||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (April 2009)|
SSM-N-8 "Regulus I" display at Bowfin Park,
Pearl Harbor, Hawaii
|Weight||13,685 pounds (6,207 kg)|
|Length||32 feet 2 inches (9.80 m)|
|Diameter||4 feet 8.5 inches (1.435 m)|
|Warhead||3,000 pounds (1,400 kg) such as the W5 warhead or the W27 warhead|
|Engine||Allison J33-A-14 turbojet 4,600 lbf (20 kN)
2 × booster rockets 33,000 lbf (150 kN)
|Wingspan||21 feet (6.4 m) extended
9 feet 10.5 inches (3.010 m) folded
|500 nautical miles (926 km)|
The SSM-N-8A Regulus was a ship- and submarine-launched, nuclear-armed turbojet-powered cruise missile deployed by the United States Navy from 1955 to 1964. Its barrel-shaped fuselage resembled that of numerous fighter aircraft designs of the era, but without a cockpit. When the missile was ready for launch, it was fitted with two large booster rockets on the aft end of the fuselage.
Design and development 
In October 1943, Chance Vought Aircraft Company signed a study contract for a 300-mile (480 km) range missile to carry a 4,000-pound (1,800 kg) warhead. The project stalled for four years, however, until May 1947, when the United States Army Air Forces awarded Martin Aircraft Company a contract for a turbojet powered subsonic missile, the Matador. The Navy saw Matador as a threat to its role in guided missiles and, within days, started a Navy development program for a missile that could be launched from a submarine and use the same J33 engine as the Matador. In August 1947, the specifications for the project, now named "Regulus," were issued: Carry a 3,000-pound (1,400 kg) warhead, to a range of 500 nautical miles (930 km), at Mach 0.85, with a circular error probable (CEP) of 0.5% of the range. At its extreme range the missile had to hit within 2.5 nautical miles (4.6 km) of its target 50% of the time.
The design was 30 feet (9.1 m) long, 10 feet (3.0 m) in wingspan, 4 feet (1.2 m) in diameter, and would weigh between 10,000 and 12,000 pounds (4,500 and 5,400 kg) After launch, it would be guided toward its target by two control stations. (Later, with the "Trounce" system, one submarine could guide it). Army-Navy competition complicated both the Matador's and the Regulus' developments. The missiles looked alike and used the same engine. They had nearly identical performances, schedules, and costs. Under pressure to reduce defense spending, the United States Department of Defense ordered the Navy to determine if Matador could be adapted for their use. The Navy concluded that the Navy's Regulus could perform the Navy mission better.
Regulus had some advantages over Matador. It required only two guidance stations while Matador required three. It could also be launched quicker, as Matador's boosters had to be fitted while the missile was on the launcher while Regulus was stowed with its boosters attached. Finally, Chance Vought built a recoverable version of the missile, so that even though a Regulus test vehicle was more expensive to build, Regulus was cheaper to use over a series of tests. The Navy program continued, and the first Regulus flew in March 1951.
Due to its size and regulations concerning oversize loads on highways, Chance Vought collaborated with a firm that specialized in trucking oversize loads to develop a special tractor trailer combination which could move a Regulus I missile.
The SSM-N-9 Regulus II missile was a completely new design with improved guidance and double the range which was intended to replace the Regulus I missile. Regulus II-equipped boats and ships would have been fitted out with the Ships Inertial Navigation System (SINS), allowing the missiles to be aligned accurately before take-off.
Forty-eight test-flights of Regulus II prototypes were carried out, 30 of which were successful, 14 partially successful and only four failures. A production contract was signed in January 1958 and the only submarine launch was carried out from the USS Grayback in September 1958.
Due to the high cost of the Regulus II (approx one million dollars each), budgetary pressure, and the emergence of the UGM-27 Polaris SLBM (submarine-launched ballistic missile), the Regulus II program was canceled on 18 December 1958. At the time of cancellation Vought had completed twenty Regulus II missiles with 27 more on the production line. Production of Regulus I missiles continued until January 1959 with delivery of the 514th missile, and it was withdrawn from service in August 1964.
Ships fitted with Regulus 
The first launch from a submarine occurred in July 1953 from the deck of USS Tunny, a World War II fleet boat modified to carry Regulus. Tunny and her sister boat USS Barbero were the United States's first nuclear deterrent patrol submarines. They were joined in 1958 by two purpose built Regulus submarines, USS Grayback, USS Growler, and, later, by the nuclear-powered USS Halibut. So that no target would be left uncovered, four Regulus missiles had to be at sea at any given time. Thus, Barbero and Tunny, each of which carried two Regulus missiles, patrolled simultaneously. Growler and Grayback, with four missiles, or Halibut, with five, could patrol alone. These five submarines made 40 Regulus strategic deterrent patrols between October 1959 and July 1964, when they were relieved by the George Washington class submarines carrying the Polaris missile system. Barbero also earned the distinction of launching the only delivery of Missile Mail.
Regulus was deployed by the US Navy in 1955 in the Pacific on board the cruiser USS Los Angeles. In 1956, three more followed: USS Macon, USS Toledo, and USS Helena. These four Baltimore class cruisers each carried three Regulus missiles on operational patrols in the Western Pacific. Macon’s last Regulus patrol was in 1958, Toledo’s in 1959, Helena’s in 1960, and Los Angeles’s in 1961.
Ten aircraft carriers were configured to operate Regulus missiles (though only six ever actually launched one). USS Princeton did not deploy with the missile but conducted the first launch of a Regulus from a warship. USS Saratoga also did not deploy but was involved in two demonstration launches. USS Franklin D. Roosevelt and USS Lexington each conducted one test launch. USS Randolph deployed to the Mediterranean carrying three Regulus missiles. USS Hancock deployed once to the Western Pacific with four missiles in 1955. Lexington, Hancock, USS Shangri-La, and USS Ticonderoga were involved in the development of the Regulus Assault Mission (RAM) concept. RAM converted the Regulus cruise missiles into an unmanned aerial vehicle (UAV): Regulus missiles would be launched from cruisers or submarines, and once in flight, guided to their targets by carrier-based pilots with remote control equipment.
Replacement and legacy 
Production of Regulus was phased out in January 1959 with delivery of the 514th missile, and it was removed from service in August 1964. A number of the obsolete missiles were expended as targets at Eglin Air Force Base, Florida. Regulus not only provided the first nuclear strategic deterrence force for the United States Navy during the first years of the Cold War and especially during the Cuban Missile Crisis, preceding the Polaris missiles, Poseidon missiles, and Trident missiles that followed, but it also was the forerunner of the Tomahawk cruise missile.
Surviving examples 
The following museums in the United States have Regulus missiles on display as part of their collections:
- Carolinas Aviation Museum, Charlotte, North Carolina
- 1956 Chance-Vought SSM-N-9a Regulus II cruise missile in launch position at the Carolinas Aviation Museum in Charlotte, North Carolina. It is mounted on a catapult launching stand used for aircraft carrier launches and was restored late 2006 after having been on outdoor display for a number of years.
- Frontiers of Flight Museum, Dallas Love Field, Texas
- Regulus II missile
- Intrepid Sea-Air-Space Museum, New York City, New York
- Regulus I cruise missile can be seen ready for simulated launch on board USS Growler at the Intrepid Sea-Air-Space Museum in New York City.
- Point Mugu Missile Park, Naval Air Station Point Mugu, California
- The museum's collection includes both a Regulus and a Regulus II missile
- USS Bowfin Museum, Pearl Harbor, Hawaii
- Veterans Memorial Museum, Huntsville, Alabama
- Regulus II missile
- Smithsonian Institution, National Air and Space Museum
- Regulus I on display at Steven F. Udvar-Hazy Center
- New Jersey Naval Museum, Hackensack, NJ
- Regulus with intact engine
- US Navy Pacific Missile Range Facility, Barking Sands, island of Kauai, Hawaii
- Regulus I restored in 2011 on static display inside the North Gate
A second generation supersonic Vought Regulus II cruise missile with a range of 1,200 nautical miles (2,200 km) and a speed of Mach 2 was developed and successfully tested, but the program was canceled in favor of the Polaris ballistic nuclear missile.
- United States Navy (from 1955 to 1964)
See also 
- Marshall William Mcmurran, Achieving Accuracy: A Legacy of Computers and Missiles, Xlibris Corporation, 2008. pp 216
- David K. Stumpf, Regulus: America's First Nuclear Submarine Missile,Turner Publishing Company, 1996. pp 21-22
- Build Special Trailer To Move Bulky Missile." Popular Mechanics, June 1954, p. 128.
- Stumpf, pp 134
- Stumpf, pp 142
- Stumpf, pp 151
|Wikimedia Commons has media related to: SSM-N-8 Regulus|
- USS Halibut Webpage
- US Navy Photos & Documentary film produced by Nick T. Spark, "Regulus: The First Nuclear Missile Submarines" which aired initially on the History Channel in Europe.
- Carolinas Aviation Museum