Energy-based metrics for fighter aircraft assessment

Aerial combat is the cornerstone of military operations. One of the seminal elements that determine its outcome is aircraft maneuver. It is not easy to decide how fighter aircrafts will perform in combat, since reliable data regarding them are not usually available. Aircraft manufacturers and air forces frequently assert that their fighters are more superior than other equivalent fighters. However, they do not provide the real capabilities information of their fighters due to confidentiality reason. This study focuses on using existing flight envelopes and energy-maneuverability metrics for fighter aircraft assessment. The flight envelopes will be used to evaluate and compare fighter capabilities while the metrics will be applied to a decision process used to determine the best input strategy for various combat maneuvers. A fighter aircraft is hardly more superior than its adversary at every altitude and at all speeds. A well experienced pilot knows how to benefit from the weak points of the adversary. He/she may force the adversary at the points where his/her aircraft possesses obvious advantages and launches offensive actions. Pilot, who enjoys and can maintain this advantage, may not only control the combat but also determine its outcome. In this study, three diagrams that can be used to assess aircraft performance and maneuverability during combat will be discussed. They are V-n diagram, Specific Excess Power (P s ) diagram, and Energy-Maneuverability (E-M) diagram. V-n diagram shows the instantaneous maneuvering capability of an aircraft while P s diagram displays its sustained maneuvering capability. E-M diagram shows both the instantaneous and sustained maneuvering capabilities. Three comparison techniques using these envelopes, will be presented. They are V-n overlay, P s overlay, and E-M overlay. The fundamental rules for a successful aerial combat are quick kill, energy management, and assessment of transient characteristics. During combat, pilot must continuously evaluate his/her energy while at the same time assess the energy of the enemy. In an effort to gain energy advantage, both opponents will trade altitude for airspeed or airspeed for altitude many times. Energy should not be expended either too fast or too large. The assessment of aircraft transient characteristics allows us to give a final remark in determining the best input strategy for fighter maneuvers.