NASA Technical Memorandum 4808

A Model for Space Shuttle

Orbiter Tire Side Forces

Based on NASA Landing

Systems Research Aircraft

Test Results

John F. Carter, Christopher J. Nagy, and

Joseph S. Barnicki

Dryden Flight Research Center

Edwards, California

National Aeronautics and

Space Administration

Office of Management

Scientific and Technical

Information Program

1997

CONTENTS

ABSTRACT .............................................................................. 1

INTRODUCTION .......................................................................... 1

NOMENCLATURE ........................................................................ 1

TESTBED DESCRIPTION .................................................................. 2

TEST PROCEDURE ........................................................................ 2

TEST CONDITIONS ....................................................................... 3

ANALYSIS TECHNIQUES .................................................................. 4

ERROR ANALYSIS ........................................................................ 5

RESULTS AND DISCUSSION ............................................................... 7

Tire Side Forces ........................................................................ 7

Main Tire Side Forces on EAFB and KSC Dry Concrete ..................................... 7

Main Tire Side Forces on EAFB Lakebed ................................................. 7

Main Tire Side Forces on KSC Wet Concrete .............................................. 7

Nose Tire Side Forces on EAFB Dry Concrete ............................................. 8

Nose Gear Tire Side Forces on EAFB Lakebed ............................................ 8

Tire Drag Forces ........................................................................ 8

Main Tire Drag Forces on EAFB and KSC Dry Concrete .................................... 9

Main Tire Drag Forces on EAFB Lakebed ................................................ 9

Nose Tire Drag Forces on EAFB Dry Concrete ............................................ 9

Nose Gear Tire Drag Side Forces on EAFB Lakebed ........................................... 9

MATHEMATICAL MODEL ................................................................. 9

SUMMARY AND CONCLUSIONS .......................................................... 11

APPENDIX A--TIRE FORCE TRANSFORMATION EQUATIONS ............................... 13

APPENDIX B--SUMMARY OF FLIGHT DATA AND CONICITY CORRECTIONS .................. 14

REFERENCES ........................................................................... 30

TABLES

1. Side and drag tire force test conditions ..................................................... 3

2. Test surface average texture depth ......................................................... 4

3. Concrete test error contributions .......................................................... 6

4. Main gear tire side force model for dry concrete or lakebed, single tire ........................... 10

III
5. Nose gear tire side force model for dry concrete and lakebed, single tire .......................... 11

B 1. Data from main tire dry concrete tire force tests ............................................. 15

B2. Data from nose tire dry concrete tire force tests .............................................. 23

B3. Data from main tire lakebed tire force tests ................................................. 25

B4. Data from nose tire lakebed tire force tests ................................................. 26

B5. Data from main tire wet runway tire force tests .............................................. 28

l,

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

FIGURES

The primary components of the CV 990 aircraft and test system ................................ 31

Yaw fixture load cell installation ......................................................... 32

Typical landing sequence ............................................................... 32

Commanded versus actual tire force data ................................................... 33

The EAFB surfaces used for tire force testing ............................................... 34

The EAFB runway 15 soil strength: average 0- to 6-in. interval ................................. 35

The KSC Shuttle Landing Facility layout .................................................. 35

Sign conventions for test tires ........................................................... 36

A tire force test on the KSC center section at 160 kn for 2.5 sec ................................. 37

Side force at 63,000 lb + 2,000 lb with LSRA dry concrete data ................................. 37

Ply steer estimate ..................................................................... 38

Main gear EAFB and KSC dry concrete side forces at a 33,000-1b vertical load .................... 38

Main

Main

Main

Main

Main

Main

Main

Figure 20.

Main gear

Main gear

Main gear

Main gear

Main gear

Main gear

Main gear

gear EAFB and KSC dry concrete side forces at a 48,000-1b vertical load .................... 39

gear EAFB and KSC dry concrete side forces at a 63,000-1b vertical load .................... 39

gear EAFB and KSC dry concrete side forces at a 80,000-1b vertical load .................... 40

gear EAFB and KSC dry concrete side forces at a 94,000-1b vertical load .................... 40

gear EAFB and KSC tire dry concrete side forces at a 110,000-1b vertical load ................ 41

gear EAFB and KSC tire dry concrete side forces at a 126,000-1b vertical load ................ 41

gear EAFB and KSC tire dry concrete side forces at a 148,000-1b vertical load ................ 42

Main gear EAFB and KSC tire dry concrete side forces at 63,000 lb + 2,000 lb ............ 42

tire EAFB lakebed side forces at 47,000 lb ......................................... 43

tire EAFB lakebed side forces at 61,000 lb......................................... 43

tire EAFB lakebed side forces at 92,000 lb ......................................... 44

tire EAFB lakebed side forces at 124,000 lb ........................................ 44

KSC wet concrete side forces at 36,000 lb ......................................... 45

KSC wet concrete side forces at 47,000 lb ......................................... 45

KSC wet concrete side forces at 63,000 lb ......................................... 46

iv
28. Main gear KSC wet concrete side forces at 93,000 lb ......................................... 46

29. Main gear KSC tire side force on wet skid abraded on corduroy section as a function of

dry concrete forces .................................................................... 47

30. Main gear KSC tire side force on wet rotopeened unground section as a function of dry

concrete forces ....................................................................... 47

31. Nose gear EAFB dry concrete side forces at 11,000 lb ........................................ 48

32. Nose gear EAFB dry concrete side forces at 33,000 lb ........................................ 48

33. Nose gear EAFB dry concrete side forces at 50,000 lb ........................................ 49

34. Nose gear EAFB lakebed side forces at 11,000 lb ............................................ 49

35. Nose gear EAFB lakebed side forces at 33,000 lb ............................................ 50

36. Main gear EAFB and KSC tire drag forces at 33,000 lb ....................................... 50

37. Main gear EAFB and KSC tire drag forces at 48,000 lb ....................................... 51

38. Main gear EAFB and KSC tire drag forces at 63,000 lb ....................................... 51

39. Main gear EAFB and KSC tire drag forces at 80,000 lb ....................................... 52

40. Main gear EAFB and KSC tire drag forces at 93,000 lb ....................................... 52

41. Main gear EAFB and KSC tire drag forces at 110,000 lb ...................................... 53

42. Main gear EAFB and KSC tire drag forces at 126,000 lb ...................................... 53

43. Main gear EAFB and KSC tire drag forces at 145,000 lb + 4,000 lb ............................. 54

44. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 46,000 lb ............... 54

45. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 62,000 ib ............... 55

46. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 92,000 lb ............... 55

47. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 126,000 lb .............. 56

48. Nose wheel gear EAFB tire drag forces on concrete at 11,000 lb ................................ 56

49. Nose gear EAFB tire drag forces on concrete at 31,000 lb ..................................... 57

50. Nose gear EAFB tire drag forces on concrete at 50,000 lb ..................................... 57

51. Nose gear EAFB tire drag forces on iakebed at 11,000 lb ...................................... 58

52. Nose gear EAFB tire drag forces on lakebed at 31,000 lb ...................................... 58

B 1. Measured roll deflection relative to the ground caused by side load from load point ................. 59

B2. Measured concrete forces from LSRA tests ................................................. 59

ABSTRACT

Forces generated by the Space Shuttle orbiter tire

under varying vertical load, slip angle, speed, and

surface conditions were measured using the Landing

System Research Aircraft (LSRA). Resulting data were

used to calculate a mathematical model for predicting

tire forces in orbiter simulations. Tire side and drag

forces experienced by an orbiter tire are cataloged as a

function of vertical load and slip angle. The mathematical model is compared to existing tire force models for

the Space Shuttle orbiter. This report describes the

LSRA and a typical test sequence. Testing methods,

data reduction, and error analysis are presented. The

LSRA testing was conducted on concrete and lakebed

runways at the Edwards Air Force Flight Test Center

and on concrete runways at the Kennedy Space Center

(KSC). Wet runway tire force tests were performed on

test strips made at the KSC using different surfacing

techniques. Data were corrected for ply steer forces

and conicity.

INTRODUCTION

Accurately representing landing gear tire forces after

touchdown is an essential element for simulation analysis of Space Shuttle orbiter landings. These forces

affect the simulated vehicle dynamics during rollout

and can play a significant role in landing safety and in

tire wear considerations. To measure aircraft tire and

wear forces, NASA modified a Convair 990 (CV 990)

aircraft (Convair Aircraft, San Diego, California) for

use as a tire testing facility called the Landing Systems

Research Aircraft (LSRA) (ref. 1). This facility was

built to support the Space Shuttle orbiter program by

providing tire wear and force data during orbiter landings. The LSRA has a landing gear test fixture between

the two main landing gears (fig. 1). This configuration

allows the LSRA to expose a test article, such as a tire

or landing gear component, to realistic combinations of

vertical load, slip angle, and speed during a single test

run on various runway surfaces. The LSRA does this by

extending the test fixture onto the runway during the

rollout phase of a landing.

Simulation models of the Space Shuttle orbiter tire

forces exist. These models were developed primarily

with the use of data from the NASA Langley Research

Center (LaRC), Aircraft Landing Dynamics Facility

(ALDF) in Hampton, Virginia (ref. 2). The ALDF gathers data using a hydraulically powered test fixture

which moves down a test track with a tire that has one

slip angle and one vertical load per test run. The inability of the ALDF to simulate tire heating during a

complete orbiter rollout and the absence of any data on

the lakebed surface caused uncertainty regarding the

tire force models. The LSRA data were used to

improve the existing tire force model by

• Measuring tire side and drag forces on dry concrete to verify the LARC model

• Obtaining tire side forces on wet concrete

• Obtaining tire side and drag forces on the

Edwards Air Force Base (EAFB), California,

lakebed surfaces

The orbiter tire force model based on data from the

ALDF (refs. 3 and 4) is under configuration control and

is used as the standard model for the Space Shuttle program. The tire force model presented here represents

the best available formulation of all the LSRA tire

force data. This report recommends implementing the

LSRA model as the standard tire force model for the

Space Shuttle orbiter program. Hence, documentation

is required for background and implementation. This

paper provides that documentation.

Preliminary LSRA tire force data were used to create

an interim tire force model in June 1994. The interim

model was implemented in a limited set of orbiter simulations to generate accurate landing profiles for further LSRA tire wear tests. That model was not widely

used or documented. The model described here also is

intended to supersede the interim tire force model.

Test methods, data reduction, and formulation techniques for this tire force model are described. A final

tabular LSRA orbiter tire side force model for nose

gear and main gear tires on concrete and lakebed

surfaces is presented. Comparisons to existing tire drag

force models are presented; however, no new tire drag

force model formulation is given. Wet runway side

force is discussed as a percentage of dry runway

tire forces.

NOMENCLATURE

ALDF Aircraft Landing Dynamics Facility,

NASA Langley Research Center,

Hampton, Virginia
CI

DFRC

EAFB

INS

KGS

KSC

LaRC

LSRA

WLLGDF

coneindex,lb/in2frompenetrometer tests

DrydenFlightResearchCenter,Edwards,

California

EdwardsAir ForceBase,Edwards,

California

inertialnavigationsystem

nauticalmilesperhourgroundspeed

JohnF.KennedySpaceCenter,Florida

LangleyResearchCenter,Hampton,

Virginia

LandingSystemsResearchAircraft

WrightLaboratoriesLandingGear

DynamometerFacility,WrightPattersonAir ForceBase,Ohio

TESTBED DESCRIPTION

The test aircraft, a NASA Convair 990 (serial

number 10-29, tail number 810) is a high-speed,

medium range, low-swept wing jet transport (fig. 1).

This aircraft is equipped with four wing-pylonmounted General Electric (Lynn, Massachusetts)

CJ805-23 turbojet engines and a fully retractable tricycle landing gear. The main gear can no longer be

retracted with the LSRA modification. This main gear

is controlled by dual wheel and columns located in the

cockpit. Control surfaces move using a combination of

mechanically driven flight tabs and hydraulics. In addition, the basic control system is augmented with a yaw

damper which drives the rudder.

The aircraft was modified structurally and mechanically to accommodate the test fixture on the centerline

of the aircraft between the main landing gears. The

resulting system can simulate vertical load, sideslip,

and speed of up to 150,000 lb, 15°, and 240 kn. Vertical

load and sideslip control are enhanced using computer

feedbacks. The pilot controls the speed using a realtime cockpit error display.

The LSRA can collect either onboard or telemetered

data. Loads data are obtained using load cells in the

three axes of the test fixture (fig. 2). The drift angle and

ground speed of the test tire were calculated from optical velocimeters mounted on the test fixture. Aircraft

Euler angles and ground speed were obtained from the

inertial navigation system (INS). Accelerations and

body axis rates were measured using conventional

accelerometer and gyroscopic packages. Stroke position transducers mounted on each landing gear strut

provide data for alternate pitch angle and bank angle

calculations. Visual data were provided by a real-time

video system which had four views of the test tire. For

safety considerations, tire temperature and pressure

were also instrumented. Data rates for the parameters

ranged from 25 to 200 Hz. Reference 1 provides additional details regarding construction and operation of

the LSRA.

TEST PROCEDURE

Figure 3 shows a typical landing test sequence. The

sequence was initiated after the pilot made a normal

CV 990 final approach. After touchdown and derotation, the pilot called for test initiation and used spoilers,

thrust reversers, and brakes to maintain the desired

speed. For tire force tests, the speed was usually held

constant. The test system was activated by an onboard

test conductor. The test gear was extended and automatically controlled to match the preprogrammed test

profiles of vertical load and slip angle on the test tire.

This automatic control made adjustments for flight test

uncertainties, such as crosswind (which would change

drift angle) and spoiler usage (which would change

vertical load of the aircraft). Upon completion of the

test, the test gear was automatically retracted. If possible, the aircraft would then rotate and takeoff. Otherwise, the aircraft would come to a full stop on the

runway. Test tires were replaced between each test run

if extreme wear made it evident that the wear would

affect the tire forces during the test. Otherwise, the test

tire was not replaced.

Tire force profiles were designed to subject the tires

to a number of vertical loads and slip angles at constant

speeds. These profiles were not intended to resemble

time history test conditions of an orbiter landing. Figure 4 shows a tire force profile plotted with the system

response. Vertical loads were held constant long

enough for the tire to be steered through three to four

discrete angles at a constant velocity. This profile

allowed for a variation in slip angle at several vertical

loads during each run. The test duration was designed

so that the test tire would rotate through at least three

times its circumference at each test condition to allow

forces to stabilize. Data used to measure tire forces

were derived primarily from these parametric test
profiles.In a few cases,additionaldatapointswere

developedfromfull-landingtestswhichwereintended

fortire weartests.Quasi-steadystateconditionswere

selectedfortheseadditionaldatapoints.

TEST CONDITIONS

Tire force tests were performed at two locations:

EAFB and KSC. Main gear and nose gear tires were

tested according to a matrix of test conditions determined by landing gear engineers at Johnson Space

Center (JSC), Houston, Texas, and LaRC. One significant factor in selecting specific conditions was the

desire to match test conditions used by ALDF in the

original tire force tests, so a direct comparison of forces

could be made. The matrix also encompassed the range

of test conditions that the orbiter tire would undergo

during a nominal landing. Table 1 summarizes the target test conditions for each type of tire and test surface.

An examination of the test results shows some small

differences between target and actual test conditions.

The EAFB concrete runway (fig. 5(a)) is a relatively

smooth surface by the majority of runway standards

because wet weather side force is not a primary concern. The surface of this runway has some grooving

and pitting, but the sharpness of these surface features

is much less severe than that of the KSC runway.

Tire force tests accomplished on the EAFB lakebed

were run on lakebed runway 15 (fig. 5(b)), to the right

of centerline. This location was far enough to the right

of centerline to avoid damaging the orbiter landing area.

Figure 6 represents the surface hardness data from a

cone penetrometer taken along the side of runway 15.

Hardness measurements were made with a cone

penetrometer at 50-ft intervals along the side of the

runway. The cone index (CI) is the projected force (lb/

in2) required to drive a square inch area rod 6 in. into

the lakebed. Cone index data were used in the computation of an EAFB lakebed drag model. Refer to the

Nose Tire Side Forces in Lakebed subsection for

additional details.

Figure 7 shows the KSC runway with the surface

textures which were present during testing (ref. 5). The

center 8000 ft of the runway had the original laterally

grooved surface designed to channel off rainwater

quickly and to provide side force in wet conditions.

The KSC dry concrete main gear tire force data were

collected on this surface. At both ends of the runway,

3500 ft were ground down leaving a surface with longitudinal ridges referred to as corduroy. The unground

center section and the corduroy section had 10-ft wide

test strips which were made using two smoothing

techniques: skid abrading and rotopeening. The skid

abrading technique involves firing steel shot at the

Table 1. Side and drag tire force test conditions.

Test Vertical load, Slip angle, Speed,

condition Surface lb x 1000 deg KGS

0, +1, _-f_2, 50, 160, KSC concrete 45, 60, 90, 120

Main gear tire forces on +4, +7 a 190

dry concrete EAFB concrete 30, 45, 60, 75, 0, +1, +2, 10

90, 105, 120 +4, +7 a

Main gear tire forces on 0, +1, +2, 50, 160,

EAFB lakebed EAFB lakebed 45, 60, 90, 120 +4, :L--6a 190

KSC skid abraded 0, +1, +2, 45, 60, 90, 120 50, 200

Main gear tire forces on on corduroy +4, +7 a

wet concrete KSC rotopeened 45, 60, 90, 120 0, +1, +2,

on unground +4, +7 a 50, 160

Nose gear tire forces on EAFB concrete 10, 30, 50 0, +_1,+2, 50, 160,

dry concrete +4 200

Nose gear tire forces on EAFB lakebed 10, 30 0, +1, +2, 50, 160,

EAFB lakebed +4 190

aMaximum sideslip angles were not executed at maximum loads.
TM

runway surface. The Rotopeener machine uses rotating drums covered with leather flaps which have steel

weights, or peens, in them. Both techniques reduce the

sharp edges on the surface for a smoother texture.

Although never used for tire force testing, a third test

strip was formed using a diamond cut saw. The KSC

runway was completely resurfaced using a Skidabrader TM machine in October 1994 as a result of the

LSRA testing (ref. 5).

Wet runway testing was performed on two KSC surfaces: the corduroy surface with skid abrading treatment and the laterally grooved surface with the

rotopeen treatment. Tests on the skid abrader on corduroy sections were accomplished at speeds of 200 and

50 kn. Tests on the rotopeener on laterally grooved

surface were conducted at 160 and 50 kn. These combinations were intended to provide the best sampling of

an orbiter landing without requiring an excessive number of test points.

Water for the wet runway tests was dispersed from a

tanker truck traveling at approximately 25 mi/hr at a

rate of 12 gal/sec. NASA LaRC observers estimated

the water depth at 0.02 to 0.03 in. All tests were conducted within 5 min of wetting. On the skid abrader on

corduroy surface, longitudinal grooves left from the

first cutting tended to trap the water on the runway.

Conversely, the transverse grooves on the center section drained the water off the surface more quickly.

Based on these characteristics, it is unlikely that the

water depth was the same for the two surfaces.

Table 2 summarizes the average texture depths on

concrete. These texture depths were taken using a

grease sample method which measures the area that a

given amount of grease will cover a surface (ref. 5).

ANALYSIS TECHNIQUES

Load cell zero biases for the vertical, side, and drag

forces were eliminated by subtracting the indicated

forces when the test tire was off the ground just before

tire extension. This subtraction takes out any external

forces, such as aerodynamics on the test fixture, that

might bias the results. These forces were then corrected

rMRotopeeneris a registered trademark of 3M Company, 3M

Center Street, St. Paul, Minnesota 55144-1000.

mSkidabrader is a registered trademark of Humble Eq. Co., 1720

Industrial Drive, Ruston, Louisiana 71270.

Table 2. Test surface average texture depth.

Average texture

Surface index a

Skid abrader on corduroy 0.0096

(wet runway tests)

Rotopeener on unground 0.0078

(wet runway tests)

EAFB concrete 0.0067

(nose tire force tests)

KSC unground-original 0.0200

(main gear tire force tests)

aBased on grease sample method.

through an Euler angle transformation into the test tire

axis (appendix A). Figure 8 provides the test tire axis

definition and sign conventions of tire forces and slip

angle. Vertical load is perpendicular to the runway;

meanwhile, side and drag loads are parallel to the runway, rotated through the steering angle. Inertial navigation system data were used for the pitch angle;

meanwhile, the roll angle was calculated from the difference in height of the left and right main gear struts.

Figure 9 shows a time segment of constant vertical

load for a typical test run. A table was created by visually averaging the stabilized time history segments of

corrected vertical load, slip angle, speed, bank angle,

and side force. The dashed lines indicate the chosen

discrete values. Data from these observations are presented in appendix B.

Before the appendix B tables could be used for the

tire force model, the side force had to be corrected for

an effect called conicity. Vertical load exerted through a

nonzero bank angle of the wheel results in a flat area of

contact between the tire and the runway. This flat area

is not perpendicular to the centerline of the tire. With

no resistance from the test fixture, this flat area would

cause the tire to travel in a circular path similar to the

way a cone would roll on a fiat surface. The test fixture

subjects the tire to side forces which resist the conical

path of travel. To calculate this force, an accurate

calculation of the total angle from the vertical, or wheel

tilt angle, is needed. The equation for the tilt angle is as

follows:

Wheel tilt = Aircraft bank angle

+ 6.8 x 10-5 x side load (1)

4
Thefirsttermisthebankangleoftheaircraftasmeasuredbythedifferenceinmaingearstrutlengths.The

secondterm,6.8x l0-5sideload,istheroll deflection

resultingfrom sideforceof all of theLSRAstructure

from abovethemainlandinggearstrutsthroughand

includingtheorbiterwheel.It wasderivedduringstatic

loadstestsconductedat the NASA DrydenFlight

ResearchCenter(DFRC),Edwards,California.Once

thewheeltilt is calculated,thesideforcecorrectedfor

conicitywill be:

Correctedsideforce= Sideforce+ 0.01465

× wheeltilt ×verticaload (2)

The factorof 0.01465wasderivedfrom specially

designedtaxi testrunson the LSRA. Both tests were

done by vertically loading the tire at 0 ° slip angle. Periodic steering pulses were placed in each run to prevent

mechanical friction from affecting results. A baseline

run was performed at 0 ° bank angle. By inflating the

right main gear strut, a bank angle of-1.5 ° was placed

on the aircraft (left wing down), and a second mn was

made. Similarly, a third run was made with the left strut

inflated higher than the right, producing a 1.5° bank

angle (right wing down). The side load from the baseline run was subtracted from both of the succeeding

runs and divided by the tilt angle. These data were now

plotted as a function of the corrected vertical load. A

linear fit of that data showed the factor of --0.01465.

Appendix B presents data for the roll deflection caused

by side force and conicity.

Once the data in appendix B were corrected for conicity, the LSRA Space Shuttle orbiter tire force model

was constructed. Side force data were plotted as a function of slip angle for a given vertical load. Solid lines in

figure 10 represent the current LSRA tire force model

described in this report. Dashed lines represent the

ALDF tire force model (refs. 3 and 4), and the circles

represent LSRA tire force data collected at that condition. The tire force model described here was created by

using a linear fit for all the data between +3 ° of slip

angle and a tabular curve fit for slip angles beyond +3 °.

An estimation of the ply steer force was made. Ply

steer is the side force that a tire produces when it is at a

0 ° slip angle and is a function of the design of the tire.

Although a recognized force bias within the tire manufacturing community, ply steer is usually ignored

because of its small magnitude. Yet, these forces

become an important factor in computing tire wear

when integrated over a complete orbiter roliout. The

exact measurement of ply steer forces was hampered

by the fact that ply steer values were close to the measurement accuracies of the LSRA system. Consistent

biases in the test data, however, indicate that ply steer

in orbiter tires is a real phenomenon.

Figure 11 shows ply steer forces which were

extracted from several tests conducted at ALDF and

Wright Laboratory Landing Gear Dynamics Facility

(WLLGDF), Wright Patterson Air Force Base, Ohio.

Ply steer values developed from LSRA data are also

shown. The solid line represents the current estimate of

ply steer based on all the sources of data. It was

believed that the ply steer trends of the LSRA at low

vertical loads (< 50,000 lb) were not as meaningful as

the ALDF or the WLLGDF data because of excessive

scatter in the data for those conditions. Ply steer data

taken from the ALDF and the WLLGDF showed less

scatter and a more consistent trend for the lower vertical loads. At increased vertical loads, the WLLGDF

data showed excessive scatter and unreasonable results;

meanwhile, the LSRA data showed increased consistency. Therefore, the ply steer model in this report

weights the ALDF and WLLGDF data more heavily for

the low vertical loads and uses the LSRA trends at high

vertical loads. The linear curve fits for main gear tire

side forces on dry concrete at the 33,000-, 48,000-,

80,000-, and 94,000-1b vertical loads were altered to

reflect the results of this decision. Note that these biases

are often well within the uncertainties of the data.

ERROR ANALYSIS

Errors in the tire force data include load cell measurement error and errors from the measurements used

in the transformation equations. The latter category

includes Euler angles, steering measurements, and drift

angle sensors. For example, the equation for vertical

load (in part) is as follows:

Vertical

forcerunway = Vertical forceaircra fl

x cosine(pitch angle) - drag forceaircraft

x sine(pitch angle) + ... n. (3)

Appendix A shows the equations for transforming the

body axis load cell forces into the test tire axis. An

error in the pitch angle measurement creates additional
errorsin therunwayaxisverticaloadoverandabove

theerrorsin theverticalloadmeasurement itself.An

accuraterepresentationof thecomputedverticalforce

isasfollows:

angleerrorhavebeenincludedin thesideloaderror.

Becauseassumingthatall errorswouldoccurin the

samedirectionsimultaneouslyis unreasonable,the

totalerrorisarootsumsquarevalue.

Vertical

forcerunway= (Verticalforcetrue

+ verticalforceer_or)

x cosine (pitch angletrue + pitch angleerror)

- (drag forcetrue + drag forceerror)

x sine (pitch angletrue + pitch angleerror)

+... n (4)

By rearranging terms, using small angle approximations, and neglecting products of error terms, an estimate of the contribution of each error may be made.

Vertical

forcerunway = Vertical forcetrue

x cosine(pitch angletrue)

- drag forcetrue x sine(pitch angletrue )

+ vertical forceerro r

x cosine(pitch angletrue )

+ vertical forcetrue

x cosine(pitch angleerror)

- drag forceerro r x sine(pitch angletrue )

- drag forcetrue x sine(pitch angleerror)

+... n (5)

Table 3 shows the possible errors for the vertical,

side, and drag load measurements from each of the

measurement components. These errors were developed using the largest component error for each of the

items in the transformation equations (shown in

column 1). Component error was then propagated

through the equations using typical (not maximum)

values for the "true" terms shown in equations 3 and 4.

Typical values used (based on main gear tire tests) were

as follows:

Load, lb Angle, deg

Vertical 60,000 Bank 1.0

Side 10,000 Pitch -1.5

Drag 1,000 Steer 2.0

Fork -0.2

The last row in table 3 shows the estimate of error for

each of the force values. Note that the affects of slip

Table 3. Concrete test error contributions.

Resultant Resultant Resultant

Error vertical side load drag load

source and load error, error,

magnitude error, lb lb lb

Vertical load cells, +_2999 +55 4-185

+3000 lb

Side load cells, 4-9 4-.500 :LS)

+500 lb

Drag load cells, +8 4-10 +300

+300 lb

Pitch angle (INS), +5 +4 +105

+0.1 °

Roll angle (struts), 4-39 .+.209 4-4

4- 0.2 °

Steering angle

resolver, _ +352 a +_.2

+0.1 °

Drift angle

(optical sensor), 4-0 4-867 a 4-0

+ 0.25 °

Root sum 2999 1083 368

square totals

aBasedon a side force and slip angle value at 63,000 lb vertical load

(3467 lb/deg).

The errors presented in table 3 apply directly to testing on concrete runways where optical velocimeters

were used to measure drift angle. This optical system is

an adaptation of a well-characterized, commercially

available system which was accurately calibrated for

this application and has an accuracy of 0.25 ° . For lakebed tests, a mechanical device with a castered aircraft

tire was used to measure drift angle. The drift angle

accuracy of the mechanical system was estimated at

0.5 ° although no analysis was completed to verify the

accuracy of the mechanical device. If an accuracy of

0.5 ° is used, the side force error increases to 4-1851 lb.

However, a 0.5 ° accuracy has little effect on the vertical

or drag loads.

6
Othererrorscouldbe introducedfrom the0° tilt

anglecorrection.The 0.01465factorin theconicity

equationwasa linearfit of datafrom LSRAtesting.

Estimatedaccuracyof this numberis approximately

_+0.004. Adeltaof0.004wouldproduceanerrorinside

forceof 288lb with a 1.2° tilt angleanda 60,000-1b

verticaload.

RESULTS AND DISCUSSION

These test data were plotted as a function of slip

angle for each of the major vertical load and surface

combinations used during the test program. These plots

have been divided into the following nine categories:

• Main tire side forces on EAFB and KSC dry

concrete

• Main tire side forces on EAFB lakebed

• Main tire side forces on KSC wet concrete

• Nose tire side forces on EAFB dry concrete

• Nose tire side forces on EAFB lakebed

• Main tire drag forces on EAFB and KSC dry

concrete

• Main tire drag forces on EAFB lakebed

• Nose tire drag forces on EAFB dry concrete

• Nose tire drag forces on EAFB lakebed.

Tire Side Forces

Figures 12 through 35 show side force data for the

various combinations of main or nose gear tires and

runway surfaces. These plots include the proposed

LSRA model, the current ALDF model, and a recently

developed lakebed drag model for main and nose gear

tires where appropriate. Unless specified otherwise,

data presented in these plots have vertical loads

_-f.2000lb. The following subsections described observations on the data for each category.

Main Tire Side Forces on EAFB and KSC Dry

Concrete

Figures 12 through 19 show dry concrete side force

data points for various vertical loads plotted as a function of tire slip angle. For the most part, only small

differences exist between the ALDF model and the

LSRA model. However, the ALDF model does not contain the affects of ply steer. Note that the ALDF curve

shown for the 148,000-1b vertical load (fig. 19) has

been extrapolated considerably outside the range of the

original ALDF test matrix and curve fitting data. The

primary benefit of the LSRA model over the ALDF

model is the incorporation of the ply steer affects and

the improvement of the curve fit at the vertical load and

slip angle extremes.

Figure 20 shows the 63,000-1b side force plot from

the main tire dry concrete data. These data points

encompass speeds ranging from 10 to 200 kn and two

surface textures: the EAFB dry concrete and the original unsmoothed dry center section at KSC. Differences

between each data set exist, but these differences are

relatively small. As a result, all these data sets were

used for the LSRA fairings. Although the conclusion

that speed and surface affects are small seems surprising, this conclusion had been predicted by ALDF engineers based on previous tire force tests (ref. 6). The fact

that the magnitude of the ply steer forces can be

smaller than the variance between these data sets is

also recognized (appendix B).

Main Tire Side Forces on EAFB Lakebed

Figures 21 through 24 show data from the EAFB

lakebed runs for four vertical loads. With two exceptions, the majority of these data matches the model

developed for the concrete data surprisingly well. One

is the 61,000-1b vertical load plot (fig. 22). The

61,000-1b data appear to be shifted in either side force

or slip angle. The shift in these data could be fully

explained by the estimated 0.5 ° accuracy of the

mechanical sideslip measuring device (see "Error

Analysis" section). The second exception is the lowspeed (51 KGS) data from the 124,000-1b vertical load

plot (fig. 24). These four side force points show

approximately one-half the side force that the LSRA

model predicts. Because the majority of these data

agree well with the concrete model, the recommendation is to use this model for concrete and lakebed

simulations (appendix B).

Main Tire Side Forces on KSC Wet Concrete

Figures 25 through 28 show tire side force measurements for wet concrete on the KSC runway. As discussed in the Test Procedure section, two surfaces were

used: the skid abrader on the corduroy section and the

rotopeener on the unground center section. Skid

abrader tests were performed at 50 and 200 KGS, and

7
rotopeenertestswereperformedat 50and160KGS.

Thesetestdataarerelativelylimitedwhencomparedto

thedryconcretetestsandwereorientedtowardtesting

theconditionsmostrepresentativeof anorbiterlanding. Testsaccomplishedon the skid abradedtouchdownzoneswereconductedathighspeedstosimulate

orbitertouchdownconditionsandlowspeedsto simulatefinalrollout.Testsaccomplishedontherotopeened

centersectionwereintendedto matchconditionsfrom

postderotationto laterollout.

Waterdepthfor thetwo testsurfaceswasprobably

notthesame,butbothconditionswouldberepresentativeof therunwayconditionshortlyafterarainstorm.

Consistentwith pretestexpectations, thewet surface

tiresideforcewaslessforhighspeedsonthecorduroy

surfacethanforthedry surface.Sideforceforequivalentloadandspeedtestconditionsshowedgreaterside

forceontherotopeenedcentersectionthanontheskid

abraderorcorduroysurface.

Figures29and30summarizesideforcemeasurementsshowingdataasapercentageof dryconcrete

values.In general,highspeedsandlowverticalloads

tendedto decreasethesideforcethemost.Tocompute

wetrunwaysideforcesin thesimulator,thesideforce

ratiosshownin figures29and30shouldbeappliedto

thedryconcreteforcesattheappropriateverticaload,

slipangle,andspeedconditions(appendixB).

Nose Tire Side Forces on EAFB Dry Concrete

Figures 31 through 33 show nose gear tire data

collected at various vertical loads on the EAFB dry

concrete runway. These LSRA data values are close to

the ALDF model. However, the LSRA data seem to

indicate a shallower slope of side forces as a function

of slip angle. Note that the ALDF model for the

50,000-1b vertical load is extrapolated well outside the

data range originally used to determine the equation.

An attempt was made to measure the ply steer affect

for the nose gear tire. The magnitude of the side force

readings at 0° slip angle was less than the accuracy of

LSRA side load cell. Similar to the main gear tire side

forces, no speed affects occurred. All data were

obtained on the EAFB concrete. As with the main tire

dry concrete model, the LSRA nose tire dry concrete

model provides improvements at high vertical loads

and slip angles.

Nose Gear Tire Side Forces on EAFB Lakebed

These data were generated from force tests using the

nose gear tire on the EAFB lakebed (figs. 34 and 35).

Note that the majority of these data compare well with

the model generated from the concrete tests. Because

these tests also used the mechanical side slip device,

they are subject to the same 0.5 ° accuracy limitation as

the main gear tire tests on the lakebed. The recommendation is to use the same model for concrete and lakebed simulations.

Tire Drag Forces

Figures 36 through 52 show drag force data for the

various combinations of main or nose gear tires and

runway surfaces. With the exception of the main gear

drag force plot at 145,000-1b vertical load which

measured +4000 lb, all other drag plots had +2000-1b

vertical load.

Drag force data developed by the LSRA for concrete

did not warrant changing the existing model. The

model used for drag force on a concrete surface was

developed by ALDF from earlier track tests with an

orbiter tire. The EAFB lakebed model was developed

by Gary Kratochvil, International Technology Corporation, and Javier Valencia, Managing Technologies,

Incorporated, under contract to JSC. This model was

built primarily on early LSRA drag tests using full-stop

landing profiles with no slip angle on several lakebed

runways. The Kratochvil model is defined by the

following equation*:

Drag = 4948 - 0.786 x soil CI

- 16.995 × velocity

+ 0.091 × vertical load (6)

The use of full-stop profiles provided data at various

combinations of vertical load and speed, but these profiles did not provide the parametric data developed by

the later tire force tests. Data provided here can be used

to increase understanding of the results from the existing lakebed, but no attempt has been made to update

*Kratochvil,Gary and Javier Valencia,"Ascent/Entry Flight Test

Techniques, number 120.Presented as part of an oral briefing given

atJohnson Space flightCenter,Houston.Texas,December 15, 1994.
that model.Additionally,the model wasprimarily

intendedforhigh-speed(>140kn)use.

Main Tire Drag Forces on EAFB and KSC Dry

Concrete

Figures 36 through 43 also present drag measurements for the main gear tire on several concrete surfaces and at several vertical loads. In general, the

LSRA drag measurements were less than those of the

ALDF model. However, a significant amount of scatter

exists in the LSRA data (fig. 41). While the LSRA values are generally lower than the ALDF values, the

magnitude of the differences and the confidence in the

LSRA data based on the high degree of scatter does not

appear to warrant development of a new model. As was

the case with the side forces on concrete, no identifiable speed or surface texture affects occurred.

Main Tire Drag Forces on EAFB Lakebed

Figures 44 through 47 show data gathered from main

gear tire tests on the right side of lakebed runway 15.

Comparisons between the lakebed drag data and the

Kratochvil model show reasonably good correlation at

the low vertical loads but less-than-predicted drag at

the high vertical loads (figs. 46 and 47). The overprediction results from the fact that the Kratochvil

model was originally developed based on LSRA full

landing profile runs made on soft soils. That data did

not include the hard surfaces found on runway 15. Surface hardness values (CI) for the right side of runway

15 varied from approximately 2500 to 4000 lb/in 2 and

indicate a relatively hard surface for soil. (Orbiter engineers were briefed that the model was conservative

(predicted increased drag) when the model was delivered.) Note that the speed affects demonstrated by

earlier soft-soil tests and predicted by the model are

greatly diminished on the hard surfaces.

At high speeds, the Kratochvil model predicts a

decrease in drag force with an increase in speed, a nonintuitive result seen in early LSRA full-stop profile test

results. Some slip angle affects on drag are apparent

although the accuracy of the slip angle is subject to the

same limitations as the side force data on the lakebed.

No attempt was made to change either the Kratochvil

model or develop a new model. However, it is evident

that the model could be improved for use on runway 15

by including the latest set of LSRA data.

Nose Tire Drag Forces on EAFB Dry Concrete

Figures 48 through 50 show data from nose gear tire

drag force tests conducted on the EAFB concrete runway. While the 0 ° slip angle magnitude of drag values

is comparable to the ALDF model, the variation with

tire slip angle does not compare at all. The LSRA data

indicate no change in drag with slip angles up to 4 ° .

Unlike data from the main gear tire, data from the nose

gear tire tests indicate increasing drag forces as the test

speed increases. This increase could not be quantified

because the magnitude of these increases is only

slightly more than the potential errors in the drag measurement. Note that the ALDF drag curve is extrapolated well outside the original range of vertical loads

considered by the ALDF polynomial and should be

treated accordingly (fig. 50).

Nose Gear Tire Drag Side Forces on EAFB

Lakebed

Figures 51 and 52 show drag data from nose gear

tests completed off the right side of EAFB lakebed runway 15. These data indicate a small affect of speed in

generating drag where high speeds increase drag values. There appears to be no affect from tire slip angle

although the slip angle measurements are subject to the

same inaccuracies as side force data. The Kratochvil

drag model plots were developed for main gear tires at

greatly increased vertical loads and should be used

only as a guide. Again, no attempt was made to develop

a new lakebed drag model for the nose gear tire.

MATHEMATICAL MODEL

The final LSRA side force model is a table based on

vertical load and slip angle. Tables 4 and 5 lists information for main and nose gear tires and apply to concrete and lakebed surfaces. These tables were created

from the LSRA curve fits of the data in figures 12

through 35. Note that these data were transformed into

the test tire axis and then to zero elastic affects. These

tables are based on vertical loads for individual tires and

will not work if the dual tire strut vertical load is used.

Dual tire strut loads must be reduced to individual tire

loads before using these tables because of the nonlinear

nature of sideslip data with respect to vertical load.
.m

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Table 5. Nose gear tire side force model for dry concrete and lakebed, single tire. a

Left Steering Right steering

Basic side force

Slip angle + -8 -4 -2 0 2 4 8

vertical load

0 0 0 0 0 0 0 0

11,000 5,100 3,500 1,770 -245 -2,260 -4,050 -5,600

31,000 9,100 5,200 2,960 -225 -3,410 -6,500 - 10,500

50,000 6,900 2,900 1,920 440 -1,040 -2,550 -6,600

awheel tilt angle correction side force = basic side force - (0.01465 x tilt angle x vertical load) where tilt angle

is positive for clockwise rotation viewed from the rear.

The use of these tables is illustrated next.

Assume the following conditions for a main gear:

Strut vertical load, lb

Tire vertical load

(50/50 share), lb

Orbiter slip angle, deg

Orbiter speed, kn

Orbiter bank angle, deg

Assuming the 50/50

126,000

63,000

split

1.3° (nose right)

160

-1.2 ° (left wing down)

for individual tire

vertical load, the basic side force on each tire would be

-3607 lb. This result is interpolated from table 4 for a

63,000-1b vertical load and a 1.3 ° slip angle. Note that

this amount of side force is experienced by the tire with

no tilt angle. In this case, it is assumed that the orbiter

bank angle is the entire wheel tilt; that is no strut and

axle bending. Based on a bank angle of-1.2 ° and a

vertical load of 63,000 lb, the corrected side force can

be calculated:

Corrected side force = Side force - (0.01465

x bank angle x vertical load) (7)

The corrected side force is then -2499. This correction takes into account the tire side force in the positive

direction developed by the vertical force acting through

the bank angle. Adding both tires, the resulting side

force per strut would be -4998 lb. For a wet runway at

KSC, the side force can be multiplied by the factor

presented in figures 29 and 30.

SUMMARY AND CONCLUSIONS

Space Shuttle orbiter tire force data were collected

using the Landing Systems Research Aircraft (LSRA)

and were analyzed in this report. Main gear and nose

gear tire forces were analyzed on Edwards Air Force

Base (EAFB) and Kennedy Space Center (KSC) concrete surfaces. In addition, main gear tires were used

for wet runway testing on KSC skid abraded and rotopeened surfaces. New side force models were produced

from the LSRA data.

The models from the LSRA improve the high vertical

load and high sideslip angle predictions over the current simulation models which were based on the Aircraft Landing Dynamics Facility (ALDF) test data. The

LSRA side force model includes a ply steer correction

which was developed from the LSRA, ALDF, and

Wright Laboratories Landing Gear Dynamometer

Facility (WLLGDF) data.

The LSRA and ALDF dry concrete side force data

have little variation with different speeds and runway

surfaces. Surprisingly, the data generated by the LSRA

on the EAFB dry lakebed also showed only small variations in side force with the data generated from the

concrete runways. Such a small amount of variation

allows the same model to be used for concrete surfaces

at KSC and EAFB as well as for EAFB lakebed site.

Tire drag data were also compared with the existing

models for concrete and EAFB lakebed runways.

Although some variation occurred in the values of drag

from the LSRA and from the existing models, such

variations are relatively small, and no new model

is proposed.

11
Limitedwetconcretetestingwasperformedontwo

surfacesontheKSCrunway.Asmeasuredbysideforce

variations,the wet runway friction rangedfrom

100percentof dry runwayfriction for high vertical

loadsandlow speedsto approximately30percentof

dry runwayfriction at low verticalloadsand high

speeds.

Dryden Flight Research Center

National Aeronautics and Space Administration

Edwards, California, April 14, 1997

12
APPENDIX A

TIRE FORCE

TRANSFORMATION EQUATIONS

These equations were applied to the load cell

measurements to transform the measured loads from

the load cell axes to the ground-based axes. Measurements include vertical load directly up as well as drag

load and side load parallel to the Earth axes and along

and perpendicular to the centerline of the tire (fig. 2).

TGNETVERT.M---Corrected test vertical force in

pounds. Positive force is up. Corrections are made for

transforming the body axis measurements into the test

tire axis. The transformation equation is as follows:

TGNETVERT.M = VERTFORCE x cos(PITCH)

x cos(BANK)

- (DRAGFORCE x sin(PITCH)

x cos(BANK))

+ (SIDEFORCE x sin(BANK)

x cos(PITCH)

TGNETSIDE.M Corrected test tire side force in

pounds. Positive force is left. Corrections are made for

transforming the body axis measurements into the test

tire axis. The transformation equation is as follows:

TGNETSIDE.M= [SIDEFORCE

- (VERTFORCE x sin(BANK))

- (DRAGFORCE x sin(W)]/cos(W)

+ VERTFORCE x sin(PITCH)

x sin(W)

TGNETDRAG.M--Corrected test tire drag in pounds.

Positive force is aft. Corrections are made for transforming the body axis measurements into the test tire

axis. The transformation equation is as follows:

TGNETDRAG.M= DRAGFORCE / cos(PITCH)

+ (VERTFORCE x sin(PITCH)

x cos (W))

-VERTFORCE x sin(W)

x sin(BANK))

+ (VERTFORCE

x sin(FORKANGLE) x cos(W))

1. DRAGFORCE = TG_GROS_DRAG - DRAGBIAS

2. VERTFORCE = 1.02 x (TG_GROS_VERT

- VERTBIAS)

3. SIDEFORCE = TG_GROS_SIDE - SIDEBIAS

4. W is the tire steering (not slip) angle.

5. THETA.M was substituted for PITCH when the INS

angle measurement failed.

6. BANK = Bank angle of aircraft.

7. DRAGBIAS, VERTBIAS, and SIDEBIAS are biases

applied to the load cells as determined from zero

force conditions.

PITCH - Aircraft pitch angle in degrees as measured by

the inertial navigation system. Nose up is positive.

13
APPENDIX B

SUMMARY OF FLIGHT DATA AND

CONICITY CORRECTIONS

These data were taken by visually averaging the time

history data. The load cell data in the time histories

were adjusted for zero bias (by subtracting the zero

load cell value just before touchdown). The result was

transferred to the test tire axis (vertical perpendicular to

the runway, side and drag force parallel to the runway,

and rotated through the steering angle).

Before these tables could be used for the tire force

model, the side force had to be corrected for an affect

called conicity. Vertical load exerted through a nonzero

bank angle of the wheel results in a flat area of contact

between the tire and the runway which is not perpendicular to the centerline of the tire. With no resistance

from the test fixture, this fiat area would cause the tire

to travel in a circular path similar to the way a cone

rolls on a fiat surface. The test fixture subjects the tire

to side forces that resist the conical path of travel. To

calculate this force, an accurate calculation of the total

angle from the vertical, or tilt angle, is needed.

The equation for the tilt angle is as follows:

Wheel tilt = Aircraft bank angle + 6.8 x side load

The first term is the bank angle of the aircraft as

measured by the difference in main gear strut lengths.

The second term is the side deflection of the test fixture

from the bank angle reference to the tire interface with

the ground. The second term was derived during static

loads tests conducted at the NASA DFRC.

Figure B 1 shows a plot from the NASA DFRC static

loads test. This graph shows the rotation angles of each

of the elements of the test fixture. The dotted line

denotes the deflection function used for the elastic

portion of the tilt angle.

Once the wheel tilt is calculated, the side force

corrected for conicity will be as follows:

Corrected side force = Side force + 0.01465 x wheel tilt

x vertical load

The factor of 0.01465 was derived from specially

designed taxi test runs on the LSRA. Both tests were

done by vertically loading the tire at 0° slip angle. A

baseline run was performed at 0° bank angle. By inflating the right main gear strut, a bank angle of-1.5 ° was

placed on the aircraft (left wing down), and a second

run was made. Similarly, a third run was made with the

left strut inflated higher than the fight, producing a 1.5°

bank angle (right wing down). The side load from the

baseline run was subtracted from the two succeeding

runs and divided by the tilt angle.

Figure B2 shows these data plotted as a function of

the corrected vertical load. Periodic steering pulses

were placed in each run to prevent mechanical friction

from affecting results. These pulses are the reason for

the apparent scatter in the data. A linear fit of that data

showed the factor of-0.01465. Similar tests were done

at the ALDE and two data points are also shown on this

plot. Side loads corrected for conicity are presented in

the far right column of tables B l-B5.

14
TableB1.Datafrommaintiredryconcretetireforcetests.

Vertical Slip Bank Side Drag

load, angle, Speed, angle, force, force,

lb deg KGS deg lb lb

Correctedside

loadfor conicity,

Ib

EAFB

33,000 -0.65 10 0.0 2,100 400

33,000 1.35 10 0.0 -4,800 400

33,000 -2.55 10 0.1 8,200 400

33,000 -0.65 10 0.1 2,100 400

63,000 -0.65 10 0.1 4,300 700

63,000 1.35 10 0.1 -4,200 800

63,000 -2.55 10 0.4 9,400 800

63,000 -0.65 10 -0.2 3,700 700

94,000 -0.55 10 0.3 1,700 1,300

94,000 1.35 10 0.3 -3,300 1,200

94,000 -2.65 10 0.8 6,700 1,400

94,000 -0.55 10 -0.1 3,500 1,300

125,000 -0.65 10 0.2 2,100 1,700

125,000 1.25 10 0.1 -1,800 1,800

125,000 -2.55 10 0.2 5,800 2,200

125,000 -0.75 10 0.0 2,000 1,800

63,000 -0.65 10 0.2 2,900 700

63,000 1.35 10 0.1 -3,800 700

63,000 -2.55 10 0.5 8,500 800

63,000 -0.65 10 0.2 3,000 700

33,000 0.05 10 -0.2 600 200

33,000 1.05 10 -0.3 -3,200 200

33,000 2.95 10 -0.3 -10,200 300

33,000 5.95 10 -0.4 -15,000 300

33,000 -0.95 10 -0.3 4,400 300

33,000 -2.15 10 -0.3 6,800 300

33,000 -3.15 10 -0.3 10,000 300

33,000 -5.05 10 -0.3 13,000 300

33,000 -8.0 10 -0.3 15,100 300

49,000 0.05 10 -0.3 1,100 400

49,000 0.95 10 -0.3 -2,700 400

49,000 3.05 10 -0.4 -10,800 500

2,169.04

-4,957.80

8,517.92

2,217.38

4,662.17

-4,371.30

10,359.13

3,747.62

2,272.32

-3,195.89

8,429.09

3,690.04

2,727.75

-1,841.02

6,888.50

2,249.05

3,266.60

-3,946.20

9,494.94

3,372.87

523.03

-3,450.23

-10,680.36

-15,686.50

4,399.61

6,878.51

10,183.71

13,282.33

15,451.37

938.34

-3,047.15

-11,614.33

15
TableB1.Continued.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadfor conicity,

lb deg KGS deg lb lb lb

EAFB

49,000 5.95 10 --0.4 -18,500 700 -19,690.20

49,000 -1.05 10 --0.4 5,400 500 5,376.45

49,000 -1.95 10 -0.4 8,300 500 8,418.01

49,000 -2.95 10 -0.4 11,300 500 11,564.46

49,000 -5.05 10 -0.4 16,000 600 16,493.88

49,000 -7.95 10 -0.4 19,500 700 20,164.73

64,000 0.05 10 -0.4 1,800 800 1,539.72

64,000 0.95 10 -0.4 -1,600 800 -2,077.05

64,000 2.95 10 -0.5 -10,800 900 -11,957.37

64,000 5.95 10 -0.5 - 19,500 1,300 -21,212.06

64,000 -0.95 10 -0.4 4,800 600 4,730.99

64,000 -2.05 10 -0.5 8,000 600 8,041.25

64,000 -3.05 10 -0.5 11,200 700 11,445.28

64,000 -4.95 10 -0.5 17,000 900 17,615.07

64,000 -7.75 10 -0.4 21,500 1,500 22,495.73

80,000 0.05 10 -0.6 1,100 900 484.47

80,000 0.85 10 -0.7 -2,500 900 -3,519.64

80,000 2.95 10 -0.8 -9,000 1,200 -10,654.86

80,000 -0.95 10 -0.7 4,600 900 4,146.20

80,000 -2.05 I0 -0.7 7,600 1,000 7,385.29

80,000 -2.95 10 -0.7 10,200 1,100 10,192.50

80,000 -4.85 10 -0.7 15,000 1,300 15,375.04

96,000 -0.05 10 -0.7 1,300 1,300 439.85

96,000 1.05 10 -0.8 -700 1,300 -1,892.06

96,000 2.95 10 -0.9 -7,500 700 -9,483.02

96,000 -0.95 10 -0.8 4,600 1,400 3,914.80

96,000 -1.95 10 --0.8 7,000 1,400 6,544.33

96,000 -2.95 10 -0.8 10,000 1,500 9,831.23

96,000 -4.95 10 -0.7 14,600 2,100 15,011.79

111,000 -0.05 10 -1.0 2,400 2,300 1,039.24

16
TableB1.Continued.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadfor conicity,

lb deg KGS deg lb lb lb

EAFB

111,000

111,000

111,000

111,000

127,000

127,000

127,000

127,000

127,000

127,000

127,000

147,000

147,000

147,000

33000

33,000

33000

33,000

33,000

33000

33,000

33,000

33,000

49,000

49,000

49,000

49,000

49,000

49,000

49,000

0.95 10 -1.0 -100 2,600 -1,737.21

2.85 10 -1.1 -5,900 2,900 -8,341.18

-0.95 10 -0.9 4,300 2,400 3,311.95

-2.05 10 -0.8 6,500 2,400 5,917.84

0.05 10 -0.7 1,900 1,900 838.00

1.05 10 -0.4 -300 1,900 - 1,082.18

3.05 10 -0.2 -5,600 2,300 -6,680.61

-0.95 10 0.0 3,300 2,000 3,717.51

-1.95 10 0.0 4,900 1,800 5,519.94

-2.95 10 0.0 7,500 2,300 8,448.88

-4.75 10 0.0 11,800 2,900 13,292.91

-0.05 10 0.0 900 2,800 1,031.80

1.05 10 0.0 -300 3,200 -343.93

3.15 10 0.0 -4,600 3,700 -5,273.63

0.05 10 -0.3 600 100 474.69

1.05 10 -0.3 -3,400 200 -3,656.81

2.95 10 -0.3 -9,000 200 -9,440.91

6.05 10 -0.3 -14,600 300 -15,225.00

-0.85 10 -0.3 3,500 200 3,470.03

-1.85 10 -0.3 6,600 300 6,671.94

-2.85 10 -0.3 9,400 100 9,563.99

-4.85 10 -0.3 12,300 100 12,559.32

-7.85 10 -0.3 14,600 100 14,934.93

0.15 10 -0.3 500 300 309.05

1.05 10 -0.4 -2,800 300 -3,223.82

3.15 10 -0.4 -10,200 500 -10,985.04

6.05 10 -0.4 -17,800 700 -18,956.03

-0.95 10 -0.4 4,500 300 4,432.52

-1.85 10 -0.4 7,500 300 7,578.96

-2.85 10 -0.4 10,500 40 10,725.40

17
TableB1.Continued.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadforconicity,

lb deg KGS deg lb lb lb

EAFB

49,000

49,000

64,000

64,000

64,000

64,000

64,000

64,000

64,000

64,000

64000

80000

80000

80000

80000

80,000

80,000

80,000

95,000

95,000

95,000

95,000

95,000

95,000

95,000

111,000

111,000

111,000

111,000

111,000

-4.95 10 -0.4 15,500 500 15,969.47

-7.85 10 -0.4 19,000 600 19,640.32

0.05 10 -0.4 700 900 369.59

1.05 10 -0.4 -1,900 900 -2,396.18

3.15 10 -0.5 -9,500 1,000 -10,574.49

6.05 10 -0.6 -18,500 1,300 -20,242.06

-0.85 10 -0.4 4,500 700 4,411.87

-1.85 10 -0.4 8,000 700 8,135.01

-2.85 10 -0.4 10,500 800 10,794.41

--4.85 10 -0.4 15,700 1,000 16,325.94

-7.85 10 -0.3 21,200 1,300 22,270.36

0.05 10 -0.5 900 1,000 385.73

1.05 10 -0.6 -2,200 900 -3,078.53

3.15 10 -0.7 -8,600 1,300 -10,105.79

-0.85 10 -0.6 4,100 1,000 3,723.55

-1.85 10 -0.6 6,600 1,000 6,422.79

-2.85 10 -0.6 9,700 1,100 9,769.85

-4.65 10 -0.5 14,600 1,400 15,177.56

0.05 10 -0.6 1,100 1,300 369.05

1.15 10 -0.6 -2,000 1,400 -3,024.33

3.25 10 -0.8 -7,200 1,700 -8,994.80

-0.95 10 -0.7 4,000 1,300 3,404.33

-1.85 10 -0.8 6,600 1,700 6,111.22

-2.85 10 --0.8 9,500 1,900 9,285.67

-4.85 10 -0.6 14,100 2,400 14,599.36

0.05 10 -1.1 2,100 2,200 543.45

1.15 10 -1.2 100 2,200 -1,840.32

3.15 10 -1.2 -5,100 2,700 -7,615.33

-0.85 10 -1.1 4,400 2,000 3,097.78

-1.85 10 -1.1 6,500 1,800 5,429.99

18
TableB1.Continued.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadforconicity,

lb deg KGS deg lb Ib lb

EAFB

111,000 -2.85 10 -1.1 9,000 1,800 8206.44

111,000 -4.65 10 -1.1 13,200 2,000 12,870.87

127,000 0.05 10 -0.6 1,700 1,500 798.75

127,000 1.15 10 -0.6 -200 1,500 - 1,341.63

127,000 3.15 10 -0.6 -5,300 1,800 -7,086.87

127,000 -0.85 10 -0.3 2,900 1,400 2,708.74

127,000 -1.85 10 -0.2 4,600 1,700 4,809.87

127,000 -2.85 10 0.0 7,100 1,900 7,998.27

127,000 -4.85 10 0.0 11,700 2,200 13,180.25

148,000 0.15 10 0.0 300 1,800 344.23

148,000 1.15 10 0.0 -800 1,900 -917.95

148,000 3.15 10 0.0 -5,000 2,400 -5,737.19

148,000 -0.85 10 0.0 2,500 2,300 2,868.59

148,000 -1.85 10 0.0 4,400 2,500 5,048.73

148,000 -2.85 10 0.0 6,400 2,700 7,343.60

148,000 --4.65 10 0.0 10,200 3,200 11,703.86

32,000 0.15 10 0.0 -1,100 200 -1,135.07

32,000 1.15 10 0.0 -4,000 200 -4,127.51

32,000 3.15 10 0.0 -10,300 200 -10,628.35

32,000 6.15 10 0.1 -15,000 200 -15,431.30

32,000 -0.85 I0 0.1 1,700 200 1,801.07

32,000 -1.85 10 0.1 4,800 200 4,999.90

32,000 -2.85 10 0.1 7,400 200 7,682.78

32,000 -4.85 10 0.1 11,300 200 11,707.11

32,000 -7.95 10 0.1 13,400 300 13,874.05

47,000 0.25 10 0.1 -1,200 400 -1,187.33

47,000 1.05 10 0.1 -4,700 400 -4,851.21

47,000 3.05 10 0.1 -11,500 500 -11,969.59

47,000 6.05 10 0.1 -18,200 700 -18,983.29

47,000 -0.85 10 0.2 3,000 400 3,278.17

19
TableB1.Continued.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadforconicity,

lb deg KGS deg lb lb lb

EAFB

47000

47000

47000

47000

65000

65000

65000

65000

65000

65000

65,000

65000

65.000

80.000

80000

80,000

80,000

80,000

80,000

96,000

96,000

96,000

96,000

96,000

96,000

96,0O0

111,000

111,000

111,000

111,000

-1.85 10 0.2 5,300 400 5,685.86

-2.85 10 0.3 8,100 500 8,685.82

-4.85 10 0.2 13,800 600 14,583.85

-7.85 10 0.2 17,900 700 18,875.81

0.15 10 0.2 -200 700 -22.50

1.15 10 0.2 -3700 800 -3,749.14

3.15 10 0.2 -11,100 900 -11,628.31

6.05 10 0.2 -20,100 1,300 -21,211.09

-0.85 10 0.3 3,000 800 3,479.93

-1.85 10 0.3 6,000 800 6,674.19

-2.95 10 0.3 8,700 900 9,549.03

-4.95 10 0.4 15,000 1,100 16,352.20

-7.85 10 0.4 21,200 1,300 22,953.66

0.15 10 0.5 -500 1,000 46.15

1.05 10 0.5 -3,200 1,100 -2,869.03

3.15 10 0.5 -10,300 1,300 -10,534.87

-1.85 10 0.4 4,500 1,100 5,327.43

-2.85 10 0.4 8,200 1,200 9,322.31

-4.75 10 0.4 13,400 1,400 14,936.73

0.05 10 0.3 -700 600 -345.02

1.05 10 0.3 -3,300 300 -3,193.68

3.15 10 0.2 -9,500 700 -10,127.25

-0.85 10 0.3 2,200 500 2,832.32

-1.95 10 0.4 4,400 600 5,383.35

-2.95 10 0.6 7,300 700 8,841.98

-4.95 10 0.6 13,000 1,200 15,087.10

0.05 10 0.4 -700 500 - 126.94

1.05 10 0.5 -2,500 500 -1,963.37

3.15 10 0.4 -8,100 600 -8,345.22

-0.85 10 0.6 1,500 600 2,641.56

20
TableB1.Continued.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadfor conicity,

lb deg KGS deg lb lb lb

EAFB

111,000 -2.05 10 0.7 3,800 700 5,358.50

111,000 -2.95 10 0.7 5,600 800 7,357.54

111,000 -4.95 10 0.7 11,800 1,300 14,243.13

127,000 0.05 10 0.7 -1,300 1,500 -162.09

127,000 1.25 I0 0.4 -2,300 1,500 - 1,846.77

127,000 3.15 10 0.3 -6,800 1,700 -7,102.15

127,000 -0.95 10 0.2 1,700 1,400 2,287.19

127,000 -1.85 10 0.1 4,200 1,600 4,917.43

127,000 -2.85 10 0.0 6,900 1,800 7,772.97

127,000 -4.95 10 0.0 11,900 2,200 13,405.56

148,000 0.15 10 0.0 300 1,800 344.23

148,000 1.15 10 0.0 -600 1,600 -688.46

148,000 3.15 10 0.0 -4,800 2,200 -5,507.70

148,000 -0.85 10 0.0 1,700 1,800 1,950.64

148,000 -1.85 10 0.0 3,800 1,800 4,360.26

148,000 -2.85 10 0.0 5,900 1,900 6,769.88

148,000 -4.95 10 0.0 10,500 2,700 12,048.09

KSC

62,000 -5.4 193 2.5 14,400 2,300 17,560.16

66,500 -5.3 136 0.1 15,500 2,500 16,624.26

62,200 -3.3 148 -0.3 10,900 1,200 11,302.03

91,900 -2.4 145 0.1 6,000 1,700 6,683.94

62,100 -2.3 147 0.1 7,600 700 8,161.14

62,000 -2.3 139 0.3 7,100 800 7,811.02

46,300 -2.4 145 0.1 8,300 300 8,750.66

62,300 -3.4 150 0.2 11,500 700 12,396.27

62,400 -2.4 154 0.7 8,100 700 9,243.43

61,500 -0.3 100 0.2 800 600 1,029.21

122,200 0.9 52 -1.4 900 2,000 -1,496.76

122,200 2.1 52 -1.6 -1,400 2,000 -4,434.80

21
TableB1.Concluded.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadfor conicity,

Ib deg KGS deg lb lb lb

KSC

122,200 3.9 52 -1.6 -4,700 2,500 -8,136.53

91,700 -1.3 52 -1.2 4,500 1,000 3,299.00

91,700 -2.0 52 -1.0 6,800 1,100 6,077.79

91,700 -4.0 52 -0.9 12,100 1,400 11,996.29

91,700 -7.0 52 -0.8 18,800 2,200 19,442.68

61,500 0.8 52 -1.4 1,200 600 12.15

61,500 1.7 52 -1.1 -3,000 600 -4,174.87

61,500 3.7 52 --0.7 -9,400 700 -10,606.59

61,500 6.5 52 -0.7 -18,600 1,100 -20,370.24

46,100 -1.0 52 -0.3 1,600 300 1,470.87

46,100 -1.9 52 -0.7 5,700 300 5,489.02

46,100 -3.9 52 --0.8 11,300 300 11,278.66

46,100 -7.0 52 -0.6 17,600 500 18,003.06

46,700 -2.3 104 0.3 7,800 300 8,368.12

122,700 0.6 152 -0.1 200 2,000 44.69

122,700 1.5 152 -0.2 -1,200 2,000 - 1,706.19

122,700 3.7 152 -0.4 -6,500 2,500 -8,013.54

92,100 -1.4 154 0.4 3,600 1,100 4,470.01

92,100 -2.3 154 0.6 4,900 1,100 6,159.13

92,100 -4.1 154 0.3 9,800 1,300 11,103.93

92,100 -7.3 154 0.6 18,800 3,500 21,334.46

61,500 0.7 159 0.4 -1,600 400 -1,337.64

61,500 1.7 159 0.3 -5,000 500 -5,036.04

61,500 3.6 159 0.4 -9,700 500 -9,933.89

61,500 6.5 159 0.4 -17,500 800 -18,211.77

46,900 -1.4 160 0.5 4,000 200 4,530.43

46,900 -2.4 160 0.7 6,400 200 7,179.98

46,900 -4.2 160 0.6 10,800 300 11,716.85

46,900 -7.2 160 0.7 16,100 500 17,333.18

22
TableB2.Datafromnosetiredryconcretetireforcetests.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadfor conicity,

lb deg KGS deg lb lb lb

EAFB

50,000 0.0

50,000

50,000

50,000

50,000

50000

50000

50000

50000

32000

32000

32,000

32,000

32,000

32,000

32,000

32,000

12,000

12,000

12,000

12,000

12,000

12,000

12,000

12,000

31,000

31,000

31,000

31,000

199 0.4 -100 1,700

1.1 199 0.3 -600 1,200

2.2 199 0.2 -1,300 1,500

4.1 199 -0.1 -2,500 1,800

7.2 199 -0.4 -5,200 2,000

0.2 199 -0.3 400 1,600

-0.8 199 -0.2 800 1,400

-1.8 199 0.0 1,700 1,200

-3.8 199 O.1 2,400 1,800

0.0 50 O.1 -500 300

1.0 50 O.1 -2,000 400

2.0 50 O.1 -3,900 400

4.0 50 O.1 -6,600 500

0.0 50 O.1 -600 300

-1.0 50 O.1 1,100 400

-2.0 50 O.1 2,200 400

-3.9 50 O.1 4,800 400

0.0 50 -0.1 --400 100

1.0 50 -0.1 -1,500 100

2.0 50 -0.1 -2,500 1O0

4.0 50 -0.1 -4,000 100

0.0 50 -0.1 -500 100

- 1.0 50 -0.1 700 1O0

-2.0 50 -0.1 1,600 1O0

--4.0 50 --0.1 3,100 100

0.0 160 0.3 -200 800

1.0 160 0.3 -2,200 800

2.0 160 0.3 -3,800 800

4.0 160 0.2 -6,500 800

188.02

-410.14

- 1,218.25

-2,697.78

-5,752.01

200.17

693.35

1,784.68

2,592.79

-469.06

-2,016.88

-3,977.45

-6,763.52

-572.25

1,181.95

2,317.01

4,999.90

-422.36

-1,535.51

-2,547.47

-4,065.40

-523.56

690.79

1,601.55

3,119.48

-69.93

-2,131.70

-3,781.11

-6,609.90

23
TableB2.Concluded.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadfor conicity,

Ib deg KGS deg lb lb lb

EAFB

31,000 0.0 160 0.1 -800 700 -779.29

31,000 -1.0 160 0.1 500 700 560.86

31,000 -2.0 160 0.1 2,200 700 2,313.36

31,000 - 4.0 160 0.1 4,700 700 4,890.56

11,000 0.0 160 0.0 -300 500 -303.29

11,000 1.0 160 0.0 -1,600 500 -1,617.53

11,000 2.0 160 0.0 -2,300 500 -2,325.20

11,000 4.0 160 0.0 - 4,300 500 - 4,347.12

11,000 0.0 160 0.0 -500 400 -505.48

11,000 -1.0 160 0.0 600 400 606.57

11,000 -2.1 160 0.0 1,400 400 1,415.34

11,000 - 4.0 160 0.0 3,100 500 3,133.97

30,000 0.0 199 0.0 0 1,000 0.00

30,000 1.0 199 -0.1 -2,200 1,000 -2,309.70

30,000 2.0 199 -0.2 -3,600 1,000 -3,795.49

30,000 4.0 199 -0.4 -6,500 1,000 -6,870.06

30,000 0.0 199 -0.4 -100 1,000 -278.79

30,000 -1.0 199 -0.3 1,400 1,000 1,309.99

30,000 -2.0 199 -0.1 2,900 1,000 2,942.72

30,000 - 4.0 199 0.1 5,000 1,000 5,193.38

12,000 0.0 200 0.3 -400 600 -352.04

12,000 1.0 200 0.3 -1,600 600 -1,566.39

12,000 2.0 200 0.3 -2,200 600 -2,173.56

12,000 4.0 200 0.3 - 4,400 600 - 4,399.86

12,000 0.0 200 0.2 -600 700 -572.01

12,000 -1.0 200 0.2 400 700 439.94

12,000 -2.0 200 0.2 1,600 700 1,654.29

12,000 - 4.0 200 0.2 3,400 700 3,475.80

24
TableB3.Datafrommaintirelakebedtireforcetests.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadforconicity,

lb deg KGS deg Ib lb Ib

EAFB

124,000 1.1 51 -1.7 3,600 4,700 956.48

124,000 2.6 51 -1.3 1,300 4,700 -900.99

124,000 4.4 51 -1.5 -800 4,300 -3,623.72

124,000 6.6 51 - 1.6 -4,500 4,600 -7,962.44

91,000 0.5 50 -0.2 500 3,200 278.70

91,000 -0.5 50 -0.4 1,600 3,300 1,211.79

91,000 -1.5 50 -0.6 4,800 3,700 4,435.25

91,000 -3.5 50 -0.6 11,100 4,000 11,306.37

91,000 --6.5 50 -0.6 18,900 4,600 19,813.47

61,000 0.3 48 -0.3 1,600 2,300 1,429.13

61,000 1.2 48 -0.2 700 2,500 563.81

61,000 2.3 48 0.1 -4,700 2,500 -4,896.25

61,000 4.4 48 0.2 -11,300 2,800 -11,807.95

61,000 7.4 48 0.0 -20,000 3,100 -21,215.36

47,000 0.5 48 0.4 -1,500 1,700 -1,294.81

47,000 -0.5 48 0.3 1,200 1,400 1,462.75

47,000 -1.4 48 0.2 4,400 1,500 4,743.72

47,000 -3.5 48 0.2 10,300 1,800 10,919.97

47,000 -6.6 48 0.4 16,600 1,900 17,652.66

123,000 1.1 159 -1.8 2,500 8,100 -437.18

123,000 2.0 159 -1.7 -100 8,100 -3,175.57

123,000 2.9 159 - 1.8 -2,200 8,700 -5,713.08

123,000 4.7 159 -1.8 -7,000 9,700 -I 1,101.24

92,000 0.3 153 -1.3 2,000 6,900 431.16

92,000 0.8 153 -1.1 1,300 6,300 -63.43

92,000 0.0 153 -1.0 2,100 6,300 944.67

92,000 -0.8 153 -1.0 3,200 6,300 2,145.48

92,000 -2.6 153 -0.9 9,500 6,400 9,157.66

92,000 -5.7 153 -0.8 17,800 7,100 18,353.14

61,000 0.8 156 -0.5 500 4,100 83.56

61,000 1.3 156 -0.4 -1,900 4,400 -2,372.92

61,000 2.4 156 -0.3 -5,400 4,600 -5,996.24

61000 4.5 156 -0.4 -11,700 4,800 -12,768.45

25
TableB4.Datafromnosetirelakebedtireforcetests.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadforconicity,

lb deg KGS deg lb lb lb

EAFB

61.000

47.000

47000

47.000

47.000

47.000

126000

126000

126000

126.000

92,000

92,000

92,000

92,000

92,000

62,000

62,000

62,000

62,000

62,000

47000

47000

47000

47000

11000

11000

11000

11000

11000

11000

11,000

11,000

31,000

7.5 156 -0.7 -18,800 5,100 -20,568.00

-0.1 160 0.0 100 3,700 104.68

-0.1 160 -0.1 500 3,700 454.56

-0.4 160 -0.2 1,500 3,300 1,432.52

-2.2 160 -0.1 7,600 3,400 7,886.99

-5.7 160 0.0 14,700 3,600 15,388.27

0.5 192 -1.5 3,200 8,000 832.82

1.3 192 -1.3 900 8,000 -1,386.70

1.9 192 -1.4 -1,900 8,200 -4,722.75

3.7 192 -1.3 -5,500 8,500 -8,590.04

0.4 186 -0.3 400 6,100 32.32

-0.4 186 -0.3 2,100 6,100 1,888.13

-1.4 186 -0.3 5,500 6,300 5,599.74

-3.6 186 -0.3 11,600 6,500 12,258.80

-6.5 186 -0.2 18,800 7,600 20,253.47

1.3 185 -0.1 -1,100 4,200 -1,258.77

1.3 185 0.1 -1,900 4,200 -1,926.52

1.8 185 0.4 --4,700 4,400 -4,626.97

3.4 185 0.3 -9,000 4,700 -9,283.39

6.1 185 0.1 - 16,600 5,000 -17,534.46

-0.1 185 0.6 -700 3,300 -319.64

0.1 185 0.3 400 3,300 625.29

-1.0 185 0.4 3,400 3,500 3,834.61

-3.5 185 0.5 9,800 3,800 10,603.12

0.3 50 0.8 -100 200 27.82

1.3 50 0.8 -1,400 200 -1,286.42

2.3 50 0.8 -2,100 200 -1,994.09

4.3 50 0.8 --4,000 200 -3,914.91

0.3 50 0.8 -300 100 -174.37

-0.7 50 0.8 900 1O0 1,038.78

-1.7 50 0.8 1,600 1O0 1,746.45

-3.7 50 0.8 3,200 1O0 3,363.99

-0.4 162 -0.3 400 2,000 276.11

26
TableB4.Concluded.

Vertical Slip Bank Side Drag Correctedside

load, angle, Speed, angle, force, force, loadfor conicity,

lb deg KGS deg Ib lb lb

EAFB

31,000

31,000

31,000

31,000

31,000

31,000

31,000

11,000

11,000

11,000

I 1,000

11,000

11,000

11,000

11,000

31,000

31,000

31000

31000

31000

31000

31000

31000

12,000

12,000

12,000

12,000

12,000

12,000

12,000

12,000

0.7 162 -0.3 -900 2,000 - 1,064.04

1.6 162 -0.3 -1,800 2,000 -1,991.83

3.7 162 -0.3 --4,600 2,000 -4,878.30

-0.3 162 -0.3 500 2,000 379.20

-1.3 162 -0.3 1,700 2,000 1,616.25

-2.3 162 -0.3 3,000 2,000 2,956.40

-4.3 162 -0.3 5,400 2,000 5,430.52

-0.4 161 0.1 300 900 319.40

0.7 161 0.1 -1,500 900 -1,500.32

1.8 161 -0.2 -2,000 900 -2,054.15

3.8 161 -0.3 -2,500 900 -2,575.74

-0.4 161 -0.2 700 900 675.44

-1.4 161 -0.2 1,500 900 1,484.21

-2.5 161 0.0 2,200 900 2,224.11

-4.4 161 0.0 3,500 900 3,538.35

-0.1 201 0.6 200 2,100 478.67

1.1 201 -0.6 -700 2,100 -994.11

2.0 201 -0.6 -1,700 2,100 -2,024.99

3.8 201 -0.6 -4,000 2,100 -4,396.02

-0.1 201 -0.7 200 2,200 -111.73

0.9 201 -0.6 1,300 2,200 1,067.66

-1.7 201 -0.6 2,500 2,200 2,304.72

-3.7 201 -0.5 4,700 2,200 4,618.07

-0.2 201 -0.3 200 1,100 149.65

0.7 201 -0.3 -700 1,100 -761.11

1.7 201 -0.3 -1,300 1,100 -1,368.28

3.7 201 -0.3 -2,700 1,100 -2,785.01

-0.3 201 -0.2 200 1,100 167.23

-1.1 201 -0.2 1,100 1,100 1,077.99

-2.0 201 -0.2 1,900 1,100 1,887.55

-3.7 201 -0.2 3,200 1,100 3,203.09

27
TableB5.Datafrommaintirewetrunwaytireforcetests.

Vertical Rotopeen Slip Bank Side Correctedside

load, or angle, Speed, angle, force, loadfor conicity,

lb skidabrade deg KGS deg lb lb

KSC

124,000

124,000

124,000

93,000

93,000

93,000

93000

63000

63000

63000

63000

47000

47,000

47,000

47,000

56,000

60,000

36,000

124,000

124,000

124,000

92,000

92,000

92,000

92,000

62,000

62,000

62,000

62,000

47,000

rot2 1.0 153 -0.1 -100 -294.01

rot2 2.0 153 -0.2 -3,000 -3,733.91

rot2 4.0 153 -0.3 -7,700 -9,196.15

rot2 -1.0 157 0.2 3,300 3,878.22

rot2 -1.9 157 0.3 4,900 5,762.70

rot2 -3.9 157 0.2 11,100 12,400.87

rot2 -6.9 157 0.3 17,400 19,420.79

rot2 1.2 159 -0.2 -3,600 --4,010.53

rot2 2.0 159 -0.1 -5,000 -5,406.10

rot2 3.9 159 0.0 -10,000 -10,627.61

rot2 7.1 159 -0.2 -15,800 -16,976.21

rot2 -1.0 159 0.0 2,900 3,035.78

rot2 -1.9 159 0.1 5,200 5,512.33

rot2 -3.9 159 0.0 9,300 9,735.44

rot2 -7.0 159 0.1 12,300 12,944.76

skidl 1.1 203 -0.8 -1,200 -1,923.26

skidl 2.6 203 -1.7 -2,600 --4,249.71

skidl 0.6 203 -1.4 -1,900 -2,706.50

skidl 1.0 52 -0.3 -1,300 -2,005.57

skidl 2.0 52 -0.5 -4,300 -5,739.47

skidl 4.0 52 --0.8 -7,800 -10,216.80

skidl -0.8 52 -0.7 1,900 1,130.68

skidl -1.8 52 -0.3 4,600 4,617.25

skidl -3.9 52 -0.2 8,500 9,009.47

skid1 --6.9 52 -0.1 12,400 13,401.68

rot2 1.0 50 0.0 -3,800 -4,034.70

rot2 2.0 50 -0.2 -7,400 -8,038.72

rot2 4.2 50 -0.4 -10,400 -11,405.67

rot2 7.0 50 -0.1 -12,600 -13,469.06

skidl -0.8 50 -0.3 1,400 1,258.98

28
TableB5.Concluded.

Vertical Rotopeen Slip Bank Side Correctedside

load, or angle, Speed, angle, force, loadfor conicity,

lb skidabrade deg KGS deg lb lb

KSC

47,000 skidl -1.9 50 -0.1 3,700 3,804.38

47,000 skid1 -3.9 50 -0.1 7,200 7,468.26

47,000 skidl --6.8 50 -0.1 9,200 9,561.90

124,000 rot2 1.2 50 -0.3 0 -544.98

124,000 rot2 2.0 50 -0.7 -2,200 -3,743.38

124,000 rot2 4.0 50 -0.8 -7,100 -9,430.33

92,000 rot2 -0.8 51 -0.6 3,300 2,793.77

92,000 rot2 -1.9 51 0.1 6,000 6,684.68

92,000 rot2 -3.9 51 0.1 11,500 12,688.76

92,000 rot2 -6.8 51 0.0 18,200 19,868.04

62,000 rot2 1.0 50 0.3 -1,900 -1,744.86

62,000 rot2 2.0 50 0.2 -6,700 -6,932.16

62,000 rot2 4.2 50 -0.4 - 12,300 - 13,423.02

62,000 rot2 7.1 50 -0.3 -17,500 -18,853.37

46,000 rot2 -0.9 50 -0.4 3,000 2,867.92

46,000 rot2 -2.0 50 0.0 6,700 7,007.03

46,000 rot2 -3.9 50 0.0 10,800 11,294.91

46,000 rot2 -7.0 50 0.0 14,500 15,164.47

59,000 rot2 1.1 195 0.8 -2,200 -1,637.83

48,000 skid1 1.9 195 0.8 -2,900 -2,476.11

48,000 skidl 4.0 195 0.6 -4,600 -4,398.04

48,000 skidl 7.2 195 0.5 -4,600 -4,468.36

62,000 skial -1.0 195 1.0 3,300 4,412.12

62,000 skidl -1.9 195 1.2 4,900 6,292.61

62,000 skidl -3.9 195 1.5 10,200 12,192.45

62,000 skidl -7.0 195 1.9 13,300 15,847.24

29
REFERENCES

1Carter, John E and Christopher J. Nagy, The NASA

Landing Gear Test Airplane, NASA TM-4703, 1995.

2Davis, Pamela A., Sandy M. Stubbs, and John A.

Tanner, Aircraft Landing Dynamics Facility: A Unique

Facility With New Capabilities, SAE Technical Paper

Series 851938, Oct. 1985.

3Daugherty, Robert H., Sandy M. Stubbs, and Martha

P. Robinson, Cornering Characteristics of the MainGear Tire of the Space Shuttle Orbiter, NASA

TP-2790, 1988.

4Vogler, William A. and John A. Tanner, Cornering

Characteristics of the Nose-Gear Tire of the Space

Shuttle Orbiter, NASA TP- 1917, 1981.

5Daugherty, Robert H. and Thomas J. Yager, Texture

Modification of the Shuttle Landing Facility Runway at

the NASA Kennedy Space Center, NASA TM-110269,

1996.

6Tanner, John A., Sandy M. Stubbs, and John L.

McCarty, Static and Yawed-Rolling Mechanical Properties of Two Type VII Aircraft 7_res, NASA TP-1863,

1981.

30
t conductor console _Linear actuators Nitrogen //_

\ j /

Hydraulic pumps

Hydraulic accumulators

950187

Figure 1. The primary components of the CV 990 aircraft and test system.

31
Front of aircraft

load cell

Vertical

load

90--

80-- __'

70 --

60--

50 --

Inches

40--

30--

20--

10--

0

Figure 2. Yaw fixture load cell installation.

load cell

load cell

velocimeters

970518

Approach with flaps up

Dero_tlon

&

Deploy spoilers

omputer-conb'olled extension

of test lending gear

Test complete: retract

nding gear

n

Safe systems

970519

Figure 3. Typical landing sequence.

32
Vertical

load,

Ib

Slip

angle,

deg

Speed,

KGS

15x10 4

_ 10 _ I I I I I I I I I I

200 r

1801-

160

1401-

1201-

100-

0

I I I I I I I I I I

2 4 6 8 10 12 14 16 18 20

Time, sac

970520

Figure 4. Commanded versus actual tire force data.

33
(a)TheEAFBconcreterunway22.

EC9744019-01

(b)TheEAFBlakebedrunway15.

Figure5.TheEAFBsurfacesusedfortireforcetesting.

EC9744019-02

34
4500

4OOO

3500

Cone

index, 3000

25OO

2000

1500

0

0

0

% o

0 0

o _5o oo o_ oo Ooo o o

°g° Oo oo%0 %_o_°°° o % _ o

0

0

cur o 0

o

0

0 d_ 0

0

0

Ooo%o_° o 00oq)O

Oq) 0

O0 OCt) 0 U_O0

0

0 0 0 0

0

6) o

I I I I I I

0.7 0.8 0.9 1.0 1.1 1.2

Runway position, ft

Figure 6. The EAFB runway 15 soil strength: average 0- to 6-in. interval.

Oo

O

0 O0 o oo

0

o 0

0

0

I I

1.3 x 104

970521

1_ Modified 3500 ft Unmodified 8000 ft

Touchdown area _ Middle rollout area 1000ft 14/I 13/2 12/3 111/4 10/5 9/6 8/7 7/6 6/9 5/10

I I I I I I I I I I I

rm *_

_ I_ Modified 3500 ft I

_ Touchdown area >

4/11 3/12 2/13 1/14 1000 ft

I I I I I

,_o!

_ C_ _

5 o,t

.. ";.,,

Original texture, laterally grooved,

0.25 in. x 1.125 in.

Corduroy texture,

4.5 blades/in.

Figure 7. The KSC Shuttle Landing Facility layout (from ref. 5).

970840

35
Vertical force

J

_'_ Drag

/ force

Aircraft nose

970523

(a) Side view.

Aircraft

nose

Drift Ground

angle velocity

Sldeforce -'_ _._ St.rlng /, angle

___'_/_Sll I angle

/

/

CV 990 centerline

(b) Top view.

970524

I

I Tilt angle

I /

Resultant I //

aide force I /

of_model _/

970525

(c)Aftview.

Figure 8. Sign conventions for test tires.

36
Vertical

load,

Ib

7 x 104

t6 F 46,900 Ib-_

Side

load,

Ib

2.0 [- 16,10_O0'b _-__ . _ .

_.5_ ,o_.6_oo,b_-_ _

1.0 L ._._._.._f _ E4OL)_Ib-,,__ ....

.5 _ .............. _ .....

0 I I I 4,000 Ib I I

oF_._....._ _'-- 1.4 °

-2p -- - Z Z Z Z Z Z Z __- :

s,p -41=-_-_2:;o- _-- - -:

angle,deg::p .... ,_ _ _ "--/z_ _./'-: z_

-10

20.0 20.5 21.0 21.5 22.0 22.5

Time, eec

970526

Figure 9. A tire force test on the KSC center section at 160 kn for 2.5 sec.

Side

force,

Ib

10

5

0

-5

-10

-15

- 20

- 25

-8

25x loa

" O Dry concrete at various speeds

_ LSRA dry concrete model

20 DF tire force model

15

-

:

I I I I I I I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg 970527

Figure 10. Side force at 63,000 lb + 2,000 ib with LSRA dry concrete data.

37
Ply

steer,

Ib

-F2500

2000

1500 -

1000

500

0 f

- 500

-1000 -

- 1500 -

- 2000

0

O WLLGDF

rl ALDF

O Averaged LSRA data

(solid ,nee are

uncertainty bounds)

-- LSRA model

O

[3 ( nl o

I

O

Vertical load, Ib

I

10

Figure 11. Ply steer estimate.

o

I

15 x 104

970528

Side

force,

Ib

25 x 103

-- O Dry concrete st various speeds

-- LSRA dry concrete model

20 .... ALDF tlre force model

15 _.-_

10-

-15

- 2S I I I I I J I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970529

Figure 12. Main gear EAFB and KSC dry concrete side forces at a 33,000-1b vertical load.

38
Side

force,

Ib

10

5

0

-5

-10

-15

- 20

- 25

-8

25 x 103

- O Dry concrete at various speeds

LSRA dry concrete model

20 _... ALDF tire force model

15 -

0

-

I I I I I I I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg 970530

Figure 13. Main gear EAFB and KSC dry concrete side forces at a 48,000-1b vertical load.

Side

force,

Ib

10

5

0

-5

-10

-15

- 20

- 25

-8

25 x 103

- O Dry concrete at various speeds

_ LSRA dry concrete model

20 force model

15 -

".

_ . _._0

I 1 I I I I I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg

970531

Figure 14. Main gear EAFB and KSC dry concrete side forces at a 63,000-1b vertical load.

39
Side

force,

Ib

25 x 103

B

O Dry concrete at various speeds

_,_-._ _ _ LSRA dry concrete model

20 - "_,_ ------ ALDF tire force model

- 25 I I I I I I I "1

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970532

Figure 15. Main gear EAFB and KSC dry concrete side forces at a 80,000-1b vertical load.

25 x 103

B

O Dry concrete at various speeds

_ LSRA dry concrete model

20 - ",_'_ -- -- -- ALDF tire force model

15 - "" ._,

10

5

Side 0

force, 0

Ib

-5

-10

-15 - _'_

20- ""

- 2S I J I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970533

Figure 16. Main gear EAFB and KSC dry concrete side forces at a 94,000-1b vertical load.

40
25 x 103

- O Dry concrete at various speeds

-- LSRA dry concrete model

201015____ -- ALDF tire force model

5

Side ,, -..

force, 0 -

Ib

-5

-10

-15

- 20 - _',_,

-25 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg 970534

Figure 17. Main gear EAFB and KSC tire dry concrete side forces at a 110,000-1b vertical load.

25 x 103

20

15

10

5

Side

force, 0

Ib

-5

-10

-15

- 20

- 25

-8

-- 0 Dry concrete at various speeds

-- LSRA dry concrete model

-- ALDF tire force model

I I I I I I I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg 970535

Figure 18. Main gear EAFB and KSC tire dry concrete side forces at a 126,000-1b vertical load.

41
Side

force,

Ib

10

5

0

-5

-10

-15

- 20

- 25

-8

25 x 103

F O Dry LSRAconcrete dry concrete at various modelspeeds

20 _ ------ ALDF tire force model

15 __ -"_,_

I I I I I I I I

-6 -4 -2 0 2 4 6 8

Sllp angle, deg

970536

Figure 19. Main gear EAFB and KSC tire dry concrete side forces at a 148,000-1b vertical load.

25 x 103

_'- O Edwards data, 10 kn

Q KSC data, 100- 195 kn

20_ _ O KSCdata, 52kn

' "',,Q LI KSC data, 160 kn

is - R -- ,s.A dryconcretemodel

10-

5

Side

force,lb 0- <> <>

-5

-10 - 0 _;>

-15

- 20

-25 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970537

Figure 20. Main gear EAFB and KSC tire dry concrete side forces at 63,000 lb + 2,000 lb. (These EAFB data were

collected on concrete, and KSC data were collected on center section on unground concrete.)

42
Side

force,

Ib

25 x 103

l'- O EAFB lakebed at various speeds

20 _ _ LSRA dry concrete model

15

10

_!

-15 -

- 20

- 25 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg 97os3B

Figure 21. Main gear tire EAFB lakebed side forces at 47,000 lb.

Side

force,

Ib

25 x 103

-- O EAFB lakebed at various speeds

LSRA dry concrete model

20-

15

10

5

O

0

-5

-15

- 20

-25 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, (:leg

970539

Figure 22. Main gear tire EAFB lakebed side forces at 61,000 lb.

43
Side

force,

Ib

I0

5

0

-5

-10

-15

- 20

- 25

-8

25 x 103

- O EAFB lekebed at varlous speeds

LSRA dry concrete model

20-

15

I I i t t i i I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg 97o_o

Figure 23. Main gear tire EAFB lakebed side forces at 92,000 lb.

Slde

force,

Ib

10

5

0

-5

-10

-15

- 20

- 25

-8

25 x 103

- O EAFB lakebed at various speeds

[] EAFB Iskebed low-speed data, 51 KGS

20 _ LSRA dry concrete model

15--

_ O n

I I I I I I I I

-6 -4 -2 0 2 4 6 8

Sllp angle, (leg 97o541

Figure 24. Main gear tire EAFB lakebed side forces at 124,000 lb.

44
Side

force,

Ib

25 x 103

m

20

15

O Wet skldabrader-on-corduroy concrete

LSRA dry concrete model

I I I I I I I I

-2 0 2 4 6 8

Slip angle, deg 97_42

Figure 25. Main gear KSC wet concrete side forces at 36,000 lb.

Side

force,

Ib

10

5

0

-5

-10

-15

- 20

- 25

-8

25 x 103

I-- O Wet ekldabrader-on-corduroy concrete

| [] Wet rotopeener-on-unground concrete

20 _ _ LSRA dry concrete model

=,.kn I

_ \ / lSgkn_\/ _-SO_

I I I I I 1 I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg

970543

Figure 26. Main gear KSC wet concrete side forces at 47,000 lb.

45
Side

force,

Ib

10

5

0

-5

-10

-15

- 20

- 25

25 x 103

O Wet skidabreder-on-corduroy concrete

E] Wet rotopeener-on-unground concrete

20 I'- _ -- LSRA dry concrete model

159 kn

i 50 kn --__gkn

I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970544

Figure 27. Main gear KSC wet concrete side forces at 63,000 lb.

Side

force,

Ib

5

0

-5

-10

-15

- 20

- 25

25 x 103

I-- O Wet skldabreder-on-corduroy concrete

L /--51 kn [] Wet rotopeener-on-unground concrete

20 _1_:"I_ " -- LSRA dry concrete model

15I"0_ l_7kn_ lkn

l°r \ ....... 0 _ _-51kn

L X / "_-157 kn

I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, dog

970545

Figure 28. Main gear KSC wet concrete side forces at 93,000 lb.

46
120 --

Dry

friction,

percent

100

8O

6O

4O

2O

126 klb

0

63 klb []

O 94 klb

_48 klb

I I I I I

0 50 100 150 200 250

Speed, kn 970546

Figure 29. Main gear KSC tire side force on wet skid abraded on corduroy section as a function of dry concrete

forces.

120 --

Dry

friction,

percent

100

8O

6O

40

2O

94 klb, 126 klb

"__--.-.-___ 63 klb

_48 klb

I I I I 1

0 50 100 150 200 250

Speed, kn

970547

Figure 30. Main gear KSC tire side force on wet rotopeened unground section as a function of dry concrete forces.

47
5

Side

force, 0

Ib

-5

10x103

- O Dry concrete at various speeds

LSRA dry concrete model

------ ALDF tire force model

-

_

-10 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg 97os4s

Figure 3 l. Nose gear EAFB dry concrete side forces at 11,000 lb.

10 x 10 3

O Dry concrete at various speeds

LSRA dry concrete model

------ ALDF tire force model

Side

force,

Ib

-10 I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970549

Figure 32. Nose gear EAFB dry concrete side forces at 33,000 lb.

48
Side

force,

Ib

-10

-8

10 x 10 3

I O Dry concrete st various speeds

LSRA dry concrete model

------ ALDF tire force model

0- ///"

--5 P--

I I I I I I I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg 970550

Figure 33. Nose gear EAFB dry concrete side forces at 50,000 lb.

10 x 10 3

-- O EAFB lakebed at various speeds

m LSRA dry concrete model

-- ALDF tire force model

5 "-..._ "-....

Side 0 _O %O O

force,

Ib

-lO I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970551

Figure 34. Nose gear EAFB lakebed side forces at 11,000 lb.

49
Side

force,

Ib

10x103

0 EAFB lakebed at various speeds

LSRA dry concrete model

------ ALDF tire force model

)o

0

0

I I I

-2 0 2

Slip angle, deg

6 8

970552

Figure 35. Nose gear EAFB lakebed side forces at 33,000 lb.

Drag

force,

Ib

6000

5000

4000

300O

2000

1000

O Dry concrete at various speeds

------ ALDF drag model

o_---_-_,_ov_, :, _, _ ,

-8 -6 -4 -2 0 2 4 6 8

Slip angle, cleg

970553

Figure 36. Main gear EAFB and KSC tire drag forces at 33,000 lb.

50
6000 -

5000 -

4000-

Drag

force, 3000 -

Ib

2000-

1000 =.....

O0

0

-8 -6

_Y

o?

-4

O Dry concrete at various speeds

------ ALDF drag model

O I I I I I

-2 0 2 4 6 8

Slip angle, deg 970554

Figure 37. Main gear EAFB and KSC tire drag forces at 48,000 lb.

6ooo

5o0o

4000

Drag

force, 3000

Ib

2000

0 Dry concrete at various speeds

------ ALDF drag model

0

0

o g o

0 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Sllp angle, deg

970555

Figure 38. Main gear EAFB and KSC tire drag forces at 63,000 lb.

51
6OOO

5OOO

4OOO

Drag

force, 3000

Ib

2OOO

1000

Dry concrete at various speeds

------ ALDF drag model

-

0 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, dog 970556

Figure 39. Main gear EAFB and KSC tire drag forces at 80,000 lb.

6000

50oo

4o0o

Drag

force, 3000

Ib

2OOO

1000

m

o

m

O "-.

O Dry concrete at various speeds

------ ALDF drag model

s"

".. 0 _"

"..0 0 s.'O _

o

0 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Sllp angle, deg

970557

Figure 40. Main gear EAFB and KSC tire drag forces at 93,000 lb.

52
6000 -

5000 -

4000 1_-,_

Drag

force, 3000 -

Ib

2000 -

1000 -

0

-8

I

-6

O Dry concrete at various speeds

------ ALDF drag model

o,-

.i J

s"

\ O /

./

O O /

0 "_ 0 11

0 0 _.__ s

0 0 0 0 0 0

I I I I I I I

-4 -2 0 2 4 6 8

Slip angle, deg 97055B

O

Figure 41. Main gear EAFB and KSC tire drag forces at 110,000 lb.

6000-

\

5000 - \

%

\

\

4OOO

Drag

force, 3000

Ib

2000 -

1000 -

\

\

\

\

\

\

\

N

N /

O x /

"x /

0 O0 -.i

0

%

al) o o

/

/

/

/

O

8

/

,/

/

/

/

/

/

/

/

/

/

/

/

O Dry concrete at various speeds

------ ALDF drag model

0 I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg 970559

Figure 42. Main gear EAFB and KSC tire drag forces at 126,000 lb.

53
6000

5000

4000

Drag

force, 3000

Ib

2000 -

1000 -

\

\

\

\

\

\

\

\

\

\

\

\

O

0 0

0

0 0

\v/

0

0

0

0 0

/

/

/

/

/

/

/

/

/

/

/

/

O

0

0

0

0

O Dry concrete at various speeds

------ ALDF drag model

o I I I I I I I I

-8 -6 -4 -2 0 2 4 6 8

Slip angle, deg

970560

Figure 43. Main gear EAFB and KSC tire drag forces at 145,000 lb + 4,000 lb.

600O

5000

4OOO

Drag

force, 3000

Ib

2000-

1000--

Lakebed test data

O 48 kn

[] 160 kn

¢ 185 kn

------ Kratochvll drag

model, CI = 3216

0 [] []

-o---_ ........

o00

160 1oi

185kn

0

0

0 0

0

0 I I I I I I I I

-8 - 6 -4 -2 0 2 4 6 8

Slip angle, deg

970561

Figure 44. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 46,000 lb.

54
6000 -

5000

4000

Drag

force, 3000

Ib

2000 --

1000 --

o <>

0

0 0

o

1 I I

0-8 2 4 6

Lakebed test data

O 48 kn

O 156 kn

O 185 kn

------ Kratochvil drag

model, CI = 3216

I I I I

- 6 -4 -2 0

Slip angle, deg

160 kn

n

185 kn

0

8

970562

Figure 45. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 62,000 lb.

10 x 103

9--

8

7--

0

3--

0

2-- []

O

1 -- ------

0

-8

6

Drag

force, 5

Ib

4

[] []

0 [] 0 oOooo

160 kn

185 kn

0

0

0 0

Lakebed test data

50 kn

153 kn

186 kn

Kratochvil drag

model, CI = 3216

I I I I I I I I

- 6 -4 -2 0 2 4 6 8

Slip angle, deg 970563

Figure 46. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 92,000 lb.

55
Drag

force,

Ib

12-

10-

8-

6-

4-

2-

[]

o O

160 kn

185 kn

O O

Lakebed teat data

O 51 kn

O 159 kn

O 192 kn

------ Kratochvil drag

model, CI = 3216

I I I

- 6 -4 -2

O

o I I I I I

-8 0 2 4 6 8

Slip angle, deg 97o_

Figure 47. Main gear EAFB and KSC tire drag forces on EAFB lakebed runway 15 at 126,000 lb.

Drag

force,

Ib

500O

4000

3O00

2OO0

1000-

0-

- lOoo_8

\ /

\ I

\ I

\ I

\ I

\ I

\ I

\ I

\ I

\ I

\ I

\ I

I

\ /

/

\ /

\ I

\ I

\ I

\ I

\ I

°

0 0 0 _ 0 0 0

KGS

O 50

1"I 160

O 2OO

------ ALDF drag model

I I I I I I I I

-6 -4 -2 0 2 4 6 8

Slip angle, deg

970565

Figure 48. Nose wheel gear EAFB tire drag forces on concrete at 11,000 lb.

56
Drag

force,

Ib

5000

4OO0

3OO0

2000 -

1000 -

0 -

- 1000

-8

\ !

\ /

\ /

X /

\ I

\ /

_, I

I

I

_, I

_, I

I

I

'l I

,_ I

,_ I

,_ I

'l I

o

[] [][],,B/o

0 0 0 "_-J 0 0 0

V

KGS

O 50

[] 160

O 200

------ ALDF drag model

I I

-6 -4

I I I I I I

-2 0 2 4 6 8

Slip angle, deg 97osee

Figure 49. Nose gear EAFB tire drag forces on concrete at 31,000 lb.

Drag

force,

Ib

5000

400O

3000

2000-

1000 -

0-

- 1ooo8

O Dry concrete at various speeds

------ ALDF drag model

t,

O O o

o

O I _O

I X

/ X

I x.

I X

I

I \

I

I \

I \

i i t i ), I I i

-6 -4 -2 0 2 4 6 8

Slip angle, deg 97o_7

Figure 50. Nose gear EAFB tire drag forces on concrete at 50,000 lb.

57
Drag

force,

Ib

5000

4OOO

3000

2000--

1000 --

0--

Lakebed test data

O 50 kn

[] 161 kn

O 201 kn

------ Kratochvil drag

model, CI = 3216

0 0 0 0 0 0 0 160kn G- -- -- -- 4:----I:- -- _] -- -G- -- _: -- -- ---Q-

_- -----6--6--8--e- _--- -e 200 kn

-lOOO I I I I I I I I

-8 - 6 -4 -2 0 2 4 6 8

Sllp angle, deg 97o56e

Figure 51. Nose gear EAFB tire drag forces on lakebed at 11,000 lb.

Drag

force,

Ib

5OOO

4O0O

300O

200O

1000--

0-

Lakebed teat data

O 47 kn

n 162 kn

O 201 kn

------ Kratochvil drag

model, CI = 3216

160 kn

. a

200 kn

0 0 0 (5) 0 0 0

-lOOO I I I I I I I I

-8 - 6 -4 -2 0 2 4 6 8

Slip angle, deg 970569

Figure 52. Nose gear EAFB tire drag forces on lakebed at 31,000 lb.

58
Roll,

deg

1.8

1.6

1.4

1.2

1.0

.8

n

L-- Fixtu re

assembly

. . Pallet \ wheel tilt equationj_

_i_' assembly \ f._,_

vrlll I/ -Fork \

I1_1 I IJ_ assembly f %_,,'_,"J

/,,.G"

_\\\\\\\\\\\\_\\\\\\\\\\\\\\ _.I ._--..j t

I _'_ _....--_ -_'_-_ _ --

- "20 2 4 6 8 10 12 14 16 18 20 x 103

Applied side load, Ib

970570

Aircraft

Pallet assembly

Fixture assembly

Fork assembly

Wheel

Figure B 1. Measured roll deflection relative to the ground caused by side load from load point.

Side force

end tilt

angle,

Ib/deg

1,0 B

• 8 D

• 6 --

°4 --

• 2 I

0 l_

--.2

1,4 m

w o6 I

I o6 I

O ALDF data

------ LSRA factor of 0.01465

- 1"00 5 10

Vertical force, Ib

15 x 10 4

970571

Figure B2. Measured concrete forces from LSRA tests. (Dotted line represents LSRA factor of 0.01465.)

59
REPORT DOCUMENTATION PAGE Form OMBApproved No0704-0188

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORTTYPE AND DATES COVERED

September 1997 Technical Memorandum

4.TITLE AND SUBTITLE 5. FUNDING NUMBERS

A Model for Space Shuttle Orbiter Tire Side Forces Based on NASA

Landing Systems Research Aircraft Test Results

6. AUTHOR(S)

John F. Carter, Christopher J. Nagy, and Joseph S. Barnicki

7.PERFORMINGORGANIZATIONNAME(S)ANDADDRESS(ES)

NASA Dryden Flight Research Center

P.O. Box 273

Edwards, California 93523-0273

9.SPONSORING/MONITORING AGENCYNAME(S) ANDADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

WU 551-15-01

8. PERFORMING ORGANIZATION

REPORT NUMBER

H-2168

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA TM-4808

11. SUPPLEMENTARY NOTES

12e. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified--Unlimited

Subject Category 05

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 word,=)

Forces generated by the Space Shuttle orbiter tire under varying vertical load, slip angle, speed, and surface

conditions were measured using the Landing System Research Aircraft (LSRA). Resulting data were used to

calculate a mathematical model for predicting tire forces in orbiter simulations. Tire side and drag forces experienced by an orbiter tire are cataloged as a function of vertical load and slip angle. The mathematical model is

compared to existing tire force models for the Space Shuttle orbiter. This report describes the LSRA and a typical test sequence. Testing methods, data reduction, and error analysis are presented. The LSRA testing was

conducted on concrete and lakebed runways at the Edwards Air Force Flight Test Center and on concrete runways at the Kennedy Space Center (KSC). Wet runway tire force tests were performed on test strips made at

the KSC using different surfacing techniques. Data were corrected for ply steer forces and conicity.

14. SUBJECTTERMS

Aircraft tire, CV-990, Landing gear, Landing system, Space shuttle orbiter test

facility

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIRCATION

OF REPORT OFTHIS PAGE OF ABSTRACT

Unclassified Unclassified Unclassified

NSN 7540-01-280-5500 Available from the NASA Center for AeroSpace Information, 800 Elkddge Lending Road,

Linthicum Heights, MD 21090; (301)621-0390

! 15. NUMBER OF PAGES

66

16. PRICE CODE

AO4

20.UMITATIONOFABSTRACT

Unlimited

Standard Form 298 (Rev. 2-89)

PrescribedbyANSI Std.Z39-18

298-102