weigh . Compatibility with the B-58 was cancelled in May 1957, and the warhead version of the weapon was cancelled in July 1957. In July 1957, tests of the contact fuze were made by firing shells through the nose of the bomb. These tests showed that there was sufficient time between contact and the firing signal being sent for the fuze design to work correctly. In August 1957, the primary of the device in a device mockup was tested during shot Smoky of Operation Plumbbob, yielding . The device was subsequently tested in shots Sycamore, Poplar and Pine of Hardtack I in 1958. Sycamore, a clean test, was a fizzle, producing only instead of the predicted . Poplar was a retest of Sycamore with a predicted yield of and only fission yield. The actual yield was . Pine was a three-stage variant of the clean device, with a predicted yield of , but the test only yielded . In June 1958, the requirement to be able to select air and ground burst fuzing modes from the cockpit was cancelled. This change meant that fuzing selection had to be made on the ground before takeoff. In August 1958, the first production date for the weapon slipped to May 1960. Issues with the weapon now meant that compatibility was limited to the B-47 and B-52 bombers. Compatibility with the B-70 would require significant changes to the aircraft. Further, due to the new emphasis on low level releases to avoid radar detection and due to the fact that the TX-41 could only be dropped from high altitude, the question of continuing the program was raised. One item raised in support of continuing the program was that the bomb could replace the Mark 36 bomb. Another proposal was to delay the program and include a full-fuzing (FUFO) capability into the weapon that would allow for laydown delivery. However, in September 1958, the Radiation Laboratory and Sandia informed Field Command that to add FUFO to the weapon would require a completely new weapon, including nuclear testing. In November 1958 it was decided that the weapon would always be deployed in the parachute retarded condition, and thus an option selector switch was no longer needed. In December, Sandia raised issues with the safety of the weapon and proposed additional safing devices. This was provided with additional switches in the aircraft monitor station. In January 1959, the