Thrust is a mechanical force, so the propulsion system must be in physical contact with a working fluid to produce thrust

Thrust is a mechanical force, so the propulsion system must be in physical contact with a working fluid to produce thrust
Frictional force refers to the force generated by two surfaces that contacts and slide against each other
The part of the total aerodynamic forces acting on a rotor that is acting along the axis of rotation
The concept of a tip loss was introduced by Prandtl to account for the
difference between an actuator disc with an infinite number of blades and a real
wind turbine or propeller with a finite number of blades
There is a reactive force of the body opposite to the centripetal force called the centrifugal force