SpeedTunnel. Shown the disappointing test results, the engineers asked the Langleyengineers if they had any suggestions. Whitcomb's first research memorandumon the area rule would not be published for another month, but he had completedhis tests on the various wing-body combinations using indented fuselageshapes. He explained his findings and the area rule concept to the Convairteam.

Intrigued, the Convair engineers worked with Whitcomb over the nextfew months to experiment with modifying the F-102 design and building amodel that incorporated the area rule concept. At the same time, however,the company continued work on the original F-102 prototype. The engineersmay have been open to exploring a possible new

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FROM ENGINEERING SCIENCE TO BIG SCIENCE 145
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option, given the uncertainty produced by the wind tunnel tests of theoriginal F-102 model, but the company had already made a commitment tothe Air Force to build two prototypes of the original F-102. In additionto any mental and institutional resistance Convair might have had to changinga design which it had touted so highly and had already made a commitmentto build, the company's commitment also created an issue of cost.

By mid-1952, when Convair tested the F-102 model at Langley, the companyhad already begun setting up a production line at its San Diego, California,facility for manufacturing the aircraft. To change the design would meannot only delays and additional engineering costs, but revamping the productionline, as well. Consequently, far from being receptive to a new design approach,Convair had a significant stake in proving that its new aircraft couldperform just fine without it. 33

Nevertheless, the company could not totally ignore the doubtful testresults of its original design, so its engineers began working on a "PlanB" with Whitcomb while production of the prototype F-102s continued. Startingin May 1953, the Convair engineers and Whitcomb began testing models ofa modified, area rule-based, F-102 design in Langley's wind tunnel. ByOctober 1953, they had developed a model that could meet the Air Forceperformance specifications. Convair noted the results but continued workingon the original F-102 prototype, which flew for the first time on October24, 1953. 34 The first prototype wasseverely damaged on its maiden flight, so test flights had to be postponeduntil January 11, 1954, when the second prototype flew for the first time.The results of the flight tests, however, proved to be largely the sameas those predicted by the wind tunnel tests of the F-102 model in 1952.The aircraft performed below expectations and could not attain supersonicspeeds in level flight. 35

Even at that point, Convair might have continued to press for productionof the design as it was, given that the tooling and production line inits San Diego plant was already set, except for one crucial factor. TheAir Force officials working on the F-102 design were aware of Whitcomb'sarea rule and the fact that a modified F-102 model, based on that concept,had achieved supersonic speeds in wind tunnel tests. Consequently, theAir Force realized that the F-102 was not the best that Convair could do.Whitcomb's experiments had proven that a supersonic airplane was possible,and the Air Force decided to settle for no less. The F-102 program managerat Wright Field in Ohio informed Convair that if the company did not modifythe F-102 to achieve supersonic flight, the contract for the fighter/interceptorwould be cancelled. 36

Incorporating Whitcomb's innovative design approach involved extra expense,but nothing compared to the cost of losing the entire F-102 contract. Convairimmediately halted the F-102 production line and began working on the modifieddesign Whitcomb and the company engineers had developed and tested. Inonly 117 working days, the company had built a new, area rule-based prototype,designated the F-102A. The F-102A flew for the first time on December 24,1954, and surpassed the speed of sound not only in level flight, but whileit was still in its initial climb. The area rule had improved the speedof the F-102 design by an estimated twenty-five percent. 37

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**146 THE WHITCOMB AREA RULE: NACA AERODYNAMICS RESEARCH AND INNOVATION**

While Convair was struggling with its F-102 design, the Grumman AircraftEngineering Corporation was also working to develop its first supersoniccarrier-based fighter, the F9F/F-11F Tiger.38Although the area rule research was classified, the NACA released a confidentialResearch Memorandum on the subject to appropriately cleared aircraft manufacturersin September 1952. Just two weeks after receiving that memorandum, Grummansent a group of its engineers to Langley to learn more about it. The informationthey brought back to Bethpage, New York, was immediately incorporated intothe design, and in February 1953, Whitcomb was flown in to review the finaldesign plans before construction on the prototype was begun. On April 27,1953, the Navy signed a letter of intent with Grumman for the fighter,based on the Whitcomb-approved design. On August 16, 1954, the GrummanF9F-9 Tiger "breezed" through the sound barrier in level flight withoutthe use of the afterburner on its Wright J-65 turbojet engine.39

The enthusiastic incorporation of Whitcomb's innovation by Grumman standsin stark contrast to the qualified experimentation and resistance thatcharacterized Convair's response. But the two companies were in differentsituations. Convair had already completed a design for the F-102 and hadbegun construction of two prototypes and a production line. Grumman, onthe other hand, was still working to design the F11F Tiger when Langleypublished its confidential report on Whitcomb's area rule breakthrough.It was the perfect time to incorporate a better design idea, and involvedfew extra costs to the company. At the same time, the Navy had not yetcontracted for the fighter, and Grumman may well have recognized that itschances of winning the contract would be improved by incorporating anyavailable new technology into its design; especially something that mightimprove its speed.

In any event, Whitcomb's innovative idea was incorporated into two productionmilitary aircraft only twenty-four months after he completed his initialwind tunnel tests on the concept. This incredibly "successful" exampleof technology transfer was a result of two important factors. First andforemost, there was a "problem looking for a solution" 40that the area rule was able to solve. Transonic drag was a real and seeminglyunsurmountable obstacle to supersonic flight. Whitcomb's area rule wasnot one of a number of potential solutions; it was the only approach anyonehad developed that had proven itself capable of overcoming that barrier.It also had the backing of a very powerful customer: the United Statesmilitary. When the Air Force decided to hold firm on its demand that Convair'saircraft fly supersonically in level flight, Convair could not simply sellits F-102s to another customer. The Air Force was its only client, justas the Navy was for Grumman.

But another important element, especially with regard to Convair, wasthe cooperation and individual relationships that existed between the Langleyresearchers, including Whitcomb, and the industry engineers. The modifiedF-102A model that proved to the Air Force that a fighter could achievesupersonic flight was a cooperative effort between Whitcomb and Convairengineers. Without that cooperation, or the informal discussions at Langleythat launched that work, the fate of the F-102 might have been different.

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**FROM ENGINEERING SCIENCE TO BIG SCIENCE 147**

The area rule undoubtedly would have been incorporated into aircraftdesigns eventually, regardless of the individuals involved. But that timeframecould have been different, which could have had an impact on the kind ofair defenses the United States had at its disposal in the early days ofthe Cold War.

As it was, the success of the area rule-based F-102 and F11F was followedby the incorporation of the area rule in virtually every supersonic aircraftbuilt after that point. The Vought F8U "Crusader" fighter and the ConvairB-58 "Hustler" bomber, both of which were on the drawing board at the timethe area rule was developed, were redesigned using Whitcomb's approach.The F-106, which was Convair's follow-on design to the F-102A, adheredeven more to the area rule. It was able to incorporate a much deeper indentationin the fuselage than its predecessor, because it was an entirely new aircraft,unencumbered by existing design elements.

The fuselage of the Republic F-105 "Thunderchief" fighter/bomber, whichflew for the first time in 1955, incorporated the area rule in a slightlydifferent manner. It could not be indented because of its complex engineinlets, so a bulge was added to the aft region of the fuselage to reducethe severity of the change in the cross sectional area at the trailingedge of the wing. The Rockwell B-1 bomber and the Boeing 747 commercialairliner also used the addition of a cross-sectional area to reduce theirdrag at transonic speeds. Both the B-1 and the 747 have a vertical "bump"in the forward section of the fuselage ahead of the wing. It is perhapsmore visible in the 747, where it houses the airliner's characteristicsecond story, but both airframe modifications were added to smooth thecurve of the design's crosssectional area .41

**
**The Collier Trophy**
**

Whitcomb's Area Rule research was classified until September 1955, sohe did not receive any immediate accolades or press on his discovery. Buttwo months after his work was made public, Whitcomb received the NationalAeronautic Association's Robert J. Collier Trophy in recognition of hisachievement the previous year, when the Grumman F9F-9 Tiger and the ConvairF-102A prototypes demonstrated just how significant the area rule was.The Collier Trophy citation read, "For discovery and experimental verificationof the area rule, a contribution to base knowledge yielding significantlyhigher airplane speed and greater range with the same power. " 42

**
**Conclusion**
**

Although an engineering design approach using formulas or algorithmsdoes not lend itself to the kind of notoriety that a project like the X-1generated, the development of the area rule was no less significant. TheX-1 proved the sound barrier could be broken. The area rule made that discoverypractical by enabling production aircraft to operate at that speed.

The fact that the area rule was discovered by an engineer sitting withhis feet up on his desk, contemplating a vision in his mind, also showsthe importance of creativity and the individual in advancing technology.Postwar science and research projects may have been growing in complexityand size, but Whitcomb's discovery was a reminder that the

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**
148 THE WHITCOMB AREA RULE: NACA AERODYNAMICS RESEARCH AND INNOVATION
**

individual researcher was more than a cog in a scientific, process-drivenwheel. Experimentation and the visions in the mind of an individual ableto put available information together in a new way have led to many innovative"breakthroughs" in technology and knowledge.

The history of the area rule research also illustrates that even a "breakthrough"discovery does not always win immediate acceptance by those who might implementit. As opposed to projects that were wholly funded, developed and implementedby the NACA and its successor, the National Aeronautics and Space Administration(NASA), or other government agencies, Whitcomb's breakthrough was justan idea. It may have been developed at a NACA laboratory, but it was notup to NACA to apply it. In order for the innovation to have any impactat all, industry had to agree to use it, which is not always as simplea process as it might seem. Whitcomb's area rule was the answer to a tremendousproblem that industry needed to solve, but the enthusiasm with which itwas received differed greatly between Convair and Grumman. The advantagesoffered by the innovation were the same; the costs of implementing it differed.

But even in the application of the area rule concept, individuals playedan important role. An Air Force demand was the primary reason Convair incorporatedthe area rule into the F-102, despite the added cost. But the Air Forcemight not have had the confidence to make that demand if it had not beenfor the model work performed by a small number of individuals at Langleyand Convair. As scientific and engineering research and projects becamemore expensive, complex, and systems-oriented, it was easy to lose sightof the individuals that made those systems work. Richard T. Whitcomb, indeveloping and helping to win acceptance for a concept that revolutionizedhigh-performance aircraft design, was a reminder that the individual stillmattered.

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