The F-4 Phantom, a par-excellence fighter bomber designed by McDonnell Douglas, has a rich history characterized by outstanding performance and far-reaching use. First going into service in 1961, the Phantom was a record-breaker with unprecedented altitude and speed achievements. It showed its value in different branches of the U.S. military and became a part of the air forces in 11 other nations, such as Israel.
The F-4X, is a planned high-speed reconnaissance version of the F-4 Phantom for the Israeli Air Force. This ambitious effort was designed to give the F-4 more thrust and lower drag, propelling it to speeds that could approach or even exceed the fastest fighters of the day.
The origin of the F-4X is found in the Israeli Air Force’s (IAF) reconnaissance problems in the early 1970s. The Soviet MiG-25 Foxbat overflights, conducted at altitudes and speeds beyond the capabilities of the IAF’s current inventory, created an urgent need for a high-speed reconnaissance airplane. This urgent need spawned the study of advanced technologies and ultimately led to the development of the F-4X concept.
The F-4X was not just an incremental step; it represented a revolutionary advance in performance. Demineralized water would be employed for pre-compressor cooling (PCC) of the General Electric (G.E.) J79 engines, which, without diving into too much technical detail, were computed to raise the engines’ thrust by 50%. On paper, the F-4X was a wonder that would cruise at Mach 2.4 and run at a mind-boggling Mach 3.2.
But, as usually seems to be the case with leading-edge aerospace projects, problems soon cropped up. General Dynamics, responsible for the program, realized that water injection might cause expansion of the engine compressor blades, with potentially disastrous engine failure. The shifting strategic environment, including the impending rollout of the McDonnell Douglas F-15 Eagle, also came to overtake the F-4X’s potential.
