Standard Methods for Aerospace Stress Analysis

5Loads on Aircraft

5.1 Introduction to Loads Acting on Aircraft

The loads acting on the aircraft can be categorized into four different types:

1. Aerodynamics Loads
2. Gravity/Inertia Loads
3. Ground Reaction Loads
4. Internal Pressure Loads

The aerodynamic loads are the lift and drag forces. The lift is calculated by L = nW, with n being a load factor.

The pitching moment around the axis through the aerodynamics center is:

Gravitational/inertia loads are the forces exerted on the fuselage by the weight of the wings and payloads. The maximum takeoff weight (MTOW) of the aircraft or aerospace flight system is the addition of the aircraft’s operational empty weight (OEW), fuel, and the weight of the payloads.

Ground reaction loads are loads resulting from ground maneuvering of the aircraft, which are transferred to the fuselage through the front and main landing gears. These forces include the landing, braking, and taxing loads.

Internal pressure loads are the loads exerted on the fuselage resulting from the equalization of the internal pressure with the ground atmospheric pressure while transporting humans at high altitudes where the pressure is less than the ground atmospheric pressure. These loads act in the form of longitudinal and hoop stresses on the fuselage skin.

(5.1)

(5.2)