lockheed lockheed attack helicopter developed lockheed united_states_army rose army program field service dedicated attack helicopter lockheed designed blade rigid system aircraft compound helicopter low mounted wings tail mounted propeller driven general_electric engine high speed dash capability provide armed escort army transport helicopters bell army awarded lockheed contract prototypes ordered simpler interim attack aircraft combat vietnam maiden flight took place september january army awarded lockheed production contract based flight testing progress fatal crash technical problems affecting performance development schedule resulting cancellation production contract development continued hope helicopter eventually enter service american involvement vietnam winding army canceled program august time cobra widely deployed army vietnam war controversy united_states_air_force role combat political climate military acquisition programs caused army amend service attack helicopter requirements favor twin engine conventional helicopter viewed technical army announced new program advanced attack helicopter august led development development background prior development armed helicopters modifications existing aircraft designed unarmed uses secretary defense convened review army aviation requirements board recommended division supported armed helicopters recommendation came time army preparing deploy armed escort helicopters vietnam modified systems mounting machine guns grenade launchers rocket pods june presented new helicopter design army officials hopes funding development envisioned purpose built attack aircraft based airframe dynamic components nose mounted ball turret belly mounted gun pod wings mounting rockets anti tank missiles attack helicopter requirements december drafted interim commercial shelf aircraft knot mph cruise speed pound seen attempt army officials anticipating potential acquire interim aircraft fill escort role army determine requirements dedicated armed helicopter secretary army disapproved interim approach directed army look advanced system dramatically improve current helicopter designs based guidance secretary army established wing aircraft knot mph cruise speed knot mph dash speed capability ground effect feet day speed requirements derived speed aircraft helicopter escort director approved changes development objectives pending review proposed program directed army determine helicopter offer improvement performance meantime result conducted study determine development objectives feasible established program office fire support recommended narrow competition compound helicopters considered helicopter configuration time capable developed meet objectives march secretary army advised modification existing aircraft approach required performance program army continue armed development proceed competition march army chief staff redesignated program development objectives document approved april august contacted prospective contractors request proposals bell submitted modification conventional helicopter design submitted featured serve tail speeds increased rotate act propeller lockheed submitted design rigid compound helicopter pushing propeller conventional tail mounted end tail army announced lockheed winners contracts february army continued pursue interim aircraft combat vietnam fielded resulting development bell cobra backbone army attack helicopter fleet vietnam war lockheed developed proposals respective designs establishing configurations satisfy development objectives revised based draft requirements document evaluation board studied company proposal submitted recommendation selection authority council october november army announced lockheed winner program army perceived lockheed design expensive able delivered sooner lower technical risk december army released final requirements document document added fourteen requirements previously addressed lockheed proposal including addition aerial rocket armament march army awarded lockheed engineering development contract prototypes designating aircraft initial operating capability planned optimistic target late lockheed began construction aircraft california facility lockheed held roll ceremony aircraft christened army flight occurred september secretary defense approved pre production funding support initial production order aircraft january manufacture prototypes completed design lockheed designed compound helicopter combines helicopter fixed wing features increased performance usually speed design included features rigid main low mounted wings propeller powered general_electric engine thrust provided propeller rear aircraft high speeds lift provided wings thrust prop reduced aerodynamic loading speeds produced lift adjusted collective pitch control changes tilt controlled achieved speeds knots mph compound helicopter unable qualify speed records helicopter categories seat tandem cockpit featuring advanced navigation fire control suite tandem seating placed pilot rear seat gunner seat unusual feature gunner station entire seat sighting system firing controls rotated gunner facing direction gun turret controlled gun sight afforded gunner direct viewing turret way sight pilot helmet mounted sight system aiming weapons weapon turrets mounted nose middle aircraft nose turret rotate aircraft centerline mount grenade belly turret included automatic cannon rotation mechanical stops prevented belly turret aiming helicopter external located helicopter wing fuselage inner wing carry pods tow missiles inch rockets rocket rocket launchers carried wing fuselage mounts dedicated carrying external fuel tanks wing allow carriage additional fuel tanks required operational history flight testing flight testing began flight second september early flight tests instability issue discovered aircraft flying low altitude ground effect flight envelope expanded instability minor problems discovered quickly addressed lockheed army held minute demonstration flight public van airport december flight demonstrated new capabilities brought propeller helicopter slow accelerate pitching nose able pitch nose causing aircraft accelerate forwards backwards demonstrated stationary knot mph end flight landed forward landing gear audience gently set tail landing gear parking march established flight envelope knots mph forward flight knots mph knots mph project suffered setback march prototype struck fuselage caused aircraft crash killing pilot accident occurred test flight pilot manipulate controls half hop vibration happens main revolutions speed accident investigation noted safety mechanisms controls apparently disabled flight investigation concluded pilot induced set vibration exceeded system ability compensate investigation control systems modified prevent problem occurring production contract canceled army issued cure notice lockheed april citing technical problems unsatisfactory progress program main issues half hop vibration issue aircraft gross weight exceeding program requirements response lockheed proposed improved flight control system reduce steps removing excess weight addressing minor issues production helicopters army felt lockheed solutions cure notice issues delay program increase costs citing lockheed inability meet production timeline army canceled production contract retained development contract hopes issues resolved september prototype underwent wind tunnel testing research half hop drag issues engineers realize fixed mounts secure aircraft wind tunnel allow helicopter relative flight result natural pitching motion remote controllers lack sensory feedback helicopter compounded situation high speed testing replicate half hop vibration quickly accelerated control struck tail boom resulting destructive breakup helicopter lockheed worked modifying design address vibration issues precaution fitted seat pilot march accident downward firing seat placed forward seat place gunner station prototype remaining envelope expansion flights prototype received upgraded transmission rear canopy place original sliding canopy new transmission allowed engine output increased horsepower horsepower new canopy eliminated canopy vibrations prototype began conducting weapons testing proving ground arizona demonstrating ability gunner pilot accurately fire separate targets helicopter end army funded work tow missile guidance night sighting systems prototypes tested evaluated proving ground january december determine stability control systems sufficient deficiencies identified lateral directional stability motion maneuvering high vibration poor directional control flying following testing prototype received improved engine producing shp planned production version system upgrades helicopter surpassed performance requirements certain conditions stability control completely satisfy test pilots lockheed studied ways prevent unstable feedback solution relocate head transmission flexible connections pilot controls connected hydraulic connected springs system prevented vibration forces flight controls called advanced mechanical control system installed improve handling stability program demise political friction increased army air_force close air support mission air_force asserted air_force mission support army mandated key west agreement conducted study concluded air_force program significantly different constitute capabilities october conducted hearings evaluate mission pending programs damaging testimony army program came commander air_force general cited helicopter casualty statistics operation son army convened special task force general marks january requirements attack helicopter purpose develop updated material needs document task force conducted flight industry alternatives comparison bell king cobra analysis helicopters determined bell helicopters fulfill army requirements army conducted weapons demonstration early firepower garner support attack helicopter development tow missile fired demonstration failed went ground second missile fired hit target previously tow missiles fired failure failure missile linked perception aircraft april senate published report report recommended funding air_force program limited marine_corps report referred offered lukewarm recommendation army continue attack helicopters long improved program canceled secretary army august helicopter large size inadequate night weather capability reasons stated army cancellation analog mechanical weapons systems date new digital systems accurate faster lighter developed unit cost increased likely increase new incorporated august army initiated advanced attack helicopter program sought attack helicopter based combat experience vietnam lower speed mph twin engines improved lockheed offered modified version engines omitted propeller success program led entered service mid-1980s cancellation army conducted evaluation seventh equipped flight control system testing showed removed remaining control problems improved stability improved handling decreased pilot workload reached speed mph level flight dive achieved mph demonstrated improved high speeds prototype fly lockheed counted establish helicopter market rigid technology ambitious project unsuccessful firm pursue development helicopter survivors display fort louisiana stored alabama display fort campbell display specifications data jane aircraft general characteristics crew pilot gunner seat length diameter height weight loaded weight max takeoff weight powerplant shp systems blades main blades tail blades propeller performance maximum speed knots mph cruise speed knots mph range nmi service ceiling rate climb min armament guns nose turret grenade machine gun belly turret cannon rockets rockets tow missiles
Lockheed AH-56 Cheyenne