SSM-N-8 Regulus

The SSM-N-8A Regulus or the  Regulus I was a United States Navy-developed ship-and-submarine-launched, nuclear-capable turbojet-powered second generation cruise missile, deployed from 1955 to 1964. Its development was an outgrowth of U.S. Navy tests conducted with the German V-1 missile at Naval Air Station Point Mugu in California. Its barrel-shaped fuselage resembled that of numerous fighter aircraft designs of the era, but without a cockpit. Test articles of the Regulus were equipped with landing gear and could take off and land like an airplane. When the missiles were deployed they were launched from a rail launcher, and equipped with a pair of Aerojet JATO bottles on the aft end of the fuselage.

Design and development
In October 1943, Chance Vought Aircraft Company signed a study contract for a 300 mi range missile to carry a 4000 lb 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 3000 lb warhead, to a range of 500 nmi, 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 nmi of its target 50% of the time.

Regulus development was preceded by Navy experiments with the JB-2 Loon missile, a close derivative of the German V-1 flying bomb, beginning in the last year of World War II. Submarine testing was performed from 1947 to 1953 at the Navy's facility at Naval Air Station Point Mugu, with USS Cusk (SS-348) and USS Carbonero (SS-337) converted as test platforms, initially carrying the missile unprotected, thus unable to submerge until after launch.

Regulus was designed to be 30 ft long, 10 ft in wingspan, 4 ft in diameter, and would weigh between 10000 and 12000 lb. The missile resembled an F-84 fighter aircraft, but without a cockpit, and test versions were equipped with landing gear so that they could be recovered and re-used. After launch, Regulus would be guided toward its target by control stations, typically by submarines or surface ships equipped with guidance equipment. It could also be flown remotely by chase aircraft. (Later, with the "Trounce" system (Tactical Radar Omnidirectional Underwater Navigational Control Equipment), 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, designated KDU-1 and also used as a target drone, 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.

Ships and submarines deployed with Regulus I
The first launch from a submarine occurred in July 1953 from the deck of USS Tunny (SSG-282), a World War II fleet boat modified to carry Regulus. Tunny and her sister boat USS Barbero (SSG-317) were the United States's first nuclear deterrent patrol submarines. They were joined in 1958 by two purpose-built Regulus submarines, USS Grayback (SSG-574) and USS Growler (SSG-577), and, later, by the nuclear-powered USS Halibut (SSGN-587). Halibut, with its extremely large internal hangar could carry five missiles and was intended to be the prototype of a whole new class of cruise missile firing SSG-N submarines.

The Navy strategy called for four Regulus missiles 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 each, or Halibut, with five, could patrol alone. Operating from Pearl Harbor, Hawaii, the five Regulus submarines made 40 nuclear deterrent patrols in the Northern Pacific Ocean between October 1959 and July 1964, including during the Cuban Missile Crisis of 1962. According to the documentary "Regulus: The First Nuclear Missile Submarines" by Nick T. Spark, their primary task in the event of a nuclear exchange would be to eliminate the Soviet naval base at Petropavlovsk-Kamchatsky. These deterrent patrols represented the first ever in the history of the submarine Navy and preceded those made by the Polaris missile firing submarines.

The Regulus firing submarines 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.

Additional submarines including USS Cusk and USS Carbonero were equipped with control systems that allowed them to take control of a Regulus in flight, thus extending its range in a tactical situation.

Regulus was also deployed by the U.S. Navy in 1955 in the Pacific on board the cruiser USS Los Angeles (CA-135). In 1956, three more followed: USS Macon (CA-132), USS Toledo (CA-133), and USS Helena (CA-75). These four Baltimore-class cruisers each carried three Regulus missiles on operational patrols in the Western Pacific. Macon last Regulus patrol was in 1958, Toledo in 1959, Helena in 1960, and Los Angeles in 1961.

Ten aircraft carriers were configured to operate Regulus missiles (though only six ever launched one). USS Princeton (CV-37) did not deploy with the missile but conducted the first launch of a Regulus from a warship. USS Saratoga (CVA-60) also did not deploy but was involved in two demonstration launches. USS Franklin D. Roosevelt (CVA-42) and USS Lexington (CV-16) each conducted one test launch. USS Randolph (CV-15) deployed to the Mediterranean carrying three Regulus missiles. USS Hancock (CV-19) deployed once to the Western Pacific with four missiles in 1955. Lexington, Hancock, USS Shangri-La (CV-38), and USS Ticonderoga (CV-14) 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
Despite being the U.S. Navy's first underwater nuclear capability, the Regulus missile system had significant operational drawbacks. In order to launch, the submarine had to surface and assemble the missile in whatever sea conditions it was in. Because it required active radar guidance, which only had a range of 225 nmi, the ship had to stay stationary on the surface to guide it to the target while effectively broadcasting its location. This guidance method was susceptible to jamming and since the missile was subsonic, the launch platform remained exposed and vulnerable to attack during its flight duration; destroying the ship would effectively disable the missile in flight.

Production of Regulus was phased out in January 1959 with delivery of the 514th missile; in 1962, it was redesignated RGM-6. It was removed from service in August 1964. Some 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 was also the forerunner of the Tomahawk cruise missile.

Following retirement, a number of Regulas I missiles were converted for target drone usage under the designation BQM-6C.

Regulus II
A second generation supersonic Vought SSM-N-9 Regulus II cruise missile with a range of 1,200 NM and a speed of Mach 2 was developed and successfully tested, including a test launch from Grayback, but the program was canceled in favor of the UGM-27 Polaris nuclear ballistic missile.

The Regulus II missile was a completely new design with improved guidance and double the range, and was intended to replace the Regulus I missile. Regulus II-equipped submarines and ships would have been fitted 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 four failures. A production contract was signed in January 1958 and the only submarine launch was carried out from Grayback in September 1958.

Due to the high cost of the Regulus II (approximately 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 20 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.

Both Regulus I and Regulus II were used as target drones after 1964.

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
 * Regulus I 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 (SSG-577) 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
 * 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, New Jersey
 * 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

Operators

 * United States Navy (from 1955 to 1964)
 * United States Navy (from 1955 to 1964)