Leveraging Technologies to Reverse Engineer a Helicopter for Simulator Development

Developing high fidelity Level D quality full flight training devices requires detailed data to accurately simulate the cockpit, instruments, aircraft systems, Automatic Flight Control System (AFCS), power plants and flight dynamics. In an ideal scenario, all the data needed for simulating the aircraft is provided by the Original Equipment Manufacturer (OEM). Without OEM data, the engineering challenges for developing the simulator are greatly increased as new methods must be used to gather this information. Recently, FlightSafety International developed a high fidelity helicopter training device without the support of the OEM. The primary resource available for the design, development and validation of the simulator was access to a production aircraft. The entire Level D simulator, from the electronic cockpit indications to the high fidelity flight dynamics model, had to be reverse engineered from this aircraft. This paper reports on the leveraging of several innovative technologies to reverse engineer a Eurocopter EC-135 aircraft for the successful development of a full flight Level D simulator. An overview of the aircraft as well as the standard simulation development process is given followed by details of how the EC-135 simulator was developed. A comprehensive description is provided on the 3D scanning methods used to noninvasively gather aircraft geometric information, from the smallest cockpit detail to the individual rotor airfoil profiles. Further discussion is provided on the Computational Fluid Dynamics (CFD) analysis applied to the airfoil profiles to identify the 2D aerodynamic coefficients that were then used in the physics-based blade element model to simulate the EC-135 main rotor and Fenestron. Finally, extensive flight testing, system testing and parameter identification methods were used to further quantify the flight dynamics model, power plant, aircraft systems, cockpit indications, mechanical flight control characteristics and the complex AFCS control laws.