Why Did McDonnell Douglas Build The C-17 Globemaster With 4 Engines?

Why did McDonnell Douglas design the C-17 Globemaster III with four engines instead of two or three? This question goes beyond a simple engineering choice: rather, it touches on the aircraft’s mission profile, operational demands, and the strategic needs of the USAF. The C-17 is one of the most versatile and capable military transport aircraft in history, and its four-engine configuration is central to its performance. Understanding why this decision was made reveals much about military aviation priorities in the late 20th century.