The B61 Family is a series of nuclear weapons based on the B61 nuclear bomb. B61 nuclear bomb Initial development The B61 bomb was developed by Los Alamos Scientific Laboratory (LASL; now Los Alamos National Laboratory) starting in 1960. The intent was to develop an aircraft bomb which was high yield (over 100 kilotons) and yet was small enough and had low enough drag to carry under the wing of a fighter or fighter-bomber type aircraft. One major feature was Full Fuzing Option, allowing various air and ground burst usage options; free fall air burst, parachute retarded air burst, free fall ground burst, parachute retarded ground burst, and laydown delivery. The B61 project started in 1960 with a study contract analyzing the potential of such a weapon. The official development program was funded in 1961, and the weapon was designated TX-61 (Test/Experimental) in 1963. The first TX-61 free fall ballistic test was held at Tonopah Test Range on August 20, 1963. The first War Reserve B61-0 was accepted by the AEC on December 21, 1966. The original models of B61 used PBX 9404, an HMX based plastic bonded explosive to implode the fissile material in the primary stage. Newer models use TATB based PBX 9502, which is an insensitive high explosive (IHE) and will resist detonation in adverse conditions such as fire, shock and impact. Design The overall B61 bomb is in diameter and long, and weighs approximately across most mods. The nuclear device within the outer B61 envelope is probably the same overall dimensions and weight as the W80 warhead, which is in diameter, long and weighs about . Warheads W69 The W69 missile warhead was produced in the early 1970s for use in the AGM-69 SRAM Short Range Attack Missile. The W69 was in diameter and long, weighed 275 pounds, and had a yield of 170-200 kilotons. 1,500 W69 warheads were produced. W73 The W73 missile warhead was designed for the AGM-53 Condor air to ground missile. Other than being described as a derivative of the B61, details of the W73 design are poorly documented. Both the W73 and the Condor missile were cancelled and never entered service. W80 Two versions of the W80 cruise missile warhead were designed and deployed. Both are the same basic size and shape and weight: 11.8 inches in diameter, 31.4 inches long, and weight of 290 pounds. W80-0 The BGM-109 Tomahawk TLAM-N