ITU LCH Structural Design Criteria and Structure Analysis March 19, 2003

Outline General Strength Requirements Load Determination Structure Analysis

General Strength Requirements Loads Factor of Safety Strength and Deformation Proof of Structure Design limitations Miscellaneous Structure Strength Requirements FAR 27

Load Determination External Loads –Flight Loads –Ground Loads Inertia Loads Component Loads

Load Determination Flight Loads –Limit Maneuvering Load Factor Maximum 3.5 Minimum -1.0 load factor envelope

Load Determination Flight Loads –Symmetrical Pull-ups and Rolling Pull-outs –Gust Loads –Yawing Conditions

Load Determination Flight Loads –Load Calculation Flight Lab Input Parameters Results Analysis

Load Determination Ground Loads –Landing Load factor Energy absorption requirements –Limit drop height: 13 inches –Reserve energy drop height: 19.5 inches –With rotor lift Determine the load factor –Software

Load Determination Ground Loads –Landing load conditions: (landing gear with skids) Level landing with Vertical reactions only Level landing with Drag load Level landing with side Load One skid landing Special conditions

Load Determination Ground Loads –Ground Handing Hoisting Mooring Jacking Towing –Emergency Landing conditions

Load Determination Inertia Loads –Weights and its distribution –Equilibrium equations –Translational and rotational load factor –Distributed inertia loads

Load Determination Component Loads –Main rotor loads Load conditions –Flight load conditions –Ground flapping, ground gust –Torque Load calculation

Load Determination Component Loads –Fuselage, landing gear, and rotor pylon structures Load conditions –Flight load conditions –Landing Conditions –Ground Handing –Emergency Landing conditions Load calculation

Load Determination Component Loads –Control System Loads Limit pilot forces and torques –Tail rotor loads Flight loads Ground gust –Empennage loads –Transmission system

Structure Analysis Rotors Fuselage (including rotor pylon Landing gear, Empennage) Control system Transmission system