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Fifty-one years ago this month, a developmental version of the USN/Lockheed Polaris A1 Fleet Ballistic Missile was test-flown from Cape Canaveral, Florida.  The successful test marked a key milestone in the flight-proving of the Polaris missile’s Inertial Navigation System (INS).

The Cold War between the United States and the Soviet Union spawned the development of a Nuclear Triad by both sides.  The concept involved delivery of atomic weapons via manned bombers, land-based ballistic missiles and submarine-launched ballistic missiles.  This diversity of delivery systems thus provided for deterrence by maximizing the ability for either side to retaliate in the event of a first strike by the other.

The submarine-launched ballistic missile (SLBM) is arguably the most effective leg of the Nuclear Triad when its comes to deterrence.  This effectiveness stems largely from the mobility and elusiveness of the nuclear-powered submarine itself.  The fact that the missile is launched while the launch platform is submerged greatly enhances the weapons’s effectiveness as well.

The challenges faced by the Navy and its contractors in developing a SLBM capability were numerous and significant.  Critical among these was the need to avoid igniting the first stage rocket motor within the confines of the submarine.  The solution was to eject the missile from its launch canister via a high pressure gas generation system.  The rocket was then air-ignited just after it broached the ocean surface.

A key aspect of the SLBM launch process is missile stability and control both in the water and in the air.  During its underwater transit from canister eject to surface broach, the missile is not under active control.  However, it must be statically stable in a hydrodynamic environment.  Once in the air, the rocket motor must be ignited quickly since missile 3-axis control comes only via thrust vectoring. 

Polaris was the first SLBM developed and deployed by the United States.  Lockheed Space and Missile Systems (LSMS) began engineering development of the Navy missile in the mid-1950’s.  Aerojet was the Polaris Program’s propulsion contractor.  Flight testing from land-based launch pads began in 1958 with the first submarine-based launch occuring in mid-1960.

The Polaris A1 was a two-staged launch vehicle.  It measured 28.5 feet in length and had a maximum diameter of 54-inches.  Weight at first stage ignition was 28,800 pounds.  The type’s MK 1 reentry body delivered a single MK 47 warhead having a yield of 600 kT.  Maximum range was on the order of 1,200 nm.

On Thursday, 07 January 1960, Polaris A1X-7 was launched from LC-29A at Cape Canaveral, Florida.  The primary purpose of the test was to prove the proper operation of the Inertial Navigation System (INS).  This system was developed jointly by MIT and the General Electric Company.  The missile flew 900 nm down the Eastern Test Range (ETR).  The flight was entirely successful.

Thirty-four (34) more tests in the Polaris A1X series took place by early July of 1960.  The majority were successful.  All set the stage for the first submarine-launch of the Polaris from a submerged Navy submarine.  Indeed, Polaris A1E-1 did so on Wednesday, 20 July 1960.  It was followed less than three (3) hours later by Polaris A1E-2.  Both missiles were launched from the USS George Washington (SSBN-598) in the waters near Cape Canaveral.  Both flights were successful.

The Polaris A1 became operational in November of 1960.  It was followed in 1962 and 1964 by the more capable A2 and A3 Polaris variants, respectively.  In the never-ending  quest for greater performance and effectiveness, the Polaris was eventually replaced by the Poseidon in the 1970’s.  The latter was subsequently replaced in the 1990’s with the mighty Trident II D5 missile which serves up to the present day as the Nation’s premier SLBM.

Posted in Aerospace, History

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