The missile that blasted out of the clear blue Gulf Stream carried the U.S. nuclear navy into new positions of power. By passing its 13th successive successful test, its first from under water, the Polaris A3, latest addition to the nation's undersea arsenal, promised that U.S. submarines would soon make their patrols with vast new freedom. The A3, with an additional 1,000 miles of range, reaches out for 2,500 miles. Subs that are now restricted to prowling narrow waters close to the coast of Europe in order to keep their Polaris warheads within 1,500-mile range of Soviet Russia will soon have millions of square miles more of open ocean in which to hide.
Heavier Rock, Bigger Bang. "We used the same paint," says Stanley W. Burriss, manager of the Lockheed Aircraft division that is prime contractor for the missile. "But just about everything else is new." Burriss estimates that only 10% of the A3's components came from the A2. The new missile is about 16 in. longer than the A2, and its bullet-shaped nose is discarded after the missile has cleared the atmosphere, uncovering the warhead (missile engineers call it the rock) which is heavier, more powerful. According to unofficial reports, the A-3 packs 750 kilotons of bang instead of 600 Kilotons for the A2. The primitive nuclear bomb that leveled Hiroshima had 20 kilotons.
To toss its heavier load 1,000 extra miles, the A-3 packs more thrust and less deadweight. First-stage fuel, made by Aerojet General Corp., is denser, so that more can be carried in the same space. It is also more powerful, producing a hotter flame (6,300 to 6,600° F.) and more thrust. The casing that restrains its pressure (800 to 900 lbs. per sq. in.) has been lightened by making it out of filament-wound glass fiber instead of metal.
Stage two, made by Hercules Powder Co., has new fuel, too, and 1,500 lbs. more of it. The casing, already of glass fiber in the A2, has been improved by a new lining to protect it from the new fuel's greater heat. Instead of nozzles for steering, it uses liquid Freon injected into the side of the gas stream.
Light Brain. One important weight saving is in the General Electric and Raytheon guidance system, the lightest ever devised for a ballistic missile. The computer, which does the missile's thinking in flight, weighs only half as much as its predecessor. But accuracy has not been sacrificed. In spite of covering a greater distance, the A-3 hits its targets more accurately than the A2.
Both the A-1 (the original Polaris) and the A-2 are shoved to the sea's surface by compressed air—a process that requires heavy tanks and complicated valving. The A-3 starts on its flight when a small rocket motor is ignited and shoots hot gas into a water chamber. Part of the water turns to steam, and the gas-steam mixture pops the missile out of its submarine cell.
Operational A-3s will start coming off the line next February, and by then most U.S. nuclear submarines will be equipped to launch them. With 16 long-range A-3s standing upright in their waists, the subs will be able to keep to the deep, safe, open ocean, while their full deterrent is still zeroed in on potential troublemakers.