The F-4 Phantom has arguably been the most glamorous, legend-airborne jet of all time—powerful, huge, and impossible to miss. Behind the legend of this aircraft, however, is the lesser-known story of the F-4X “Super Phantom” and its reconnaissance variant, a high-altitude machine born of audacious Cold War aspirations and desperate operational needs. It was an experiment in courage, marrying requirement to visionary engineering.
Early in the 1970s, the Israeli Air Force faced a critical dilemma. Soviet MiG-25s were cruising at speeds and heights that ruled out interception, while Israeli intelligence requirements continued to mount. Egyptian missile batteries were being hurriedly deployed across the desert, and RF-4 Phantoms had to fly low down enemy lines to locate them—the lethal game that had crewmen taking heavy fire. The Israelis needed a wiser, less dangerous way of collecting necessary intelligence.
The answer was to create a Phantom that would match or better the capabilities of the MiG-25, but with the finest recon technology available then. The center of this was the HIAC-1 LOROP camera, which had a detection capability as low as 25 centimeters at more than 20 nautical miles.
First, the G-139 camera pod of the aircraft, awkward and large, helped to slow the aircraft, and left the engineers with the task of fitting it into an airframe that was fast as well as survivable.
General Dynamics, the U.S. Air Force, and Israeli engineers rose to the challenge. After the lessons learned from record-breaking attempts like Operation Skyburner, they improved the F-4X in several different ways.
Conformal tanks of water and a water-methanol fuel injection system were fitted, cooling air as it entered the engines. This pressurized the airflow, boosting the power of the J79 engines by 50 percent. The Phantom could theoretically cruise at Mach 2.4, fly at top speed to Mach 3.2, and climb to nearly 78,000 feet.
The innovations did not stop there. The F-4X had bigger intakes, improved flight controls, a strengthened polycarbonate cockpit area, and a redesigned tail. Recce equipment was streamlined as well: the camera was miniaturized and installed directly into an elongated nose section, eliminating the drag of the external pod. Cooling systems flushed out optics at extreme altitude, and the jet still retained AIM-9 Sidewinders for defense.
On paper, it was the perfect high-altitude, high-speed spy aircraft—high enough to remain over harm’s way, too fast to outrun Soviet interceptors, and with unmatched photography capability. But life intervened. American officials did not want to export such a highly performing aircraft, so the Israeli RF-4X variant was downgraded, removing radar and guns, emphasizing only reconnaissance.
Meanwhile, the F-15 program was already in process, and the Air Force also viewed the F-4X as a probable budget and priority issue. Technical issues existed, too: the water-methanol system was overheating turbine blades, resulting in costly maintenance headaches that Israel was not able to take by itself alone.
But Israel refused to abandon the project. In 1974, the first Phantom thus adapted flew with the new camera. Two more aircraft were built as RF-4E(S) models—the “S” for “special.” These flew as usual at heights of some 70,000 feet, pilots and photographers dressed in pressurized suits copies of American high-altitude labor. They functioned for decades, only being taken out of service in 2004, one of them now on display at Hatzerim Air Force Base.
The story of the F-4X is one of vintage Cold War legend concerning ambition pushing technology to the breaking point. Never ever so much the revolutionary fighter its designers envisioned it to be, the F-4X left an indelible signature on reconnaissance aviation that demonstrated how passion and determination could push the boundaries of what was possible through times of crisis.