This was one of the original YRF-4C prototypes that was converted into the YF-4E. The YF-4E was used in the development of the F-4E fighter as well as in fly-by-wire Precision Aircraft Control Technology (PACT) and Control Configured Vehicle (CCV) test programs. Three conversions.
A "Fly-by-Wire" control system was installed in Number 266, and a distinctive color scheme was applied to the airplane for this flight test program, which commenced on 29 April 1972.
The museum's airframe served as a prototype for the RF-4C reconnaissance version and later the F-4E fighter-bomber variant. It also was the test bed for such advanced ideas as F-4 leading edge slats and the "Fly-By-Wire" concept (electrical rather than mechanical interconnections between pilot and control surfaces). A final modification added distinctive wing-like canard surfaces to examine the Precision Aircraf
