north american prototype nuclear armed deep penetration strategic bomber late 1950s north american aviation designed bomber large engined aircraft capable reaching flying feet speeds expected immune aircraft effective weapon bomber aircraft time bomber spend minutes particular radar station flying range controllers position fighters suitable location interception high speed aircraft difficult radar displays high altitude flight matched contemporary soviet fighter introduction soviet surface air missiles late 1950s near doubt response air_force began flying missions low level missile radar line sight limited local terrain low level penetration role offered little additional performance meant replace far expensive shorter range alternate missions proposed limited scope strategic role passed bombers intercontinental missiles late 1950s manned bombers increasingly seen obsolete eventually gave fighting production program canceled development turned research program study effects long duration high speed flight prototype aircraft built designated aircraft test flights prototype crashed mid air smaller jet aircraft remaining bomber near ohio development background boeing manned boost bomber project boeing partnered january explore sort bomber aircraft needed deliver nuclear weapons development time nuclear weapons weighed tons need carry fuel fly continental united_states soviet_union demanded large bombers concluded release bombs aircraft need speed escape critical blast radius aviation industry studying problem time interest nuclear powered aircraft bomber role conventional jet engine thrust provided heating air jet fuel accelerating nuclear engine heat supplied months instead hours designs carried small jet fuel use high power portions flight high speed possibility explored time use enriched improves energy density jet fuel percent modified versions existing jet engine designs appeared offer sufficient performance improvement produce strategic bomber speed followed developments closely issued general operational requirement new bomber combining intercontinental range speed new bomber expected enter service nuclear conventional designs considered nuclear powered bomber organized weapon system pursued simultaneously jet powered version weapon system requirement asked chemical fuel bomber cruising speed maximum possible speed nautical miles entrance exit target requirement called pound combat radius nautical miles air_force formed similar requirements intercontinental reconnaissance system later canceled better options july contractors selected bid studies boeing submitted proposals november awarded contracts phase development initial designs presented companies fuel improve range percent conventional fuel designs featured huge wing tip fuel tanks fuel depleted dash target tanks included outer portions wing produce smaller wing suitable speeds wings time highest performance known featured flush maintain highest ratio possible spite effects visibility designs takeoff weights approximately pounds large fuel loads air_force evaluated designs september deemed large complicated operations general curtis dismissive airplane ship formation ended phase development october instructed contractors continue design studies new designs period original proposals studied advances flight proceeding rapidly narrow delta establishing preferred flight replacing earlier designs like swept wing seen designs like lockheed earlier concepts engines able cope higher temperatures widely varying intake ramp air speeds design allowing sustained speeds work led interesting discovery engine specifically high speed burned twice fuel speed running speeds aircraft flying times fast economical cruise speed terms fuel mile maximum speed entirely unexpected implied point dash concept aircraft able reach fly entire mission speed question remained concept technically feasible march engine development wind tunnel testing progressed suggest redesigned aircraft flying entire mission fuel retained engine increase range north american boeing returned new designs long large delta wings differed primarily engine layout design arranged engines semi circular rear fuselage boeing design separate engines located individually wing like north american literature find additional advantage led obscure report wind tunnel experts wrote report titled aircraft configurations developing high lift drag high speeds known today compression lift idea use shock wave generated nose sharp points aircraft source high pressure air carefully positioning wing relation shock shock high pressure captured wing generate additional lift maximum advantage effect redesigned underside aircraft feature large triangular intake area far forward engines better positioning shock relation wing north american improved basic concept adding set wing tip panels lowered high speed helped trap shock wave wing wing tips added vertical surface aircraft maintain directional stability high speeds solution additional advantage decreased surface area rear wing panels moved high speed position helped offset shift center pressure average lift point increasing speeds normal conditions caused increasing nose trim offset moving control surfaces increasing drag wing tips surface area rear wings lowered moving lift forward effect reducing need control buildup heat skin friction sustained flight addressed cruise aircraft reach average leading edges reaching engine compartments proposed building design sandwich panels panel consisting thin sheets steel opposite faces shaped foil core expensive high temperature areas like leading edge horizontal nose cooling interior pumped fuel route engines heat august air_force decided data available boeing designs competition begin september air_force issued operational requirements called cruising speed target altitude range gross weight exceed aircraft use handling procedures december north american proposal declared winner competition january contract issued phase development february proposed bomber designated prototypes receiving experimental prototype designation winning submission early selected entries contest air_force approved month program acceleration march rescheduled flight december late service announced acceleration possible lack funding december contract issued reviewed air_force march provisions air surface missiles external fuel tanks requested afterward time north american developing reduce program costs share engines escape capsule smaller systems early north american released drawing public missile problem planned use high speed high altitude bombing approach followed trend bombers flying progressively faster higher start manned bomber use period weapons proved effective bombers fighter aircraft anti aircraft artillery aaa flying higher faster difficult higher speeds allowed bomber fly range weapons quickly higher altitudes increased time needed fighters climb bombers greatly increased size aaa weapons needed reach altitudes early german commanders concluded aaa essentially useless jet aircraft began development guided missiles fill role forces reached conclusion soon starting missile development programs war ended attempts develop useful high altitude aaa weapon development ended aircraft improving performance remained effective anti bomber weapons early 1950s having problems keeping latest designs soviet late 1950s intercept high altitude reconnaissance aircraft spite relatively low speeds later discovered flying faster radar detection difficult effect known scan ratio reduction tracking efficiency interfere operation guidance fighters introduction effective anti aircraft missiles late 1950s changed picture dramatically missiles stand ready immediate launch eliminating operational delays like time needed pilot cockpit fighter guidance require wide area tracking calculation intercept course simple comparison time needed fly altitude target returned required missiles greater altitude capability aircraft improving adapt new aircraft low cost development path aware soviet work field reduced expected operational lifetime knowing vulnerable missiles improved later happened downing flown faced problem military doctrine started shifting away high altitude bombing low altitude penetration radar line sight aircraft dramatically detection distances flying close earth hiding terrain missile sites spaced overlap range attacking bombers high altitudes leave large gaps coverage bombers flying lower levels appropriate map missile sites bombers fly defences additionally early missiles generally flew period time radar systems able track missile start sending guidance signals missile minimum altitude roughly feet flying bomber effectively missiles happened fly range flying low level provided protection fighters radars era ability look radar aimed detect targets lower altitude reflection ground signal returned target flying normal altitudes effectively blind bombers far descend lower altitudes increase visible sky limit radar range way missile sites greatly increasing fuel use reducing mission time soviet_union introduce look capability radar model limited capability found uncomfortable position bombers tuned efficiency high speeds altitudes performance purchased great cost engineering financial terms replace long range role sac introduced replace boeing medium range role expensive develop purchase required enormous amounts fuel maintenance comparison estimated cost times operate larger longer ranged designed higher speeds altitudes range suffered relative terms high altitudes times fast low altitudes limited faster altitudes smaller shorter range major advantage ability use high speed areas missile cover especially long journey usa ussr value limited doctrine stressed primary reason maintaining bomber force era bombers remain air long ranges bases immune sneak attack case higher speed short period time staging areas soviet coastline adding problems fuel program canceled burning fuel turned increased wear moving turbine engine components intended use avoid problem enormous cost program limited gains led cancellation fatal problem newly developed high energy like available difference range lost change fuel restored filling bomb bays fuel tank problem arose program canceled september ended shared development benefited program cancellation secret meetings november chairman recommended air_force plan strike rail mobile soviet chief staff air_force general white admitted soviets able hit rockets requested downgraded bare minimum research development program million fiscal year president responded reconnaissance strike mission crazy nuclear mission attack known production military complexes emphasized saw need cheaper effective way thing identified manufacturing years said thought talking bows arrows time gunpowder spoke bombers missile age december air_force announced project cut single prototype planned longer developed interest increased politics presidential campaign central campaign republicans weak defense pointed example told san_diego audience near facilities endorse manned aircraft kennedy similar campaign claims aircraft near seattle boeing plant affirmed need praised air_force changed program weapon development awarded contract prototype august november program received million appropriation nixon trailing home state california publicly endorsed october helped republican campaign pledge additional million development program taking office january kennedy informed missile gap illusion march million spent program kennedy canceled project unnecessary economically stood little chance penetrating enemy defenses successfully instead kennedy recommended program carried forward essentially explore problem flying times speed sound airframe potentially useful bomber congress approved million add funds president modified budget administration decided planned million funds subsequently presented data congress add little performance high cost new air_force chief staff july curtis increased advocacy including interviews august reader digest november aviation week articles allowing february general_electric tour press provided artist congress continued effort bomber development secretary defense explained january subsequently argued house senate committees march march members having work districts written bill direct law use nearly million appropriated unsuccessful address march march 11th hour white_house agreement kennedy chairman retracted bill language bomber remained canceled experimental aircraft intended advanced study propulsion subjects related large transports crew reduced pilots navigator needed research role production order reduced prototypes march aircraft incorporate improvements previous prototype order later reduced experimental named air vehicle completed rolled california report stated like existed completed october manufacture prototype canceled july completion carried maiden flight september test flights followed data test flights materials development later bomber program american transport program espionage soviet_union program development lockheed reconnaissance aircraft prompted soviet engineers design develop high altitude high speed design designed high altitude bomber engines harrison storms shaped aircraft surface delta wing built largely steel panels designed use technologies developed modified form guidance system compression lift arose shock wave generated sharp leading edge central engine intake plate wing cruising speed shock wave attached wing leading edge preventing high pressure shock leaking wing compression lift provided percent total lift wing included effectively use higher pressure field strong shock wave unique aircraft size outer portions wings downward degrees acting type variable geometry device increased aircraft directional stability speeds shifted center lift favorable position high speeds strengthened compression lift effect downwards compression lift shock wave trapped wings equipped general_electric engines designed use jet fuel engine stated pound class actually produced lbf lbf fuel cooling pumped heat reaching engines reduce likelihood nitrogen injected fuel system supply liquid nitrogen fill fuel tank vent space maintain tank pressure operational history maiden flight september flight test engine shut shortly malfunction warning meant flight flown precaution limiting speed mph half planned landing rear wheels port main gear locked tires fire started test flight october flew minutes following flight october wing tips lowered partially flight surpassed october reaching aircraft found suffer weaknesses panels primarily inexperience quality control new material occasions panels failed torn flight necessitating limit placed aircraft deficiencies discovered completely solved second flew july january attained speed flying reached speed maintained minutes april reached flew minutes covering minutes total flight joint nasa research program conducted november january measuring intensity signature sonic testing planned cover range sonic boom ground similar higher proposed selected program outfitted test sensors flew sonic boom test june attaining speed days later crashed following mid air collision flying multi aircraft formation sonic boom later testing continued second flight research program nasa investigated control structural dynamics april flight high altitude high speed experienced unwanted changes altitude nasa testing june included small nose measuring response aircraft stability system flew total flights flight took place december february took final flight museum display flight data collected trip north american completed volume report published nasa april variants prototype built model number completed flights spanning hours minutes model number flew times hours minutes crashed june model number originally march advanced prototype canceled early manufacture planned version improvements based planned bomber production version fleet operational bombers planned reconnaissance strike version crew flight capability incidents accidents incidents separating left right halves engine intake ramp broke flight engines damaging repair october surpassed heat stress damaged panels leaving leading edge left wing missing aircraft limited mid air collision june close formation aircraft behest general_electric manufacturer engines aircraft completion drifted contact right wing flipped rolled inverted striking vertical left wing bomber exploded destroying damaging left wing loss damage wings entered spin crashed ground north california nasa chief test pilot pilot pilot killed pilot ejected sustaining injuries including arm crushed closing like escape crew capsule moments prior summary report accident investigation stated given position relative pilot able wing looking left shoulder report said likely walker maintained position looking fuselage forward position estimated fuselage report concluded position appropriate sight cues walker unable properly perceive motion relative leading aircraft drifting contact wing accident investigation pointed wake vortex right reason sudden roll bomber aircraft display display near ohio aircraft flown museum february following conclusion testing program museum signature aircraft appearing museum appearing chief design feature museum restaurant cafe display museum alongside experimental aircraft completion fourth hangar museum main campus moved late october specifications data pace sheet aircraft study general characteristics crew length wingspan height wing area modified root modified tip weight operating weight loaded weight max takeoff weight powerplant dry thrust lbf thrust lbf internal fuel capacity gallons performance maximum speed mph cruise speed mph range nmi combat mission service ceiling wing loading lift drag thrust weight
North American XB-70 Valkyrie