NACA/NASA and the National Unitary Wind Tunnel Plan, 1945-1965

(c)2002 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.

AM*AQ2-14248

AIAA-2002-1142NACA/NASA and the National Unitary WindTunnel Plan, 1945-1965

R.D. LauniusHeadquartersNational Aeronautics and Space AdministrationWashington, D.C.

T.B. Irvine Glenn Research Center at Lewis FieldNational Aeronautics and Space AdministrationCleveland, Ohio

E.A. ArringtonQSS Group, Inc.Brook Park, Ohio

40th AIAA Aerospace SciencesMeeting & Exhibit

January 14-17, 2002 Reno, NV

For permission to copy or republish, contact the American Institute of Aeronautics and Astronautics1801 Alexander Bell Drive, Suite 500, Virginia 20191-4344

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(c)2002 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.AIAA 2002-1142

NACA/NASA and the National Unitary Wind Tunnel Plan, 1945-1965

R.D. Launius*Headquarters

National Aeronautics and Space AdministrationWashington, DC

T.B. Irvine**Glenn Research Center at Lewis Field

National Aeronautics and Space AdministrationCleveland, OH

E.A. Arrington***QSS Group, Inc.Brook Park, OH

Abstract

Just at the conclusion of World War n theNational Advisory Committee for Aox>nautics (NACA)began efforts to advance the aerospace sciences througha high-speed/high altitude research program aimed atrevolutionizing flight To do so, the NACA recognizedthat it would need a host of new tools, especially windtunnels, enabling than to collect data on the transonic,supersonic, and hypersonic flight regimes. At the sametime flie United States Army Air Forces (USAAF)recognized a similar need and set out to establish itsown research facilities for high-speed flight. Whatresulted from these separate and competing efforts was adecision to assess the current state of aerospace researchtools in the United States and to fashion a unified effortto meet the varying research needs of all constituenciesby building several new facilities. The National UnitaryWind Tunnel Act of 1949 addressed these needs,providing for NACA funds to build three newsupersonic wind tunnels at its laboratories, to upgradeother NACA facilities, and to support selected facilitiesat educational institutions. It also provided funding forwhat became the Arnold Engineering DevelopmentThis paper is declared a work of the U.S.Government and is not subject to copyrightprotection in the United States.* Member; Chief Historian, NASA.** Senior Member, AIAA; Supv. AST,Experimental Fac. Techniques, NASA Glenn.*** Associate Fellow, AIAA; Task Manager, QSSWind Tunnel Test Engineering

Copyright©2002 by the American Institute of Aeronautics andAstronautics, Inc. No copyright is asserted in the United States underTitle 17, U.S. Code. The U.S. Government has a royalty-free licenseto exercise all rights under the copyright claimed herein forGovernmental Purposes. Al other rights are reserved by thecopyright owner."

Center operated hy the U.S. Air Force. Recently, thestate of the aeronautics industry and the availability/utilization of the existing suite of ground test facilitieshave both been the subject of intense scrutiny. Severalnoteworthy facility assessments are reviewed and putinto the historic context of the Unitary Plan. Arecommendation is made that legislation, similar to theNational Unitary Wind Tunnel Act, offers the bestchance to revitalize the nation's investment inaoxmautics research and technology and the requiredground testing.

The NACA and the Quest for a SupersonicWind Tunnel

The <<unitary wind tunnel" program1 originatedas two independent—in fact competing—effortsbegun almost simultaneously by the United StatesArmy Air Forces and the NACA just at the end of

World War n. Indeed, some have suggestedthat the efforts were complementary, seeking to gaincongressional attention for the same actions fromtwo separate federal agencies. Such does not seem tohave been the case, however, as variousgovernmental bodies pursued their goals in thisarena to the exclusion of the requirements of otherinterested organizations. Ultimately, compromiseresulted and three new supersonic wind tunnels werebuilt at NACA facilities, and a new capability wasadded at Tullahoma, Toinessee.

The NACA effort began in April 1945 with aletter to the committee's director of research, GeorgeW. Lewis, from an engineer at the Aircraft EngineResearch Laboratory (AERL) in Cleveland. BruceAyer wrote because he believed that that laboratoryhad not given "sufficient consideration" to the needsof supersonic flight. Ayer recommended not only

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building new instruments for researching in thisflight regime at existing NACA facilities, but alsoestablishing an entirely new "Altitude andSupersonic Research Laboratory" at a site near therecently completed Bonneville Dam on the ColumbiaRiver, where there would be ample water for coolingand power generation.2

Ayer suggested that the advent of jet propulsionensured that research problems for the foreseeablefuture would emphasize high-speed flight. Windtunnels capable of operating in this flight regimewould require enormous amounts of power, farbeyond the capacity of existing facilities. Thesefacilities would also need to be located in areaswhere they would not disturb businesses andresidences. All of these requirements pointed towardthe need to create an entirely new research center.

Ayer received a polite and non-committalresponse from Lewis, but not until the followingsummer when NACA representatives returned fromGermany did the need for new wind tunnels winsupport at NACA headquarters. When first viewedin 1945, the 100,000-horsepower water-drivensupersonic wind tunnel built by the Germans justoutside Munich greatly impressed the NACArepresentatives, as did a planned 500,000-horsepower tunnel designed to produce airspeedsbetween Machs 7 and 10. In a November 7, 1945,memorandum to NACA headquarters, AERLdirector Edward Sharp concluded, "the utilization ofwater power for wind tunnel drive appears to be theonly feasible method for large supersonic windtunnels." He recommended that the NACA contactthe Federal Power Commission and the ReclamationService "with a view to determining the bestlocations for future laboratory sites at which wouldbe located all of the future large supersonic tunnelsto be built by this country." He commented that "theCommittee should at once take steps to preempt thisfield of high-speed research and an aggressive andvigorous policy should be adopted in the interest ofkeeping America first in scientific developmentalong these lines."3

Sharp received a positive response from NACAheadquarters and a charter to open negotiations withthe Reclamation Service. He learned that BoulderDam near Las Vegas offered an excellent site for anew facility.4 Sharp presented his proposal to theNACA High Speed Panel in December 1945, andafter further preparation again in January 1946, andreceived that group's endorsement. When Sharpreported on progress in February 1946, the newfacility had been given a name, the SupersonicResearch Center.5

With the acceptance of this proposal at theNACA, the die for the agency's future had been cast.In essence, in a period of only nine months the newsupersonic laboratory had started as an interestingbut essentially unfeasible idea offered by ajourneyman research engineer. It had gained supportalong the review process, and with its adoptionthrough the NACA committee structure a newsupersonic wind tunnel research facility had becomethe cornerstone of the agency's plans for futureaeronautical research.

USAAF and the Need for High Speed Aircraft

At the same time, the Army Air Forces hadalso been working quietly on a proposal remarkablysimilar to that of the NACA. Sensing that the NACAwas already on to something important for thefuture, and seeing firsthand the German researchfacilities under construction at the end of the war, inJune 1945 the USAAF began developing their ownproposal to support research for a new generation ofjet fighters that would revolutionize aerial combat.The Army Air Forces investigated the need for newsupersonic research facilities informally at WrightField until October 1945, and then established aformal committee to prepare plans for an "airengineering development center." On December 10,1945, the USAAF published a formal plan and sentit through Army Air Forces and War Departmentchannels in search of support.6

At the beginning of 1946, then, the NACA andthe U.S. Army Air Forces each had concrete plansfor new research centers, both necessitated by the jet-propulsion revolution and both stimulated by thediscovery of advanced facilities in Germany. In bothinstances, these responded to perceptions thataeronautical research capabilities in the UnitedStates were behind those of Europe. The NACA andthe USAAF, therefore, were scrambling to catch up.

The NACA, not wanting to lose thisopportunity to advance supersonic flighttechnology—in the same way that it had with the jetpropulsion revolution of the early 1940s—pursuedthe effort with diligence. The Army Air Forces,concerned that the NACA might be unable to makethe rapid advances the military desired and at afundamental level wanting a "piece of the action" foritself, was equally tireless.7 Both started as rivals inthe unitary wind tunnel plan, only to be forced intocooperation through an intense political process.

Rivalry


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Exactly when each the NACA and US AAFproponents learned of the plans of the other is notclear, but many people believe that working levelengineers from both organizations were talking toeach other and coordinating their efforts. At theOctober 1945 meeting of the NACA, General of theArmy Hap Arnold mentioned that several agencieswanted supersonic research facilities. The subjectwas also discussed at the December 17, 1945,meeting of the NACA's Executive Committee, whereboth NACA and USAAF reported on their interest indeveloping supersonic research facilities.

These discussions prompted Edward Sharp inCleveland to ask a friend at Wright Field, Ohio,about the details of the USAAF plan. He learned thatthe Army Air Forces' proposed center wouldprobably be located in the Rocky Mountains, wouldinclude five tunnels—one of which could achievespeeds in excess of mach 8—and would cost about$100 million. Armed with this information, NACAcommittee member Jerome C. Hunsaker suggestedthat the two organizations seek to work together ontheir plans. Hunsaker wrote that these facilities"obviously cannot be duplicated for all the services,and that the same tools must be used by all."8

Hunsaker tried to achieve unity on the matter atan NACA Executive Committee meeting held March21, 1946. He urged development of a single"National Supersonic Research Center...adequate tomeet the needs of industry and of the militaryservices." The army and navy representatives agreedthat such a project should be large enough to meetfuture needs of the services, and joined inrecommending that the staff prepare a supplementalestimate to be considered at the next meeting.9

On the next day, however, General Curtis E.LeMay, recently appointed to the new office ofDeputy Chief of Air Staf£ Research, andDevelopment, entered the offices of the AircraftIndustries Association (AIA) and presented whatamounted to a "sales pitch," complete with slickbrochures, for what would become the AirEngineering Development Center. His estimatedprice tag was $500 million. That estimate surprisedindustry and AIA personnel, who recognized thatLeMay's scheme was so expansive "that it could bedone only once" and feared that the NACA, theirfirst choice to run such a facility, was in danger ofbeing cut out of the effort.10

The AIA suggested that the NACA quickly calla meeting with key government and industryrepresentatives and present its own plan forproviding supersonic facilities for the whole country.Presumably the industry was prepared to endorse an

NACA plan. The NACA could save the situation,but speed was of the essence, for "the high-poweredand high-pressure presentation of the Army'sproposal [was] such as to lead laymen andcongressmen to jump at it."11

The NACA leadership acted quickly. Withindays they decided to send to key industry andgovernment personnel their own proposal for asupersonic research center. They asked for commentsby the time of the next meeting of the NACAExecutive Committee on April 25. A separate memowent to Edwin Hartman in the Western CoordinationOffice, asking him to get what response he couldfrom industry. Hartman replied on April 29 that "thecompanies had agreed among themselves, to give outno information regarding their individual feelingstoward the NACA proposal until a joint statementhad been prepared and submitted to the NACAthrough the AIA."12

Unfortunately, the industry could not agree tosupport publicly the NACA proposal. They failed toagree among themselves on how research should bedivided between industry, the NACA, the militaryservices, and various educational institutions. Theyalso failed to agree on how to choose between theUSAAF and NACA proposals, on where newlaboratories might be located, and on how to ensurethat industry had adequate facilities for its owndevelopmental work. What they did agree to was anindependent review panel that would help merge thetwo proposals into a cohesive supersonic wind tunnelplan.13

The Raymond Panel

Convergence of the two proposals becameessential for the effort to have much chance inCongress. At the April 25, 1946, meeting of theNACA, the Committee appointed Arthur E.Raymond of Douglas Aircraft Corporation chair of aspecial panel chartered to merge the two proposalsinto a single package acceptable to all concerned. InJune 1946 Raymond's panel recommended a unitarywind tunnel plan incorporating the main features ofthe rival proposals, a national supersonic researchfacility for the NACA, and an air engineeringdevelopment center for the Army Air Forces. Theprincipal addition recommended by the Raymondpanel was a provision for wind tunnels atuniversities, both to allow independent testing andresearch and to serve as training tools for theengineers of the future.14

The estimated $2 billion effort Raymond'spanel had recommended, which most believed was


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still not enough to do everything, appeared to manyadvocates as a "poison pill" for the whole effort.15

Always a voice of reason, Hugh L. Dryden of theNational Bureau of Standards recommended anapproach to supersonic facilities less aggressive thanthose advocated by the NACA and the Army AirForces. Commenting on the report of the Raymondpanel in 1946, Dryden wrote:

I believe that this plan answers anyforeseeable demands of the next twenty years,but there are some doubts in my mind as towhether the 8 ft and 15 ft supersonic and thelarge hypersonic facilities should be built onthe time schedules proposed. If our diplomaticand military leaders feel that a new war is soimminent that active technical preparationsshould be expedited, the whole program shouldbe prosecuted vigorously. If this is not the case,ordinary engineering prudence would dictatethat some operating experience be accumulatedin the five large supersonic tunnels now underconstruction before building facilities of adifferent order of magnitude. The fact that noother nation has facilities or so far as known iseven contemplating facilities remotelyapproaching those already undo: constructionin this country and that the Germans designedthe V-2 and other supersonic missiles on thebasis of tests in a 1.3 ft intermittent supersonicwind tunnel appear to me to justify somedegree of conservatism.16

Dryden's reservations about the Raymond plandid not necessarily convince the NACA and theUSAAF of the need to restructure grandiose plans,but a similar skepticism from Congress eventuallyled to legislation more in keeping with his concerns.When Dryden became director of the NACA in 1947he also served as a conduit for iurther convergenceon the details of the plan, and a reduction in size ofthe effort.

Key Interest Groups in the Debate over theUnitary Wind Tunnel Act

Even with a convergence of proposals throughthe Raymond study in 1946, the steps leading topassage of the Unitary Wind Tunnel Plan Act of1949 were intricate.17 The interested parties eachhad their own perspectives, priorities, and politicalinterests. Eight principal entities were dominant inthe act's passage.1. Joint Chiefs of Staff: Attempted to decide where

air power and guided missiles would fit into

American defense policy in the face of anescalating cold war.

2. National Research and Development Board:Sought to reconcile the enormous expense ofthis unitary wind tunnel proposal with otherworthy priorities.

3. United States Air Force: Sought to ensurecontinued supremacy of American air power, asuperiority that rested on technical advancesproduced by intensive research anddevelopment. They could afford to be second tonone, but could they entrust that responsibilityto any other organization.

4. United States Navy: Also sought to ensurecontinued supremacy of American air power, butalso was increasingly concerned about its powerwithin a defense establishment where an army-air force alliance seemed a real threat.

5. Bureau of the Budget: Wanted to coordinate theproposals so as to prevent interagency rivalry.

6. Congress: Spoke with multiple voices, as it hadin the past and would in the future, seeking toensure an appropriate defense posture whilefailing to define what was appropriate, and asalways searching for duplication and waste.

7. NACA: Wanted to regain its role in fundamentalresearch and dominate the new field ofsupersonic research.

8. Industry: While speaking with multiple voices,it wanted to protect its development prerogativesagainst encroachment by government agenciesand at the same time gain access to facilitiesbuilt at government expense,18

These major groups were neither monolithicnor mutually exclusive, and members of one wereoften also members of another of the remainingseven. Sometimes dedicated scientists, such asTheodore von Karman, were also business leaders,as he was for a time in the Aerojet General Corp.Some advocates from the military, such as Air ForceScientific Advisory Board chair Vannevar Bush, alsoserved on the NACA and the National Research andDevelopment Board. All of these actors, regardlessof their membership in other interest groups, wereoften adamant cold warriors. The interplay of theindividuals making up these various groups created aclimate in which passage of the National UnitaryWind Tunnel Act was difficult but certainly possible.

That was true largely because everyone wantedsomething done. The public policy debate, therefore,was over the substance and the amount appropriatedfor supersonic wind tunnels rather than on whetheror not to build them. What had to take place,however, was to find a way to negotiate the


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differences between the needs of the NACA, themilitary, and the aerospace industry. Each had itsown perspective.

The NACA believed that it had the necessaryexpertise as well as the responsibility for conductingall fundamental supersonic research for the nation.The military services believed that they had to ensuretheir readiness for any military threat the UnitedStates might face, and that could well involveresponsibility for whatever research might benecessary to meet that threat. They nominally agreedthat their proper field was testing and evaluation, butthe line between development and evaluation was nomore distinct than the NACA's line betweenresearch and development. Squeezed between themwas an industry that feared encroachment by twoarms of government on the area it insisted onholding exclusively—product development. Unableor unwilling to build expensive supersonic tunnels,industry wanted the government to pay for thetunnels and then make them available to industry—either at government laboratories or at universities—where tunnels might serve dual purposes of trainingand testing.

Convergence of these differing priorities,which everyone knew would be required for anyoneto obtain any new research tools, involved severalcompromises. First, they agreed that NACA shouldreceive supersonic research tunnels that it wouldoperate. Second, tunnels for industry would besituated at universities or at government laboratorieswhere they would be clearly earmarked fordevelopmental work. Third, the Air Force shouldgain tunnels for the military. Finally, some existingNACA laboratories would get still more tunnelsearmarked for industry's developmental work.Everyone understood that some NACA researchwould spill over into development, as would somemilitary evaluation, but there would be plenty oflatitude to work out boundaries andresponsibilities.19

In some respects these relationships reflect thedynamics that Brian Balogh cumbersomely labeledthe "proministrative state," a union of government,university, political, and business elites thatdeveloped policy aimed at furthering their respectiveagendas. "Armed with unprecedented organizationalresources," Balogh concluded,

the Federal government emerged from WorldWar n as a formidable political actor in its ownright. It not only responded to well-organizedinterest groups, it now had the capacity tocreate them. It not only had access to vastnetworks of expertise, it helped to create them

and to define the research agenda of a host ofprofessional disciplines.20

Each of these groups was initially empowered by thegovernment and in turn sought to effect its direction.Their loose alliance created a critical mass in favorof passing the National Unitary Wind Tunnel Act of1949.

The key interest groups jockeyed for position asthe policy debate took place in Washington. Refusingat first to work for compromise, they emphasized theneed to give each competitor everything requested.Leaders on the House Armed Services Committeerecognized these rivalries for what they were,concluding that many of the same "conditions whichpreviously led to our taking second place in the racefor more advanced aeronautical weapons [in WorldWar II] may still be present today and that theexistence of such conditions can lead to a repetitionof our earlier experience-possibly with moredisastrous consequences."21 Only through concertedeffort by Congress, especially its staffers, did thevarious groups agree to the act as finally hammeredout in 1949.

The Legislation

The National Unitary Wind Tunnel Plan Act of1949 consisted of two titles. Title I authorized $136million for the NACA to build three new supersonicwind tunnels, one at each of its existing laboratories,and $10 million to build tunnels at educationalinstitutions. The tunnels to be built at the NACAlaboratories were to be shared with industry 'Tortesting aircraft and guided missiles underdevelopment by industry." The committee reportemphasized, "It is absolutely essential that tests bescheduled and conducted in accordance withindustry's requirements and the laboratory time beallocated with proper emphasis upon therequirements of the various contractors engaged inthe development of new types of military aircraft forthe services." Title II provided for an AirEngineering Development Center, allocating $100million to this construction effort. The committeeallotted this sum with the understanding that futureconstruction would be necessary to expand thecenter.22

Several important points should be madeconcerning the final legislation. First, the effort toobtain legislation for supersonic research facilitieswas successful. While the process was neitherstraightforward nor without pain, the end result wasa political decision to expend significant resourcesfor new supersonic wind tunnels. Second, at virtually


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every step of the review and authorization process,the National Unitary Wind Tunnel Plan had to be cutback. While unfortunate for the organizationsseeking these new facilities, the discipline involvedin multiple reviews, in-depth negotiations betweencommunities with different ideas on the subject, andinteragency ''murder boards" that looked forweaknesses in the plan and arguments for itsnecessity served the public decisionmaking processwell. Third, not surprisingly and indeed most of thetime in the history of flight, the industry enjoyed asignificant level of influence in shaping thislegislation.23

In the end, the legislation gave everyone somebut not all of what it wanted. The House ArmedServices Committee suggested in its report on thelegislation's hearings that it would be inappropriateto "place the bulk of our aeronautical research eggsin one basket—the NACA basket. Even the mostcompetent and best qualified scientists and researchworkers can always profit from the stimulatingeffects of healthy outside competition."24 Concerningthe Air Force's role in this legislation, congressionalleaders added, "A serious question may very well beraised as to whether the military may not be steppingoutside of its proper sphere when it enters into thearena of research as distinguished from developmentand evaluation."

The committee then presented an informedcommentary on the "Differentiation betweenResearch, Development, and Evaluation." It assignedthe first responsibility to the NACA and privateinstitutions, the second to industry, and the third tothe military. It concluded that "the services, by theirvery nature and organization and the training oftheir personnel, are not well qualified to, undertakeactivities in the fields of research and developmentas distinguished from evaluation."25

So What?

This debate over the National Unitary WindTunnel Act of 1949, and by extension the nature ofsupersonic research and development in the UnitedStates, led to complex political interaction andeventually a decision to proceed with a program fardifferent from what any of the advocates hadoriginally envisioned. In this political process theextreme positions were identified and compromisedto a middle ground so that a majority of decision-makers could live with the outcome. Competingpeople, positions, institutions, and interest groupshaggled over a myriad of specific issues. While therewas not a clear-cut winner, the negotiation moved

the debate toward a centrist position. Such a processis basically government by a large committee, and init all give up what they passionately believe, so thatthey can dispassionately agree about something noneof them believe.

This debate was the first instance in which theNACA had ever been forced to participate in thistype of political decision-making process for anexpensive and far-ranging initiative. Other federalagencies were seasoned veterans in the political giveand take of Washington, and accomplished theirduties within a framework that required cageypartisan activity. The challenges and competitionbetween them and their leaders ensured that in mostinstances middle-courses were agreed upon. Becauseof this environment, the ability to navigate thelabyrinth of the Washington political communitywas a hard-won and highly-prized skill within thefederal government.26 As a result the NACA was notforced to operate in this political arena in anythingapproaching the intensity of most other federalagencies.

The National Unitary Wind Tunnel Act wasbased on what was then known about the political,economic, social, and technological issues raised atthe time. It was informed by the realities felt by thoseinvolved in the process. It was an example ofheterogeneous engineering, which recognizes thattechnological issues are simultaneouslyorganizational, economic, cultural, and political.These interests often clash in the decision-makingprocess as difficult calculations have to be made.What perhaps should be suggested is that a complexweb or system of ties between various people,institutions, and interests brought forward theNational Unitary Wind Tunnel Act of 1949.27 Thesecame together to make it possible to build a set ofsupersonic wind tunnels that satisfied the majority ofthe priorities brought into the political process by thevarious parties concerned with the issue at the timebut that left others untamed, most of which aroselater. What resulted from these separate and competingefforts was a decision to assess the current state ofaerospace research tools in the United States and tofashion a unified effort to meet the varying researchneeds of all constituencies by building several newfacilities.

The Wind Tunnels

The Unitary Plan as implemented by theNACA and by the Army Air Force included fivewind tunnel complexes, one each at the three NACALaboratories and two wind tunnels plus an engine


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test facility at what would eventually become knownas the Arnold Engineering Development Center(AEDC). These ground test facilities were built andoperated to meet the needs of industry, the militaryservices and other government agencies. Primarily,these organizations needed large, or as near to flightas possible, Reynolds Number (Rn) testing ofsupersonic aircraft and missiles and high speed/highaltitude testing of engines.

During World War H, the United States haddeveloped weapons, including the atomic bomb, butlacked advanced weapon delivery systems. Thenecessary systems required that the government andindustry perform extensive research anddevelopment of airplane propulsion systems andswept wing aircraft, as well as long-range rocket andguided missile technologies. In these areas, theUnited States lagged behind Europe, and especiallyGermany. Entirely new wind tunnel capability wasrequired to take these systems from concept to designto fabrication and assembly. At the time, however,the significant technical obstacle to high speedresearch in wind tunnels was the choking affect astest section airspeeds approached Mach 1.0.Breakthroughs at the NACA laboratories, includingthe creative use of expanding nozzles and of slottedwall test sections, made possible the large scalesupersonic wind tunnel technology envisioned byauthors of the Unitary Plan Act.

Precursor Facilities

Prior to the availability of supersonic windtunnel capability, high speed research was doneprimarily by one of two methods. The first, knownas the 'Tailing-body technique," required droppingmodels from high altitude bomber aircraft Data wastransmitted to the ground via radio-telemetry. Thesecond method was to use solid propellant rockets toachieve supersonic speeds. This method, for themost part, limited researchers to the study ofaerodynamic shapes.28

In order to address the need for supersonicground test capability and prior to the Unitary PlanAct becoming law, the NACA had committed to theconstruction of five supersonic wind tunnels locatedat it's various research laboratories. At the LangleyAeronautical Laboratory, a 9 in. supersonic tunnelwas operating, in which much of the pioneeringresearch on swept wing drag reduction wasperformed. Langley also committed to designingand building a 4 X 4 ft. supersonic research windtunnel. This tunnel would become operational in1948 following installation of 45,000 horsepower

drive system. At the Ames Aeronautical Laboratory,two supersonic research wind tunnels wereconstructed. These included the 1 X 3 ft. SWT thatoperated to a maximum test section airspeed of Mach2.2. A larger 6 X 6 ft. supersonic research tunnelwas also constructed at Ames. This tunnel is notableas it was the first large supersonic tunnel that madeuse of the asymmetric supersonic nozzle (see figurela) that would be successfully used in several of theyet to be designed Unitary Plan Wind Tunnels. Italso contained for purposes of flow visualization a 50in. Schlieren window system. Tests performed in theAmes tunnels included research on wing shapes,dynamic stability, aircraft control, panel flutter andair inlet design. At the Lewis Flight PropulsionLaboratory a large 8 X 6 ft. transonic wind tunnelwith the capability to operate at test section .airspeedsfrom Mach 0.4 to 2.0, was built for testing aircraftpower plants and was operational by 1949. Thiswind tunnel was an open circuit tunnel whore the airwas vented to atmosphere in order to dispose of theengine combustion products.29

Through the design of these supersonic windtunnels, NACA engineers perfected theirunderstanding of the differences between supersonicand subsonic wind tunnels. Some of thesedifferences included the wind tunnel nozzle designupstream of the test section, the energy losses in thewind tunnel circuit and the required cleanliness anddryness required to successfully operate wind tunnelsat supersonic speeds. Lessens learned by NACAengineers in the operation of these five supersonicresearch wind tunnels at the three NACA sites laidthe groundwork for that organization's futuresuccesses in designing and building the Unitary PlanWind Tunnels.

New Tunnels

As mentioned previously the plans beingforwarded by the various interested parties in thenation's supersonic ground testing capability werewide ranging in scope and magnitude. One planenvisioned a complex of up to 33 large transonic,supersonic and hypersonic wind tunnels to be built atNACA sites, an Air Force Center, industry andacademia. What was finally built was less expansivein scope and reflected the political and budgetaryrealities discussed previously. Under the UnitaryPlan Act, a large supersonic wind tunnel wasconstructed at each of the three NACA sites and theAir Force was authorized to go forward withconstruction of the Air Engineering DevelopmentCenter.


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Air Engineering Development Center

Initially, the plans for AEDC included two 16ft. supersonic wind tunnels, a jet engine altitudechamber, an aeronautics laboratory and thenecessary support facilities. AEDC was dedicated byPresident Truman on June 25, 1951. The firstfacilities at AEDC included an engine test facility,the Gas Dynamics Facility, later renamed in honor ofTheodore von Karman, and the Propulsion WindTunnel Complex.30

The Engine Test Facility made extensive use ofcaptured German and Japanese WWII vintageequipment. It was designed for turbojet and ramjettesting. It operated at pressures equivalent to 80,000ft. altitude and at temperatures down to -125 °F. Itincluded three separate test chambers. The GasDynamics Facility was designed for test andevaluation of aircraft and guided missiles throughthe supersonic and hypersonic range. Initially, therewere two test sections both with adjustable nozzles.The transonic leg of the Propulsion Wind Tunnelwas constructed with money from the originalUnitary Plan appropriation. The construction of thesupersonic leg required additional appropriatedfunds at a later date. The purpose of the PWT wasfor testing of full-scale, operating ramjet and turbojetpowerplants. The size of the PWT test sections, both16 X 16 ft., also allowed for testing of full-scalecomponents of aircraft and missiles.

The performance parameters of the PWT,including test section size, total temperature, speedrange, pressure altitude and dynamic pressure andReynolds Number (Rn) are shown in Table 1 alongwith data for the NACA wind tunnels31'32. Aschematic of the PWT is shown in figure 2.

National Advisory Committee for Aeronautics

The NACA constructed three supersonic windtunnels as part of the initial Unitary Planappropriation. These included the AmesAeronautical Laboratories Unitary Plan WindTunnel with three test sections including the 11X11ft. transonic test section, a 9 X 7 ft. supersonic testsection and an 8 X 7 ft. supersonic test section. Atthe Langley Aeronautical Laboratory, a Unitary PlanWind Tunnel was constructed with two 4 X 4 ft.supersonic test sections. At the Lewis FlightPropulsion Laboratory, a 10 X 10 ft. SupersonicWind Tunnel was erected.

The business management of the NACA windtunnels was retained at NACA Headquarters, whilethe technical management was delegated to thelaboratories. Business management responsibilitiesincluded facility/test schedules, responding torequests for testing and cost estimating and billing.Technical management included facility operationsand maintenance, test support equipment/facility-to-test model template management, and disseminationof facility technical performance information. Alltests performed in the wind tunnels were conductedunder NACA supervision provided by thelaboratories.

The NACA distinguished between the types oftests being conducted in the Unitary Plan WindTunnels as being either "Company Projects" or"Government Projects." The priority assigned to agiven test activity, a company's access to the windtunnels, and the fees associated with the tests weredependent on the type of tests being performed. Themaster schedule of the Unitary Plan Wind Tunnelswas maintained by NACA Headquarters and wasreleased on the 20th day of each month for thesucceeding six month period.

Company tests were defined as work forindustry on projects not undo* contract to thegovernment or not supported by a letter of intentfrom a Government Agency. This category alsoincluded tests related to a government project thatwas beyond the scope of test requested by thegovernment. Sixty working days per NACA facilitywere set aside for company tests, in four, 15 dayblocks. No more than 15 days in a given facility wasallocated to any single company. Priority wasestablished via order of test request receipt.Previously scheduled time for a given company wasalso considered. The company defined the testobjective and program. The only non-negotiableconstraints on the test program were personnel andfacility related safety requirements.

The fees associated with a company test werecomprised of an occupancy charge (ranging from$25,000 to $35,000, depending on the fecility ofchoice), electric power, data reduction and reportpreparation, and special charges associated withpropulsion testing (fuel usage, open loop operationsexpenses). A company had access to the test facility24 hours a day but only one, 8 hour shift wasdedicated to actual testing. The myriad conditionsassociated with performing company tests in NACAwind tunnels, such as delays, cancellations, billing,and damages, were defined in "Regulations forDevelopment Work for Industry in NACA Wind

8American Institute of Aeronautics and Astronautics

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Tunnels and Engine Test Facilities," FederalRegister, Vol. 19, No. 178, Sept. 14, 1954.

Government projects were defined as industrywork being done under contract with, or letter ofintent from, the government. There were no feespassed on to industry for this type of test. Twomanagement groups decided priority and test timeallocation for government projects. These groupswere the "Aircraft and Missiles Projects AllocationGroup" and the "Propulsion Projects AllocationGroup," One representative from each of the AirForce, the Navy, the Army and the NACA sat onthese groups. Scheduling of tests and dueconsideration of priorities also fell under the purviewof these groups.33

The Langley Unitary Plan Wind Tunnel (UPWT)

The purpose of the Langley UPWT was for theaerodynamic development of high-speed missiles.As such, the test section size could be limited to 4 ft.by 4 ft. Missiles were tested for high speedperformance, stability and control, maneuverability,jet-exhaust effects and other miscellaneousperformance factors. The construction of theLangley UPWT was completed in 1955. Basicexperimental fluid-mechanics research that gave riseto methods for predicting supersonic aerodyanamicperformance were a staple of the Langley UPWT.34

Development test of nearly every supersonicairplane, missile and spacecraft, including suchaircraft as the F-4 Phantom, the X-15 and the F-l 11were performed here.29

The Langley UPWT is comprised of two testsections, both 4 ft. (h) X 4 ft. (w) X 7 ft. (1). Testsection 1 operates in the airspeed range from MachL5 to 2.9 at maximum stagnation pressure of 60psia. Test section 2 operates in the airspeed rangefrom 2.3 to 5.0 at maximum stagnation pressure of150 psia. Both test section have upstreamasymmetric sliding block nozzles. The tunnelstagnation pressure and temperature are controlledindependently. A schematic of the Langley UPWTis shown in figure 3.

Model support systems were designed toaccommodate the extreme range of orientations thatmissiles transition through during normal flight.The models installed in the wind tunnel aresupported by a string/horizontal strut system. Theangle of attack (AoA) range using the standardconfiguration is ±20°. Pressure measurements andelectrical leads were available through the strut. Aset of internal strain-gage balances were available

from the NACA for use in the tunnels. Pressuremeasurements were taken via a manometer. ASchlieren system was installed in the test sectionwall with a 49 in. diameter field of view and a 9 X 9in. aerial camera was available for photographingthe shock waves. A force data readout system wasavailable to record strain-gage and other electricalsignal output.

The operating characteristics of the LangleyUPWT are found in Table 1. The average powercosts to run the Langley UPWT was $15/M-hr.33

The Ames Unitary Plan Wind Tunnel

The Ames Unitary Plan Wind Tunnelrepresented a continuing commitment on the part ofthe NACA to update it's inventory of wind tunnelsin order to provide the U.S. aerospace industry withadvanced testing facilities. The Ames UPWT wasused extensively by the west coast aerospaceindustry, including Boeing and Douglas Aircraft, toimprove cruise efficiencies and enhance landingperformance. The Ames UPWT has contributedequally to the development of aircraft and mannedspacecraft. Construction of this complex started in1950 and was completed in 1955.35

The Ames Unitary Plan Wind Tunnel iscomprised of three test sections including the 11 X11 ft. transonic leg that operates from Mach 0.7 to1.4, the 9 X 7 ft. supersonic leg that operates fromMach 1.4 to 2.6, and the 8 X 7 ft. supersonic leg thatoperates from Mach 2.4 to 3.5. The air speed in allthree test sections is continuously variable over theranges given. Initially, plans called for building asingle wind tunnel with an 8 ft. test section.However, over the desired airspeed range, this didnot prove to be practical. In the end, three testsections were constructed in order to best simulatethe entire range of aircraft and missile flight. Attransonic airspeeds, the wall reflected shocks requirethat the model be smaller in scale or that the tunnelbe larger. This requirement leads to the designrequirement that the compressors required to achievetransonic and supersonic flow are much different.Therefore, a decision was made to build three testsections. The airflow in the supersonic test sectionsis driven by a shared 11-stage axial-flow compressor.The airflow in the transonic test section is driven bya 3-stage axial flow compressor. Both compressorsare coupled to a common 4 electric motor, 100,000hp drive system. Each test section has it's ownstand-alone control room. A schematic of the tunnelis shown in figure 4.


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The test section of the transonic leg of thecomplex is 11 ft. X 11 ft. X 22 ft. long. Slotted wallswere used in this test section to control the shock-wave reflection. A flexible wall nozzle is locatedupstream of the test section. Continuous variation ofthe test section airspeed is accomplished viacompressor speed and flex wall positioning. Thenozzle of the 9X7 supersonic test section is theasymmetric sliding block type whereas the nozzle ofthe 8X7 test section is the flex-wall type.Continuous Mach number variation is accomplishedvia positional variation of the fixed contour block orthe flex wall. Provisions were made in both testsections for flow field imaging via Schlierenequipment with circular coverage of up to 4.22 ft.(dia.).

The model support systems in all three testsections were sting-mounted models on traversingstruts. The string to model attachment used identicalmounting heads for transportability between testsections. The sting/strut combinations are setup forautomatic angle-of-attack (alpha) variation andsideslip, or beta, variation. Straight and bent stingswere available, the latter allowing for shifts (greaterrange) in both alpha and beta. Internal strain-gagebalances for measuring the forces and momentspresent on the models were available from theNACA. Pressure leads were routed through thesting-strut configuration and patched to sets of 64tube manometer boards. A 17 channel data recorderwas available including the capability to visuallymonitor the 10 channels of strain gage data. Onechannel was used for run identification and theremaining six were available for supplemental datasuch as AoA, sideslip, Mach No., total pressure, orstatic pressure via an analog signal from atransducer.

The operating characteristics of the tunnels areshown in Table 1. The estimated power costs tooperate the complex was $10/M-hr.33

The Lewis Unitary Plan Wind Tunnel

The Lewis Unitary Plan wind tunnel is asupersonic propulsion wind tunnel with a 10 X 10ft. cross-sectional area test section that operates inthe airspeed range from Mach 2.0 to 3.5. This windtunnel was unique within NACA in that it operatedin two distinct modes, the first being aerodynamiccycle and the second being propulsion cycle. In theformer, the wind tunnel was operated as a closedreturn-type tunnel whereas, in the latter, it operatedas an open non-return type tunnel. In propulsioncycle, the exhaust gases were expelled from the

tunnel circuit prior to returning through the aircompressor. A schematic of the tunnel is shown infigure 5.

Because the requirements for testing full scalesupersonic jet engines are restrictive, especially withregards to air density, temperature and humidity, theauxiliary equipment of the 10X10 posed a challengeto it's designers. The main components of the 10 X10 ft. supersonic wind tunnel included the air dryerbuilding in which air was dryed to a dewpoint of-40°F, an exhauster to reduce the air density in thetunnel for start-up, the flexible wall nozzle that wasmade of two 10 ft. high by 76 ft. long by 1 3/8 in.thick stainless plates actuated by hydraulicallyoperated screwjacks (fig. Ib), the test section, asecond nozzle-type throat that reduced the testsection Mach no. prior to the normal shock wave soas to reduce power requirements, a primary 8 stageaxial flow compressor driven by 4 wound rotorinduction motors rated at 150,000 hp, a secondary 10stage axial flow compressor driven by 3 wound rotorinduction motors rated at 100,000 hp, an exhaustmuffler to quiet discharge when operating inpropulsion cycle, and the control room.

Models were installed in the test section bylowering the entire test section floor to a shop levelvia a set of screwjacks. Models were mounted onstings that were in turn supported by one of twostruts. The first strut penetrates the test section floorand is retractable when not in use. The second is asuspended model strut wherein the model issuspended from the ceiling. When using thesuspended model strut, an auxiliary strut forsupporting a tail-rake pressure measurement systemcould be used.

Three component bearing-type strain gagebalances were available over a wide range offerees.On the suspended model strut, the balance wasintegral to the strut itself. Other measurements thatcould be taken as part of the standard data setincluded attitude indication, pressure measurements,and temperatures via self-compensatingthermocouples. In the control room, a closed circuittelevision system was available. Still and high speedmotion picture capability existed to capture Schlierenimages. Two clear window openings, each 33 in.dia. offset eccentrically in a larger 60 in. dia. diskare available for viewing and for flow visualizationvia a Schlieren system.

As the 10X10 was designed as a propulsionwind tunnel, multiple engine fuel systems weredesigned and installed. These included gaseoussystems with the capability to provided 1800 Ibs/hr


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at 200 psig and liquid fuel systems with independentpilot and main high-pressure systems.

The operating characteristics of the 10X10 areas shown in Table 1. The nominal cost of operatingthe 10X10 was $9/M-hr on 3rd shift (midnight to 8am) operation.

Upgrades and Improvements

Significant technological advances in the areasof supersonic wind tunnels and data acquisition weremade as a result of the Unitary Plan. Whenoriginally proposed in 1945, the government ownedsupersonic wind tunnel capability was to becollocated along side significant hydroelectric powergeneration capability. The German experience,wherein the air compressors were run by waterdriven turbines, influenced conceptual designs. Theavailability of power in the near urban settings of theNACA Laboratories or from the Tennessee ValleyAuthority hydroelectric grid, in the case of AEDC,meant that large electric motors could be utilized todrive the air compressors. This opened the door tothe construction of supersonic ground testingcapability on a scale previously not attainable.Secondly, the state of the art in data acquisition waschanging and the engineers of NACA and the ArmyAir Corp took full advantage of automated dataacquisition and recording and display devices foracquiring and recording analog data.

Since being built, the Unitary Plan WindTunnels have had active maintenance programs tokeep the facilities operable and the Air Force andNASA have funded improvement and modernizationprograms to meet evolving aircraft program needs.These improvement and modernization programshave resulted in the ability to acquire largerquantities of data, more accurate data, and lowertesting costs.

In the Propulsion Wind Tunnel Complex atAEDC, this has included adding capability such as ahigh angle-of-attack automated sting, a captivetrajectory system for trajectory tracing of separatedstores, diffuser improvements that have loweredpower consumption, flow quality devices suchscreens and honeycomb in the upstream of the testsection to improve velocity uniformity and flowangularity, and numerous improvements to the dataacquistion system. In addition to modifications tothe ground test facilities built under the Unitary PlanAct, AEDC has added significant testing capabilityto it's original set of ground testing capability.Additions include electric arc facilities andhypervelocity ranges to simulate the environment

experienced by flight vehicles re-entering the earth'satmosphere from orbital or ballistic trajectories. TheAeropropulsion Systems Test Facility (ASTF) wascommissioned in 1986 after nearly 20 years ofplanning, design, construction and activation. TheASTF's large 28 ft. diameter test cell allows fortesting of full scale engines at nearly all practicablealtitudes.29 More recent efforts at AEDC havefocused on reducing design/testing cycle time asaircraft and munitions developers and manufacturersseek dramatic reductions in cost and productdevelopment cycle time.36

Modifications and improvements to theNACA/NASA Unitary Plan Wind Tunnels havebeen documented in various reports and papers.34'37'38, 39,40,41 jft Qf the NASA Unitary plan Tuiuiels

have been rehabilitated since being brought on-line.This has included, for example, rewinding of thedrive motors and and the installation of new motorcontrols that has allowed for improved speedcontrol.42

The decade of the 70s are noted as the periodwhen wind tunnel test calibrations were reportedupon extensively. Prior to this time, little wasdocumented on many of the wind tunnel airflowperformance parameters such as flow angularity,turbulence and boundary layer characteristics.Significant strides were being made in terms of windtunnel instrumentation and flow visualization.Scanivalve systems, a pressure scanning system thatwas based on solenoid activated pressure passages,were introduced to be able to acquire more pressuredata in less time. Expanded digital data acquisitionsystems were installed as this technology matured.

The decade of the 80s brought measurement ofvortex patterns via vapor-screen imaging at theLangley facilities. Later, laser Doppler velocimetryfor flow field analysis and determination ofaeroelastic properties was successfully used in theLewis wind tunnels. Coherent Raman spectrometrywas used at Langley to measure velocity, pressureand temperature. Remote, computer controlledmodel support systems with multiple degrees offreedom were installed to allow expanded modelorientations.

In the 90s, measurement techniques continuedto be updated and refined to include electronicallyscanned pressure systems, non-intrusive flowmeasurement techniques such as pressure sensitivepaint, infrared thermography, and Moireinterfromemtry. Data quality was improved asstatistical methods for quantifying uncertainties wereintroduced and overall test time was reduced viaintroduction of automatic test sequencing.43


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Recent Developments

The National Unitary Wind Tunnel Plan—despite the twists and turns that it took in thepolitical process—represented one of the morerational approaches to aerospace research planningundertaken in the twentieth century. At a basic level,would that more planning efforts evolved sorationally. Instead of convergence in all too manycases, various organizations have pursued theirpriorities to the exclusion of all others, following awinner take all strategy that ultimately may provedetrimental to the cause of aerospace technology andthe leadership of the United States in it.

In the 1990s the DoD and NASA, and otherorganizations, conducted several studies relative tothe current state of wind tunnels:® Future Aerospace Ground Test Facility

Requirements - AEDC (NCR - 1992)« Aero/Thermodynamic T&E Facilities Reliance -

DoD (1994)• DoD Aeronautical Test Facilities Assessment

(1997)• Wind Tunnels Preferred by Boeing (1998)• National Wind Tunnel Study - DoD and NASA

(9/2000)Each of these peered forward twenty years with aview to recognizing that budgets are tight and willremain so. They identified existing facilities that cancontribute significantly to development work so theycan be properly maintained, operated, and utilized.They also went about cautiously and selectivelyidentifying new facilities that might be needed topursue the technologies envisioned. Always theyrecognized the need to understand requirements androles before committing to any specific facility. Eachof these five studies deserve some discussion.

Future Aerospace Ground Test Facility

This study, completed in 1992, explored theresearch facilities that would be required forsubsonic and supersonic airplane development.Tunnels at NASA LaRC and AEDC were consideredto be essential, including:• AEDC 16 foot transonic tunnel• AEDC 16 foot supersonic• LaRC National Transonic FacilityThe study team found that few, if any, facilities wereadequate for transonic wing development andvalidation, and that required upgrades wouldnecessitate the expenditure of more than $100

million. The study recommended working withNASA and industry to develop strategies onproviding cost-effective transonic ground testcapability with near-flight realism.

This study drew a distinction between"research" facilities and "development" facilities.The research facilities are generally highlyinstrumented and generate high-resolution data forwell defined and controlled test conditions. They areused to provide phenomenological insights and todevelop and validate computational codes. They arealso usually smaller in size and shorter in test timethen development facilities. In short, they providethe detailed data for understanding the physics andvalidating and refining computer codes. Thedevelopment facilities help to validate overall designand system durability and performance. Acquiringnew development facilities would be a a challengenot without difficulties. They are generally larger insize, emphasize measurements of macroquantitiesand near-flight conditions, have relatively long testtimes, cost more to build and operate, and require avery long lead-time for acquisition.

Aero/Thermodynamic T&E Facilities Reliance

This 1994 study recommended that NASAprovide service to DoD for large subsonic T&Efacilities. And it asked that DoD and NASAReliance type coordination be pursued and MO Asdeveloped. The study also recommended that NASAand DoD jointly pursue a National Wind TunnelComplex (NWTC) that would advance the cause ofboth organizations. The study team found that therecould be significant added value to DoD systemsdevelopment, provided DoD requirements areincluded in the NWTC specifications.

The study also found that the DoD and NASAhad been too oriented toward their own priorities andshould pursue policies that enhanced cooperationrather than made it more difficult. As an example, itrecommended adopting a uniform pricing policy forall T&E facilities, preferably with institutionalfunding provided to cover indirect costs.

DoD Aeronautical Test Facilities Assessment

In 1997 the DoD undertook an aeronautical,test facilities assessment that considered near-, mid-and long-term needs for core transonic wind tunnelsfacilities for military needs for the AEDC 16 foottransonic facility and the NASA Ames ResearchCenter 11-foot tunnel. It made several importantrecommendations.


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• DoD should invest $100 million over 5 years in16T/16S for upgrades and productivityimprovements.

• DoD/NASA/industry should consort to build anew high Re transonic wind tunnel (the NWTCProject, a industry /government partnership hadbeen canceled at the end of fiscal year 1996.The NWTC Final Report documents projectinformation available at the time of it'scancellation).44

® Government should enhance wind tunnel andCFD capabilities:

® Government should develop national technologyprogram addressing both wind tunnel and CFDneeds.

« DoD and NASA should increase funding to$30M/yr for these technologies.

The study also suggested founding a new office tomanage the investment and technology funds for thenation's core government wind tunnels.

Wind Tunnels Preferred by BoeingThe next year, 1998, an assessment of wind

tunnel capabilities required for Boeing work foundthat the nation was in rather dire straits for thefuture. This study found that none of the tunnels fortransonic development of a new subsonic transportwas scored as high as "satisfactory" (3 out of a 5point scale). Only one tunnel, the Ames ResearchCenter's 11-foot tunnel, scored as high as"Satisfactory" for the transonic development of aderivative subsonic transport. Only the NationalTransonic Facility was scored as high as"satisfactory" for transonic development of a newsubsonic transport (ETW was the backup and justbelow "satisfactory"). Finally, the BSWT and BTWTwere the primary and back-up tunnels for transonicdevelopment of a supersonic aircraft (rated above"satisfactory").

National Wind Tunnel Study

The National Wind Tunnel Study of 2000 bythe DoD and NASA reviewed all of these previousstudies, as well as some additional ones, and foundseveral common issues from previous studies• Need for NASA/DoD Alliance.• Shortcomings in wind tunnel and technology

investments.• Need for integrated T&E (wind tunnel, CFD and

flight test).• Uniform pricing policy.• Identification of core capabilities.

The study's authors agreed with recommendationsfrom 1997 and 1998 studies and seconded the needto develop a National Wind Tunnel Business Planunder NASA. They also called for implementing theprovisions of the NWTA without further delay. Theycalled for a strengthening of the NATA charter andfor NASA to complete an internal assessment of corewind tunnel requirements.

The bottom line this study found: Numerousstudies have been made, all making, and oftenechoing, recommendations on the future direction ofground testing in the US; however, none of the majorrecommendations have been implemented. 'What weneed now is not another study but theimplementation of the recommendations from theprevious studies," the author's commented.

Conclusion

What has not happened during the experienceof the 1990s that did take place during the 1940s isthat the studies of that earlier era eventuallyconverged on positive legislation that all could agreeto and resulted in tunnels being built and put intooperation. The situation at present seems to be aboutwhere the United States was in the National UnitaryWind Tunnel Plan about 1947 or 1948 beforelegislation emerged that yielded results. In that era adriving force was national defense, as the Cold Warwas just beginning. Absent some driving futureimperative, convergence of proposals might not takeplace anytime soon. At present there is not consensuson:• Military imperative.• Impact to national security.• Impact to economic security.• Critical need in aerospace research and

development programs.The current state of aeronautics and aeronauticsresearch in the United States is the subject ofnumerous recent articles and papers. Excellentexamples from the perspective of the airframe andpropulsion segments of the industry cover the gamutfrom workforce issues to government investment.45'46

We might suggest that the United States iscurrently threatened just as thoroughly at present asit was by the Soviet Union in the latter 1940s. Thethreat today, however, is economic competitionrather than military competition. In the last decadethe United States has been losing market share in allmajor aerospace sectors. In passenger aircraft, forexample, Airbus Industrie's analysis suggests that tosatisfy an expected average annual growth rate in


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passengers and cargo of 5.2 per cent during the nextten years, the number of passenger aircraft in servicewill increase from some 10,350 in 1999 to 14,820 in2009 and 19,170 in 2019. Satisfying thatrequirement is Airbus' objective for the indefinitefuture. And they are showing remarkable stayingpower there. At the Paris airshow in 2001 theynailed down 110 orders for new aircraft to Boeing'sless than 40.47

Commercial aviation is quickly evolving, bothtechnologically and in the context of the globalbusiness climate. Pacing world economic growth, airtravel is evolving through profound changes toprovide better service at lower cost. The world fleetis currently three times as large as it was twentyyears ago, and todays fuel-efficient jetliners offerairlines greater choice in terms of range, passengercapacity, and operating economics. More than half ofall flights are made on routes bounded by few, if any,regulatory constraints. Flag carriers are privatizing,"open skies" agreements are replacing bilateral airservice agreements, and global alliances are on therise. As a result, airlines now have unprecedentedflexibility to pursue strategies that meet the needs ofthe next century's global community. They will notpurchase American aircraft because we want them todo so. Indeed, with the growth of overseas carriers,there is an ideological reason to refrain from buyingAmerican if for no other reason than to thumb theirnoses at the last remaining superpower. Accordingly,U.S. technology must be clearly superior.

The only way to meet this threat is to ensurethe technical superiority of American aerospacetechnology. There is a direct correlation betweenR&D investment and excellence in technology. Sincethe 1960s the percentage of investment by the UnitedStates in aerospace technology has stabilized at aboutone percent of the Federal budget. The aerospacecorporations and some universities invest in R&D aswell, but that is a decidedly small amount and atleast in the case of the private sector limited toalmost entirely short term research

A Recommendation

The American nation should commit todoubling the investment in aerospace R&D duringthe first decade of the twenty-first century. This isfully within the bounds of our capability, and it willhelp assure American economic, military, andcultural competitiveness in the new century. Withregards to ground testing capability specifically, thepresent over-capacity/under-utilization of theavailable testing capability has led the idustry to

ignore new wind tunnel requirements when doingprogram planning for new flight systems. Asdocumented in several of the afore mentionednational studies, the existing suite of wind tunnels isdeficient with regards to the design of new aircraft.The likely result is conservative designs, or, worseyet, undetected design problems. Converging thevarious ground-test and wind tunnel studies of thepresent into meaningful legislation is the best andperhaps only workable means available to ensureAmerica's aeronautics capabilities into the twenty-first century.

Notes1 A general discussion of this legislation is containedin Alec Roland, Model Research: The NationalAdvisory Committee for Aeronautics, 1915-1958(Washington, DC: NASASP-4103, 1985), 1:211-21,2 Bruce E. Ayer to Lewis, April 24, 1945, NASAHistorical Reference Collection, NASA HistoryDivision, NASA Headquarters, Washington, DC.3 Lewis to Ayer and Lewis to Sharp, both May 15,1945; Edward R. Sharp to director of research,'Wind Tunnels," November 7, 1945, NASAHistorical Reference Collection.4 Sharp to director of research, "Wind Tunnels,"December 14, 1945. By this time the Ameslaboratory was also recommending new supersonicfacilities, but, in contrast with the AERL proposal,Ames was promoting itself as the center to build andcontrol them. See Smith J. DeFrance to NACA,"High-speed Research Facilities," December 7, 1945,both in NASA Historical Reference Collection.5 Sharp to NACA Director of Research, "Proposalfor a Supersonic Research Center," February 5,1946, NASA Historical Reference Collection.6 Arnold Engineering Development Center,"Chronology," n.d., 11 pp., typescript; Thomas O.Sturm, The USAF Scientific Advisory Board(Washington, DC: OflSce of Air Force History, 1978ed.), p. 6; and Frank L. Wattendorf to Gen. F. O.Carroll, "Proposal for a New Air ForcesDevelopment Center," June 19, 1945, in which amember of the Army Air Forces team wrote that "thescope of German plans make[s] it essential that ourown plans be certainly not less ambitious in the lightof our future security."7 The NACA's overall story is related in George F.Gray, Frontiers of Flight: The Story of NACAResearch (New York: Alfred A. Knopf, 1948). Onthe inability to foresee the jet revolution see, RogerD. Launius, '"Never Was Life More Interesting':


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The National Advisory Committee for Aeronautics,1936-1945," Prologue: Quarterly of the NationalArchives 24 (Winter 1992): 361-73; Edward W.Constant II, The Origins of the Turbojet Revolution(Baltimore, MD: The Johns Hopkins UniversityPress, 1980); Roland, Model Research, pp. 186-94.8 Minutes of NACA annual meeting, October 25,1945, p. 5; minutes of special meeting of ExecutiveCommittee, December 17, 1945, pp. 2-4; Sharp todirector of research, "Proposal for a SupersonicResearch Center," February 5, 1946; Sharp todirector of research." Telephone Conversation withMajor Jay AuWerter December 20, 1945 RegardingLocation for Wind Tunnels," December 20, 1945,with note by Charles H. Helms; D.B. Langmuir,"Extract of Remarks by Dr. Hunsaker Made at the15th Meeting of the Joint Committee on NewWeapons and Equipment] Guided MissilesCommittee on 1 March 1946, "attached to RG.Robinson to Hunsaker, March 20, 1946, all in NASAHistorical Reference Collection.9 Minutes of Executive Committee meeting, March20, 1946, p. 4, NASA Historical ReferenceCollection.10 RG. R[obinson]., "Army Air Force plan for AirEngineering Development Center," memo for file,March 25, 1946, handwritten, marked "Secret VeryLimited Internal Distribution," NASA HistoricalReference Collection.11 LeMay actually revealed the plan to the press onApril 20, 1946, but apparently did not publish theplan at that time. See New York Herald-Tribune,April 21, 1946. The NACA received a copy of"Proposed Air Engineering Development CenterSummary for Air Staff," undated, 12 pp., on April16, 1946, but there seems to have been no indicationof the campaign that was about to begin to sell theplan. Roscoe C. Wilson to George Lewis, April 16,1946; Lewis to E.R Sharp, April 16, 1946, both inNASA Historical Reference Collection.12 "Notes on Conference with Dr. Lewis, Messrs.Crowley, Victory, Chamberlin, Ulmer, Helms, andRobinson," March 27, 1947; Lewis to Reid,DeFrance, Sharp, "Proposed National SupersonicResearch Center," April 2, 1946, with enclosures;NACA, "A Proposal for the Construction of aNational Supersonic Research Center," April 1946;T.L.K. Smull to Hartman, April 4, 1946; Hartman tochief of research coordination, "Industry Reaction toNACA Proposal for a National Supersonic ResearchCenter," April 29, 1946, all in NASA HistoricalReference Collection.

13 For examples of the studiously noncommittalreplies from industry, see G.S. Schairer (Boeing) toLewis, April 19, 1946; J.C. Miller (General Electric)to Lewis, April 18, 1946; J. Carlton Ward(Fairchild) to Lewis, April 17, 1946; and RE.Hopper (Hughes) to Lewis, April 16, 1946, all inNASA Historical Reference Collection.14 The Raymond panel did not resolve all thequestions surrounding the need for new tunnels, so aspecial committee on supersonic facilities succeededit, chaired by Jerome Hunsaker. That committee metOctober 21, 22, and 24, 1946, to iron out differences.The minutes reveal that one of the major problemswas Hunsaker's hostility toward the Army AirForces, which he claimed "have arrived at the pointof wanting to duplicate NACA equipment." The AirForce representatives denied this, but they seem tohave done nothing to allay Hunsaker's concern. Theharsh tone of this exchange was edited out of thefinal version of the minutes, but the source ofcontention remained. See "Report of SpecialCommittee on Supersonic Facilities," October 24,1946.15 In fact, Raymond was sure it would cost more than$2 billion and asked for an outside audit. Theengineering firm of Sverdrup and Parcel wascontracted to carry out this review and subitted areport in the fall of 1946 that estimated the total costto be in excess of $3 billion.16 Hugh L. Dryden to Arthur E. Raymond, May 29,1946, NASA Historical Reference Collection.17 Key events in this processcan be traced in "ShortHistory of Unitary-Wind-Tunnel Plan." 4 p.typescript, November 7, 1949; "Addendum to ShortHistory of Unitary-Wind-Tunnel Plan." 6 p.typescript, July 31, 1950; "Arnold EngineeringDevelopment Center chronology," lip. typescript,n.d.18 These interest groups are essentially the same asthose found in other NACA initiatives.19 These differing perceptions can be seen in thesummary of proceedings of the "NACA IndustryConference on Unitary Plan," held in Los Angeleson November 14, 1949, where NACA-industrysuspicion of Air Force intentions was especiallyevident. The NACA's own plans appear most clearlyin a staff memorandum for Lewis, "Analysis ofSupersonic Facilities," October 18, 1949, NASAHistorical Reference Collection.20 Brian Balogh, "Reorganizing the OrganizationalSynthesis: Federal-Professional Relations in ModemAmerica," Studies in American Political


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Development 5 (Spring 1991): 119-172, quote frompp. 121-122.21 House Committee on Armed Services, Report toAccompany S. 1267, 81st Cong., 1st sess., H. Kept.1376, p. 4.22 Ibid, p. 10-13.23 Industry influence was evident throughout thelegislative hearings, as evidenced in the Report toAccompany S. 1267: "While the committee is fullyaware of the ramifications of the NACA system ofcommittees and subcommittees and the fact thatprovision is made for industry representation amongthese various groups, it would appearnotwithstanding that there is considerable room forthe development of adequate procedures which willinsure at all times that basic scientific information iscirculated freely and made available to all researchgroups and technical workers having an interest inthe subject matter, except in those cases where thereis a very clear and unquestionable need for placingthe information in a classified category on groundsof military security alone and for no other reason"(p. 8).24 Ibid., p. 5.25 Ibid., pp. 10-11.26 This has been appreciated in assessing the careersof several senior appointed government leaders. SeeJameson W. Doig and Erwin C. Hargrove, eds.,Leadership and Innovation: A BiographicalPerspective on Entrepreneurs in Government(Baltimore, MD: Johns Hopkins University Press,1987).27 John Law, "Technology and HeterogeneousEngineering: The Case of Portugese Expansion," pp.111-34; and Donald MacKenzie, "Missile Accuracy:A Case Study in the Social Processes ofTechnological Change," pp. 195-222, both in WiebeE. Bijker, Thomas P. Hughes, and Trevor J. Pinch,eds., The Social Construction of TechnologicalSystems: New Directions in the Sociology andHistory of Technology (Cambridge, MA: MIT Press,1987).28 "This New Ocean - Chl-2: Conquest of the Air,"available athttp://www.hq.nasa.gov/office/pao/ffistory/SP-4201/chl-2.html.29 Donald D. Baals and William R Corliss, "WindTunnels of NASA." pp. 49-73, NASA SP-440, 1981.30 "What were the first test facilities built atAEDC?," available athttp://www.arnold.af.mil/aedc/highmach/stories/firstfacilities.html.

31 J. G. Mitchell, "Current wind tunnels and plannedimprovements at the Arnold EngineeringDevelopment Center (AEDC)", A86-24763.32 "Aeronautical Facilities Catalogue, Volume 1:Wind Tunnels," Editors: Frank E. Penaranda and M.Shannon Freda, NASA RP-1132, 1985.33 "Manual for the Users of the Unitary Plan WindTunnel Facilities of the National AdvisoryCommittee for Aeronautics," NASA TM-80998,Washington, 1956.34 Charlie M. Jacobson, William A. Corlett, andWilliam J. Munta, "Description and Calibration ofthe Langley Unitary Plan Wind Tunnel," NASA TP1905, 1981.35 Man in Space: A National Historic LandmarkTheme Study, available atHTTP://www.cr.nps.gov/history/omline_books/butowsky4/spacea.html.36 William L. Peters, et. al., "Cycle Time ReductionStrategies and Improvements in Transonic Testingin the AEDC Wind Tunnel 16T," AIAA-99-0179,1999.37 Robert A. Aiello, "NASA Lewis 10- By 10- FootSupersonic Wind Tunnel," NASA TMX-71625,1974.38 David N. Bowditch, "Current Wind TunnelCapability and Planned Improvements at LewisResearch Center," NASA TM 87190, 1986.39 Robert E. Bower, "Current Wind TunnelCapability and Planned Improvements at the NASALangley Research Center," AIAA-86-0727-CP,1986.40 John R Micol, "Langley Research Center'sUnitary Plan Wind Tunnel: Testing Capabilities andRecent Modernization Activities," AIAA-2001-0456,2001.41 Lado Muhlstein Jr., "Wind Tunnel TestProductivity and Technology Accomplishments atAmes in the ADTE Program," AIAA-98-0141,1998.42 Edward A. Becks, "Drive System Enhancementsin the NASA Lewis Research Center SupersonicWind Tunnels," AIAA-98-2886, 1998.43 Jerome T. Kegelman, "Accelerating Ground-TestCycle Time; The Six-Minute Model Change andOther Visions for the 21st Century," AIAA-98-0142,1998.44 NWTC Final Report, NAS3-27330 Phase 2ADeliverable No.: NWT-03-A-9000-01, April 22,1996.


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45 John H. McMasters and Russel M. Cummings,"Airplane Design - Past, Present and Future,"AIAA-2001-0535,2001.46 Carol Cash, "Crisis in Aeronautics", AIAA-2001-0133, 2001.47 Global Market Forecast, 2000-2019 (Blagnac,France: Airbus Industrie, 2000), 4-5.


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O

8

CD

Wind TunnelTransonic

16T11 ft (Unitary)8 x 6 ft*

Supersonic16S9 x 7 ft (Unitary)8 x 7 ft (Unitary4 ft Unitary #14 ft Unitary #210x 10ft

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AEDC - Arnold Engineering Development CenterARC - NASA Ames Research CenterGRC - NASA Glenn Research CenterLaRC - NASA Langley Research Center

(C) - Closed(O) - Open

Table 1. Unitary Plan Wind Tunnel Operating Characteristics

COI§


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Figure la. Aysymmetric Sliding Block Supersonic Nozzle

of

2.03.S

AT

Figure Ib. Flexible Wall Supa-sonic Nozzle


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Figure 2: Schematic of the AEDC Propulsion WindTunnel Complex

UNITARY PLAN WIND TUXNEL

Figure 4: Schematic of the Ames Unitary Plan WindTunnel

Cooing tower-

/-Dry air/ r'

air storage spheres

/~M8in drive control oararis~ • ft monitoring stet

Data acquisition room

Low fetecfi number Ujst section

10x10 Supersonic Wind Tunnel

Figure 3: Schematic of the Langley Unitary PlanWind Tunnel

Figure 5. Schematic of the Lewis Unitary Plan WindTunnel


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NACA/NASA and the National Unitary Wind Tunnel Plan, 1945-1965

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Transcript of NACA/NASA and the National Unitary Wind Tunnel Plan, 1945-1965