Skip Hudspeth and Gordon Hayhoe 112/20/2015

Pavement Roughness Subjective Pilot Rating Study Phase I - Develop a surface roughness model on the B flight simulator for input of real world airport surface elevation profiles. Phase II - Develop runway and taxiway pavement roughness rating scales for determining pavement condition for maintenance. The rating scales will be based on pilot's subjective ratings in response to simulator cockpit motions. 12/20/20152

Acknowledgements Federal Aviation Administration 312/20/2015

B Simulator Overview Surface Roughness Model Enhancements Challenges and Resolutions Roughness Model Testing Future Work 12/20/20154

FAA B Flight Simulator Located at the FAA’s Mike Monroney Aeronautical Center in Oklahoma City. Level D Full Flight Simulator Six-degree-of-freedom motion system. High resolution visual display and sound system. Does not provide real world surface roughness models 512/20/2015

Flight Simulator Overview Flight Compartment Host Computer Motion Control Cabinet Motion Platform 612/20/2015 Visual Display Visual Image Generator Interface

Flight Simulator Overview Flight Compartment Host Computer Motion Control Cabinet Motion Platform 712/20/2015 Visual Display Visual Image Generator Interface

Flight Simulator Overview Flight Compartment Host Computer Motion Control Cabinet Motion Platform 812/20/2015 Visual Display Visual Image Generator Interface

Flight Simulator Overview Flight Compartment Host Computer Motion Control Cabinet Motion Platform 912/20/2015 Visual Display Visual Image Generator Interface

12/20/ B Simulator Motion Platform

Simulator Motion System Due to limited travel, sustained accelerations are not possible. Motion system designed to provides acceleration onset cueing. Flight model accelerations are filtered to optimize the available motion response for training maneuvers. An accelerometer mounted below the pilot seats provides measurement of cockpit vertical accelerations. 1112/20/2015

Motion System Inputs from the Flight Model Receives rigid body accelerations from flight model Other motion effects are simulated through the use of buffet and special effects generators within the motion system. These include stall and flap buffets, touchdown bumps, etc. 1212/20/2015

Flight Simulator Overview Flight Compartment Host Computer Motion Control Cabinet Motion Platform 1312/20/2015 Visual Display Visual Image Generator Interface

Flight Model Overview Equations of Motion ThrustWeightAtmosphere GroundAerodynamics Simulator Motion System Simulator Visual System Simulator Flight Model 1412/20/2015

Existing B Simulator Surface Roughness Model The simulator provides a generic roughness model using randomly generated vertical surface deviations. The generic roughness amplitude is selectable with range from 0 to /20/2015

Random vs Actual Surface Roughness 12/20/ Generic (random) surface roughness Regional heavy runway surface roughness

New Surface Roughness Model Replaces the random roughness generation with profiles measured on airport pavements. Allows selection of surface profiles from simulator instructor station. Integrates with existing simulator models. Aligns airport surface profiles with visual scenes. Provides realistic simulator cockpit motion. 1712/20/2015

Surface Profiles Formatted for use on the Simulator Surface elevation is uniform across width of the profile. Elevation units changed from inches to feet. Surface profile sample spacing of four feet. Profiles were filtered to remove very low frequency variations in elevation. 12/20/201518

Profile Filtering Example 12/20/ Runway elevation profile before high-pass filtering Runway elevation profile after high-pass filtering

Integration of Surface Roughness Profiles into the Simulator Flight Model 12/20/ Surface Profile Strut Model Gear Forces

12/20/ Surface Profile Strut Model Flight Model Linear /rotational accelerations at CG Flight Model Generates CG Accelerations

Motion System Transforms CG into Cockpit Accelerations 12/20/ Surface Profile Strut Model Flight Model Motion System

Aircraft Flexible Modes The simulator flight model assumes a rigid aircraft body. However, aircraft body flexing provides a large component of the cockpit acceleration response to surface roughness. 12/20/201523

12/20/ Cockpit vertical accelerations with rigid body modes Cockpit vertical accelerations with rigid body and four flexible body modes

Flexible Mode Simulation Assumes lightly damped linearly flexible continuous body. Four flexible modes were modeled. Implemented on the host computer. Strut force used to excite the flexible modes. Outputs vertical accelerations at the cockpit position. Cockpit vertical accelerations were transformed into CG pitch accelerations for transfer to the motion system. 12/20/201525

Surface Roughness Model Evaluation Tests were developed to evaluate the roughness model performance through the collection of time histories of aircraft and surface profile parameters such as: Landing gear position along profile Surface height at each gear position Ground speed Landing gear vertical force C0mputed cockpit vertical acceleration Actual cockpit vertical acceleration 12/20/201526

12/20/ Cockpit vertical acceleration knots Cockpit vertical acceleration knots Cockpit vertical acceleration - 50 knots Effect of ground speed on cockpit accelerations

12/20/ Cockpit Accelerations: Computed (top) and Measured (bottom) Rigid Body OnlyOne Flexible Mode

Subjective Pilot Evaluation Two industry pilots were asked to evaluate the realism of various runway roughness profiles. The pilots performed the following maneuvers: Taxiing Takeoffs Landings The pilot’s feedback indicated that the profile roughness models provided a realistic simulation of the real world runways except for the absence of background tire rumble and cockpit response to centerline lights and concrete joint bumps. 12/20/201529

Summary A B simulator surface r0ughness model was successfully implemented allowing use of actual airport surface profiles and providing realistic cockpit motion response to the profile elevation changes. The surface roughness model provided a distinct enhancement over the existing runway random roughness models through the use of selectable real world surface profiles. 12/20/201530

Further Work Phase II of this project is currently in progress with a preliminary test of subjective pilot rating tests planned for this summer. 12/20/201531

12/20/ Contact Information Gordon F. Hayhoe FAA Airport Technology R&D Branch, AJP-6312 William J. Hughes Technical Center Atlantic City International Airport, NJ Skip Hudspeth Hudspeth & Associates, Inc Johnson Davis Road Huntersville, NC