The North American ''Rapier'' was a short lived, Long Ranger Interceptor, specifically designed to engage possible Soviet Bombers. First envisioned in 1957, The XF-108 ran into (2) major problems. The first, was it's overall expense of $142 Million USD each (1950s Currency). By today's standards, The ''Rapier'' would have easily hit 1.24 Billion USD each. This coupled with The Soviet Union deciding to concentrate of ICBM Programs, cost North American to scrap The XF-106 before a functional prototype could be produced (1959).
Easily one of the heaviest Interceptors ever built (at 76,000-lbs), The ''Rapiers'' would have been 90-feet long with a modified swept-wingspan of 60-feet. Piloted by (2), The XF-108 was to receive Twin GE J93 Afterburning Turbojets capable of a rated IBF (Thrust) of 20,000. Airspeed was rated to over 1,900-mph with a Mission Range of 1,100-miles. The ''Rapier'' touted an operational ceiling of 80,000-feet. Armament was to be (6) Hughes AA Rotary Missiles.