Energy Maneuverability theory is a model of aircraft performance. It was promulgated by Col. John Boyd, and is useful in describing an aircraft's performance as the total of kinetic and potential energies or aircraft specific energy. It relates the thrust, weight, drag, wing area, and other flight characteristics of an aircraft into a quantitative model. This allows combat capabilities of various aircraft or prospective design trade-offs to be predicted and compared.
![P_s = \left [ \frac{T - D} W \right ] V](../../_Media/pastedgraphic-5.jpeg)
Specific power equals thrust minus drag, divided by the aircraft's weight, times the current velocity. Power is a force times a velocity; any parameter termed "specific" is normalized to either the mass or weight, hence the "s" subscript.
Boyd, a skilled U.S. jet fighter pilot in the Korean War, began developing the theory in the early 1960s. He teamed with mathematician Thomas Christie at Eglin Air Force Base to use the base's high-speed computer to compare the performance envelopes of U.S. and Sovietaircraft from the Korean and Vietnam Wars. Their work was unwelcome, but they were able to complete a two-volume report on their studies in 1964. Energy Maneuverability came to be accepted within the U.S. Air Force and brought about improvements in the requirements for the F-15 Eagle and later the F-16 Fighting Falcon fighters.
