Following the service entry of the F-15A Eagle air superiority fighter in the U.S. Air Force in 1975, which gave the service a much needed counter to the similarly sized Soviet MiG-25 interceptor that had previously dominated the skies, the aircraft would be developed into a wide range of modernised variants. The F-15 today is the oldest fighter type in the world still in production, although variants built for specialised air superiority missions which the aircraft was originally designed for were phased out of production in the 1980s, with all subsequent variants being derivatives of the F-15E Strike Eagle design. The F-15E’s development was a major turning point in the program, and provided a highly versatile fighter with a combat potential for air-to-air engagements not too far inferior to that of the original F-15, and with a much needed long range strike capability.
The structure of the F-15E differed significantly from the original design, with the new aircraft’s thrust/weight ratio being significantly poorer primarily due to the aded weight of both conformal and external fuel tanks. Increasing fuel capacity was critical due to the F-15’s limited range, which although unrivalled for a fighter in a Western air force, was far shorter than new Soviet aircraft such as the Su-27 air superiority fighter and MiG-31 interceptor. While the original F-15 was built primarily as a single seat fighter, all F-15Es were built as twin seaters, allowing a second seat to accommodate a weapons systems officer who could engages ground targets while the pilot flew the aircraft and was responsible for air-to-air engagements. Unlike older American two seat aircraft, the crew of the F-15E were both able to control the aircraft, with each seat being equipped with its own controls and throttle.
The F-15’s avionics were also heavily modified to develop the F-15E variant, with the new AN/APG-70 radar system allowing it to detect ground targets at long ranges. To allow for low altitude flights and attacks on ground targets with precision-guided and unguided weapons, the aircraft was equipped with the low-altitude navigation and targeting infrared for night (LANTIRN) system, which profoundly increased the accuracy of air-to-ground weapons. This facilitated engagements at night and in poor weather regardless of visibility. The aircraft’s terrain following radar also incorporated autopilot system, optimising the fighter to fly at very low altitudes to evade radar detection when conducting strikes deep into hostile territory.
The F-15E would have a mixed combat record, with the shootdowns of two of the aircraft by Iraqi air defence systems that dated back to the 1950s raising serious questions regarding its survivability in airspace defended by more modern systems. The aircraft’s role would grow more significant following the retirement of the ageing F-111 strike fighter in 1996. The fighters would be incrementally modernised, most notably with the integration of new generations of armaments such as AIM-120 air-to-air missiles with active radar guidance, and with the AN/APG-82(V)1 active electronically scanned array radar which revolutionised situational awareness. Although a program was considered to develop a next generation successor to the fighter, the FB-22, the termination of these plans, deep cuts made to F-22 fifth generation fighter production, and major delays and cuts to F-35 production, have ensured that the F-15E fleet will continue to be relied on indefinitely with no sign of a replacement being under development.