Fundamentals of Helicopter Aerodynamics

The language of instruction is English.

Upon successful completion of the class, the students have a good understanding of the fundamentals of rotor aerodynamics, and to a lesser extent, of the overall helicopter aerodynamics. The taught theories form the basis of any further and more advanced treatment of specific flow problems in helicopter aerodynamics and helicopter design. Therefore, this class focuses on laying the groundwork for more advanced analyses of rotorcraft. That is, the treated aerodynamic principles of rotary-wing hover and forward flight are fundamental to any more advanced studies of rotor and helicopter aerodynamics, as they are taught, e.g., in the class "Helicopter Aerodynamics: Advanced Topics" (summer semester).

Course content:

  • Hovering theory: Momentum Theory (principles, flow model, assumptions)
  • Hovering and vertical flight performance (FM, DL, PL, induced velocity curves, rotor working states, etc.)
  • Factors affecting hovering and vertical flight performance
  • Aerodynamics of forward flight
  • Momentum theory in forward flight (Glauert)
  • Blade element theory and blade element momentum theory
  • Blade twist, taper, rotor solidity, etc., and their effects on rotor performance
  • Concepts of blade motion and control
  • Forward flight performance: induced, profile, parasitic power, drag synthesis, theoretically derived and semi-empirical equations describing power requirements
  • Operational envelope: range and endurance, factors affecting max. speed, etc.
  • Rotor limits: compressibility effects (drag divergence Mach number, etc.), retreating blade stall, reverse flow
  • Autorotational performance: quantification, height-velocity diagram, etc.