FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1963
1963 - 1951.PDF
754 MISSILES 1963 A2 to their present high reliability and esteem is confidently apply ing its skills and competence to the task of producing an equally reliable and successful Polaris A3. During 1958 it became likely that a reasonable measure of success would attend the development of an even more advanced Polaris missile—the Polaris A3, representing an advance over the A2 model even greater than that of the latter compared with the original Al. By 1960 the main elements of A3 were decided, and these are out lined in the table describing the main characteristics of the three types of missile. As already suggested, the design of Polaris A3 is very ambitious by previous standards, and (as reported in this journal last August 1) the early stages of the flight-test programme were noteworthy for the consistency of the failures; but things are now going much better. The first flight test of the A3 took place at Cape Canaveral on August 7, 1962. The A3 is scheduled to be operational by mid-1964. Missile Guidance The airborne inertial guidance system of the Al and A2 missiles is a refinement of earlier inertial systems, and is the smallest in use in US ballistic missiles. Using extremely precise gyroscopes, accelerometers and its own electronic computer, the system puts the missile on correct course at the time of the launch. Should the missile be moved off course by high winds or other disturbance, it automatically computes a new correct course and puts the missile on it. It also maintains the stability of the missile in pitch, yaw, and roll planes. At the precise instant required it shuts off the second-stage motor and triggers separation of the re-entry body from the missile. The re-entry body then follows a ballistic trajectory to the target. A new guidance system developed for use on the A3 missile is about one-third the size and weight of earlier Polaris guidance systems, making it the smallest and lightest so far developed for US ballistic missiles. The Submarine FBM submarines of the George Washington class are about 389ft long, with a beam of about 33ft, and surface displacement of about 5,900 tons. The George Washington herself (SSBN 598) was originally laid down as USS Scorpion. During construction she was cut in two and had a 130ft missile section added to convert her into the first FBM submarine. SSBN 599-602 were constructed to the same design. The first class of submarines designed to carry Polaris began with SSBN 608 Ethan Allen, the subject of the cutaway drawing. Ethan Allen class submarines are about 410ft long, and displace about 6,900 tons. Lafayette class submarines are about 425ft long, and displace some 7,000 tons. Ethan Allen and Lafayette FBM submarines will be able to launch all three generations of Polaris missiles. Ships of the George Washington class will be given this capability as they return to the United States for overhaul; at present, they are Al capable only. All three classes are driven by steam turbines powered by water- cooled nuclear reactors. Each class carries 16 missiles stowed in eight pairs of vertical launching tubes in the space immediately behind the sail. Each submarine has a 300-ton capacity (or greater) air-conditioning plant. FBM submarines are also equipped with air scrubbers and precipitators, to remove irritants from the air and maintain the proper balance of oxygen, nitrogen and other atmos pheric elements. Electrolytic oxygen generators permit the sub marine to manufacture its own oxygen from sea water. Navigation Two positions must be known for success in missile launching: target and launcher. In the FBM system this puts great FLIGHT International, 7 November 1963 importance on navigation, since the position of the launcher is the position of the ship and may be continuously changing. Several methods complement each other in the FBM submarine to provide a very high order of accuracy in determining this position. Heart of the system is the Ship's Inertial Navigation System (SINS), a complex system of gyroscopes and accelerometers which relates movement of the ship in all directions, ship speed through the water and over the ground, and true north, to give a continuous report of ship position. Each submarine has three SINS, each checking on the other. Systems similar to the SINS used in FBM submarines guided the Nautilus and Skate on their historic voyages beneath the polar ice in 1958 and, more recently, Triton on her 84-day underwater cruise around the world. The converted Mariner-class cargo ship USS Compass Island (EAG 153), serving as navigation test ship, has steamed well over 100,000 miles in development tests of the sub marine navigation system. A number of equipments are included in the submarine navigation system to provide an all-weather capability of checking on the accuracy of SINS. These include both optical and electronic devices; all are highly automated. Fire Control The fire-control system feeds to the missile guidance system co-ordinated information upon ship location, local vertical, true north, target location and trajectory to be flown. Corrections are supplied until the instant of fire. The fire-control mechanism can prepare missiles for launch at the rate of about one per minute. Communications Radio communication with submerged sub marines has been possible for a number of years. The systems used have been devised with special care to protect the location of the submarine and leave the advantage of concealment unimpaired. Recent tests have again demonstrated that the US Navy's world wide communication system has the power and coverage necessary to exercise command of the always-submerged FBM submarines. Cutaway illustration revealing major features of the Polaris A3, the latest of the family to be built. An A3X development missile is illustrated on page 756 1 Lockheed re-entry vehicle 2 Warhead 3 Equipment bay 4 Mk 2 inertial guidarce package , 5 Second-stage glass-wo. " 6 Liquid-injection TVC system 7 Four fixed nozzles 8 First-stage glass-wour. case 9 First-stage protective us ing 10 Launch-tube sealing Baps 11 Nozzle actuator grou!- 12 Four rotating nozzles
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
