The Williams F107 (company designation WR19) is a small turbofan engine made by Williams International. The F107 was designed to propel cruise missiles. It has been used as the powerplant for the AGM-86 ALCM, and BGM-109 Tomahawk, as well as the experimental Kaman KSA-100 SAVER and Williams X-Jet flying platform.
The Williams International F122 is a twin-shaft, axial-centrifugal-flow turbofan that is similar to the F107 in configuration but has a maximum thrust of 900 lbf (3.33 to 4.0 kN).
The F122 is used to power the KEPD 350 air-launched cruise missile, and was the powerplant for the cancelled AGM-137 TSSAM air-launched cruise missile. Although the AGM-137 was cancelled, the F122 was first used for the Taurus KEPD when it was flown aboard that missile in April 2002.