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Aviation History
1961
1961 - 1593.PDF
FLIGHT, 2 November 1961 697 TABLE I: STRATEGIC MISSILES SM-65 Atlas D SM-65A Atlas E SM-78 Jupiter SM-80 Minuteman Polaris A-l Polaris A-2 Polaris A-3 SM-75 Thor SM-68 Titan 1 SM-68B Titan 2 Propulsion Thrust (Ib) 2x 150,000 + 60,000 2> 164,500 + 60,000 150,000 three stages two stages two stages — 150,000 2/ 150,000 -i 80,000s 2X2I5,O00TIOO,00O3 Propellants LOS + RP-I LOj-t RP-ILO. + RP-I PBAA/PU PU/AP PU/AP — LO. + RP-I LO^-RP-I N,O4 + UDMH/H Length (ft) 82.5' 82.5 60.3 59.5 28 31 65 98 102 Body dtam (in) 120 120 105 71 54 54 54 96 120 120 Launch weight (Ib) 255,000 260,000 110.000 65,000 28,000 105,000 220,000 300.000 Range (n.m.) 9,000 10,000 1.500 5.500 1,200 1.500 2,500 1,500 8,000 12,000 Burnout Mach number 26 27 12 22 10 12 15 12 26 28 Estimated warhead (megatons) 3* 3 1.5 2 0.5 0.5 1.5 4 5 Notes: I, 75ft with Mk 2 re-entry vehicle: 2. can carry Titan heads: 3, in vacuo of a solid-propellant ICBM. Some of the problems loomed very large, but the obvious advantages of such a missile, and the steady progress made by the Navy Polaris, resulted in the programme being placed on a firm basis at the end of 1957. During 1958 the basic design was sketched as a three-stage vehicle standing no more than 60ft high, with a first-stage diameter of only about 6ft. It was envisaged that the first stage, or first and second, could be employed separately in order to meet requirements for "area-defence" or intermediate-range mis- sions; but at an early stage it was realized that the correct course of action was to develop a 5,500 n.m. ICBM of the highest possible quality, and not to compromise its design by trying to make portions of the vehicle fulfil other tasks. It is particularly worth noting that the new techniques introduced into the design of this missile reversed the normal trend in that, for the first time, a better weapon was being produced at a substantially re- duced cost. An outline of the basic design of the system is contained in this extract from an article published in the journal Ordnance, by Capt Frank King of the former Ballistic Missile Division: "Minuteman is the optimum ICBM configuration considered after years of extensive research ... It will be our first 'push-button' weapon system . . . The basic objective of the program is to initiate the complete development of a simple, low- cost weapon system capable of destroying enemy industrial areas with a high degree of reliability. The system is also designed to develop a capability as a counterforce weapon capable of attacking hard targets, such as other protected missile sites. . . . The Minute- man concept essentially encompasses a force of large numbers of missiles with fast-reaction, single-target capability per missile, hardened and dispersed operating facilities, utilization of existing DOD [Department of Defense] land, and a minimum of operational personnel. . . . Minuteman's smaller size, compared with liquid-propellant missiles, is primarily due to its three solid-fuel rocket engines, and lightweight warhead and guidance and control package. The third-stage motor also will permit thrust termination. Weight of the total missile will be in the 60,000 to 70,0001b class. . . . Minuteman will require approxi- mately only 10 per cent as many men per missile as the larger ICBMs.'" In October 1958 the Boeing Airplane Company (now the Boeing Company) were made the prime contractor for assembly and test. Although the focal-point of the large industrial team responsible for the weapon system, Boeing's Aero-Space Division at Seattle actually manufactures little of the missile itself. Development is managed by the Air Force Systems Command, and system engineering and technical direction are pro- vided by Space Technology Laboratories Inc. Essentially the missile consists of three solid-propellant motors of very advanced design, topped by a guidance bay and re- entry vehicle. After a great deal of develop- ment, the severe problems inherent in the manufacture of the cases and motor nozzles appear now to have been solved. Neverthe- less, the breadth of the research programme into these components makes it virtually cer- tain that no design will ever be regarded as final. For example, although high-tensile metals are at present used for the manufac- ture of the first- and second-stage motor cases, it is hoped that weight can be reduced still further in the future by the substitution of reinforced plastics. Contractor for the first-stage engine is the Thiokol Division of Reaction Motors, whose Wasatch division have built a special plant in Utah for this purpose. Several companies, especially Allison division of General Motors, have made the cases for this stage, but all production models appear to be fabricated b> precision-welding stainless-steel sheet with a u.t.s. of some 300,0001b/sq in. The lower end closure bulkhead is a convex pressing perfo- rated by four large holes into which are screwed the four propulsive nozzles. Development of nozzle systems capable of providing thrust-deflection for trajectory control was initially the chief mechanical problem facing the Minuteman designers. The only previous example of a large solid engine of such advanced design was the first stage of Polaris. In the latter missile four nozzles were preferred to one large nozzle in order to reduce missile length, while jet- evators (curved-section rings surrounding the nozzle exit) were considered to be the only feasible method of achieving such thrust deflection in the uncooled nozzles of a solid engine. MORE STRATEGIC MISSILES: 5, Minuteman; 6, Jupiter; 7,800-mile Russian missile first seen this year; 8, 500-mile Russian missile seen since 1957; 9, Polaris A-2; 10, Polaris A-l © Miffe Transport Publications Ltd 1961
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