In the annals of military aviation history, the F-15N Sea Eagle stands as a fascinating “what if” scenario. The brainchild of the early 1970s, this navalized version of the Air Force’s F-15 Eagle was to be McDonnell Douglas’s ambitious proposal to the U.S. Navy for something faster, lighter, and more maneuverable than the F-14 Tomcat.
This proposal was against the backdrop of the Navy’s ongoing quest for an advanced carrier-based air superiority fighter. Initial consideration was given by the Navy to the General Dynamics F-111B, which was to have commonality with the Air Force’s F-111A in keeping with the Department of Defense’s desires. However, the F-111B was canceled in April 1968 because it was too heavy for carrier operations.
Subsequently, the Navy issued a new design competition, known as the VFX program, in which McDonnell Douglas and Grumman became the two main competitors. Grumman’s proposal—the Model 303—was a variable-geometry design centered on the Hughes AWG-9 weapons system that evolved into what would become the F-14 Tomcat. McDonnell Douglas offered a navalized version of its then-new F-15 Eagle, known as the F-15N Sea Eagle.
The Sea Eagle would require numerous changes to make it suitable for carrier operations: folding wings, a proper arresting hook, and landing gear strengthening. Nevertheless, McDonnell Douglas avowed that the F-15N would be much faster and more maneuverable than the F-14. But the original proposal dispensed with the AIM-54 Phoenix missiles and the AN/AWG-9 radar necessary for the Navy’s long-range interception requirements.
A Navy study investigated equipping the F-15N with these systems, but a Navy-configured aircraft would have been 10,000 pounds heavier than an F-15A, negating the F-15’s performance advantages. McDonnell Douglas offered to upgrade the F-15 radar, the AN/APG-63 to communicate with the AIM-54, but that came to nothing.
In March 1973, the naval F-15 proposal was given an initial review by a Senate subcommittee. The other candidates under scrutiny were a stripped-down F-14 variant and an F-4 spiced-up. Though some points were brought forward regarding a fly-off between the F-14A and the F-15N, this was never carried out.
Eventually, this aircraft, the F-14 Tomcat, became very capable with the Navy. The Tomcat first flew in December 1970, went through a series of variants, and finally entered fleet service in June 1972. Its ability to attack numerous enemy aircraft at long ranges with the AIM-54 Phoenix missile made it an asset during the Cold War.
While the F-15N Sea Eagle never came into being, the effort to develop it influenced the broader naval aviation environment. The Senate hearings and subsequent studies spawned Navy Fighter Study Group IV, from which the F/A-18 Hornet emerged.
The story of the F-15N Sea Eagle is instructive, showing just how design requirements and technological capabilities are interwoven with the political considerations that shape military aviation. It never flew, yet the legacy of the Sea Eagle survived as a fitting tribute to ingenuity during those times.