Bell 309 The Bell Model 309 King Cobra was an experimental attack helicopter developed by Bell Helicopter Textron based on the AH - 1 Cobra . Design and development . The AH - 1 Cobra was developed in the mid - 1960s as an interim gunship for the U . S . Army for use in Vietnam . The Cobra shared the proven transmission , rotor system , and the T53 turboshaft engine of the UH - 1 " Huey " . By June 1967 , the first AH - 1G HueyCobras had been delivered . Originally designated as UH - 1H , the " A " for attack designation was soon adopted and when the improved UH - 1D became the UH - 1H , the HueyCobra became the AH - 1G . Bell built 1 , 116 AH - 1Gs for the US Army between 1967 and 1973 , and the Cobras chalked up over a million operational hours in Vietnam . The US Army purchased the AH - 1G as an " interim type " for the " jungle fighting " role , but the Army ' s broader concern was the task of protecting Western Europe from the legions of Warsaw Pact armor to the east . The Army had initiated the Advanced Aerial Fire Support System ( AAFSS ) program to develop the Lockheed AH - 56 Cheyenne for the anti - tank gunship role , but development of the Cheyenne did not go smoothly , and as one writer put it , " the vultures began to gather " , with Sikorsky and Bell trying to sell unsolicited alternatives to the Army . The Sikorsky offering was the S - 67 Blackhawk , a sleek gunship , which despite the name was no real relation to the later S - 70 Black Hawk utility - transport helicopter . The Bell offering was a refined HueyCobra , the Model 309 KingCobra . Bell announced the KingCobra program in January 1971 . Two prototypes were built , one with a P & WC T400 - CP - 400 Twin Pac dual turboshaft engine system much like that used on the AH - 1J , but with a stronger drive train allowing full 1 , 800 shp ( 1 , 340 kW ) operation , and the other with a single Lycoming T55 - L - 7C turboshaft engine with 2 , 000 shp ( 1 , 490 kW ) . The twin engine KingCobra first flew on 10 September 1971 . It looked much like an AH - 1J , except for a longer and distinctive " buzzard beak " nose and a ventral fin like that on the original Model 209 demonstrator . However , there were significant changes that were less noticeable : New avionics were incorporated , including a Litton inertial navigation system ( INS ) that could store 16 different preprogrammed navigation waypoints ; a radar altimeter with a ground warning system ; and other improved navigation and communications gear . The primary weapon of the KingCobra was to be the new wire - guided BGM - 71 TOW anti - tank missile , which had proven highly effective in combat test firings in Vietnam from Huey gunships . This weapon could be carried in a pack of four missiles , with one pack under each stub wing for a total of eight missiles . On launch , the TOW trailed out wires to communicate command guidance updates . The missile had two infrared flares on its tail to allow the SMS to track it . All the gunner had to do was keep the target in his sight , and the missile fire control system adjusted its flight appropriately . Both the gunner and the pilot had Sperry Univac helmet - mounted sights to allow them to acquire targets for the KingCobra ' s missiles and gun . A long - span " big wing " , 13 feet ( 4 m ) wide , was designed for the KingCobra , but apparently never fitted except as a static mockup . The " big wing " was to provide additional fuel and stores carriage capability at the wingtips . Operational history . The single - engine KingCobra first flew in January 1972 . Other than engine fit , it was almost identical to the twin - engine KingCobra . As it turned out , the single - engine prototype was wrecked in an accident in April , and to complete US Army evaluation the twin - engine KingCobra was modified to the single - engine configuration . The evaluation , which pitted the KingCobra against the Lockheed Cheyenne and Sikorsky S - 67 in a competitive fly - off , began in the spring of 1972 and was completed in July . In August , the Army rejected all three to everyone ' s surprise . Legacy . Many of the sensors and subsystems used on the 309 were years ahead of their time . The Cobra family developments after the AH - 1G and AH - 1J variants were connected to the Bell 309 . Based on the Model 309 and AH - 1 Cobra , Bell derived a new prototype attack helicopter , the Model 409 / YAH - 63 , for the Army ' s Advanced Attack Helicopter ( AAH ) competition beginning in 1972 . Hughes ' Model 77 / YAH - 64 was selected over Bell ' s Model 409 / YAH - 63 in 1976 .