Flight Theory for Pilots

This is a good introductory flight-mechanics reference for commercial pilots and instructors. It covers all the elements of primary and advanced aeronautics that arise in pilot training courses. The text is divided into several principal sections for flight students:

Subsonic flight
Transonic flight
Supersonic flight
Propeller-driven aircraft
Turbojet powered aircraft
Rotorcraft

This book offers excellent explanations of such key concepts as Range and Endurance, Lift/Drag relationships, flight at minimum controllable speed (slow flight), stalls, spins, power-required curves, transonic flight and mach effects, and rotary-wing flight. Some schools prefer Understanding Flight, or Aerodynamics for Naval Aviators [both use American units]. They're all useful.