AGM-69 SRAM

White Sands Missile Range Missile Park SRAM display

The Boeing AGM-69 SRAM (Short-range attack missile) was a nuclear air-to-surface missile designed to replace the older AGM-28 Hound Dog standoff missile.

History

The requirement for the weapon was issued by the Strategic Air Command of the United States Air Force in 1964, and the resultant AGM-69A SRAM contract was awarded to Boeing in 1966,^[1] After delays and technical flaws during testing,^[2] it was ordered into full production in 1971 and entered service in August 1972.^[3] It was carried by the B-52, FB-111A, and, for a very short period starting in 1986, by B-1Bs based at Dyess AFB in Texas. SRAMs were also carried by the B-1Bs based at Ellsworth AFB in South Dakota, Grand Forks AFB in North Dakota, and McConnell AFB in Kansas up until late 1993.

SRAM had an inertial navigation system as well as a radar altimeter which enabled the missile to be launched in either a semi-ballistic or terrain-following flight path. The SRAM was also capable of performing one "major maneuver" during its flight which gave the missile the capability of reversing its course and attacking targets that were behind it, sometimes called an "over-the-shoulder" launch. The missile had a Circular Error Probable (CEP) of about 1,400 feet (430 m) and a maximum range of 110 nautical miles (200 km). The SRAM used a single W69 nuclear warhead with a variable yield of 17 kilotons as a fission weapon, or 210 kilotons as a fusion weapon with tritium boost enabled. The aircrew could turn a switch on the Class III command to select the destructive yield required.

The SRAM missile was completely coated with 0.8 in (2.0 cm) of soft rubber, used to absorb radar energy and also dissipate heat during flight. The three fins on the tail were made of a phenolic material, also designed to minimize any reflected radar energy. All electronics, wiring, and several safety devices were routed along the top of the missile, inside a raceway.

On the B-52, SRAMs were carried externally on 2 wing pylons (6 missiles on each pylon) and internally on an eight-round rotary launcher mounted in the bomb bay; maximum loadout was 20 missiles. The capacity of the B-1B was 8 missiles on up to three rotary launchers (one in each of its three stores bays) for a maximum loadout of 24 missiles, all internal. The smaller FB-111A could carry two missiles internally and four more missiles under the aircraft's swing-wing. The externally mounted missiles required the addition of a tailcone to reduce aerodynamic drag during supersonic flight of the aircraft. Upon rocket motor ignition, the missile tailcone was blown away by the exhaust plume.

About 1,500 missiles were built at a cost of about $592,000 each by the time production ended in 1975. The Boeing Company sub-contracted with the Lockheed Propulsion Company for the propellants, which subsequently closed with the end of the SRAM program.

An upgraded AGM-69B was proposed in the late 1970s, with an upgraded motor to be built by Thiokol and a W80 warhead, but it was cancelled by President Jimmy Carter (along with the B-1A) in 1978. Various plans for alternative guidance schemes, including an anti-radar seeker for use against air defense installations and even a possible air-to-air missile version, came to nothing.

A new weapon, the AGM-131 SRAM II, began development in 1981, intended to arm the resurrected B-1B, but it was cancelled in 1991 by President George Bush, along with most of the U.S. Strategic Modernization effort (including Peacekeeper Mobile (Rail) Garrison, Midgetman small ICBM and Minuteman III modernization) in an effort by the U.S. to ease nuclear pressure on the disintegrating Soviet Union.

In June 1990, Defense Secretary Dick Cheney ordered the missiles removed from bombers on alert pending a safety inquiry.^[4][5] A decade earlier in September 1980, A B-52H on alert status at Grand Forks AFB in northeastern North Dakota experienced a wing fire that burned for three hours, fanned by evening winds of 26 mph (42 km/h). Fortunately, the wind direction was parallel to the fuselage, which likely had SRAMs in the main bay. Eight years later, weapons expert Roger Batzel testified to a closed U.S. Senate hearing that a change of wind direction could have led to a conventional explosion and a widespread scattering of radioactive plutonium.^[6]

The AGM-69A was retired in 1993 over growing concerns about the safety of its warhead and rocket motor. There were serious concerns about the solid rocket motor, when several motors suffered cracking of the propellant, thought to occur due to the hot/cold cycling year after year. Cracks in the propellant could cause catastrophic failure once ignited.

The SRAM was effectively replaced by the AGM-86 cruise missile.

Service history

The number of AGM-69 missiles in service, by year:

• 1972 - 227
• 1973 - 651
• 1974 - 1149
• 1975 - 1451
• 1976 - 1431
• 1977 - 1415
• 1978 - 1408
• 1979 - 1396
• 1980 - 1383
• 1981 - 1374
• 1982 - 1332
• 1983 - 1327
• 1984 - 1309
• 1985 - 1309
• 1986 - 1128
• 1987 - 1125
• 1988 - 1138
• 1989 - 1120
• 1990 - 1048 (deactivated by President George H.W. Bush)

Specifications

• Length: 15 ft 10 in (4.83 m) with tail fairing, 14 ft 0 in (4.27 m) without tail fairing
• Diameter: 17.5 in (0.44 m).
• Wing span: 2 ft 6 in (0.76 m).
• Launch weight: 2,230 lb (1,010 kg).
• Maximum speed: Mach 3.5
• Maximum range: 35–105 miles (56–169 km) depending on flight profile
• Powerplant: 1 × Lockheed SR75-LP-1 two stage solid-fuel rocket motor
• Guidance: General Precision/Kearfott KT-76 IMU and Stewart-Warner radar altimeter
• CEP: 1,400 ft (430 m)
• Warhead: W69 thermonuclear (17-200 kt of TNT)

See also

• Strategic Air Command

References

• Gunston, Bill (1979). Illustrated Encyclopedia of the World's Rockets & Missiles. London: Salamander Books. ISBN 0-517-26870-1

External links

• Air University and the 42nd Air Base Wing
• Strategic Air Command