In 1986, two consortiums were created to develop prototypes for the next generation fighter plane.  One group, led by Lockheed, was contracted to build two YF-22A prototypes; the second, led by Northrop, was to build two YF-23A prototypes.  Together, they would have a fly-off to determine which plane the government would order.  The competition was made more intense by the specification that two engines -- the GE YF120-GE-100 and the Pratt & Whitney YF119-PW-100 -- be tested along with the airframes.   The two engine manufacturers had already been engaged in a heated competition, and the fly-off was going to be the final shoot-out.