ROSS R. HATCH, JOSEPH L. LUBER, and JAMES H. WALKER FIFTY YEARS OF STRIKE WARFARE RESEARCH AT THE APPLIED PHYSICS LABORATORY This article recounts the Applied Physics Laboratory's contributions to the field of cruise missiles and their application to strike warfare from the initial concepts through the development of the U.S. Navy antiship Harpoon and the Standoff Land-Attack Missile to the long-range Tomahawk land-attack and antiship missile variants. The first operational use of Tomahawk and the Standoff Land-Attack Missile in January 1991 made significant contributions to the neutralization and destruction of Iraqi air defense, command and control, and weapons storage facilities. The more than four decades of hard engineering work by dedicated teams from the Navy, industry, and the Laboratory that contributed to this success will be surveyed chronologically with an emphasis on the complex interactions that occurred among various mission areas. Strike warfare or the projection of power has been a battleships, attack submarines, cruisers and destroyers is principal role of the U.S. Navy from its inception. For a precursor to the multi-mission utility we must continue most of the last fifty years, the U.S. Navy has primarily to emphasize in the future. " been dedicated to the containment of the Soviet Union's The Applied Physics Laboratory has contributed to the attempts to spread communism throughout the globe. field of cruise missiles and their application to strike This effort has involved both the frequent show of force warfare from the initial concepts in the late 1940s and and, when required, the application of seapower to ac­ in the 1950s through the development of the U.S. Navy complish a specific end. Most recently, although the antis hip Harpoon and the Standoff Land-Attack Missile threat of Soviet expansionism has greatly diminished, the (SLAM) to the long-range Tomahawk land-attack and anti­ security of the United States and world order was threat­ ship missile variants. The first operational use of Tom­ ened by the actions of Iraq. The response to this threat ahawk and SLAM in January 1991 made significant con­ once again pointed out the flexibility of the Carrier Battle tributions to the neutralization and destruction of Iraqi air Group but for the first time brought into play the use of defense, command and control, and weapons storage fa­ ship- and submarine-launched cruise mis ile as a com­ cilities and therefore played a significant role in the suc­ plement to air strikes. cessful outcome of Operation Desert Storm. This success In response to the significant changes throughout the reflects over four decades of hard engineering work by world, the Navy has developed a new strategic policy dedicated teams from the Navy, industry, and APL. The termed "The Way Ahead." The policy emphasis has history of cruise missile development is complex, for the shifted from one of containment of the Soviet Union to emphasis continually shifted between strategic and tac­ one of worldwide crisis response. In the April 1991 Pro­ tical roles and between land-attack and antiship missions. ceedings, I Secretary of the Navy Lawrence Garrett and The story could be told in a multitude of ways empha­ ADM Frank Kelso, the Chief of Naval Operations (C 0 ), sizing each of these areas. To simplify the story we will noted that, ' Untethered from the earlier predominant use a chronological approach and describe events as they concern with the global war at sea scenario, we have a happened over broad periods of time. As a result, we will new flexibility to shape our combat punch to prescribed move across various mission areas and try to reflect the missions and expected threats." The article also noted intricate synergism that occurred among the various pro­ that greater flexibility exists in the selection of weapons grams and subprograms. for use in the application of this new policy. "Comple­ menting carrier airpower is the formidable firepower dis­ THE 1950s tributed through our modem surface combatants and at­ The success of the proXImIty fuze program at APL tack submarines. Major advances in weapons technology during World War II led to significant new assignments have brought longer ranges and greater accuracy in from the U.S. Navy's Bureau of Ordnance. At this time, weapons and combat systems small enough to be em­ in keeping with the Navy's great concern over the air­ ployed from a variety of platforms, making it possible to launched antiship missile, APL'S priority was the devel­ disperse a significant amount of firepower. The effective opment of air defense missile systems. Though strike employment of Tomahawk missiles against Iraq from weapons received less attention, the potential for long- Johns Hopkins APL Technical Digest, Volume 13, Number I (1992) 113 R. R. Hatch, 1. L. Luber, alld 1. H. Walker range mjssile was fully appreciated, and the Bureau initial studies was enormous. The great size of the inertial charged the Laboratory with the conduct of a research navigator motivated experiments in magnetic midcourse effort for a strategic application that became known as guidance as previously described. Inertial system size and the Triton Program. Early studies of long-range missile weight, however, proved to be a temporary problem. The technology concluded in the selection of a ramjet power rapid pace of improvements in inertial navigation has plant for Triton that would propel the mi ile at very high continued into the 1990s with laboratory products of altitude and at supersonic speed. This choice resulted in great accuracy now emerging that can be held in the palm a synergi tic relation hip between the Triton and Talos air of one's hand. defense program , and the fea ibility of ramjet propul­ Low-level effort continued on Triton until mid-1955. sion, large solid-fuel rocket boo ters, and a large 48-in. Notable progress in all technjcal areas encouraged the ramjet combu tor wa quickly demon trated. Nuclear Navy to fund a full-scale effort to provide a tactical warheads, an outgrowth of World War II, were part of weapon. A. George Carlton provided leadership of the every conceptual strategic long-range missile study of the program in this expanding phase. The principal contrac­ period. The Applied Physics Laboratory, with an appre­ tors were McDonnell Aircraft Corporation (vehicle and ciation for the role of accurate deli very of ordnance integration), Goodyear Aircraft (radar map matcrung), gained in the proximity fuze program, tressed the im­ Kearfott (inertial navigation), Convair (ramjet propul­ portance of accuracy in minimizing warhead yield re­ sion), and Allegheny Ballistics Laboratory (rocket boost­ quirements and collateral damage to nonmilitary targets. er ). Construction of flight test verucles was progressing Accuracy was recognized as an es ential, and absence of well in September 1957, when the program wa returned a workable approach delayed the initiation of full-scale to a research phase. This phase was terminated in 1959 Triton development for several years. following documentation of an improved performance Researchers conducted surveys, analyses, and exper­ version of Triton that featured a further reduction in size. iments to provide a ound basis for assessing the guid­ The Triton program contributed to the rapid pace of ance situation. Magnetic lines of force were considered technology advancement, some of which had broader for midcourse guidance, and anomalies in the Earth's application than just the particular usage in Triton or field were examined to see if they could be used to missile guidance. One remarkable example is in the area provide a fix near the target. Visual and infrared radiation of signal filtering. In brief, Triton's map-matcher results and reflection from various objects as well as the alter­ were applied to its inertial navigator by a Conection nating cunent magnetic field and the electrostatic field Computer developed by APL. The Conection Computer from cities, tran mission lines, and power plants were was a forerunner of the Kalman filter. The next several considered. Of the concepts investigated in this early paragraphs outline the story of this development and its period, only radio frequency beacons placed near the significance. target by an agent provided a satisfactory solution with In the late 1940s and early 1950s APL had become a available technology. The tactical deficiencies, however, leader in optimal guidance and control technique with were all too obviou . application to surface-to-air missiles. In 1956, Jame W. A British development from World War II appeared to Follin, Jr., developed the theory for the transient re ponse have promise as a guidance system. The system, code­ of a tracker with noise and maneuver and determined the named H2S, depended on an airborne active radar to il­ optimum time-varying gain.2 He presented hi results for luminate cultural and prominent geographic features; a one-dimensional tracker at an Advisory Group for Aero­ the return signal was processed to obtain range and bear­ space meeting on guided missiles. In 1957 James E. ing to object in the field of scan and displayed on a Hanson used the calculus of variations to prove that the cathode ray tube. The re ult was a "live" radar map that method was mathematically sound and extended the re­ could be compared with a chart and u ed by an aircraft sults to systems with acceleration constraint .3 When the crew to navigate accurately even if the route to the target Triton problem arose, engineer recognized that little dif­ were obscured by clouds. The H2s-equipped aircraft ference exists between tracbng a maneuvering target and would fly in a pathfinder role, dropping marker flares for tracbng randomly varying inertial system drift, 0 that the following aircraft that conducted area bombing.