Sergeant began in 1948 as a solid-propellant successor to the Corporal battlefield ballistic missile. However both JPL and Thiokol concluded that large solid-motor technology was not yet ready. New motors with star configuration propellant loads tested under General Electric's Hermes A2 project provided the necessary breakthrough. Hermes was cancelled in 1953 due to interminable delays, and the Army requested proposals for Sergeant from other contractors. In January 1955 JPL was selected as development contractor, and the first missile was launched in 1956. Sperry Utah was selected as production contractor, and Sergeant replaced Corporal in Army service beginning July 1962. Sergeant was in turn replaced by the Lance missile in 1972-1977.
Sergeant's inertial guidance and solid propellant motor meant that logistics were vastly reduced. The missile could be launched within 90 minutes after reaching the launch location, compared to nine hours for Corporal. Range was controlled on Sergeant by drag-brakes, which counteracted the solid motor's thrust to reduce range from the maximum achievable.
Failures: 3. Success Rate: 98.31%. First Fail Date: 1958-11-20. Last Fail Date: 1985-06-17. Launch data is: complete. Development Cost $: 172.100 million. Recurring Price $: 0.750 million in 1960 dollars. Flyaway Unit Cost $: 0.405 million in 1960 dollars. Standard warhead: 820 kg (1,800 lb). Maximum range: 139 km (86 mi). Number Standard Warheads: 1. Standard warhead: W52. Warhead yield: 200 KT. Boost Propulsion: Solid rocket. Maximum speed: 5,650 kph (3,510 mph). Initial Operational Capability: 1962. Total Number Built: 473. Total Development Built: 64. Total Production Built: 409.
Historical Essay © Andreas Parsch
JPL-Sperry SSM-A-27-M15-MGM-29 Sergeant
The Sergeant was the first solid-fuel surface-to-surface missile deployed by the U.S. Army, and replaced the MGM-5 Corporal as the Army's medium-range tactical ballistic missile.
As early as 1948, JPL (Jet Propulsion Laboratory) and Thiokol studied new solid-propellant rocket designs for the U.S. Army under the name Sergeant, but this didn't produce an acceptable motor for tactical missile applications. However, solid-rocket development continued for General Electric's XSSM-A-13 Hermes A2 project, and a new motor with an internal "Burning Star" design was tested in the RV-A-10 test vehicles. This was a core-burning solid-fueled rocket engine, in which the surface area of the burning fuel remained constant. Therefore this engine type combined the advantages of the earlier end-burning (constant thrust) and core-burning (light-weight structure, because fuel acted as insulator) rocket designs. In late 1953 the RV-A-10 test program was completed, but the SSM-A-13 Hermes A2 had been cancelled. At the same time, the Army requested proposals from several companies for the development of a new solid-rocket SSM, to be named Sergeant. The Sergeant tactical surface-to-surface missile program was finally officially started in January 1955 with JPL as prime contractor, and the designation SSM-A-27 was assigned to the missile. Some sources show a designation of SSM-A-26, but this is definitely incorrect. The SSM-A-27 designator was short-lived anyway, because the U.S. Army stopped to use this designation system in June 1955.
The first experimental Sergeant missile was launched in 1956, and the Sperry Utah Company was chosen as primary subcontractor for missile production. In 1960, Sperry became prime contractor for the Sergeant, and in July 1962 the Sergeant was operationally deployed for the first time. By that time, the missile had received the designation Guided Missile, Artillery XM15, and quickly began to replace all MGM-5 Corporal missiles.
Compared to the Corporal, the Sergeant was a much better operational missile. Its solid-fuel rocket motor was safer and more reliable than the Corporal's liqued-fueled one. The guidance method was also different. Instead of command guidance, the Sergeant used an AN-DJW-8 inertial guidance system by Sperry Gyroscope. This was more resistant to countermeasures and required much less ground equipment. Because the solid-rocket motor could not be shut off once ignited, range was controlled by drag-brakes, which were opened by the guidance system about halfway through the planned flight path. These drag-brakes neutralized engine thrust, causing the missile to follow a ballistic flight path back to the ground. A complete Sergeant system could be moved with significantly less effort than a Corporal system, and the first missile launch could be achieved less than 90 minutes after the launch site had been reached (compared to 9 hours for Corporal).
In 1963 the XM15 Sergeant missile was designated as XMGM-29A, which was soon changed to MGM-29A. In 1972 the new MGM-52 Lance missile began to replace the MGM-29A, and the last Sergeant was retired from U.S. Army service in May 1977. In German Army service, the Sergeant lasted two years longer, until it was also replaced by the Lance. About 500 MGM-29 missiles were produced for the U.S. Army.Specifications
Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!
Data for MGM-29A:
|Length||10.5 m (34 ft 6 in)|
|Finspan||1.5 m (5 ft)|
|Diameter||0.78 m (31 in)|
|Weight||4570 kg (10100 lb)|
|Range||Min: 46 km (25 nm); Max: 140 km (75 nm)|
|Propulsion||Thiokol XM100 solid-fueled rocket motor; 200 kN (45000 lb) for 34 sec|
|Warhead||W-52 thermonuclear (200 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
AKA: M-20; MGM-29A; Sergeant; SSM-A-26 / M15.
Status: Retired 1994.
Gross mass: 4,530 kg (9,980 lb).
Payload: 820 kg (1,800 lb).
Height: 10.52 m (34.51 ft).
Diameter: 0.79 m (2.59 ft).
Span: 1.80 m (5.90 ft).
Thrust: 200.00 kN (44,960 lbf).
Apogee: 80 km (49 mi).
First Launch: 1956.01.19.
Last Launch: 1994.08.18.
Number: 177 .