Boeing Ground-to-Air Pilotless Aircraft

The Boeing SAM-A-1 Ground-to-Air Pilotless Aircraft (GAPA) was a short-range missile for USAF anti-aircraft research by the Boeing Aircraft Company with Aerojet rocket boost that was launched over 100 launched times by 1950 from the GAPA Launch Site (cf. Green River Launch Complex). The predecessor of the long range CIM-10 Bomarc, GAPA was based on a preliminary 1945 study for a supersonic vehicle with "a range of 35 miles".

At the 100 x missile launch complex on the WWII Wendover Bombing and Gunnery Range beginning June 13, 1946, "38 GAPA launchings in a 2-week span…ended with a July 1 shot"; and by October 1957, the GAPA range was identified as only 30 miles in a report to the President's Air Policy Commission (by the end of 1947 a "50-mile", Mach 0.9 version was identified as needed for the "interim" air defense system.) In early 1948 the USAF was "ready to buy complete GAPA missiles for test and training purposes, [but] guidance components were not available", and of the planned $5.5 million for GAPA, only $3 million was identified in July 1948. Boeing produced the Boeing Electro-Mechanical Analogue Computer (BEMAC) and the Boeing Electronic Analogue Computer (BEAC) for developing GAPA and at the end of 1948, Air Material Command "was instructed to buy 70 test vehicles". Over 74 launches were at the Alamogordo Guided Missile Test Base beginning on July 23, 1947 (the 39th launch) with 3 JATO for initial liftoff, and the program was cancelled in 1949 when the Joint Chiefs of Staff designated the Army be responsible for short-range air defense. The last GAPA, "number 114, was launched 15 August 1950."

In early 1950 Boeing collaborated on a >100 mile anti-aircraft missile study with the University of Michigan, which was developing a long range defense against ballistic missiles. The study's conclusion announced in June 1950 identified a proposed range of 250 miles against supersonic aircraft, and the resulting program was for the CIM-10 Bomarc.