Several warheads were available for use in the Regulus I tactical missile:
- MK5 – The MK5 Mod 0 (W-5-0) warhead was placed into production in April 1954. The W-5 weighed 3,000 lbs. and had a yield between 40-50 KT, depending on the nuclear components selected.
- XW-8/Regulus – The Mk-8 was a derivative of the earlier “Little Boy” gravity bomb. On February 15, 1951 authorization was given by the AEC to develop the XW-8/Regulus warhead. Only one flight test was conducted, and the warhead work was suspended in May 1955, when the Navy decided to investigate thermonuclear warheads for Regulus.
- W-27 – The W-27 was the warhead derivative of the first lightweight thermonuclear bomb, which began development in May 1955. Twenty warheads were produced. The W-27 weighed 2,800 lbs. and had a yield of several megatons.
The decision to use the W-27 warhead necessitated the only major structural change in the Regulus I design. The nose section of the tactical missile was redesigned with a “bulged chin” to accommodate either the long and narrow W-27 or the spherical W-5. The W-27 was finally retired in July 1965.
More Regulus I:
General Characteristics for an Interim Guided Missile
Able, Backer, Charlie and FTV-1
Operation Splash and FTV-3
Regulus I and II
Regulus I Subsystems
Airframe, Engine and Fuel Systems
Autopilot, Radio Control, Guidance and Instrumentation
Landing Gear and Hydraulic Systems
Nose Boom, Wing and Fin Fold
Launch Slippers, Parabrake, Smoke Systems and Jato