# Presentation: 484769

## FAA Airport Pavement Roughness R&D

- Gordon Hayhoe, AAR-410, FAA William J. Hughes Technical Center, Atlantic City, New Jersey, U.S.A.  			www.airporttech.tc.faa.gov
- Continue development and maintenance of ProFAA (in process).
- Develop a standard for CA Profilograph simulation (in process).
- Compare measured and simulated aircraft response (data analysis in process).
- Conduct a pilot subjective rating study using the FAA 737 full-motion simulator (planning).

- December 5, 2006

## ProFAA Computer Program

- Intended to provide analysis of airport pavement roughness by computing indexes and simulating aircraft response.
- An inertial profiling system was developed for measuring runway and taxiway longitudinal elevation profiles from threshold to threshold.
- Constant profile measurement speed not necessary.
- Profiles are not absolute – somewhere between absolute and normal high-pass filtered.
- Suitable for high-speed aircraft simulation.

- December 5, 2006

## Profile Measurement

- FAA Methodology

- Standard High-Pass Filter Methodology

- Measurement speed – profile measured from zero speed to zero speed

- December 5, 2006

## ProFAA Computer ProgramBasic Index Display

- December 5, 2006

## Airport Pavement Profile Data Measured At

- Sixteen Airports
- U.S.A. and Foreign
- 4 Large Hub, 3 Medium Hub, 5 Feeder  4 Foreign large international
- Flexible and Rigid Pavements
- Runways and Taxiways

- December 5, 2006

## Straightedge versus Profilograph

- December 5, 2006

## Straightedge versus Boeing Bump

- December 5, 2006

## FAA TC Boeing 727-100QC Instrumented Aircraft, N40

- The FAA WJHTC operated a fully instrumented Boeing 727-100 until it was damaged about five years ago during an arrestor bed test.
- Measurements were made with N40  in 1997 on a runway and taxiway at a medium size regional airport.
- At the same time longitudinal profile measurements were made with the FAA profiler.
- The data from these test is now being analyzed to compare measured airplane responses with simulated responses.

- December 5, 2006

## Why Wait Until Now to Analyze the Data.

- Development of pavement thickness design procedures and associated full-scale traffic testing consumed most available R&D resources.
- The AAR-410 budget has recently been increased and a significant portion of the increase is assigned to roughness work over at least the next three years.

- December 5, 2006

## N40 on Jacks in the Hangar

- December 5, 2006

## Installation of Axle Strain Gages

- December 5, 2006

## Installation of Axle Strain Gages

- December 5, 2006

## Installation of Axle Strain Gages

- December 5, 2006

## Main Gear Force Calibration

- December 5, 2006

## Interior and Instrumentation Racks

- December 5, 2006

## Speed Sensor on Nose Gear

- December 5, 2006

## N40 on Jacks in the Hangar

- December 5, 2006

## Variables Measured on N40.

- Vertical and side forces and torque at each wheel on main and nose gears.
- Speed at nose gear.
- Three-axis accelerations at aircraft cg and floor of cockpit.
- Inertial guidance system outputs.
- Displacement of control surfaces, throttle, etc.

- December 5, 2006

## Tests Run November 3 and 4, 1997

- December 5, 2006

## Tests Run December 12, 1997

- December 5, 2006

## Tests Run December 12, 1997

- December 5, 2006

## Tests Run December 12, 1997

- December 5, 2006

## Slide 23

- December 5, 2006

## Slide 24

- December 5, 2006

## Slide 25

- December 5, 2006

## Slide 26

- December 5, 2006

## These are Preliminary Steps

- Continuing work will include variation of simulation parameters such as:
- Flexible body modes.
- Pitch moment of inertia for cockpit comparisons.
- Strut model parameters – primarily Coulomb and hydraulic friction.
- Modify simulation program to accept varying speed.

- December 5, 2006

## Includes damping forces due to:
Velocity squared hydraulic damping.
Strut seal Coulomb friction.
Strut bearing Coulomb friction due to strut inclination.
Two-to-one breakaway-to-sliding friction.
All wheels lumped into one equivalent wheel.
Unsprung mass is ignored.
Gas compression spring.
Linear tire spring with linear damping.

- Velocity squared hydraulic damping.
- Strut seal Coulomb friction.
- Strut bearing Coulomb friction due to strut inclination.
- Two-to-one breakaway-to-sliding friction.
- All wheels lumped into one equivalent wheel.
- Unsprung mass is ignored.
- Gas compression spring.
- Linear tire spring with linear damping.

*ProFAA Computer Program**Strut Model*

- December 5, 2006

## Subjective Pilot Rating Study Using Full-Motion Simulator - Objectives

- Develop a rating scale for pilot subjective response to vertical cockpit vibrations excited by longitudinal pavement surface elevation disturbances.
- The scale to range from very smooth to exceedingly rough.
- Identify on the rating scale limits for cockpit vibration resulting in uncomfortable conditions and unacceptable conditions.
- A similar project has been proposed to ACRP but using field data.

- December 5, 2006

## Why Use a Simulator and Not Operational Airplanes

- For
- Test repeatability.
- Rapid change in profile characteristics.
- Cost.
- Safety.
- Against
- Concerns about simulator fidelity.
- Difficult to change cockpit characteristics.

- December 5, 2006

## FAA Full-Motion 727 Simulator, Now replaced with a 737 Simulator.Located at Oklahoma City

- December 5, 2006

## Previous Experience

- AAR-410 has run projects on the FAA 727 simulator for about 15 years.
- High-speed exit geometry and lighting configurations.
- High-speed ground handling.
- Airplane landing into and arrestor bed.
- General lighting and visual guidance studies.
- The person responsible for simulator operation has a Ph.D. in human factors as well as being a National Resource Specialist in Simulators.
- E1927 “Conducting Subjective Ride Quality Pavement Ratings.

- December 5, 2006

## Subjective Pilot Ratings - Schedule

- FY06 (funding obligated)
- Develop scope and test plan.
- Establish procedures for setting roughness profiles in the simulator computer program.
- Develop preliminary rating scale and questionnaire.
- FY07
- Continue test plan, etc.
- Preliminary simulator study with a small number of pilots to test the scales and other procedures.
- Finalize procedures.
- FY08
- Run the full experiment with the necessary number of subjects and profiles.
- Analysis and report

- December 5, 2006