|Directory of U.S. Military Rockets and Missiles|
|Copyright © 2002 Andreas Parsch|
The Lacrosse was an SRBM (Short-Range Ballistic Missile) briefly deployed by the U.S. Army in the late 1950s, designed for close support of ground troops. It was designed for very high accuracy, but the technology of the day wasn't quite up to the task, and so the missile was not very successful in service.
Development of the Lacrosse began in late 1947 as a U.S. Navy project. The U.S. Marine Corps had a requirement for a short-range guided missile to supplement close-support artillery, and initial studies were made by the Applied Physics Laboratory (APL) of the John Hopkins University and the Cornell Aeronautical Lab. In June 1949, Cornell was tasked to develop a guided missile system conforming to the Lacrosse specifications. Around that time, the missile designator SSM-N-9 was assigned by the Navy to the Lacrosse project. In late 1949, the Joint Chiefs of Staff decided that responsibility for short-range ballistic surface-to-surface missiles should be assigned to the Army, and in August 1950, Lacrosse was officially turned over to the U.S. Army. The Army initially assigned a new basic designation of SSM-G-12 (the Navy reused the dropped SSM-N-9 designation later for the SSM-N-9/RGM-15 Regulus II), but in mid-1951, the Army slightly revised its missile designation system, and the designator was changed to SSM-A-12.
Component tests for Lacrosse began in late 1951, but development of the Lacrosse by Cornell and the Army was slow. E.g., it was not before January 1953, that the decision to use a solid-propellant rocket motor was finalized. The radio command guidance system of Lacrosse was first tested by air-launched RV-A-22 Lark test vehicles. These were converted Fairchild/Convair CTV-N-9/10 test missiles, which were itself derivatives of the XSAM-N-2/4 Lark naval surface-to-air missile. The RV-A-22 flights were conducted between April 1953 and January 1954. In August 1954, the first flight of an XSSM-A-12 Lacrosse prototype took place, and in April 1955, Martin was selected as prime contractor for the production of the SSM-A-12 tactical missile. Various production-related problems delayed the first flight test of a Martin-built Lacrosse (by that time known as Guided Missile, Field Artillery, XM4) until January 1957, and it took another two years of testing until the missile was ready for deployment. In July 1959, the M4 Lacrosse missile was finally delivered to operational Army units.
|Photo: U.S. Army|
The M4 Lacrosse SRBM was powered by a Thiokol XM10 solid-fuel rocket motor to a maximum range of about 19 km (12 miles). It was guided via radio commands by a forward observer/operator team within visual range of the target. When the observer had selected a target, he would fire the missile (located behind the lines on an XM398 transporter/launcher truck) by remote control. As soon as the portable tracking equipment detected the missile's tracking beam, the missile operator would optically track the missile and put it on the proper ballistic flightpath towards its target. The Lacrosse's large cruciform wings were fixed, and the missile was steered by its movable tailfins only. The visual tracking and manual guidance method meant that the Lacrosse was of very limited use in night or bad weather. Additionally, the radio command system was susceptible to jamming and countermeasures, which could render an approaching missile uncontrollable, endangering friendly troops. Furthermore, the Lacrosse required extensive maintenance and suffered from poor reliability. Although the Lacrosse was theoretically the most accurate field artillery missile of the time (it couldn't hit a moving target, though), its numerous problems prevented a successful service career.
|Photo: U.S. Army|
Because of all the shortcomings of Lacrosse, the USMC, which had been the original potential customer for the missile, backed out of the program in August 1959. In March 1960, the first overseas deployments of U.S. Army Lacrosse units occurred, but in January 1961, the Army decided to terminate Lacrosse procurement, and retire the missile as soon as possible. Withdrawal began in 1963, and in February 1964 the Lacrosse was no longer in the active Army inventory. Shortly before, in June 1963, the Lacrosse had received the designation MGM-18A.
Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!
Data for MGM-18A:
|Length||5.85 m (19 ft 2.4 in)|
|Wingspan||2.74 m (9 ft)|
|Finspan||1.43 m (4 ft 8.4 in)|
|Diameter||0.52 m (20.5 in)|
|Weight||1040 kg (2300 lb)|
|Range||19 km (12 miles)|
|Propulsion||Thiokol XM10 or XM10E1 solid-fuel rocket|
|Warhead||245 kg (540 lb) T-34 shaped-charge or W-40 nuclear fission (1.7 kT, 10 kT)|
 James N. Gibson: "Nuclear Weapons of the United States", Schiffer Publishing Ltd, 1996
 Bill Gunston: "The Illustrated Encyclopedia of Rockets and Missiles", Salamander Books Ltd, 1979
 Redstone Arsenal Historical Information Website
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