GearDropSim A Tool for simulating landing gear drop tests. Dr. Dan Retief PhD (Mech. Eng.)

Background / History  1982 – BE Mechanical – University of Pretoria  National Service in SA Air Force  1985 – Complete ME at University of Pretoria  1989 – PhD Mechanical Engineering.  1983 – 1986 Armscor – A-Vehicles.  1987 – 1990 Armatron Systems.  1990 – 1993 Aero Projects and Epsilon Eng.  1994 Settle in NZ – Computer Programming  Fisher & Paykel Laundry – Washer Dynamics and Structures  Pacific Aerospace Ltd – 750 XL Ag conversion, IFR, electric upgrade.  Alpha Aviation – Chief Designer  2009 – Started Aero Design Ltd

Tyre Model

Windmill Blade Development

Mirage F1 Dive Brake

UAV Seeker Head Cooling Design and Mechanicals

Aero Design’s Office 400 Raynes Road RD 2 Hamilton

F18 Landing Gear Drop Test

Component Element Method Newton’s Second Law Reference: The Component Element Method in Dynamics Samuel Levy And John Wilkinson

Component Modelling Elements  Mass  Spring  Damper Simple mass-spring-damper system. Free body diagram.

Finite Differences

Finite Difference Equations Solving for y1

Multiple mass systems

Algorithm  Masses as objects with attach points  Force elements as objects with nodes  Calculate starting values for all object positions and velocities  Calculate attach point location and velocities from mass location and orientation.  Calculate forces in force elements  Calculate mass acceleration, velocity and next position from sum of forces on it.

Landing Gear Simulation

Open Model File

Tyre Characteristics

Simulation Parameters

Oleo Damping Characteristics

Oleo Spring Characteristics

Load Factor Results

Oleo Displacement

Tyre Displacement

Applications  Landing Gear Design Optimisation  Oleo stroke length and diameter  Oleo Damping Characteristics  Oleo Inflation Pressure  Tyre Inflation Pressure  Calculation of landing gear fatigue forces based on sink rate.  Reduce design iterations and avoid expensive mistakes in hardware.