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The Hound Dog was the first fully operational standoff attack missile deployed by U.S. strategic bombers.

 

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GAM-77 (AGM-28A)

AGM-28B

In 1956, the USAF decided that its new B-52 Stratofortress bombers should have the option to use nuclear armed long-range standoff missiles to avoid direct over flight of heavily defended targets. By early 1957, the project was known as Weapon System 131B. The design competition was won by North American, and in October 1957, the designation GAM-77 was allocated to the WS-131B missile. The first powered flight of an XGAM-77 Hound Dog prototype occurred in April 1959, and the first fully guided flight succeeded in August in August 1959. The GAM-77 Hound Dog production missile was declared operational with SAC in December 1959. The quick development of the GAM-77 was made possible by the use of existing technology and components. The canard/delta layout of the airframe was proven by North American's own X-10 and XSM-64 Navaho vehicles, and the Pratt & Whitney J52 engine and W-28 thermonuclear warhead were also no new developments.

The GAM-77 was a turbo-jet powered air-launched cruise missile deployed by B-52G/H Stratofortress bombers, which could carry two missiles on underwing pylons. It used an inertial guidance system, whose data was continuously updated until immediately before launch by Kollsman KS-120 astro-trackers mounted in the launch pylons. The missile's navigation system could even be used by the B-52 crew, should the bomber's own system fail. The Hound Dog could fly high- and low-level missions, including pre-programmed changes in course and altitude. Maximum range for pure high-altitude flights was about 1100 km (700 miles).

Specifications
Data for AGM-28B:
Length	12.95 m (42 ft 6 in)
Wingspan	3.66 m (12 ft)
Diameter	0.71 m (28 in)
Weight	4500 kg (10000 lb)
Speed	Mach 2.1
Ceiling	16800 m (55000 ft)
Range	1100 km (700 miles)
Propulsion	Pratt & Whitney J52-P-3 turbojet; 33 kN (7500 lb)
Warhead	W-28 thermonuclear (1.1 MT)

The initial operational tests exposed some shortcomings, which led to the development of the improved GAM-77A version. In this version, the KS-120 astro-trackers were replaced by improved Kollsman KS-140 units, which were located in the missile. The GAM-77A also featured a radar altimeter to improve low-level performance, and a slightly larger fuel tank. The first XGAM-77A flew in June 1961, and the GAM-77A became operational in September that year.

In June 1963, the GAM-77 and GAM-77A were redesignated as AGM-28A and AGM-28B, respectively.

It was originally planned to replace Hound Dog in the mid-1960s by the AGM-48 Skybolt ALBM (Air-Launched Ballistic Missile), but the latter was cancelled in 1962. Therefore the AGM-28 remained in service until the 1970s, much longer than anticipated. Tests occurred with a TERCOM (Terrain Contour Matching) guidance system in 1971, and an anti-radiation seeker head in 1973. These features were not incorporated in any operational Hound Dogs, although the designation AGM-28C was reportedly reserved for a TERCOM-equipped Hound Dog. Beginning in 1972 the Hound Dog was replaced by the AGM-69 SRAM, and in 1976 the last AGM-28 was retired from USAF service. Between 1959 and 1963, North American had built more than 700 Hound Dog missiles, with a peak deployment level of about 600 in 1963.

Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Main Sources

[1] James N. Gibson: "Nuclear Weapons of the United States", Schiffer Publishing Ltd, 1996
[2] Bill Gunston: "The Illustrated Encyclopedia of Rockets and Missiles", Salamander Books Ltd, 1979
[3] Dennis R. Jenkins, Brian Rogers: "Boeing B-52G/H Stratofortress", Aerofax, 1990

 

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