with the nose substituted for four wedge fins and the tail replaced with a blunt nose containing radar antennas and contact crystals. In this configuration the weapon had a length of and weighed approximately . The design met almost all of the specified military requirements with some exceptions. One of these exceptions is still classified while the others were that the weapon did not have a visual indication of arming and that the weapon could not be stored for 18 months at the ready condition. Instead of a visual indication, the weapon relied on electrical signals to confirm that the weapon was not armed. The storage requirement was not met, as the weapon initially required pressure-testing at 30-day intervals. RE and RI weapons Initial discussion about a ruggedized laydown weapon was discussed in August 1955 by the TX-Theta Committee. It was noted that Soviet radar capabilities were improving and that high-altitude attacks were becoming less certain. A low-altitude approach would help overcome this but would require a weapon that could survive impact with the ground before detonating once the aircraft was a safe distance away. Sandia had been investigating the problem and believed that designing a bomb to survive an impact shock of was possible. In October 1955 the Special Weapons Development Board met. Sandia stated that they had examined parachutes, rotochutes and retrorockets. Rotochutes could not handle the weapon's weight, while retrorockets placed special operating restrictions on the weapon. Parachutes showed promise, but existing designs were unsuitable, with Sandia working on developing an improved parachute. Sandia had also worked on developing shock-absorbing honeycomb materials, which included drop tests from a tower to simulate the impact expected in a parachute-retarded weapon. In early 1956, Sandia concluded that a non-impact-resistant warhead could be used to produce an interim retarded weapon and this weapon system would meet weapon objectives 2 years before the development of a true laydown weapon. The weapon would use a pilot-parachute to deploy a larger drogue-parachute. This required a new bomb tail to be designed, which might aggravate ground and aircraft-clearance problems. Production authorization for the RE weapon was issued in January 1957 and design release made in April 1958. The changes included a new altitude-sensing arming system to replace the baroswitches based on velocity sensing. This removed certain delivery restrictions on the Mk-28 Mod 0. The design also included an acceleration-integration system to detect if the parachute