[1] Quail contained electronics and radar reflectors intended to make it indistinguishable from a B-52 approaching at low altitude.

Design of an improved version of Quail began in January 1968, with the system being termed the Subsonic Cruise Aircraft Decoy.

A requirement was established by the USAF Power Plant Laboratory at Wright-Patterson Air Force Base to support follow-on production of the XQ-4.

This requirement called for a small jet engine in the 2,000 lbf (8.9 kN) thrust class with a high thrust-to-weight ratio of 10:1.

During April 1955, the USAF began a program to develop a short range air-launched decoy missile to simulate the radar cross section of a bomber.

McDonnell Aircraft Corporation submitted a design which included a cropped-delta-wing decoy constructed largely of fiberglass and carried internally within a B-52.

The following month on February 1, 1956, the McDonnell Aircraft Corporation was awarded a contract to develop Weapon System 122A which included the GAM-72 Green Quail missile.

A slab-sided fuselage and two sets of vertical stabilizers contributed to the GAM-72s ability to simulate the radar cross section of a bomber.

[2] The GAM-72s guidance system could be pre-programmed on the ground to execute two turns and one speed change during a flight time of 45 to 55 minutes.

Before launch the bomber's radar navigator lowered the GAM-72 using a retractable arm from the airplane's weapons bay into the slipstream below the aircraft.

Flight testing of the XGAM-72 began in July 1957 at Holloman Air Force Base and the adjacent White Sands Missile Range.

Operational testing then moved to Eglin Air Force Base, Florida, United States where the 4135th Strategic Wing launched a GAM-72 on June 8, 1960.

This increase in weight when combined with a slightly smaller wing area reduced the maximum range of the GAM-72A to 402 statute miles (647 km).