Regulus II missile was clearly superior to the first model, with a flight ceiling of more than 18,000 meters, a speed of Mach 2 and a range of 2,200 km. The landing gear was only mounted on the missiles used for the tests.A class of nuclear submarines was projected to carry and launch this missile, but only one was completed, the USS Halibut, which was later transformed to use the Regulus I missile. The other 3 submarines in the class were canceled and their names were gave to ships of the Thresher class.Regulus II had a solid fuel booster engine with 51,750 or 60,750 kg of thrust and one for the flight with 6,750 kg of thrust. Its warhead was the 1Mt thermonuclear W-27 and an automated launcher system was installed experimentally on an LST-type vessel, the USS King County.
