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Boeing B-52A~H Stratofortress_Profile Publications 245

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Profile Publications 245
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  BoeingB-52AIH SI atofoi 'LJi~=S Iby Peter 1M. 80 e Irs ãT____ ~  'WhiletheoriginalAir Force desig-nation of B...52 - , remained C0I1st81n t, the different designswhich were evaluated by Boeingmustberegarded as [entirelydifferentair-craft. In the event, the design study ultima..tely selected nlay nowbe 100 ked \1 pon.asan excellentexampleof a. basic design capableof major modificationseveral times after delivery, Indeed, 'modifications plannedtoextend the life of the airframeand '00 adapt the'bomber'tomeetchanging operational requirements, Th~'p1.·()totYjNt B'ot-iJ'l!! XB-!2JU~A.P serJal number 49:'~230). On .01'1: ea:dytes.'f,fi~glu act:otr~p(lm~~ by aNo.rth A,I'Ue1'I~can F~8(i Sal;r,g ~'Ch,~'iJ~R aN'€'I·'·, TJj_(! deviceetthe top of the iJert lcalfi~1 IS part o/tne test equTpmeru. (Photo: Boeing) S f trato ortress oeing B-52AI by' [Peter M~ Bowers THEEIGHT-ENGINE, s.wep1t-wmg .BoeUtg~52Strate.. fortress,('tbegiven.po-pularname ls rarely used) has. been. theprincipallong... ange healYjetbomber ofStrate.lie Air Command, ,(SAC; formed1946); United. StatesAirFeree,since it became operationalin195:Si 11te B-52·:is a ,dl~S:tiDglliiSbed examp[leof active ~o:Dgel~ty ~'-.lIt 20 years after iris .first :fli:gbt, the Su.pe:dortress bas. I iii. i !..ã i seen bea.vily '€Dga ged moperatioasover VIet Nsm, This :*a.~ be ·r·egar~~ed,ã.as tile half-way m;,,~r~, fOf ~~_a~. a~e_ ~n. hand to .Mapt the B-5·:z, to. ansv. r missile wea,o.n system L'=.-..Ill...wl! :' k th'· 80'.~ L.....·b,-~'( uI 'ft'JLU I 0n OOwiu, .oop. !IS-~'.. emg OODl.-e:r operntttonl._ an_. competitIveuntil19·5!t INO·T B,I'G[GER. B-4'1 Becauseofits generalconfiguration, higher B,-desigua· , tion and tater dateof :in troduction in t.o service, theB-.52 hasoften anderroneously been regardedas a scaled-up developmentofthe revolutionary-Boeing 13,-47 Stratojet (AircraftProfileNo. 83)~TheB,~4 7, incidentally, was firstflown on December17)1'947; some 52months before '[be,'YB~52 proto type. tool to the airin April ill 952..Farfrombeing abigger B=47 the B-52 startedalong an en tirelv di fferentlineofdevelopment, Severalmajo r ;'1 ! configuration changes weremade in. the earlydesign stages 10 adapt the newlong-range heavy bpmbe.,f to the rapidly changing technology ofthe years immediately following World War Two,Anyexternal similaritywith theB~47 was arrived at by ev elutionandnot asa develop- Tuell t of tha t previou sly -esta blished design.. .AC121l DisplaymodeloftheBoeingMo.d.el462, pho Mgrap,hed j'fl AIJr if 1946. This wastheo.riginalstraight~w{ng.. turboprop concep: ofth« Bi~52. ului de.a,,.lysiwwS' i'iflMe.~ceofwar time /Joeing 8-29.(Photo; Boei ng) ,241  '-'11 Dr,'. 6.-ã., III_ . l~:·_ '::JJ:'_.: ':'.' [11:: .... (Photo:Boeing) S~~1r; stagersof de'jJ'(doping the JJ.j 2 S tt a; tofo r tress ORIU)I!N OF THE DIE,S,~GN Model46,2, 11 J une 1946,the 'Boeing Airplane Company was awarded.aUnitedStatesAirForcecontractfordesignstudies of at long-rangebea vy bOIU ber,TheAirF orce allocateditthe.ExperimentalBombardmentModel numberXB=52while, similarly, Boeing assignedModel 462 for the first basic designstudy.This. resulted. in a conven tionalstraight-wing design clearly showing 'theinfluenceof the wartimeBoeingB-29' Superfortress (Profile No 101)., Propeller-inrbines == six in all-wereselectedfortheModel462thepowerplantbeingthestillexperimental5-500shaft horsepower Wright XT.35-W· Typhoon . Themainplanespanned221 feet (wing area 3 .250 sq U3I'e feet)and the lengthwas ),61 feet 2 inches,Thegrossweightincreased with various studiesfrom.360,000 to 400-,000 pounds, Initially ,the Model 462was to carry a. 9-mancrew and upto 1. 0,540 pou ndsofbo nibs for a. rangeof 3,mOO nauticalmiles (3 ,570 statute miles) Top'speedwas.calculated as. 382 knots (440 milesper 'hour) ... at 35,,000 feet, A peculiarityofthedesign 'was that the: fourmain wheels of the nosewheel undercarriage each retracted separatelyin to' thefour inner enginenacelles. Thechiefinnovation of theModel462 \VaS~ however,thechoiceofturbopropengines..In tills. immediate post-warperiod,the piston enginewas.abouttogive way to thejet engine. I:ut thepure jet engine was, for the timebeing,ruledoutbecauseofitshighspecificfuel ·Th~W['mght.!?5~ w ·T.Y~~~QO:fi' ~i8S fllightB~~st~ lnthe noseofa Y e,g8J~'b'I)j:i1It B'ee~ 1If!; B~~ _70-11 o- VE (ser-laJl ,44~~158~. ) operated by theWrigMAeronauticelDivn. {:I~ the Cur tiss-Wl''1ghJt Corp,- H!lJI11JR 242 consumption. Turbopropswouldbridge the gap- it was l l'be h... dth re t oetween t·· ereel procatmg engine and.e gastur- bine f orbigger aircraftsuch as transports and long-rangebombers,Inthis case, intercontinental distances forbig bombers could. beviewedas.up to lO~OOOmiles.The maximum rang-e of the- ea. rlier 'U S'~Ac. Strateaic A·· 1·' -,.'-1,( .-:'......~. - .~...'.;., . I.. i!. !C~. 'b)..-~;. ,,1 Command Long Rifle''. thesix-engine Convair B·=36, wasinthis category, Deficiency in tbe desired. range wastheproblemof th. ·i l itial X··B:,'~5.2:!·M·····1 rdel4 6 2 desien dv T\..,'. ','1.. ..;. l, eInlla~. .'.- .·,,0_ o. _eslgn study... ![J.e so uuon materializedwhen the Air Force decided to' adopt. the hoseandtankerin -flight refuellingsystem developed mBritainbypioneer Sir AlanJ.Cobham's '00 mpany, Flight Refuelling,Ltd.Althoughthismanually-con- nected. hose-aad-grapnel was notsuited to the. speedsofnew-generationaircraft, it 'was usedona number of wartimeB-29sand post-war B-50As adapted tothe. techniq ue in[9 1 48.Theproblem of faster aircraftwasresolved whenBoeing developed.its OM} Flying Boom' aerialrefuellingsystem, Model464~17 ContinuingstudiesandrefmementoftheModel462 resultedin thenewdesignation of Model 464,. IntheModd.464-17.forexample,thenumberofengineshadbeencutfromsixtofourandrnainplanespanreduced from. 221 to 205 feet; while retain j ngthe gross 'weight 0. f 400~ 00'0 pounds.Effective range was ex trended by the '1lJ seoflargeexternaltanks. ,Modell 46,4-2,9' 'With in-flight refuellingtaking care.of therangeprob-[em, the Air.. orce Project Office for 'the XB,-52 became  interested in modifications tl1:?d would increase the bomber'sspeed, Boeinghad.beenstudying im'p~oved designs on its ownand respondedwitha new model ·the . - -- . - --,~ - - . . - . -,. - , - - . - - . ; .. -, . 464=29. This'featured! a. more sharply-tapered wing 'with 20degrees of sweepback 'while retaining the fourWrightXT35turboprops.ofthe 464= 17.A 'majorchangewas. the adoption of (ill centrelinelandinggear 1LUld er the fu selage superl1:ciaUy after 'the fashion ofthe B,-47 but withtheforward andaft unit s much closer together.On the Model464=.29~ the span remainedat205 feet land, 'the weightat 400~OOO pounds, butthecalculated maximumspeed increased to 3'9'5 knots (4.45 rn.p.h.). Mode~ 4!t14=35 Pro gressive studies and improvemen ts resu 1 ed in yet anothertur bopropmodel,the464-35 'Thisvariant bad co-axial propel]ers 'and the. wings pan reduced to.' 18,$ feet and length to 13llifeet 4- inches.But,mostimportant,theweigh t was reducedto 280,0 on P OlJ nds, With the SHJn.e four WrightXT35 turboprops and1~OO()quare feet less, of wing area, the Model 464=35 promised, atop speed of435knots(500m.p.h..) atanaltitudeof 41 ,OOe} feet, i\1'I d'I'4£:44- -' VII,o~,e.'.u-..~: I Thedevelopmentof the large, turboprop (XT35) engine wasnotadvanci ng as rapidly asexpected.'Wi th an, order f Of' twoexperimentalXB..5 28 pending, it beganto ].0.0 k as if no turboprops wouldbe available forthem.Turbo- jets, on the otherhand,wereimprovingrapid Jy BOlting engineerscarne to. theconclusionthat theXB~.s2 would-bebetterwith tur boj ets than tu rboprops., To this. end fo-iLl-.. dd th ModI4~435'. f, 1k., tney a aptec,,- e Mode -u,-., atr .rame to. use eight Westinghouse,XJ40..W&'] 2axial= flow turb ojetspaired,in , , fou r nacelles similartothe inboardpo ds of the B,=47. Still in the 280 OOO=p··.u nd 'wei ct,l. t bracket thespeed - --- '--,&1_ ,!y.,. I....., :'j',-,. AI to AA ilio '~i..'. ts (507 ,-'_. h.) ·t 4'7- 'OIif1i(~ c-- t m-creas1eu,o '¥' t- U' I'!..no.:' ,,>., m,p .u., a. ·.,.vv tee. TheBoeing engineerstook their Mode], 464-40 studiesto the, AirF orce ProjectOfficer only to findthat lite to o had reached the same conclusion and was. about to suggest aturbojet,XB~52 to them,Government procure- .. mentprocedures, however~ are of necessity slow andlag way behindthethoughtsofprojectoffic~rgand designers, InJuly1948~Boeing'wasawardeda contract forthe constructionoftwoexperimental B,~52s., Although these were tobe powered with tTl!Jrboprops, Boeing: was urged to continue 'theturbojetstud lies. Models464=46and ~,47 Tl....-.--,- ,~b.-, ,t~ . ,~,t... n,.-·,'.' I ...... - n~ , '*'o.'U II emontns,Later IUJ.e D oemgengineers ~O z l[.W 0 revisions of theModel464~40 tothe Air Forc€ at WrightField,Thesestu dies'were: essen ti~]lY. thesame airffamewith six J,;fO 'engines in a Model464-46 and thesamenumberof the 11~'gh'lY promising axial ~f), ow J S7~thenunderdevelopment by 'Pratt~ Whitney inthe -47, The ProjectOfficer wasimpressed.but also saw' a. potenriaJ forstill]more speed. Pointingoutthatthe 20 P sweep 0 f thewing WBlS theprincipalspeed -lirniting factor,he suggestedan increase of sweep,angleto, raisethespeed,. ThiswasonaFriday,The Boeing engineershelda short conferenceandthentold the Project Officerthatthey lid' k.-. bk Ik ,iI. 1'1, 'M A. h WOU:Jl I., ee oack on tne ~O, ,OWUl,g...ã..... nday witl an, improveddesign, MQ,d,e~,4 6,4\-49- the X,IB~52 emerges Theengineersretu rued .to theirhotel r001113 where H singresearchdata that they' had broughtwiththem,theyproceeded toredesignthe bestfeatures 'Of 'the Models 464~40and ~47into a new model, the'464=49 which featured eight J 51 engines 'In the podded. arrangementof the464=40.The wingspan \Va.S keptat 185 feet, 'b1!J the sweep 'was angled afurther 15° to35° and t be wi ng area jumped];400 square feet to. 4~OOO squarefeet,greatestof any oftheXB,-52stu dies, In spite of this great increase; thegrossweight roseto only 330,000 pounds.While one' engineerconverted thenew configuration to mode] form-with balsa. wood hurried liy pu rchased from a. local bobby shop-others organized the revised aerodynamicand structu tal data in to a presentation do cumen t that was. typed by a pu blic stenographer, The new modelwas unquestiona b]y superior to its. predecessors in spite of the.greater weight, The PUr 243
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