Skip Hudspeth and Gordon Hayhoe

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Pavement Roughness Subjective Pilot Rating Study

Phase I - Develop a surface roughness model on the B737-800 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.

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Acknowledgements

Federal Aviation Administration

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B737-800 Simulator OverviewSurface Roughness Model Enhancements

Challenges and ResolutionsRoughness Model TestingFuture Work

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FAA B737-800 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

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Flight Compartment

Host Computer

Motion Control Cabinet

Motion Platform

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Visual Display

Visual Image Generator

Interfac

e

Flight Compartment

Host Computer

Motion Control Cabinet

Motion Platform

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Visual Display

Visual Image Generator

Interfac

e

Flight Compartment

Host Computer

Motion Control Cabinet

Motion Platform

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Visual Display

Visual Image Generator

Interfac

e

Flight Compartment

Host Computer

Motion Control Cabinet

Motion Platform

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Visual Display

Visual Image Generator

Interfac

e

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B737-800 Simulator Motion Platform

Simulator Motion SystemDue 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.

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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.

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Flight Compartment

Host Computer

Motion Control Cabinet

Motion Platform

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Visual Display

Visual Image Generator

Interfac

e

Equations

of Motion

Thrust Weight Atmosphere

Ground Aerodynamics

Simulator Motion System

Simulator Visual System

Simulator Flight Model

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Existing B737-800 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 5.

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Random vs Actual Surface Roughness

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Generic (random) surface roughness

Regional heavy runway surface roughness

New Surface Roughness ModelReplaces 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.

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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.

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Profile Filtering Example

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Runway elevation profile before high-pass filtering

Runway elevation profile after high-pass filtering

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Surface Profile

Strut Model

Gear Forces

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Surface Profile

Strut Model

Flight Model

Linear /rotational accelerations at CG

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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.

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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.

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Surface Roughness Model EvaluationTests 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 profileSurface height at each gear positionGround speedLanding gear vertical forceC0mputed cockpit vertical accelerationActual cockpit vertical acceleration

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04/21/23 27Cockpit vertical acceleration - 130

knots

Cockpit vertical acceleration - 100 knots

Cockpit vertical acceleration - 50 knots

Effect of ground speed on cockpit accelerations

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Cockpit Accelerations: Computed (top) and Measured (bottom)

Rigid Body Only One Flexible Mode

Subjective Pilot EvaluationTwo 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.

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SummaryA B737-800 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.

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Further Work

Phase II of this project is currently in progress with a preliminary test of subjective pilot rating tests planned for this summer.

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Contact Information

Gordon F. HayhoeFAA Airport Technology R&D Branch, AJP-6312William J. Hughes Technical CenterAtlantic City International Airport, NJ 08405 gordon.hayhoe@faa.gov

Skip HudspethHudspeth & Associates, Inc.11130 Johnson Davis RoadHuntersville, NC 28078skip@hudspethandassociates.com