GearSim software logo

SDI Engineering’s GearSim is a landing gear simulation tool for performing ground loads analysis and landing gear systems analysis.

GearSim has been developed and validated by SDI over many years with several industry partners.


This work continues in collaboration with the USAF Landing Gear Test Facility and major aircraft OEMs.  


  • Integrated modeling of landing gear and nonlinear aeroservoelastic aircraft dynamics

  • Simulation of the entire aircraft, individual landing gear components, landing gear facility testing and performance evaluation

  • Hydraulic and actuation system models

  • Propulsion and flight control system modeling integrated with full aircraft aeroelastics

  • Detailed braking, steering and tire dynamics

  • Shimmy and gear walk, stability analysis

  • Primary focus on military and commercial aircraft for landing gear or aircraft subsystem analysis, ground maneuvering, and flight test cases

  • Validated against military and commercial aircraft landing gear and subsystem test data

Technologies & Tools

  • Aeroservoelastic analysis

  • Landing gear and flight control system modeling (including actuators and sensors)

  • Nonlinear subsystem modeling

  • Professional and friendly user interface

  • MATLAB/Simulink and C/C++

  • Easily integrates with Nastran and other 3rd party aeroelastic and CFD software

Anticipated Benefits

  • Landing gear design process improvements, enabling more reliable evaluations of integrated design and performance characteristics

  • Cost and timescale savings with increased safety from reduced testing requirements and avoidance of hazardous test cases

  • Enables assessment of many scenarios that were not previously amenable to reliable evaluations

  • Certification support

  • Evaluation of tire wear and landing gear reliability

GearSim in Action


Nose Landing Gear Drop Test

  • Based on military aircraft

  • Single-wheel landing gear

  • Dropped height: 2.5 m

  • Impact velocity: 3 m/s

Nose Landing Gear Shimmy Test

  • Based on military aircraft

  • Single wheel landing gear

  • Hammer strike at 2 seconds

  • Flexible oscillations damped for this case

  • Frequency and damping post-processing tools available

Whole Aircraft Landing

  • Based on wide-body commercial aircraft

  • Aircraft mass: 174,000 kg

  • Four-wheel main landing gear and two-wheel nose landing gear

  • Initial ground speed: 75 m/s

  • Descent rate: 3 m/s