F-4S Phantom II

The F-4S variant of the Phantom incorporated leading edge slats as well as advanced radar. A total of 302 [other sources place the number at 248 or 265] were converted to this configuration from existing Navy and Marine Corps F-4J airframes in the mid-1970s. The upgrade was intended to extend the service life of the aircraft pending replacement by the F/A-18 Hornet in Marine Corps service and by the F-14 Tomcat in Navy service. The F-4S was fitted with smokeless J79-GE-10B engines, solving the long-standing defect of earlier engines which produced a rather prominent trail of sooty black smoke.The principle mofidications included strengthening the airframe and landing gear. The aircraft were stripped and inspected, and received landing gear, wing and fuselage structural improvements as needed. Straps were added to the wing spar to improve structural integrity. The electrical system was completely rewired, and the hydraulic system was replumbed. Two-position wing leading-edge maneuvering slats were fitted, providing a 50 percent improvement in turning capability compared to the unslatted F-4J. The slats were were later retrofitted the initial batch of 43 F-4S aircraft. The F-4S was equipped with a digital AWG-10B weapons control system, a pair of new AN/ARC-159 l UHF radio, and some were fitted with the ARN-118 TACAN. The ALQ-126 or 126A electronic countermeasures set of the F-4J was retained.