Chapter 4: Small Unmanned Aircraft Loading  stabilized level flight, when the lift force is equal to the weight force, the aircraft is in a state of  equilibrium and neither accelerates upward or downward. If lift becomes less than weight, the vertical  speed will decrease. When lift is greater than weight, the vertical speed will increase.  Stability is the inherent quality of an aircraft to correct for conditions that may disturb its equilibrium  and to return to or to continue on the original flight path. It is primarily an aircraft design  characteristic.  In aerodynamics, the maximum load factor (at given bank angle) is a proportion between lift and  weight and has a trigonometric relationship. The load factor is measured in Gs (acceleration of gravity),  a unit of force equal to the force exerted by gravity on a body at rest and indicates the force to which a  body is subjected when it is accelerated. Any force applied to an aircraft to deflect its flight from a  straight line produces a stress on its structure. The amount of this force is the load factor. While a  course in aerodynamics is not a prerequisite for obtaining a remote pilot certificate, the competent  pilot should have a solid understanding of the forces that act on the aircraft, the advantageous use of  these forces, and the operating limitations of the aircraft being flown.  For example, a load factor of 3 means the total load on an aircraft’s structure is three times its weight.  Since load factors are expressed in terms of Gs, a load factor of 3 may be spoken of as 3 Gs, or a load  factor of 4 as 4 Gs.  With the structural design of aircraft planned to withstand only a certain amount of overload, a  knowledge of load factors has become essential for all pilots. Load factors are important for two  reasons:  Remote Pilot – Small Unmanned Aircraft Systems Study Guide  30  1. It is possible for a pilot to impose a dangerous overload on the aircraft structures. 2. An increased load factor increases the stalling speed and makes stalls possible at seemingly  safe flight speeds. Load Factors Stability  Stability in an aircraft affects two areas significantly: • Maneuverability—the quality of an aircraft that permits it to be maneuvered easily and to  withstand the stresses imposed by maneuvers. It is governed by the aircraft’s weight, inertia,  size and location of flight controls, structural strength, and powerplant. It too is an aircraft  design characteristic. • Controllability—the capability of an aircraft to respond to the pilot’s control, especially with  regard to flight path and attitude. It is the quality of the aircraft’s response to the pilot’s  control application when maneuvering the aircraft, regardless of its stability characteristics.