ASM - A - 1 Tarzon The ASM - A - 1 Tarzon , also known as VB - 13 , was a guided bomb developed by the United States Army Air Forces during the late 1940s . Mating the guidance system of the earlier Razon radio - controlled weapon with a British Tallboy bomb , the ASM - A - 1 saw brief operational service in the Korean War before being withdrawn from service in 1951 . Design and development . Development of the VB - 13 Tarzon began in February 1945 , with Bell Aircraft being awarded a contract by the United States Army Air Forces for the development of a very large guided bomb . The VB - 13 was a combination of a radio - command guidance system as used on the smaller VB - 3 Razon ( ' Range And azimuth only ' ) guided bomb with the British - developed Tallboy " earthquake " bomb , known to the USAAF as M112 . The ' Tarzon ' name was a portmanteau , combining Tallboy , range and azimuth only , describing the weapon and guidance system ; and was pronounced similarly to that of " Tarzan " , the popular " ape - man " fictional character . The VB - 13 , redesignated ASM - A - 1 in 1948 , was developed under the project code MX - 674 . It had an annular wing around the midsection of its body , mounted near the weapon ' s center of gravity . At the rear of the bomb was an octagonal tail surface containing the Razon control surfaces . Intended to be carryed by the Boeing B - 29 Superfortress medium bomber , the Tarzon bomb used the combination of AN / ARW - 38 [ Joint Army Navy , Piloted Aircraft , Radio , Automatic Flight or Remote Control ] command link transmitter on the B - 29 and an AN / URW - 2 [ Joint Army Navy , Utility , Radio , Automatic Flight or Remote Control ] receiver on the Tarzon to provide manual command guidance of range and azimuth . This was done with visual tracking of the bomb ' s course , aided by a flare mounted in the tail of the weapon . Gyroscopes on board the ASM - A - 1 aided in stabilisation , while a pneumatic system drove the bomb ' s control surfaces . The guidance system was considered effective ; Tarzon proved in testing to have an accuracy of . In addition to the nominal weight of the Tallboy it was based on , the annular wing and control surfaces boosted the weight of Tarzon by an additional . As a result , the size and weight of the ASM - A - 1 were such that the weapon would not fit inside the bomb bay of a Superfortress ; instead , the weapon was carried in a semi - recessed mounting , half the weapon being exposed to the airstream . This increased drag on the carrying aircraft , in addition to causing turbulent airflow that could affect the handling of the B - 29 . Operational history . Although the VB - 13 project had not reached the testing stage by the end of World War II , it avoided being cancelled , proceeding as a low - priority project . Limited testing was conducted during 1948 and 1949 ; additional testing at Alamogordo , New Mexico in 1950 led to the Tarzon being approved for operational service in the Korean War . Tarzon saw its first combat use in December 1950 , the ASM - A - 1 replacing the Razon in operational service ; the smaller weapon had been determined to be too small for effective use against bridges and other hardened targets . Used solely by the 19th Bomb Group , which had previously conducted the Razon ' s combat missions , the first Tarzon drop in combat took place on December 14 , 1950 . The largest bomb used in combat during the war , Tarzon was used in strikes against North Korean bridges and other hardened targets , the Tarzon ' s improved accuracy over conventional ' dumb bombs ' led to the confirmed destruction of at least six high - priority targets during approximately six months of combat use ; these included a hydroelectric plant , proving the effectiveness of guided weapons against conventional targets as well as bridges . Thirty Tarzon missions were flown between December 1950 and March 1951 ; the weapon ' s success led to a contract for the production of 1 , 000 additional ASM - A - 1 missiles . On March 29 , 1951 , however , a Tarzon strike against Sinuiju went awry ; the group commander ' s aircraft was destroyed as a result of the premature detonation of the bomb when , the aircraft suffering mechanical difficulties , the weapon was jettisoned in preparation for ditching . The thirtieth , and as it proved final , mission , three weeks following the Sinuiju mission , also suffered an unintentional detonation of a jettisoned , " safed " bomb , although this time without the loss of the aircraft . An investigation proved that the fault lay in the construction of the bomb ' s tail ; breaking up on impact , a ' safed ' bomb would have its arming wire removed , rendering it ' unsafe ' and detonating the weapon . Modifications were made to solve the problem , but the damage had been done ; the safety issues , increased maintenance costs compared to conventional bombs , the fact that the bomb ' s guidance system required clear - day use only , rendering the bombers vulnerable to enemy fighters , and required that the weapon be released at a prime altitude for the aircraft to be in danger from enemy flak . These combined with the weapon ' s poor reliability – only six of twenty - eight bombs dropped successfully destroyed their targets – to result in the production order being canceled by the USAF ; following this , the Tarzon program as a whole was terminated in August 1951 .