as well. To reach the intended range, this new Extended Range Version (ERV) would have to be lengthened to contain more fuel, or external fuel tanks would have to be added. Either change would make it too large to fit on the SRAM launchers, and more annoyingly, the extended-fuselage version would be too large to fit in the bomb bay of the new B-1 Lancer bomber. The Air Force intended to replace the original ALCM with the new version at some future date. The Navy was also in the midst of its own cruise missile project, the Sea-Launched Cruise Missile (SLCM), which ultimately emerged as the BGM-109 Tomahawk, which was similar to ALCM in many ways. In 1977, the Air Force and Navy were ordered to collaborate under the "Joint Cruise Missile Project", JCMP, with the intention of using as many parts in common as possible. After considering the two designs, the Air Force agreed to modify the ALCM with the SLCM's McDonnell Douglas AN/DPW-23 TERCOM system, as well as using its Williams F107 turbofan engine. While the JCMP program was taking place, the B-1 was canceled. This eliminated the need for ALCM to fit in the B-1's bomb bay, and the length limitations that implied. The Air Force decided to cancel production of the A-model ALCM, and replace it with either an air-launched version of the SLCM, or the ERV. The ERV flew in August 1979, and was declared the winner of the head-to-head fly-off against the SLCM in March 1980. Initial production Production of the initial 225 AGM-86B missiles began in fiscal year 1980. It entered operational use on the B-52H in August 1981 and became its primary weapon in December 1982. Production of a total 1,715 missiles was completed in October 1986. The air-launched cruise missile had become operational four years earlier, in December 1982. More than 100 launches have taken place since then, with a 90% approximate success rate. CALCM In June 1986 a limited number of AGM-86B missiles were converted to carry a high-explosive blast/fragmentation warhead and an internal GPS. They were redesignated as the AGM-86C CALCM. This modification also replaced the B model's TERCOM and integrated a GPS capability with the existing inertial navigation system computer . In 1996 and 1997, 200 additional CALCMs were produced from excess ALCMs. These missiles, designated Block I, incorporate improvements such as a larger and improved conventional payload