Development proved too difficult and complicated for the early experimenters because they did not
have an engine that could ensure flight. When larger, lighter, and more reliable engines were developed,
the dream of a helicopter became a reality.
The same laws of force and motion that apply to fixed wing aircraft also apply to the helicopter.
Controls for the helicopter are complex, and torque, gyroscopic precession, and dissymmetry of lift must
be dealt with. Retreating blade stall limits the helicopter's forward airspeed.
This chapter presents a basic discussion on helicopter controls, velocity, torque, gyroscopic
precession, dissymmetry of lift, retreating blade stall, settling with power, pendular action, hovering,
ground effect, translational lift, and autorotation.
3.2. THE FOUR FORCES ACTING ON A HELICOPTER
Weight and drag act on a helicopter as they do on all aircraft. However, lift and thrust for a
helicopter are obtained from the main rotor. In a very basic sense, the helicopter's main rotor does what
wings and a propeller do for an airplane. Moreover, by tilting the main rotor, the pilot can make the
helicopter fly to either side or to the rear. The controls used by the pilot are discussed in the next
Figure 3.2. Forces Acting on a Helicopter.
The sketch in figure 3.3 shows the main rotor, cyclic and collective controls, antitorque pedals, and
antitorque rotor. Basically, the cyclic