By the early 1980s the U.S. Air Force needed something to replace the ageing F-111 in the deep-interdiction role — an aircraft able to fly hundreds of miles behind enemy lines at night, in any weather, and hit point targets with precision. Two very different answers competed in the Enhanced Tactical Fighter / Dual-Role Fighter programme. General Dynamics offered the F-16XL, a dramatically re-winged single-seat Fighting Falcon with a cranked delta that could carry far more than a standard F-16. McDonnell Douglas offered the two-seat F-15E, developed largely at company expense.

On 24 February 1984 the Air Force chose the F-15E. The decisive factors were the Eagle’s two-crew cockpit — a dedicated back-seater to manage the growing workload of night, low-level precision attack — its greater growth potential, two engines for survivability, and the fact that it retained a first-rate air-to-air capability rather than trading it away. The F-16XL was shelved; the two prototypes later became NASA research aircraft. The Strike Eagle went on to become the backbone of American tactical strike aviation.

Standard fighters trade weapons for fuel: every underwing drop tank is a hardpoint you can’t use for bombs, and a lump of drag that eats range. The F-15E’s conformal fuel tanks solve both problems. Moulded to the contour of the fuselage beneath the wing roots, they add roughly 5,000 kg of fuel with only a small drag penalty, and they carry tangential weapon racks so ordnance sits close against the body rather than hanging in the airstream. The pay-off is a strike fighter that can fly a long, unrefuelled interdiction mission while still carrying a heavy mixed load of air-to-ground and air-to-air weapons — the reason the E can reach targets other tactical jets simply can’t.

The single most important difference between the F-15C and the F-15E is the second seat. Flying fast and low at night, hunting point targets while managing radar, targeting pod, defensive systems and weapons, is more than one person can safely do. The Strike Eagle’s weapon systems officer (WSO) sits behind the pilot with four multifunction displays, running the sensors and directing the attack while the pilot flies and handles the air-to-air fight. It is the same crewing philosophy that made the F-4 Phantom and F-111 effective at deep strike — and it lets a single F-15E prosecute complex attacks that would overwhelm a solo pilot.

The U.S. Air Force fact sheet lists a flyaway cost of about $31 million in constant 1998 dollars for the F-15E — but that figure should be read with care. It reflects late-1990s production accounting; in today’s money, and set against the far more expensive new-build F-15EX Eagle II (widely reported at well over $80 million per aircraft), the real cost of a modern Strike-Eagle-class jet is much higher. Operating cost is similarly steep: a twin-engine, two-seat, sensor-heavy jet is expensive per flight hour, with public estimates for the F-15 family generally in the range of tens of thousands of dollars per hour. Treat any single dollar figure as an order-of-magnitude guide rather than a precise price.