How Smooth Is It?
One reason why helicopters are smoother is due to the fact that the rotor blades are attached to the helicopter airframe through flapping hinges-or flexible blade roots. When they are suddenly subjected to additional lift, the blades respond by coning (the blades ‘bend’ upwards towards the tips causing a ‘coning’ effect). This means that there is an “inertial relief” as some of the force is expended in accelerating the blades upward before they can exert a force on the airframe. Most airplanes get no such relief.
The only exceptions are large jet airplanes, whose wings do have some flexibility. Nervous passengers readily notice this during a takeoff roll or in flight, in turbulent air.
For a single sharp-edged gust, the relief is short lived, since the coning will be complete in a fraction of a second. However, it might be significant in “choppy” air, where the gusts are coming up and down rapidly. In this case, the rotor actually will act as a vibration absorber.
In other words, a helicopter will provide a much smoother ride than an airplane under the same flying conditions.