What is specific excess power (Ps) and why is it important?

Specific excess power Ps = (T-D)*V/W = (Thrust - Drag) * Velocity / Weight, representing the rate of energy change per unit weight available for climbing or accelerating. When Ps > 0, the aircraft has excess energy for climb or acceleration; Ps < 0 means it is descending or decelerating; Ps = 0 represents level, unaccelerated flight. Ps diagrams (energy-maneuverability diagrams) compare aircraft performance for air combat analysis. Higher Ps means better ability to gain altitude or speed, crucial for fighter aircraft maneuvering.