Development of Winged Reentry Vehicles 1952- 1963 Becker1983

8/2/2019 Development of Winged Reentry Vehicles 1952- 1963 Becker1983

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THE DEVELOPMENT OF WINGED REENTRY VEHICLES,1952 - 1963

May 23, 1983John V. Becker.

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CONTENTS

Bell Aircraft Company Studies of Boost-Glide,Military Systems 7

Ames Exploratory Comparative Study of Hypersonic Systems 12The First Manned Winged "Reentryll Vehicle - The X-15 9

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The Brown-Zimmerman-O'Sullivan Study The O u ~ l o o k in 1952Foreword

SAB Review of Dyna-Soar and "Phase Alpha"

The NACA "Round III" M e e ~ : r n g at Ames on October 16-18, 1957I

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Project "InWARDS"

Langley Parametric Analysis of Glider and ReentryVehicle Coolant ~ e q u i r e m e n t s

Pr . tllDy S "Jec na- oa r

John Stack's Attitude Towards Space Projects Early Manned Satell i te Vehicle Concepts

Rocket-Model Flight Tests Supporting DS-l

References .

The Lifting-Body Diversion .on the Way to the Shuttle The Winged Space Shuttle

The Decline and Termination of Dyna-Soar

The Last NACA Conference on High-Speed Aerodynamics,March 18-20, 1958

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2The Outlook in 1952

The overriding real-l ife focus for hypersonics research in 1952 wasthe problems of the various long-range missile concepts. Our Hypersonicsand Gas Dynamics groups at Langley, which had been formed in 1945 and1948, were busily engaged in general exploratory hypersonic aerodynamicsand heating research, and in occasional specific missile configurationtesting for RAND and others. Our princ ipal tool was the Langley ll-inchhypersonic tunnel which was this country's f i rs t hypersonic facili ty,conceived and proposed in 1945, and operated successfully at Mach 6.9 fo rthe f i rs t time in"1947 ...our Gas Dynamics Laboratory, which contained.,vseveral hypersonic nozzles, came into operation a few years later, inthe early '50 's. In 'the late '4Os, Ames also became involved in missile-related research, 'and in the early '50's H. J . Allen completed hisfamous "blunt-body" contribution. Many of us had rea:d the Sanger-Bredtpapers, and more recently the f i rs t progress reports on the studies ofmilitary manned boost-glide systems being undertaken at Bell Aircraft

These documents were most stimulating, but there was such a multiplicityof enormous technical problems that these systems seemed very far in thefuture. Manned space flight with i ts added problems and the unansweredquestions of safe return to earth was seen then as a 21st Century enter-prise. In our wildest fancies none of us visualized i t actually happen-ing, as i t did, within the decade.

The 1952 recommendation of the NACA Aerodynamics Committee fo rincreased emphasis on hypersonics research at Mach 4 to 10 had l i t t leimmediate effect on the existing Langley programs, with the exceptionthat i t inspired the PARD group to evaluate the possibilities of increas ing the speeds of their test rockets up to Mach 10 (Ref. 1). The
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3rest of us who had actually been expanding our efforts in hypersonicssubs tant ia lly for the past 5 years were gratified to see NACA management"getting up to speed." The final part of the recommendation "to devotea modest effort" to the speed range from Mach 10 to the speeds of spaceflight was responded to at Langley by setting up an ad hoc 3-man studygroup consist ing of C. E. Brown, Chairman, from my CompressibilityResearch Division; C. H. Zimmerman of Stability and Control; and W. J.0 1Sul livan of the Pilotless Aircraft Division (PARD). The Brown groupwas asked to assess the problems, develop research program ideas, and,following the suggestiope of Bob Woods of Bel l Ai rcraf t, to define a

Imanned research airPlBne capable of penetrating the hypersonic flight- .regime. The group met periodically fo r s evera l months and then dis-

banded. Their ~ e p o r t was circulated internally in June of 1953 (Ref. 2)


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4The Brown-Zimmerman-O'Sullivan Study

Outside of our two small groups in the Compressibility ResearchDivision, very few others at Langley in 1952 had any knowledge ofhypersonics. Thus the Brown group filled an important educationalfunction badly needed at that time. In the process they had to educatethemselves, since none of the three had any significant previous back-ground in hypersonics. When Floyd Thompson told me of his plan to setup such a group, I suggested adding one of our hypersonic aerodynamicistsand also a budding specialist in hot-structures from the StructuresDivision. Thompson r e j ~ c t e d the suggestion saying that he was lookingpfor completely fresh_unbiased ideas and had picked three individuals who- .had previously shown much originality in their respective fields; theywould ask for help from the experts when they needed i t .

The Brown group made an interesting review of the potentialities ofhypersonic systems at speeds up to orbital and they became interestedespec ia lly in the commercial possibilities of the boost-glide rocketsystem for long-range transport, a scheme not previously explored to anyextent in the l i terature. As regards needed research programs theyrejected the traditional use of ground facil i t ies and indicated thattesting would have to be done in actual flight where the true high-temperature hypersonic environment would be generated. To do this theysuggested extending the Wallops-Island rocket-model technique to muchhigher speeds with possible test model recovery in th e Sahara. Inresponse to their directive to consider a manned research a irplane tofollow the X-2, they endorsed an earlier proposal of Dave Stone toextend the X-2 to the Mach 4 to 5 range, a proposal shortly rejectedby the Research Airplane Panel.


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I( 5Listening to Brown summarize the study early in 1953 our hypersonic

specialists felt a strong sense of deja-vu, especially at his pronounce-ment that "the main problem of hypersonic flight is aerodynamic heating."Nevertheless this ~ ' a s t imely education in the basics for the uninitiatedin Langley and NACA headquarters managements. Fortunately the group'sconclusion that flight testing, rather than ground-based approaches,would have to be relied on for hypersonic R&D, which proved to be quitewrong, did not slow the progress of any of our developing ground tech-niques. As everyone in the business now knows hypersonic ground facili ties generally do n o t ~ t t e m p t to simulate the high-temperature features"of the hypersonic en'l1:ironment at the higher speeds; however, i t has

inter-center Board was never carried out.

but ground-based techniques - rather than flight - remained the primaryoften desirable just as i t has always been throughout aircraft history -

simulation in a variety of ground facUit ies both to advance basic te ch -

This New Ocean for example

Selective flight testing, Usually of the final article, is

proved possible and quite practical through the principles of partial

The original plan to have the Brown Group's results reviewed by an

Several misconceptions regarding presumed connections of the Brown

tools of hypersonic R&D.

the problem since 1952," - presumably the Brown group - was the source

nology and to support the development of uniformly successful hypersonicsystems ranging from ICBM's to the Space Shuttle (see Ref. 3, for

of MACA's proposal in July of 1954 leading to the X-15. Actually, as

example).

literature which need to be corrected.states on p. 57 that "the Langley Study group which had been working on

Group's study with subsequent projects have appeared in the historical

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6has been documented in full detail in Ref. 4, the X-15 concept originatedin a 1954 study by Becker, Faget,Toll , and Whitten which made no usewhatever of any of th e Brown group 's s tudy. This misconception, whichhas arisen on other occasions, probably has i ts roots ir . the carelessand incorrect :"lording found in the ''NACA Views l t document of August 1954(Ref. 5), where no clear d is tinction was made between the Brown group of1952 and the X-15 group of 1954. Written in the s lanted off ic ious styletypical of the promotional literature of federal agencies the NACA Viewscontains other inaccuracies, for a notable example, th e statement onpage 2 that "independezrt-studies l t at the other NACA Labs "were markedlyp

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in agreement (with Langley's pre-X-15 study) concerning feasibility,. ,.goals, and general arrangement of the airplane." The truth isthat Ames favored a military-type air breather for Mach 4 to 5 TheLewis Lab recommended against a manned airplane (Ref. 4).

Another unwarranted claim is seen in A New Dimension, NASA Ref.Publ. 1028, onp. 288 where author Shortal states that th e Brown groupstudy "excited Langley interest" in a boost-glide system follow-on toth e X-15 "to become known as Round III and later as the NACAjUSAFDyna Soar Project." As one of the 2 or 3 individuals at Langley mostdeeply involved in these later boost-glide programs I can state positively that their origins sprang solely from military applications andinterests.- At most the Brown group study provided Langley with usefulbackground education. The commercial transport version of boost-glidethat the Brown trio visualized did not survive in later studies (seeNASA SP-292, p. 429-445).


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7Bell Aircraft Company Studies of Boost-Glide

Military SystemsWalter Dornberger, former German Army Commander of Reenemunde who

was hired by Bell after the war, directed a succession of studies atBell which had great educational value fo r the NACA and the Air Force.Essentially these were greatly advanced and improved Sanger conceptsincorporating advanced technology and greater technical depth. Ofspecial value and interest were Bell'S new structural concepts, duelargely to Wilfred Dukes' group - the f i rs t hypersonic aircraft hotstructures concepts t o ~ e developed in realistic meaningful detail .1/These included wing ~ t r u c t u r e s protected by non-load-bearing flexiblemetallic radiative heat shields or "shingles", cabin structures employingboth passive and active cooling systems to keep the interior temperatureswithin human tolerance, and water-cooled leading-edge structures. Bellrecognized that there were enormous gaps between their preliminary con-cepts and actual realization, and like most of their contemporaries in

the f if t ies they usually recommended "vigorous" research programs to f i l lthe gaps.

Periodic progress reports of the Bell Studies of the 1950-'57 periodwere circulated to the interested NACA research groups, including theBrown group, the X-15 group, and the Round 3 groups. Unfortunately, theywere usually classified "Secret" by the Air Force and thus were generallynot used as references in NACA reports, which o r d i n a r i l ~ were classified"Confidential" or lower. With l i t t le question Bell 's "BOMI", "BRASS BELL",and ''ROBO'' studies provided the principal stimulus for USAF interest inboost-glide systems culminating in 1956 in USAF's proposals for theHYWARDS research program and later fo r the Dyna-Soar program. The rapid


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expansion after 1954 of NACA studies of boost-glide systems andhypersonic glider aerodynamics heating, and structures was greatlystimulated and benefited by Bell 's work on these military systems.

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9The First Manned Winged "Reentry" Vehicle-

The X-15Dr. Dryden used to liken the X-15's great ell ipt ic excursion out of

the atmosphere into space to the leap of a fish out of water. Ouroriginal intent was to create a period of 2 to minutes of weight lessness for a f irst exploration of the effects of this characteristicfeature of space flight. But as the Langley study of March 1954 pro-gressed we soon realized that the problems of attitude control in spaceand the transition from airless to atmospheric flight during reentrywere at least equally significant to the weightlessness question

II,.(Ref. 4). And as t ~ went on th e dynamics of the reentry maneuvers and"associated problems of stabilitY,control, and heating emerged as clearly

the most difficult and significant of the entire program (Ref. 3).The X-15's reentry problems were similar in a l l important respects

to those of the Space Shuttle: the transition from space reaction con-trols to aerodynamic controls; the use of high angles of attack to keep

the dynamic pressures and the heating problems within bounds; and th eneed for ar t i f ic ia l damping and other automatic stability and controldevices to aid the pilot . These automatic systems were in an earlystage of development in the '50's and the X-15 pUots had to contributepiloting skil ls beyond those required in the Shuttle operation. Anyadvantage over the Shuttle reentry accruing from the lower speed of theX-15 tended to be offset by the much steeper reentry paths of the X-15.The pioneering X-15 reentry systems and their derivatives and the X-15'sreentry flight experiences le d directly to the systems and techniquesemployed in the Dyna-Soar and later in the Shuttle. The reaction con-t rol system used in the X-15's space leap also found application in the


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10Mercury, Gemini, and Apollo systems.

An interesting facet of the original heating ana lysi s o f the X-15'sreentry from i ts "space leap", made by Becker and Peter F. Korycinski,under forced draft in their long work days of March and April, 1954, isworth noting. We discovered that Mach 7 reentry at low angles of attackwas impossible: the dynamic pressures quickly exceeded by large marginsthe limit of 1000 l l isq . f t . set by structures considerations, and theheating loads became disastrous. However, we found that these problemswere solvable by using sufficient l i f t during reentry - the higher theangle and the associattf"dlift the higher the flight altitude and the/I,.lower the peak dynam1c pressure and the lower th e heating rates. Thereduced L/D's characteristic of the higher angles o f attack reduced the

,times of exposure to high heating rates, thus reducing the reentry heatloads as well as the heating rates. On reflection i t became obvious tous that what we were seeing here was a new manifestation of H. J. Allen's' 'blunt body" principle. As we increased angle o f a tta ck our cOJ1figura-tion in effect became more ' 'blunt'' t disipating more of i t s kinetic energythrough heating of the atmosphere and less in th e form of frictionalheating of the veh icle . Clearly Allen's concept was as meaningful in ourhigh-lift X-15 reen try as i t was in the non-lifting missile cases he hadconsidered in 1952.

The figure in ref . 4 which depicts th e t r ~ e c t o r i e s and vehiclealtitudes which were found feasible from the heating standpoint showsthat dive brakes could be employed in conjunction with l i f t to increasedrag and further reduce L/D in order to ease the hea ting problem -again in accord with Allen's "Blunt-Body" concept. Unfortunately thelimited treatment of the heating studies reported in ref. 4 did not


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11include a ll of the implications of high-lift high-drag reentry. Thesedetails were discussed, however, in most of the oral presentations wemade throughout 1954. The problems of how to make the X-15 configura-t ion s tabl e and controllable in the high-angle-of-attack (11 to 26degrees) regime involved in i t s "reentry" trajectory outweighed theheating considerations at that time. Nevertheless our heating analysisprovided the f i rs t clear deta il ed ins ight s into the reentry heatingproblems of winged vehicles and their possible solution by use of com-bined high l i f t and high drag. This new lmowledge was invaluable inour later work on the "ljPIIARDS" and ''Dyna-Soarl t projects in which weHextended s tudie s o f h ~ g h - l i f t and high-drag reentry to near-orbital

- 0speeds for delta wings operating at angles of attack up to 45


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12Ames Exploratory Comparative Study

of Hypersonic SystemsThis 1954 study (Ref. 6) was started at about the same time as the

pre-X-15 work at Langley. I t was.concerned solely with sub-orbitallong-range flight and did not consider orbital operations or reentry.H. J . Allen made the f i rs t review of the ir r esul ts a year and a halflater in November 1955 at the Langley Conference on High-Speed Aero-dynamics. In retrospect the study was interesting and important onthree counts:

1) I ts c o m p a r i s o ~ o f rocket and a ir breathing systems.I2) The unvei14g of the Ames so-called "flat-top" drooped-wing-t ip glider for intercontinental ranges.

3) The f ~ d i n g that the simple, blunt-shaped, ballistic capsulewas the optimal vehicle from an energy stand.point for verylong ranges (semi-global or greater).

In regard to item 3 Allen liked to expla in , "For very long ranges i t isbetter to throw i t than to fly i t ." Of course, his ball ist ic vehicle

had some unpleasant characteristics: high deceleration rates and thenecessity of an uncontrolled parachute landing i f i t were to be re-covered.

Over four years later after much additional study and new technologyfor satell i te reentry had been added by Industry, by Langley, by Ames,and by others, a "f inal" version of Ref. 6 - having the same t i t le butmuch embellished - was published as NACA TR 1382. The authors ofNew Ocean (pp. 66-68) mistakenly assumed that a ll of the insightsacquired by 1959 in this study were at hand in 1954. I t should be noted


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13especially that the desirable features and operational techniques ofwinged satell i te r eent ry veh ic le s d id not exist either in the 1954study or in Allen's 1955 review.

What true and what should be noted by historians is the factthat the s tudies o f hypersonic glider systems by Bell, Langley, Ames andothers in the early '50's were a most pertinent and important prelude tothe successful satell i te reentry vehicle technology developed la ter inthe decade. In many respects th e environmental and operational problemsof reentry from orbit along a shallow (gradually descending) trajectoryare quite similar to - t ~ of the sub-orbital glider system. Thus X-15,IIHYWARDS, and Dyna-Soar were important precursors of the Shuttle. AndAllen 's sub-orbita l ball is t ic system of 1954-55 le d directly to theproject Mercury concept.


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14Project I'mWARDS"

We were surprised in March, 1956 to learn from the ARDC staff a tAndrews AFB that USAF was establishing a specific pro je ct to develop aresearch airplane successor to the X-15. After one of the Bell AircraftCompany briefings on their ROBO study we NACA invitees were to ld th atUSAF/ABDC management was determined never again to find themselves un-prepared as they were when NACA proposed the X-15 and gained technicaldirection of the X-15 project. USAF's only specification for such a newresearch vehicle at that time was Ita rocket glider with a speed of aboutMach 12. 1t "HiWARDS"wa:B- the acronym for this .!spersonic :!,eapon .!,1ld".! and stem. -Although we were very busy at Langley in the spring of 1956 with

Isupporting research for the X-15, i t was obvious that the question of asuccessor merited high-priority attention. F. L. Thompson immediatelyset up an ad hoc inter-divisional stUdy group patterned directly afterthe X-15 group. I t was larger, however, and had more time to fulf i l l-i ts task. The principal members of our " ~ A R D S " study group were:

J . V. Becker, Chairman; a lso leader of the Heating Analysis groupM. Faget, Propulsion Be ConfigurationL. Sternfield Stability, Control, PilotingF. J . BaileyI . Taback, Instrumentation, Range, NavigationR. Anderson Structures, MaterialsP. PurserP. Doneley, Loads and FlutterA. Vogeley, Operations and X-15 CoordinationP. Korycinski, Coordination; Heating group


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15As the work progressed a number of others were added, notably

P. Rill, Configuration, PropulsionE. Love

Configuration, Aerodynamics, Stability &ControlN. BertramAs a starting point we decided to focus on a design speed of Mach 15

for purposes of analysis, not at a l l sure that i t would prove feasible,but believing that i t was about the lowest speed for which an attractivemilitary boost-glide mission could be defined. Perhaps the mostimportant recommendation in our firs t formal report of the study onJanuary 17, 1957 (Ref. ;n was that the des ign goal should be raised to1118000 feet per second or about Mach 18. We ha4 learned in our heatingana lysis tha t at this speed boost gliders approached their peak heatingenvironment. The rapidly increasing f ligh t a lt itudes a t speeds aboveMach 18 caused a reduction in heating rates; at sate l l i te speed, ofcourse, on the outer fringe of the atmosphere the heating rates becamenegligible. Mach 18 was an enormous step beyond the X-15, requiring new.developments in every area of applicable technology. Promising generalconcepts for these developments were formulated; however, in many areas,especially in high-temperature internally-cooled structures, we wereconfronted by enormously complex development problems. Our expressedhope that such a system could be developed and ready for flight in 5years appears , in r et rospec t, t o be far too optimistic.

Our proposed vehicle system embodied advanced glider prototype con-cepts both aerodynamically and structurally. The heating analysescarried out by Becker and Korycinski bad revealed major advantages fora configuration having a f la t bottom surface for the delta-wing, and afuselage located in the relatively cool shielded region on the top or lee


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16side of the wing - i .e . the wing was used in effect as a part ial heat.shield for the fuselage and i ts cri t ical contents. This "flat-bottomed"design had the least possible crit ical heating area for a given wingloading and this translated into leas t c ircula ting coolant, least areaof rad ia ti ve heat shields, and least total thermal protection in flight(Fig. 1). In these respects the configuration differed importantly fromthe previous Bell designs, which employed mid-wing arrangements. Thiswas the f i rs t clear delineation of the possibility of aerodynamic designfeatures which could significantly aleviate the heating and ease the hotstructures problems . ~ t e r application of these principles to actualIflight systems was f i rs t made in the Dyna-Soar program, and they arealso obViously applied in the current Space Shuttle.

In the major' review of our BYWARDS study for Langley top managementon January 11, 19;7 Becker also discussed operation of the Langleyglider i f boosted to the near-orbital velocity r e q u i r ~ d for once-aroundor "global" range. Using Fig. 2 he pointed out that the maximum-LID mode

of operation resul ted in much more difficult temperatures and heatingloads than i f the glider were operated at half i ts maximum LID and highangles of attack. St i l l further alleviations would be expected i f thevehicle were operated a t i ts maximum l i f t ( L / D ~ l , 4;0 angle of attack)(Ref. 8, copy attached). High L/D operation made sense only for theshorter ranges.

During the period in 19;; when the work statement for the X-l;design competition was being formulated at Langley I had receivedseveral phone calls from A. J . Eggers at Ames expressing concern thatthe work statement did not 'specify very high aerodynamic efficiency


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17(i .e. very high LiftjDrag rat io) . They proposed to add to the X ~ 1 5design problems the enormous complications that would have been involvedto make i t an advanced prototype of their early notions at that time ofwhat the ultimate long-range glide vehicle should look like. I pro-t es ted tha t this would delay the procurement unacceptably without addingmaterially to the research products envisioned for this exploratorypenetration into the realm of manned hypersonic flight. Soule and NACAHQ personnel agreed.

When "BYWAIIDS" appeared in the spring of 1956 the Ames group saw atlast an opportunity to .FOmote their penchant for high Lift/Drag andpthey set up a study group consisting of A. J . Eggers, G. Goodwin, R

Crane, H. J . Allen, L. Clausing and others. Their proposal (Ref. 9)called for a speed of Mach 10 which produced a range of only about2000 miles even though their glider was designed for the highest conceivable hypersonic Lift/Drag ratio (about 6). To favor h igh L/D they madeuse of the favorable interference l i f t that occurs when the pressure

field of an underslung conical fuselage impinges on the w i n g ~ In thisconcept, unfortunately, the entire fuselage with i ts critical specialcooling requirements was located in the hottest region of the wing flowfield - on the high pressure lower surface where added thermal protectionweight was required. Although the Ames report virtuously stated that theconfigurati.on should be "capable of the h ighest possible Lift/Drag ratioconsistent with (other requirements)" i t was apparent to us thatactually their configuration had 'the highest possible L/D without regardfor the other requirements.' The drooped wing tips of the Ames con-figuration were supposed to add slightly to the LID but their use did


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18not survive later careful evaluations in the Supersonic Transportprograms.

A comparison of the Ames and Langley vehicles init ially proposed forEYWARDS i s seen in Fig. 3. A rather noticeable feature of the Langleydesign is the large cones attached to the elevons. These were proposedby E. S. Love to provide sure effectiveness for.both directional andlongitudinal stability and control at the higher speeds. They wereshortly discarded in favor of separate toed-in tip fins and rudderswhich proved better from the L/O and heating standpoints.

Aside from the q u e ~ i o n s relating to the "flat-top" arrangement,#the least supportable_'"feature of the Ames proposal was the low design. .speed they recommended, about Mach 10. Eggers made a mild attempt to

j us ti fy th is speed at the f i rs t meeting of the Steering Committee forthese Research Vehicles on February 14, 1957 (Ref. 10). Shortly afterthis meeting, however, Ames decided to accept our reasoning for 18000ft/sec, and on May 17th they forwarded a Supplemental Report describing..their 18000 ft/sec system (Ref. 11). High L/O was s t i l l retained as theprimary feature of their new design.

Ames' predilection for high-L/O needs to be explained. The possi-bil i t ies for combining a e r o d y ~ c bodies - wing and fuselage inparticular - so as to produce beneficial aerodynamic interference effectshad become.one of the most intriguing aspects of configuration researchin the late '40 ' s and early '50' s - stimulated perhaps by the greatsuccess of Whitcomb's Transonic Area Rule developments. A number ofresearchers at Ames were deeply involved in the improvement of super-sonic configurations through favorable interference. At the same timeAmes did not have a significant effort in high-temperature structures
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19and heat protection. This area of research was centered at Langley.Thus the Ames emphasis on high-LID in the hypersonic research airplaneswas simply a reflection of their established primary research interestrather than any special understanding or analysis of the real- l i fetrade-offs that must be made between high-LID, structural height, and,espec ia lly for hypersonic aircraft , h e a t - ~ r o t e c t i o n - s y s t e m weight.

NACA management was now faced with the problem of how to deal withthese two distinctly different configuration philosophies. To providesome needed background information and at the same time promote ourLangley ideas in which ,rbelieved strongly, I constructed Fig. 4 forpdiscussion at a maj0I"'presentation to Langley management in May 1957.

"Based on ana ly si s o f the range equation for a circular earth, theresults showed that due to the large centrifugal l i f t at Mach 18, thetraditional aerodynamic efficiency factor, Lift/Drag, has less thanhalf of the relative effect on range that i t has at low flight speeds.At the same time, aircraft weight, which is increased by high L/D,retains the same large importance that i t exerts a t low speeds. Tofurther stress the point I prepared Fig. 5 showing that for the extremecase of once-around or "global" range an L / D = ~ vehicle required only aslightly higher boost speed than the L(D=4 vehicle. More importantly,the L / D ~ l vehicle, operating at i ts maximum l i f t angle o f a tta ck (450)had greatly reduced heating problems, and this meant that i t could besmaller and lighter than the L(.D-4 vehicle. This result, of course,came as no surprise to us at Langley since we had discovered the heatingadvantages of high-lif t low L/D operation in our X-15 study as mentionedpreviously. This was the f i rs t specific del inea tion of an important


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20princ ip le of operation later employed in the Dyna-Soar and Space Shuttlesystems.

A "NACA Views" document for the HYWARDS s tudy (Ref. 13) was writtenat Langley, chiefly by key members of the Langley team, during the latespring of 1957. In the interests of peace and brotherhood both theLangley and Ames vehicles were included, to i l lustrate two alternativeapproaches, "low-heating" and "high_LID." Editing by Soule and Mulacat Langley and Clotaire Wood in NACA HQ strove fo r fine impartiality.A number of presentations of the content of this document were madeduring the spring at . ~ l e y , Ames, NACA HQ, and at the Pentagon on/IJuly 11. General P u ~ t and Dr. Dryden indicated that fur ther s teps

.' .towards an advanced program of this kind were in order, but should betaken with discretion so as not to jeopardize the X-15 program whichwas s t i l l having funding problems.


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21The NACA "Round III" Meeting at Ames

on October 16-18, 1957The intent of this gathering was to permit detailed discussion and

coordination of the work of the four NACA Laboratories relating toEYWARDS, at the working level and at upper management levels as well.I t was very much needed because of the strong differences of opinionwhich had developed, particularly in regard to the glider configurationc o n c e p t s ~ In the "Views" (Ref. 12) i t was stated that the Ames highL/D approach would have a range advantage of some 1300 miles i! launched.!! speed, 1 ~ 1 t / s e c , as the Langley glider. However, i t waseasy to show by simple engineering calculations that the glider weight"penalty associated with the higher L/D would,for equal system weights,nullify this range advantage. This important fact had been edited ou tof the "Views" in the interest of harmony.

Reflecting on the above as objec tive ly as possible, I rea lized tha tboth the Ames and th e Langley designs were probably far from optimum

We had simply selected "reasonable" but arbitrary values for wingloading, skin temperature, etc. A truly optimized vehicle - in whichthe trade-offs among the key variables had been systematically evaluated -might have different proportions, features, and R&D problems. I t wasrather foolish for both groups to be so vociferously wedded to theirpresent configurations. I decided this was the most important pointI could make at the Round III meeting. To make the point convincinglyI analyzed the effects on the performance of the Langley glider due tochanges in wing size and wing loading. The results were dramatic: byusing a wing 40 percent sma lle r the range of our glider system was


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22increased from 4700 to 5600 nautical miles (Fig. 6). The LID with thesmaller wing was reduced about 14 percent, bu t this was far outweighedby the associated 4000 lb reduction in glider empty weight. I concludedthat we should concentrate not on increasing L/O by every known means,but rather on seeking "optimizedl t configurations which generally wouldhave much smaller wings than the high-LID designs.

By the time of the Round I I I meeting we had also eliminated Love'shigh-drag tip cones - substituting toed-in t ip fins - and thus makingthe range of our system with both improvements 6900 nautical miles,or more than 1000 mileS'greater than the claimed performance of the AmesII

/."high-L/D1t design.These results.and other details of the Langley study were included

in my summary talk at the f irst Round III session on October 16th(Ref. 13,14). The ideas were accepted with l i t t le question.

Many of the Ames people had begun to realize that design for veryhigh L/D was frought with enormous technical problems of hea tin andstructural heat protection which had no easy practical solutions (Ref.15). But a s t i l l more compelling new development of cris is proportionshad captured the interest and imagination of a l l of us - Sputnik I wasorbiting overhead. Now, only ~ o m e 11 days after i ts launch, we a llfel t mounting pressures to come to grips with the problems of mannedsatellites, . particularly the crit ical reentry problem. The Ames viewexpressed by Eggers and others said in effect, ItNACA should be workingon the satell i te reentry problem rather than on the BYWARDS sub-orbitalgliders. Very low L/O should suffice fo r satell i te reentry and thiswill make the technology much easier to develop than that fo r thegliders."


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23I t should be noted here parenthetically that the ideas of pure

ball is t ic and slightly-lift ing wingless hypersonic vehicles did B2!emerge for the f i rs t time in NACA thinking at the Round II I meeting ashas been suggested (Ref. 15). "Lifting bodies" without wings had beenstudied since the early '50 1 s by both Langley and Ames. I t had beenabundantly demonstrated in the prior ICBM developments that ball is t icoperation generally m i n i m i z ~ d the heat load problem, and i t was equallywell understood that th e high decelerations of ball is t ic reentry couldbe greatly alleviated by small LID, in the range achievable by bluntwing-less bodies (see- for- example Ref. 6 and This New Ocean). The new1/contribution of the Rpund I I I meeting was the NACA decision to take on

"satel l i te re entry a s a major new challenge for research.Ames also i n"ef fect said l ~ have lost i nt er es t i n the sub-orbital

glide systems and believe we should focus a l l of-our R&D activities onsatel l i te systems, for which we no longer need high LID." The Majorityview expressed by I . H. Abbott of NACA HQ was that th e satell i te reentryproblem for non-lifting or only slightly-lifting vehicles should bestudied, bu t as an addition to the boost-glide system rather than analternate (Ref. 13). Notwithstanding this management dictum Amesterminated i ts hypersonic Winged vehicle work shortly after the RoundII I meeting and devoted a l l of i ts energy to the low-LID l if t ing capsule.Their h y p e r ~ o n i c winged glider concept was lef t stranded in th e earlyconceptual state i nd icated in Fig. 3, and they never moved ahead towinged reentry vehicles . In fact, as we will see later, they developeda strong antipathy to such vehicles. Thus, within NACA, i t was lef tentirely up to Langley not only to pursue winged gliders and Winged


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24reentry vehicles technology, but also to provide the logic and thepromotional support for winged systems.

Immediately after the f i rs t day of the Round III meeting I camedown with the flu. Henry Reid and Pete Korycinski kept me informed ofthe later sessions at my bedside at t he motel. I had plenty of time toreflect on Sputnik which had been launched 12 days earl ier and whichwas passing overhead periodically, announcing the advent of the SpaceAge. However, at that time the boost-glide sub-orbital system seemedmuch more immediate and more urgent from a military point of view thansatell i tes either manne.d:-or unmanned. The Dyna-Soar project had been,proposed by USAF/ARDQ"only 2 months earlier, and would no t be approved,unti l the month after Round III , s t i l l specified as primarily aimed atboost-glide applications in spite of due consideration by USAF of theimplications of Sputnik (Ref. 16).

At the same time my optimization study for Round I II had convincedme that the ''NACA Views" vehicles we had recommended were far too large

and too complex for an effective new research airplane system. Iresolved to take a fresh new look upon returning to Langley.


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25Langley Parametric Analysis of Glider and

ReentrJ Vehicle Coolant RequirementsThe most disturbing feature of the large boost-gl iders proposed in

the "NACA Views", by far, was the large weight of internal coolant theycarried and the complex internal systems requi red to circulate the coolantto large surface areas. We a l l realized from the outset, of course, thatthe use of a circulating coolant was a highly undesirable complication,but our structures group saw no alternative pending the fu tu re develop-ment of a better high-temperature material, which at that time was oftenreferred to as "unobtai'nl.um. I t The required coolant fo r each of NACA' s1/

t"hypersonic vehicles prior to 1958 had been determined on an ad hoc basisusing the particular wing loading, skin temperature, etc. , assumed foreach case. I t was clear by mid-1957, however, that the problem was ofsuch controlling importance that a systematic, parametric analysisrevea ling the inf luences of the key variables was justified. P. F.Korycinski and I initiated such an analysis about two months prior to-Round I I I . Exciting preliminary results were realized early in November1957, and a final report of the work was published early in 1959 (Ref.17). We found that skin temperature exercised an enormous over-ridingeffect on the coolant required, which increased inversely with skintemperature raised to the 16th powerl The conservative peak skintemperature for HYWARDS advocated by our structures group, 18000 F,required very large coolant weights. However, a nominal rise in allowable temperature to 22000 F, which was not beyond reasonable expectationsfor improved metallic or ceramic surface materials, completely eliminatedthe need fo r surface coolant except for the small-radii wing leading


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26edges of the high-LID gliders. That is , raaiation from the hot wingsurface would balance peak frictional heating for skin temperatures of22000 F. For global-range gliders or delta-wing reentry vehic les, whichrequired maximum L/D' s in the range of only 1 to 2, leading edge radii ofthe order of 6 inches are permissible , and our analysis revealed espe-cially interesting results for these winged vehicles, i f they weredesigned to operate at high angles of attack approaching maximum wingl i f t in the peak-heating region of their g lid er o r reentry trajectories:For a peak skin temperature of only 20000 F no coolant whatever wasrequired. To achieve - t result a flat-bottom wing large enough for a,wing loading of the o ~ a e r of 20 lb per sq. f t . was required, operating

.-- ,near i ts hypersonic maximum l i f t coefficient of 1, at an angle of attackof about 45 degrees. This high-lift operation of course produced a high-altitude reentry trajectory - near the upper l imit of the cor rido r forpractical vehicles. Thus i t was possible later on, in the Dyna-Soarproject, to design the metallic DS-l vehicle with zero skin coolant. Andin the current winged Space Shuttles, which use advanced ceramic t i lescapable of sur face temperatures well in excess of 20000 F, (Ref. 18), thesame result is enjoyed with considerable relaxation of the wing loadingand other limiting design variables.

After this study no further consideration was given to internally-cooled g l i d ~ or winged reentry vehicles. The cumbersome and impracticalvehicles advocated in the "NACA Views l t were now obsolete and convenientlyforgotten.

I t should be recorded here that Glen Goodwin of Ames carried out aparametric analysis f glider cooling generally similar to ours, at aboutthe same time. Neit: ,er of us had seen the other 's study until we met to


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27discuss possible papers for the forthcoming 1958 High-Speed AerodynamicsConference. Goodwin proposed to give a summary paper but Langley arguedthat a detailed discuss ion of cooling was now unnecessary since the realmessage of these studies was that cooling could be avoided for both long-range gliders and reentry vehicles. This all-important result could betreated in the papers dealing with the individual vehicle concepts. Thus tthe Goodwin cooling paper was dropped from the agenda t and to the best ofmy recollection the Ames study was never published.

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28Early Manned Satellite Vehicle Concepts

Pressures to develop technology for a manned satell i te continued togrow and soon enveloped the mili tary services and their contractors.USAF initiated studies of "Manned Ballistic Rockets" in 1956j init ial lysub-orbital missions were considered fo r comparison with the boost-glidesystem bu t now (in the fal l of 1957) the focus was shifted to theminimal orbital mission referred to as "Man-in-Space-Soonest" (MISS).At least 11 contractors s tudi ed as many concepts and we soon became awareof their problems by visits and calls from the company people involved.

In November of 195Z-I made a f i rs t crude attempt to apply the resultsIof our coolant study to the design of a minimal one-man satell i te vehicle(Fig. 7). I selected only enough LID (about 3 / ~ ) to insure low decelera-tion and nominal la teral maneuverability. The vehicle would be landed byparachute. I ts wing loading, quasi-flat bot tom, and other features werechosen to permit metal skin temperatures no higher than 20000 F at thepeak heating point in i ts reentry, with zero internal coolant. John

.-Stack took this sketch to a meeting of the High-Speed Aerodynamics Com-mittee in November 1957. However, there is no evidence that he ever usedi t , and if reentry vehicles were discussed at wll i t would probably havebeen in unrecorded pre-meeting discussions with the other NACA members.

By the time Stack had returned from his Committee meeting I had foundthat for only a small increase in weight a far more attractive wingedreentry vehicle could be achieved, one capable of much greater rangecontrol and conventional glide landing while s t i l l retaining the advantageof zero coolant. The general specificat ions for such a vehicle werestated and illustrated specifically in my paper on winged reentry vehicles


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29given the following spring at the last NACA High Speed Conference, whichwill be covered la ter in these notes.

The early concepts developed by th e I I "MISS" contractors emergedin late January 1958 at an Air Force briefing which I was invited toattend. Figure 8, summarizing the concepts, is taken from my report ofthe meeting upon returning to Langley. Seven of the concepts wereballis t ic, with McDonnell showing a shape similar to what eventually be-came Mercury, obviously benefitting from their contacts with Faget. Thefour winged vehicles with L/O 's ranging upward to 6, showed the generallack of understanding i n ~ h e Industry at that time of how the wingedhypersonic glider could be great ly s impli fied and i ts mode of operationaltered to f a c i l i t a t ~ reentry. The Ames concept of a blunt l i f t inghalf-cone with L/O of about 1/2 at this t ime was in i ts earliest forma-tive stage - too early to have been utilized by th e MISS contractorseven i f they had been interested in i t .

Historians and lay readers should not be confused by the multiplicityof aircraft-like vehicle configurations appearing in the semi-technical

l i terature of th e '55 to '65 period under the general subject heading of"Space Transportation System Studies." Vehicles carrying hundreds ofpassengers and cargo to and from orbit were often depicted in detail byimaginative ar t i s ts . The main interest of nearly a l l of these studiescentered on the propulsion system and the "cost-per-pound-in-orbit" ofoperating the system. The enormous p r o b l ~ m s o f reent ry were no t treatedexcept for arbitrary and usually meaningless weight allowances for myth-ical "guidance and control" systems or equall y non-exis tent "heat pro-tection systems." Obviously none of these ~ t u d i e s contributed anythingtowards solut ion o f the reentry problem.


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30Of g r ea t er s i gn i fi ca n ce were a number o f unconventional reen try

schemes that appeared in th e years following Sputnik. Most of theseattempted to a lle via te th e reentry heating problem by using extremelylow wingloadings o r, in th e case o f b a l l i s t i c designs, very low discloadings, i .e . , very la rg e s ur fa ce a re as which permitted higher a t t i t u d ereentry t r a j e c t o r i e s . These schemes included infla ta ble s, erectablek i t e - l i k e arrangements, and a variety of o th er variable-geometry inven-t i ons. More often than no t the heating problems were t reat ed inade-quately. Some of th e more i nt erest i ng schemes are depicted and assessedin Ref. 19 and 20. None,ever materialized i n any act ual application.I,.


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31John Stack's Attitude Towards Space Projects

I t should be noted parenthetically that Stack was not really muchi nt eres ted in the reentry problem or in space flight in general. TheX-l5 promotion was the only space-related project that he clearly sup-ported in the '50's, to the best of my recollection, bu t even so withonly a semblance of t he notor ious promotional fire he could generate i fhe was really interested. His main enthusiasms in the '50' s were th eSST and ~ d v a n c e d military aircraft . To a degree he seemed to havedeveloped a hostile, adversary attitude towards Space, perhaps becausei t threatened to drain resources that otherwise might belong in aero-1/nautics. When the A ~ o l l o project was established he sneeringly toldme, ItI don't bUy this ' to the Moon by noon' stuff ." Noting the enormoussizes of the rocke t boosters ("like the Washington Monument"), he sidedwith the abortive early attempts to find viable air-breathing aircraft-like launch systems. After l eaving NASA and going to Republic he con-tinued to favor advanced aircraft as opposed to Space projects. All ofthe developments discussed in the present document, i .e . X-l5, BIWARDS,Round I I I , Dyna-Soar, the Langley reentry concepts, etc. took place withl i t t le or no technical or managerial inputs from Stack. Most of them wereunder the aegis of H. A. Soule - who wore a NACA HQ hat l abel ed "ResearchAirplane Projects Leader." However, this fact would never have deterredStack from all-out participation i f he had been interested.

For one with his previous record in the forefront of high-speedaircraft developments Stack's decision to remain in the aeronautical campand glare at the dramatic space developments as they were accomplished byothers is one of the most curious personal enigmas in NACA history.
http://crgis.ndc.nasa.gov/crgis/images/5/5c/StackBio.pdfhttp://crgis.ndc.nasa.gov/crgis/images/5/5c/StackBio.pdfhttp://crgis.ndc.nasa.gov/crgis/images/5/5c/StackBio.pdf


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32The Last NACA Conference on High-Speed

Aerodynamics, March 18-20, 1958Since the mid-forties NACA's periodic conferences on High Speed

Aerodynamics had successfully high-lighted the agency's most advancedresearch in aeronautics for Industry-wide audiences of as many as 500specialists. This final meeting under the NACA banner focused principallyon manned satell i tes; vehicle concepts and supporting technology. Anyhistorian who doubts NACA's viri l i ty in i ts last days or i ts ability torespond quickly, fulfill ing both advisory and research functions in atruly outstanding" way, should read the Conference document (Ref. 21) and-/interview a sampling of those who attended.

As originally planned at a meeting in NACA headquarters onDecember 16, 1957 the agenda did not include any papers dealing explicitlywith reentry vehicle concepts. Supporting technology. was included inseveral papers to be given on the second day. Some of Faget 's work withthe ball ist ic concept was mentioned, but i t was buried in a general dis-

cussion of operational problems. Following traditional NACA policy to thee ff ec t t ha t the development of aircraft designs was properly the provinceof Industry, nothing else was to be said about vehicle concepts.

The week following this BQ meeting one of the contractors respondingto USAF's ''Man-in-Space Soonest" study visited me to d iscuss his candidatereentry vehicle, an LID "'6 winged gl ider, forcefully impressing on me theneed for NACA to d iscus s winged reentry vehicle concepts at the forth-coming conference . Right after the holidays I called on Bob Gilruth, whowas coordinating the Langley papers, with a proposal to prepare such apaper. Be was in ful l agreement, and he pointed out that Faget's study also


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33deserved to be a separate paper. Not to be outdone, Ames then proposedto add a paper covering their L I D ~ 1 / 2 half-cone approach. These threeconceptual vehicle papers were programmed for the f i rs t session, imme-diately following Chapman's analytical study of reentry mechanics andheating.

My paper on the winged concept opened with a brief discuss ion ofthe general unsui tabil ity of high-LID gliders as reentry vehicles. LID'sin the range 1 to 2 were shown to be adequate for both g-alleviation andrange control. A general comparison of the relative heating of l ift ingand non-lifting reentry _ ~ p h a s i z e d the large reduction in both heating

IIrates and heating loads made possible by low LID, high-lift opera tion ofwinged vehicles. Included in the comparisons was the case of a con-ventionally-shaped fighter-type aircraf t reentering at 90-degrees angleof attack, i .e . as a non-lifting or ball ist ic v e ~ i c l e which converted toconventional flight for low-speed range and landing. This mode ofoperation, feasible in principle, did no t appeal to me because i t re-

tained most of the crudities of ball ist ic vehicles and sacrificed theadvantages of l i f t , except for approach and landing. Nevertheless Iincluded this concept (top of Fig. 9) for th e sake of completeness andout of deference to my friends in the Flight Research Division, some of

-whom were interested in i t . The paper concluded with the small con-figuration (bottom of Fig. 9) which embodied a l l of th e features we nowadvocated on the basis of our HIWARDS work and our coolant study: LIDin the range 1 to 2 for range control, hypersonic maneuvering, andinherent capability for conventional glide-landing; radiative solutionof the heating problem by operation near maximum wing l i f t ; use oflarge leading edge radii, flat-bottom wing, and fuselage located in th e


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protected lee sid e of the wing. Roger A. Anderson of th e StructuresDivision p ro vi de d t he s t r u c t u r a l design and weight estimates fo r t h i sminimal winged s a t e l l i t e , and E. S. Love assi st ed with th e aerodynamiclay o u t. The estimated a ll-u p weight was ;060 lb . , only about 1000 lb .more than th e minimal b a l l i s t i c capsule.

T his pa per created more industry reaction - almost a l l of i tfavorable - than any ot her I had w ritten . I f we had had a more energeticbooster than Atlas a t th a t time th e f i rs t U.S. manned s a t e l l i t e might wellhave been a landable winged vehicle.

,r. g


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35Project Dyna-Soar

The source evaluation and selection activities for the Dyna-soarresearch ~ ~ test vehicle (DS-l) afforded major opportunities in thesp ring of 1958 for NACA to influence the program and the vehicle con-cept. In broad terms th e declared inte nt of D5-1 was "to research thecharacteristics and problems of flight in the boost-glide flight regimeup to and including orbital flight." We in NACA thought of DS-l as afollow-on X-15, covering the speed range from Mach 7 to near-orbitalspeed. I had been appointed NACA Co-chairman, Scientific and TechnicalArea, serving with my o p ~ o s i t e number, USAF's W. E. Lamar, who also

II..headed the entire evaluation exercise. I found Lamar to be a shrewd,

Itable, effective manager. We soon developed an excellent rapport andexercised a controlling influence on the outcome of the evaluation.

Our background experiences with X-15, BYWARDS, Round III , and thewinged reentry vehicle study had established in my mind very cleardesirable guidelines for the D5-l vehicle which were now quite different

from the official ''NACA Views" of Ref. 12. In the NACA/USAF meeting ofthe source evaluation groups in late March at Wright-Patterson AFB I putforward the following ideas relating to D5-l:

1) Instead of the large high-LID, structurally complex, water-cooled glider recommended in the NACA HYWARDS study of 1957,D5-l should be a small L/D""2, relatively simple, radiation-cooled vehicle. Such a small simple vehicle could be procuredmuch more quickly , with le ss ris k, and would greatly ease thebooster problem.

2) A DS-l vehicle in the L/DN2 category would serve equally as anadvanced prototype for the semi-global-to-global-range,
http://crgis.ndc.nasa.gov/historic/1146http://crgis.ndc.nasa.gov/historic/1146


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boost-glide system (for which low L/D is actually preferable)and fo r the future maneuverable, landable, space reentrysystem (for which L/D- 2 is also the likely category).Research-wise this class of vehicle would be more valuablethan the high-L/D glider which was applicable only to glideranges of the order of l/4-global.

There were two problems with my new views: they had no officialstatus in NACA as yet, and they were at variance to the boost-glide workstatement to which the contractors would be responding in the presentsource selection exerciae. Nevertheless these views were discussed with1/great interest by ~ of the USAF and NACA members of the evaluation

groups and they apparently had an effect on the outcome of the evaluation.Of the nine 'contractors bidding on DB-I only one offered a small

vehicle in the L/D - 2 category. Boeing's design, however, was chargedwith several flaws (top of Fig. 10): their use of features whichaggravated heating and their too-optimistic heating estimates, among

others. Martin and Bell had teamed to submit a higher-L/D mid-wing design.Their proposal, overall, was rated close to Boeing's primarily because ofBell 's obvious depth of experience in hot structures, acquired in theirprevious boost-glide studies. USAF decided on June 16, 1958 to acceptthe recommendations of the Source Selection Board to continue both Boeingand Martin/Bell in a Phase I competition for the ensuing 9 months duringwhich revised and improved designs would be advanced to the mock-up stage.Both teams were briefed on the new design features now recommended by theNACAjUSAF DB-I group.

Boeing's Phase I efforts produced an entirely new design incorporat-in g a ll of the government recommendations in a wholly satisfactory way


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37(Bottom sketch of Fig. 10). Their new LID 2 vehicle had a flat-bottomwing, nose t i l t for trim, toed-in tip fins, fuselage on the upper surfaceof the wing in the protected "hypersonic shadow" at reentry attitudes,large leading-edge radii , and radiation-cooled structure with no internalsurface coolant. Martin/Be11 developed a s t i l l lower-LID vehicle withsomewhat similar other features. Figure 11 is the free-hand chart usedduring the Phase I design evaluations in April 1959 to compare the glidecorridors and associated research aspects of the two vehicles - Boeinghaving the edge here w ith a broader meaningful corridor explorationpotential. In a l l o t h e ~ r e s p e c t s except propulsion Boeing was judged

IIthe more desirable system. Martin, however, was continued as the boosterudeveloper, primarily because of their involvement with the Titan.

At this stage DS-l seemed to be everything that NASA desired. This,we believed, was the research airplane that would extend the flight spectrumfrom the X-15's Mach 7 on up to orbital speed, and th e research data wouldbe equally applicable to boost-glide and sophisticated reentry systems

NASA top management had readily accepted th e drastic changes. in the con-figuration described above; however, they never formally repudiated thelarge high-LID water-cooled gliders advocated in th e NACA-Views (Ref. 12).

Several of Langley's research divisions became heavily committed tosupporting projects bearing on the prime development problems of Dyna-Soar. The contractor negotiated directly with appropriate Langley staffmembers for wind tunnel and other testing and then cleared the p lans withthe Dyna-Soar project office at Wright/Paterson AFB. MY long-time col-league, P. F. Korycinski, had been assigned to the project off ice asNASA's official representative, and he was e ff ec tiv e in expediting the


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38support work. In the next three years some 3900 hours of wind tunneltesting (NASA-wide) were accomplished throughout the broad speed rangeof DS-l. Unnumbered additional hours were devoted to testing in special-ized facil i t ies related to problems in hot structures, landing system,dynamic leads, panel flutter, noise, heat transfer, communications throughthe plasma sheath during reentry and others. Analytical and theoreticalwork essential to these experimental projects absorbed added prime man-power. Much of the fruit of these programs was, of course, of specificuse primarily to Dyna-Soar; but a s ignif icant par t proved of gene ralfundamental value and w reported in general research papers. Reference.....20 contains a substant"ial sampling of the results in hand by April 1960,two years after the in i t ia l source selection.

I t is desirable at this point to identify the principal Langleyindividuals who ' contributed to Dyna-Soar. Starting at the top, F. L.Thompson provided relaxed, shrewd general management which allowed greatfreedom at the divisional and project levels. His assistant, B. A. Soule,

. .who also served as Research Airplane Proj cts Leader for NASA Headquarters,handled effectively the day-to-day top management of Dyna-Soar. WhenStack moved up to his Washington off ice pos it ion in 1959, he was succeededby L. K. Loftin, Jr . as an assistant to Thompson. Unlike Stack, Loftinshowed much interest in Dyna-Soar and he participated in the front-officeactivities along with Thompson and Soule. As Chief of the Aerophysicsresearch division where a major part of the Langley support work forDS-l was centered, I was naturally involved in a l l phases of the program.I was often also called upon to be the technical spokesman for the entireLangley program, although no formal annointing for this function was evermade.


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39Following i s a l i s t of th e pri nci pal Langley contributors to winged

reentry vehicle technology in th e '58-'63 period. These a re i nd iv id ua lsshown by t h e i r publications or other evidence to have made noteworthypersonal t e ch n ic a l c o nt r i bu t i on s . I am aware of th e hazards in settin gup such a l i s t . If there are any omissions, in spite of th e care I havetaken to include everyone, I offer my apologies.

Pri nci pal Langley Contributors to Winged ReentryVehicle Technology, 1958-'63

HYpersonic aerodynamics. configuration. s t a b i l i t y and controlM. H. Bertram -rM. Cooper 1/--D. E. Fetterma.ziA. Henderson, J r .E. S. Love'c. H. McLellanM. Moul

J . A. Penlandw. H. PhillipsR. w. RaineyL. Ste rnfie ld

Heat t ransferI . E. 'BeckwithJ . C. Dunavantw. V. F e l l e rP. F. Korycinski


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40Aeroelasticity, dynamic loads, panel flutter, launch vehicle dynamics,landing system dynamics, noise

S. A. BattersonL. D. GuyJ . c. HouboltH. H. Hubbardu. T. JoynerH. G. MorganA. G. RaineyH. L. Runyan -I,.Low-speed flight characteristicsD. E. HewesJ . R. PaulsonR. E. Shanks

Trajectory analysisF. C. Grant

Reentry communications (blackout problem)J . BurleckM. C. EllisW. L. GranthamP. W. HuberR. A. BordD. E. McIver, Jr .T. E. Sims


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41Hot structures, materials

M. S. AndersonR. A. Andersonw. A. Brooks, Jr.L. R. JacksonE. E. MathauserR. A. PrideR. T. SwannDoubts about Dyna-Soar f i rs t began to surface during the summer of-59. To many Air Forc# R&D specialists the growing prospects of military

operations in space yere more exciting than boost-glide operations in theatmosphere. I learned first hand from my USAF contacts of another dis-turbing point of view - said to be shared by General Schriever - to thee ff ec t th at NASA's Project Mercury was believed likely to fail , makingi t necessary for USAF to put the f i rs t American in orbit . This reasoningwas based partly on the Vanguard fiasco, and partly on Schrievew's allegedbelief that NASA's .use of ex-researchers to manage Mercury was a mistake.Researchers supposedly were inept at management and operations. USAF, onthe other hand, would succeed because of their BMD know-how and experience.In the event of such a USAF take over, Dyna-Soar would be the candidatevehicle for the f i rs t manned orbital flight, and as such should i t be asophisticated winged system or a simpler semi-ballistic system that wouldbe quicker to develop and perhaps more reliable?

J . Charyk, Assistant Secretary, had become a believer in USAF'sfuture in space and he was influential in instituting the so-called"Phase Alpha" study in November 1959 at about the same time that formal


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42USAF approval for DS-l was obtained. Phase Alpha asked the DS team ineffect to "take another broad look and see i f you really want a wingedvehicle or whether you can do better with a ball ist ic or slightly-liftingtype ." The intent here, was clear: if another type of system could beshown to have important advantages DS would be re-directed and every-thing that bad been done to support winged system technology would beset aside. Probably there would be no manned explorations of the glidecorridor in the Mach 7 to orbital speed range.

USAF space advocates had found an important ally within NASA. Sincethe Round III meeting w}ere he bad proposed to work exclusively on/Islightly-lifting c a p ~ . u l e - t y p e reentry vehicles A. J . Eggers, Jr . , bad

. "been cultivating a growing personal distaste for winged reentry vehicles.As he saw i t the 'problem of placing sizable payloads in space was aggra-vated by having to cope w i ~ h the added weight of wings - especially withthe marginal boosters then available. What about la teral range, byper-sonic maneuvering, conventional landing, etc.? His answer was Itlf USAF

has a real reason for boost-glide or maneuvering reentry and conventionallanding - OK. ~ i f what they really want is the maximum possiblepayload in space then they should use a simple light-weight semi-ballisticreentry system." He spread this doctrine very effectively and i t doubt-less contributed to USAF's decision to proceed with "Phase Alpha." As amember of ~ h Aero and Space Vehicles Panel of the SAB, Eggers had manyopportunities to hammer away against winged reentry configurations.


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43SAB Review of Dyna-Soar and "Phase Alpha"

The five members of the Aero and Space Vehicles Panel and11 consultants, mostly from Industry, met at Ames Research Center for3 days, December 2-4, 1959, for this review. They listened to presen-tations by the DS project office and by NASA. Those of us involved inthe project believed that a major threat to our L I D ~ 2 winged systemexisted, and we anticipated that Eggers might attempt to strike amortal blow.

Realizing that his L I D ~ 1 / 2 blunt half-cone reentry vehiclecandidate waS not l i k e l ~ - t o find a sponsor now that Faget's ballistic/.'shape had been s e l e c ~ e d for Mercury, Eggers had recently proposed a

"ore slender half cone the "M-2" which had an LID of about 1, and whichmight conceivably be landable as a glider (Ref. 23). I ts great sellingpoint in his mind of course was that i t was "wingless", a "lifting body" -even though i ts planform was about the same as the DS, as i t would haveto be i f there were any hope of achieving necessary low-speed handling

characteristics. In anticipation that we might hear the propaganda forM-2, I built my presentation around Fig. 12 which compared two half-conebodies (LID -1 .5) with a DS-type wing-body of the same planform and aspectratio (LID ""2). We lalew from low-speed testing that the wing-body shapecould develop an LID as great as 5 for low-speed approach, while thehalf cones would certainly have lower (then unknown) low-speed per-formance, perhaps about L/DIV3. Thus the main virtue of the half-cones,bought at sacrifices in LID, would be increased body volume - a uselessfeature in Dyna-Soar which had more than enough fuselage volume for i tsanticipated payloads.


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44I closed my presentation with a review of the impressive benefits

achievable by a winged vehicle in the L/D - 2 range as covered in my1958 conference paper, reminding the SAB that the sophisticated per-formance of these winged vehicles involved only a nominal weight incre-ment of the order of 1/3 over comparable ball ist ic systems. This modestincrement would certainly be tolerable as booster capacity advancedbeyond the Atlas which was the limiting factor in selecting the smallballistic capsule for Mercury.

We were gratified when a large majority of the consultants agreedwith the choice of L/Drv2, as the proper goal for DS, and this was under--scored in the Panel's Teport (Ref. 24) which said ' ~ / D of the order of 2is considered correct." In the executive session held on Saturday,December 5, Chairman C. D. Perkins stated at the outset that Dyna-Soarat this point waS "easily killable," that USAF wanted Dyna-Soar, andthat, "BAa should help USAF." Perhaps because of this admonition, Eggerswas quieter than usual and did not attempt a hard-sell of the Mool or M-2

at this meeting.The Panel was concerned about the adeq,uacy of advanced technology

in s everal areas of DS-l design and they suggested that Phase Alpha,rather than being a "do better" exercise should concentrate on programplanning to raise the confidence level. This suggestion was disregardedin the ensuing Phase Alpha study (Ref. 20) which turned out to be largelya comparison of alternate vehicle systems. However, the ground ruleslaid down by the Project Office were such that only a winged L/DN2system could possibly meet a l l the r e q u i r e m e n t s ~ and thus Phase Alpha*as pretty much wasted effort, a gesture to upper management. When the*It did produce some valuable comparative weight analyses.See page 53.


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It . if the overr id ing requirement were to get large payloads

class might w e l L b ~ - i l r e f e r r e d th e Panel did want to beth e (LjD 1/4 to 1/2) vehiclen orbit as soon a s pos sibl e

1/sure that the Air"Force was aware of this alternate "

prepared for the forthcoming USAF/NASA Conference on Lifting MannedHypervelocity and Reentry Vehic les (Ref. 20). The Panel was generally

inserted the following s ta tement at Eggers' instigation:

Panel met again on March 28-30, 1960 they were provided Nith a massivereview of supporting technology, much of the key mater ia l tha t had been

satisfied regarding the adequacy of technology to support DS-l. Significantly, however, at the end of their report (of April 15, 1960) they

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46Rocket-Model Flight Tests Supporting DS-l

After the SAB meeting of December, 1959 I was convinced of thepolitical desirability i f not of the t e c h n ~ c a l necessity fo r a high-priority attempt to obtain f lig ht te sts data to validate questionableDS wind tunnel results i n cer ta in cri t ical heating and aerodynamic areas.The attempts within NASA to extend the Wallops Island rocket techniqueto Mach 15 or higher had proved disappointing. From the standpoint ofsetting new PARD speed records these flights were a success (See NASARef. Publ 1028), but a careful review of results presented in NACA!NASAconferences shows the .. technical contributions to be disappointing; the-Iflights were always SUbject to rapidly changing velocity and altitudeconditions, l i t t le or' no structural data were obtained, and the modelswere not recovered.

I had recently learned from colleagues on the NASA Missile andSpacecraft Aerodynamics Committee of the possibility of attaching"hitch-hike" or "piggy_back" tests to recoverable USAF/BMD RVX-2 nose-

cones. (The RVX was the f i rs t a b l a t i o n - p ~ o t e c t e d IBM nose cone r ~ c o v e r e dafter a long-range flight over the Atlantic in May, 1958). Scheduledfuture flights would be Atlas-boosted to reentry speeds of about Mach 22 -id ea l fo r the cri t ical heating and aerodynamic tests that we needed.To explore this possibility I travelled to BMD and STL headquarters inLos Angeles on February 19, 1960. George Solomon and his cohorts thoughtour type of add-on aerodynamic test would be feasible and urged me toproceed. Accordingly, we organized an ad hoc design group underC. H. McLellan which came up with the rather unlikely constellation oftest models arrayed about the RVX-2 shown in Fig. 13. About half of the


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48The Decline and Termination of Dyna-Soar

NASA's influential involvement with Dyna-Soar came to an abrupt endin 1961. I t was probably no coincidence that this decline started soonafter General Schriever's accession as head of ARDC. The charts used bySoule t Becker t Koryc inski t and otheJ:S of NASA's Dyna-Soar Team to describethis situation to Administrator Webb on January ,4, 1962 are shown inFigs. 15, 16, and 17. W. E. Lamar had rather apologetically informed usduring the fal l of 1961 of the drastic red irec tion tha t was to be imple-mented in December 1961, without any participation or consultation withNASA. The series of .sub-orbital manned flights down the Atlantic missi le-.range at progressively increasing speeds, which constituted the "research

"irplane"-type of exploration of the boost-glide and the reent ry cor-ridor of prime ~ t e r e s t to NASA, was entirely eliminated. Now in ~ h interests of economy, and perhaps following the lead of Project Mercury,only two unmanned sub-orbital flights would be made, from Cape Canaveral toEdwards, p ri or to s im ila r sub-o rb ita l manned flights, and orbital flights.

. .USAF also cancelled their support for our RVX-2, a relatively minorbut for us a particularly unpleasant act. (We subsequently made arather half-hearted and unsuccessful attempt to ~ o n t i n u e RVX-2 underNASA funding). As far as our NASA DS team was concerned Dyna-Soar as aresearch airplane was dead.

During the remaining two years of Dyna-Soar I s existence NASA con-t inued as a largely inactive nominal partner, completing the tests towhich we were committed. I t was now obvious that USAF was interestedin DS only as a prototype of an orbital system and not as a researchvehicle. Whatever R&D aspects might be involved could be treated in


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lesser unmanned programs like ASSET or START, according to theirphilosophy. As time went on i t also became increasingly apparent thatUSAF did not have a clear bel ievable vision of what t he ir o rb it al systemre;uirements really were, and thus doubts increased as to whether DS-lwas an appropriate development vehicle. The fact that DS was a wingedsystem was now cited as a l iabil i ty - due l ~ g e l y to the effective wide-spread anti-wing propaganda of the Ames group. "Wings are for airplanes"they said.

A few months befo re the final denouement the DS-l Project Off ice,in desperation, called ojr i ts old partner for help. I spent a day inIIWashington in March, ~ ~ 6 3 with Calvin Hargis, Milton Ames, and several

"others making th e best case we could for sav ing the project. Much ofthe argument centered on the technology advances that would acrue. Andmuch of i t had a hollow ring. We a ll sensed that by now, the case wasprobably hopeless.

Driving back to Newport News that evening on icy roads an oncomingcar skidded into my lane, wiping out my small convertible, bu t leaving

me intact. I bad suffered much in my travels for Dyna-Soar. Previously,an eng ine fire on take-off over San Francisco, a three-hour hold overWashington followed by a hair-raising late night landing in a blizzard,and now this!

Some valuable lessons were learned on Dyna-Soar. By the time oftermination in December 1963 one cou ld see that step-wise ascent throughthe glide or reentry corridors in the manner of the earlier mannedresearch airplanes was no t rea lly essential to reentry vehicle technologyadvancement. For one thing the ranges became too long to be practical


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50as the speeds approached orbital. The great successes of ProjectMercury underscored other more appropriate development procedures, andat the same time provided an enormous increase in confidence level inground facil i t ies and in the viable technology achieved from intelligentcombination of theory and partial-simulation data from a variety offaci l i t ies.

I t might be argued that Dyna-Soar should have been terminated in thefal l of 1961 when i t was re-oriented losing i ts research-airplane func-tiona. Certainly, this would have re su lted in major cost savings.(Troubled projects are seldom terminated as promptly as they should be..."rom purely cost considerations; Ref. 25 gives an example). However, ifthat had been done many of the engineering developments of Dyna-Soarwould have been stopped in such an early stage as to be of l i t t le value.I t was the f i t t ing of successful detailed engineering solutions into thegeneral conceptual framework of a winged reentry vehic le tha t cons ti tu tedDyna-Soar's principal contribution. The NACA/NASA conceptual recommenda-

tions of 1958/59 were now tested, substantiated, and "fleshed out" in areal system.

Strong differences of opinion between Ames and Langley,. which wereoften debated with some heat, reached their peak in the Dyna-Soar pro-gram and continued in milder form in the landable lifting-body workdescribed in the next section. I t would be quite wrong for readers toassume, however, that there were any lasting personal animosities 10-volved here. On the contrary, this competitive situation generallyincreased mutual respect, stimulated thinking, and enhanced the qualityand pace of our R&D work.


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SlThe Lifting-Body Diversion on the Way

to the ShuttleThe solid advances in a l l facets of winged reentry vehicle technology

produced by Dyna-Soar seemed to have limited acceptance by the aerospacecommunity of the early sixties. Instead, the demise of Dyna-Soar wasinterpreted by some as a failure or repudiat ion of winged reentryvehicles. There was an obvious psychological reaction. Like the pro-verbial rats, many aerospace vehicle specialists flocked over into the"lifting body" camp in 1963.

A month before t ~ ~ e r m i n a t i o n of DS the AIAA had published my survey-article on Entry Vehicfes in which I had reviewed the cases for both-winged and wingless 1ehicles (Ref. 26). I pointed to the relatively un-developed state of technology of the l i f t ing bodies, particularly in theareas of low-speed aerodynamics, handling qualities, heat protection, andrelated weights. Although I personally was s t i l l strongly biased towardsthe winged approach, i t seemed obvious that we now must develop and assess

the l ift ing bodies in serious detail in order to provide a firm basis forchoice.

A 1963 chart which I used in several "reentry" talks is reproducedin Fig. 18. I t suggests that the lifting-body concept is a hybridderiving features from both aircraft and missile developments. Figure19, with a 1967 perspective (Ref. 27), enlarges on these relationshipswith more detail, and wit4 the addition of a time scale. ( I t may benoticed that a l ift ing body of extreme slenderness and hypersonic LID of"3" is mentioned for completeness in Ref. 27 and Fig. 19 to indicate theupper possible l imits. As shown on Fig. 19 such shapes would have to


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utilize switch-blade wings or other special devices for low-speed flightand landing.)

E. S. Love, R. W. Rainey, B. Z. Henry, and others in Langley'shypersonic and configuration groups undertook the development of a flat-bottom, delta planform ligting body, starting in late '62. They soughta vehicle which would offer improvements over th e Ames M-2, the mosthighly-developed concept up to that time. In particular they were aimingfor a large fraction of usable volume, natural self-trimming at high-l i f t altitudes, and improved low-speed handling characteristics. TheLangley BL-10 (horiz0!ltal.:lander, design 10) was the result some 18

.,

months l at er a ft er e x t ~ n s i v e analytical and wind tunnel work. A largescale piloted versiod s ta rte d f lig hts a t Edwards in December of 1966.Two versions of the Ames M-2 J the M2-Fl and M2-F2, and the Air Force'sSV-5P (X-24A) were also flown successfully in th e Edw.ards program. Thusi t was apparent beyond any further doubts that with careful design,sufficiently high aspect ratio, and with appropriate stabili ty augmenta-

tion and ar t i f ic ia l damping, l i f t ing bodies in the hypersonic L I D ~ l to1.5 category could be made capable of piloted glide landings.

However, i t was also clear from these programs that the low-speedLID of the l if t ing bodies was always significantly less than that ofwinged vehicles similar planform and aspect ratio. This means that theirdescent rates are higher, and other factors being equal, their approachand landing characteristics are more crit ical with smaller margins forerror than for th e winged designs. A principal advertised advantage ofthe lifting body, ~ e ~ e d volume per pound of weight, was found partlyillusory, because balance, packaging, and other requirements made a


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(. 53s izab le par t of the volume unusable, even in the HL-10. Furthermore thehigh volume cost something in added heat protection weight. That is ,( i f any)the net weight savingAdue to elimination of the wings was less than theweight of the sbed wings.

In contrast to the weight "savings" hoped for by\the early aerodYriamicist promoters of wingless l i f t ing bodies.

i t had been known since the time of "PhaseDc'" (1960) that thebodies were always heavier than winged vehicles of the same. hypersonic LID. In "PhaseeX" an M-2b body of L/DI"! .J-was foundto weigh 9391 lb a t orbital injection, while a str ict lycomparable winged vehicle weighed only 8590lb. These carefulestimates were m a d e . ~ qualified specialists from four aerospacefirms. ('R e.f Z0) ,!'


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The Winged Space ShuttleWith the successful flights of the small piloted lifting-body

vehicles at Edwards, and with winged reentry systems having been dormantsince 1963, i t was naturally assumed by the lifting-body promoters thatthe Space Shuttle would employ one of their products. I t came as ashock to them when the series of system studies starting in 1969 (Ref.28) revealed that the Shuttle would have to be a winged configurationbasically similar to Dyna-Soar but some 20 times heavier. The enormouscargo bay demanded for the anticipated payloads, 60 feet long and 15 feetin diameter, was p r a c ~ i c ~ l y impossible to f i t into any reasonably pro-portioned l if t ing b o d y ~ The higher hypersonic L/D of the winged designwas needed for cross range. The wing also provides a higher reentrytrajectory, shielding of the fuselage, better handling qualities, andextra margins fo r sa fe ty in approach and landing. The prospect of the"dead-stick" landing from space of this 180,000 lb. behemouth was farless fearsome and less risky with the extra aerodynamics of the wing

Our basic 1958 postulate used in promoting the many advantages ofwinged reentry - that the modest weight increment of the wings wouldcease to be a cr i t ical consideration after booster technology advancedbeyond i ts embrionic stage - was now amply confirmed.

In addition to enormous advances in booster technology, the Shuttleenjoys a thermal protection system far ~ o r e effective and more durablethan the metallic radiative structure of Dyna-Soar. In essence i tslightweight ceramic b1.ocks are the "unobtanium" that we could on1.y dreamof in the 'SO's and early '60's. In other sub-systems, however, theDyna-Soar experience provided a technology base on which Shuttle designers


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55could build . V irtua lly a ll of the reentry configurational andoperational principles developed by NACA/NASA in the late '50's andapplied in Dyna-Soar are followed in the Shuttle.

Tom Wolfe has discussed the winged Shuttle and i ts relationships to .the previous research aircraft and space capsules from the point of viewand emotional r eact ions of the Edwards airplane test pilots (Ref. 29).Their personal satisfactions on the realization of this flyable wingedaircraft/spacecraft are shared by the researchers and engineers whovisualized the possibilities and developed much of the underlying tech-nology some 20 years befo re the f i rs t flight of the Shuttle

.. ,-II,.....


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56References

1 . PABD proposal document, "Hypersonic Research" t ransmi tted to Langleymanagement June 5, 1953.2. Brown, C. E., et al, A Study of the Problems Relating to High-Speed,High-Altitude Flight, Langley Memo, June 25, 1953.3. Becker, J. V., The X-15 Program in Retrospect.Raumfahrtfors chung,March/April, 1969.4. Becker, J . V.ground. The X-15 Program. Part 1: Origins and Research BackAstronautics &Aeronautics, Feb. 1964.5. "NACA Views Concerning a New Research Airplane." NACA, Washington,Aug. 23, 1954.6. -Eggers, A.

Documents

Development of Winged Reentry Vehicles 1952- 1963 Becker1983