CIM-10 Bomarc

The Boeing CIM-10 Bomarc ("Boeing Michigan Aeronautical Research Center") (IM-99 Weapon System prior to September 1962) was a supersonic ramjet powered long-range surface-to-air missile (SAM) used during the Cold War for the air defense of North America. In addition to being the first operational long-range SAM and the first operational pulse doppler aviation radar, it was the only SAM deployed by the United States Air Force.

Stored horizontally in a launcher shelter with a movable roof, the missile was erected, fired vertically using rocket boosters to high altitude, and then tipped over into a horizontal Mach 2.5 cruise powered by ramjet engines. This lofted trajectory allowed the missile to operate at a maximum range as great as 430 mi (690 km). Controlled from the ground for most of its flight, when it reached the target area it was commanded to begin a dive, activating an onboard active radar homing seeker for terminal guidance. A radar proximity fuse detonated the warhead, either a large conventional explosive or the W40 nuclear warhead.

The Air Force originally planned for a total of 52 sites covering most of the major cities and industrial regions in the US. The United States Army was deploying their own systems at the same time, and the two services fought constantly both in political circles and in the press. Development dragged on, and by the time it was ready for deployment in the late 1950s, the nuclear threat had moved from manned bombers to the intercontinental ballistic missile (ICBM). By this time the Army had successfully deployed the much shorter range Nike Hercules that they claimed filled any possible need through the 1960s, in spite of Air Force claims to the contrary.

As testing continued, the Air Force reduced its plans to sixteen sites, and then again to eight with an additional two sites in Canada. The first US site was declared operational in 1959, but with only a single working missile. Bringing the rest of the missiles into service took years, by which time the system was obsolete. Deactivations began in 1969 and by 1972 all Bomarc sites had been shut down. A small number were used as target drones, and only a few remain on display today.

During World War II, the US Army Air Force (USAAF) concluded that existing anti-aircraft guns, only marginally effective against existing generations of propeller-driven aircraft, would not be effective at all against the emerging jet-powered designs. Like the Germans and British before them, they concluded the only successful defence would be to use guided weapons.

As early as 1944 the United States Army started exploring anti-aircraft missiles, examining a variety of concepts. At the time, two basic concepts appeared possible; one would use a short-range rocket that flew directly at the target from below following a course close to the line-of-sight, and the other would fly up to the target's altitude and then tip over and fly horizontally towards the target like a fighter aircraft. As both concepts seemed promising, the Army Air Force was given the task of developing the airplane-like design, while the Army Ordnance Department was given the more ballistic collision-course concept. Official requirements were published in 1945.

Official requirements were published in 1945; Bell Laboratories won the Ordnance contract for a short-range line-of-sight weapon under Project Nike, while a team of players led by Boeing won the contract for a long-range design known as Ground-to-Air Pilotless Aircraft, or GAPA. GAPA moved to the United States Air Force when that branch was formed in 1947. In 1946, the USAAF also started two early research projects into anti-missile systems in Project Thumper (MX-795) and Project Wizard (MX-794).

Formally organized in 1946 under USAAF project MX-606, by 1950 Boeing had launched more than 100 test rockets in various configurations, all under the designator XSAM-A-1 GAPA. The tests were very promising, and Boeing received a USAF contract in 1949 to develop a production design under project MX-1599.