SAM-A-1 GAPA

SAM-A-1 GAPA
Final check of Model 601 prior to launching at Holloman Air Force Base, c. 1949.
Type	Surface-to-air missile
Place of origin	United States
Service history
In service	1946-1950
Used by	United States Air Force
Production history
Designed	1946
Manufacturer	Boeing
Specifications (Model 603)
Mass	2,000 pounds (910 kg) w/o booster[1]
Length	21 ft (6.4 m) w/o booster
Diameter	10 in (250 mm)[2]
Wingspan	9 ft (2.7 m)
Engine	Sustainer: Ramjet Booster: Solid-fueled rocket
Operational range	31 miles (50 km)[3]
Flight ceiling	59,000 ft (18,000 m)
Maximum speed	1,500 mph (2,400 km/h; Mach 2.0)
Guidance system	Midcourse: Beam riding Terminal: Active radar homing
Launch platform	Rail Launcher

The Ground-to-Air Pilotless Aircraft (GAPA) was a short-range surface-to-air missile (SAM) developed in the late 1940s by Boeing for the United States Army Air Forces, and then the United States Air Force after 1948. It was given the reference number SAM-A-1, the first Surface-to-Air Missile (SAM) in the 1947 tri-service designation system. By 1950, over 100 test rockets had been launched using a variety of configurations and power plants, with one launch in 1949 setting the altitude record for a ramjet powered vehicle at 59,000 ft (18,000 m).

GAPA faced strong competition from the United States Army's Nike missile system, and was eventually cancelled in favour of Nike for deployment. The GAPA work was later re-used by the Boeing and Project Wizard team at the Michigan Aeronautical Research Center to develop a much longer-ranged missile, the CIM-10 Bomarc for the Air Force. The Bomarc would end up competing with the Army's Nike Hercules, and was deployed only in small numbers.