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1 AD-A AIR FORCE WRIGHT.AERONAUTICAL LABS WRIGHT PATTERSON AFB OM F/9 1/3 WET TRACTION TESTS - MARCY SI PED T IRE. C U) FEB 82 P C ULRICH UNCLASSIFIED *3 EEEEEEEllEEE AFWAL-TR N mhmhhhmhh EEEEEEEIIIEEEE EEEIIEEEEEEIIE IIIEEIIIIIIIIII IIIIuuuuuuuuu.. EahglEEEEllEEI

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3 AFWAL-TR WET TRACTION TESTS - MARCY SIPED TIRE Paul C. Ulrich Mechanical Branch Vehicle Equipment Division 1fhriirv lq82 Final Report For Period August September 1979 Approved for public release; distribution unlimited. I16 FLIGHT DYNAMICS LABORATORY AIR FORCE WRIGHT AERONAUTICAL LABORATORIES AIR FORCE SYSTEMS COMMAND WRIGHT-PATTERSON AIR FORCE BASE, OHIO 45433

4 NOTICE :;oer nc drawinqs, specifcat-ons, or other Jata are used for any purpcse rhcr than zn onnect:on with a definitelu related (.overnment crocurement operat:on, '::-nit'ed States government thereby incurs no responsibility nor an.' obligation a:dtsoever; and the fact that the ;overnment may have formulated, furnished, or :n iny way supplied the saij drawings, specifications, or other data, is not to be re- ;arfed by implicacion or otherwise as in any manner licensing :he holder or any other person or corporation, or conveying any rights or perm 'ss:on to manufacture use, or sell any patented invention that may in any way be related thereto. 7h-s renort.as been reviewed bu the Office of Public Affairs (AS0/PA) and is re:0saze.'.he t'atonal Technical Information Service NTS). At VT:S, it wifi - a a)o.e to the general publ:c, including foreign nations. 7.-as tecn.uca report.has been reviewed and is approved for publication. PAUL C. ULRICH Project Engineer Vehicle Fquipment Division FLight Dynamics Laboratory AIVARS V. PETERSONS Chief Mechanical Branch Vehicle Equipment Division Flight Dynamics Laboratory Solomon R. Metres, Director- Vehicle Equipment Division Flight Dynamics Laboratory -' "rf uour address has changed, if you wish to be removed from our mailing list, or if -he addressee is no longer employed by your organization please norif'afwal/fifma, :';-PAFB, OH to help us maintain a current mailing list". Covies of this report snould not be returned unless return is required by security considerations, contractual obligations, or notice on a specific document. - { "..." l...- "' : " ai'... Il - '- " I - ll i " 1 i I ii i i

5 Unclassified SECURITY CLASSIFICATION OF THIS PAiE (When Dete Enlered) REPORT DOCUMENTATION PAGE RO DO READ INSTRUCTIONS EFORE COMPLETIN(I FORM I REPORT NUMBER 2 GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER AFWAL-TR q I SL 9i'? 4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED WET TRACTION TESTS - MARCY SIPED TIRE Final Report August 1977-September PERFORMING ORG. REPORT NUMBER 7. AUTHOR(e) 8. CONTRACT OR GRANT NUMBER(c) Paul C. Ulrich 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK AREA & WORK UNIT NUMBERS Flight Dynamics Laboratory Air Force Wright Aeronautical Laboratories, AFSC Project 2402 Wright-Patterson Air Force Base, Ohio Task Work Unit CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Flight Dynamics Laboratory February 1982 Air Force Wright Aeronautical Laboratories, AFSC Wright-Patterson AFB OH NUMBER OF PAGES 14. MONITORING AGENCY NAME & ADDRESS(if different from Controlling Office) I5. SECURITY CLASS. (of thto repor, Unclassified IS.. DECLASSIFICATION DOWN$RADINC- - SCHEDULE 16. DISTRIBUTION STATEMENT (of this Report) Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (of the abltract entered in Block 20. If different from Report) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverae side it necesaury and identify by block number),wet Traction - Lab Tests F.A Aircraft Tires Wet Traction - Track Tests Aircraft Tires, '35 Aircraft Tires Aircraft Tires Tire Tread Siping 20. ABSTRACT (Continue on reverse side If neceaary and Identify by block number) This report describes an in-house effort by USAF AFWAL/FIEM personnel in which a new method for siping aircraft tires was evaluated. The method, developed by Marcy Inc., promised improvements in wet surface traction without ompromising tread wear or high speed tread integrity. The purpose of this program was to laboratory test, track test, and evaluate the improvements in viscous hydroplaning or wet surface traction provided by the Marcy siped aircraft tire treads and to determine if this process compromised F ORM DD,JAN EDITIONOF I NOV SS IS OBSOLETE Unclassified k66 SECURITY CLASSIFICATION OF THIS PAGE '1h, Dlaia F.tetf

6 SECURITY CLASSIFICATION OF THIS PAGE(Whe Data Entered) -the tread integrity of the tires. -The results of the hiqh spe J dynamometer tests indicated that the tread integrity of the F-4 and F-16 main gear tires were not adversely affected by the Marcy tread sipe configurations that were tested.. The results of the F-4 tire wet traction laboratory tests and the KC-135 tire track tests indicated significant improvements in lateral force, developed brake torque, and stopping performance for the 1/4 inch deep by 3/16 inch spacing Marcy siped tire tread configuration when compared to a standard (unsiped) tread design. This improvement in wet traction, however, was reduced to a negligible amount when the sipe depth is reduced by tire wear to depths less than 1/8 inch as demonstrated by the wet portland cement track tests.- None of the Marcy sipe configurations, however, prevented dynamic hydroplaning when the tires encountered standing water at high speeds during the track tests. Unclassified SECURITY CLASSIFICATION OF T-11 PAGE(Vien Date Efered)

7 AFWAL-TR FOREWORD This report describes an in-house effort conducted by personnel of the Mechanical Branch (FIEM), Vehicle Equipment Division (FIE), Flight Dynamics Laboratory, Air Force Wright Aeronautical Laboratories, Wright-Patterson Air Force Base, Ohio, under project number 2402, "Mechanical Systems for Advanced Military Flight Vehicles," task number , "High Performance Landing Gear for Advanced Military Flight Vehicles," work unit number , "Tire Ground Performance Criteria." This report covers work performed during the period of August 1977 to September 1979, under the direction of the author, Paul C. Ulrich (AFWAL/FIEMA), project engineer. the author in December The report was released by The author wishes to acknowledge the various suggestions received during this program from Aivars V. Petersons of the Flight Dynamics Laboratory and Dr. Howell K. Brewer of the Department of Transportation. The contributions received from personnel of the Airport Technology Division, ACT-400, at the Federal Aviation Administration (FAA) Technical Center who conducted the track tests and personnel of the Naval Air Engineering Center (NAEC) at Lakehurst, New Jersey who provided the test track facility are greatly appreciated. The author also acknowledges the assistance contributed by Juergen Mollnau (exchange engineer) of the Federal Republic of Germany, Ted Dull (co-op) student at the University of Cincinnati, J. L. Leiter, and A. R. Blazer of Systems Research Laboratories. For

8 AFWAL-TR TABLE OF CONTENTS SECTION PAGE I INTRODUCTION I 1. Background 1 2. Objective 6 II SUMMARY 7 III DESCRIPTION OF TEST TIRES 9 IV TEST EQUIPMENT Tire Force Machine (TFM) Inch Conventional Dynamometer Inch Programmable Dynamometer NAEC Test Track Facility 12 V TEST REQUIREMENTS AND PROCEDURES Static Tests Dynamic Tests 14 a. High Speed Tread Integrity Tests Inch Dynamometer 14 b. Quasi-Static Lateral Force and Braking Tests - TFM 15 c. High Speed Lateral Force Tests Inch Dynamometer 15 d. High Speed Braking Tests with Mark III Anti-Skid 192 Inch Dynamometer 16 e. High Speed Traction Tests - NAEC Test Track 16 VI TEST RESULTS AND DISCUSSION Static Tests Dynamic Tests 18 a. High Speed Tread Integrity Tests Inch Dynamometer 18 v

9 AFWAL-TR TABLE OF CONTENTS (Concluded) SECTION PAGE b. Quasi-Static Lateral Force and Braking 19 Tests - TFM1 c. High Speed Lateral Force Tests Inch 20 Dynamometer d. High Speed Braking Tests with Mark Anti-Skid Inch Dynamometer e. High Speed Traction Tests - NAEC Test Track 25 VII CONCLUSIONS 26 VIII RECOMMENDATIONS 27 APPENDIX A TABLES 29 APPENDIX B FIGURES AND PHOTOGRAPHS 42 APPENDIX C ANALOG TRACES, HIGH SPEED BRAKE ANTI-SKID STOPS DYNAMOMETER APPENDIX D X-Y PLOTS, FLYWHEEL VELOCITY VS BRAKE STOP DISTANCE, HIGH SPEED BRAKE ANTI-SKID STOPS 152 APPENDIX E CALCULATION SHEET 189 REFERENCES 190 vi

10 AFWAL-TR LIST OF ILLUSTRATIONS FIGURE PAGE 1 Water Depth Comparison for Various Facility Traction Tests 43 2 Relative Surface Textures of Test Facilities and Runways 44 3 Marcy Siping Machine Siping F-4 Main Tire 45 4 Marcy Helix Sipe-Cutting Blade 46 5 Marcy Tread Sipe Configuration, F-4 Tire 47 6 Marcy Tread Sipe, F-4 Tire, 5/32 Inch Deep by 3/16 Inch Spacing 48 7 Marcy Tread Sipe, F-16 Tire, 7/32 Inch Deep by 3/16 Inch Spacing 8 Marcy Tread Sipe, KC-135 Tire, 4/32 Inch Deep by 3/16 Inch Spacing 50 9 TFM Test Set-Up, F-4 Flooded Traction Tests TFM, F-4 Flooded Traction Tests NAFEC/NAEC Dynamometer and KC-135 Tire/Wheel Assembly - 5 Test Track Set-Up NAFEC/NAEC Test Track #1, 200 Foot Test Section NAFEC/NAEC Test Track #1, Broomed Surface Finish Approximate Flywheel Water Depth vs. Flywheel Speed for 56 Various Water Flow Rates 15 Contact Area vs Normal Load Contact Area vs Inflation Pressure 17 Contact Area vs Percent Deflection, 245 Psig Pressure Contact Area vs Percent Deflection, 145 Psig Pressure Contact Area vs Normal Load Contact Area vs Percent Deflection Brake Torque and Lateral Force vs Slip Angle, Flooded Surface, Tire Code Number 3-N (Siped 8/32" Deep X 3/16" 63 Spacing) vii

11 AFWAL-TR LIST OF ILLUSTRATIONS (Continued) FIGURE PAGE 22 Lateral Force vs Slip Angle, Flooded Test Surface, Tire Code Number 5-N (Siped 9/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Flooded Test Surface, Tire Code Number 6-N (Siped 9/32" Deep X 1/8" Spacing) Lateral Force vs Slip Angle, Flooded Test Surface, Tire Code Number 11-N (Siped 5/32" Deep X 1/8" Spacing) Lateral Force vs Slip Angle, Dry Test Surface, Tire Code Number 11-N (Siped 5/32" Deep X 1/8" Spacing) Lateral Force vs Slip Angle, Damp Test Surface, 5 MPH, 1/2 GPM, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Damp Test Surface, 10 MPH, 1 GPM, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Damp Test Surface, 30 MPH, 3 GPM, Ti-e Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Damp Test Surface, 60 MPH, 6 GPM, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Damp Test Surface, 60 MPH, 2 GPM, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" 7 Spacing) Lateral Force vs Slip Angle, Dry Test Surface, 5 MPH, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Dry Test Surface, 10 MPH, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Dry Test Surface, 30 MPH, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Lateral Force vs Slip Angle, Dry Test Surface, 60 MPH, 76 Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) Brake Stop Data vs Water Flow Rate, Tire Code Number 18-N 7 36 Brake Stop Data vs Water Flow Rate, Tire Code Number 20-N 78 viii

12 AFWAL-TR LIST OF ILLUSTRATIONS (Coltinued) FIGURE PAGE 37 Brake Stop Data vs Water Flow Rate, Tire Code Number 22-N Brake Stop Data vs Water Flow Rate, Tire Code Number 21-N Brake Stop Data vs Water Flow Rate, Tire Code Number 18-N Variable Opening Nozzle High Speed Braking Tests, Dynamometer Set-Up Brake Stop Data vs Water Flow Rate, Tire Code Number l-r-2, Case I Tests Brake Stop Data vs Water Flow Rate, Tire Code Number l-r-2, Case II Tests Application of Water to Flywheel, High Speed Brak~ng Tests, 40 MPH - Test Speed Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number 18-N, Tire Load 25,000 Lbs, Test Wheel/Tire Speed vs Time, 1/2, 1 and 2 GPM Water Flow Rates, Case 1-Water Applied Prior to Landing Tire Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number 18-N, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 1/2, 1 and 2 GPM Water Flow Rates, Case 1-Water Applied Prior to Landing Tire Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number l-r-2, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 1/2, 2 and 3 GPM Water Flow Rates, Case 1-Water Applied Prior to Loading Tire Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number l-r-2, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 1/2, 2 and 3 GPM Water Flow Rates, Case 2-Water Applied After Loading Tire Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number l-r-2, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 3 GPM Water Flow Rate, Case 1-Water Applied Prior to Landing Tire Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number l-r-2, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 3 GPM Water Flow Rate, Case 2-Water Applied After Loading Tire 90 ix

13 AFWAL-TR LIST OF ILLUSTRATIONS (Continued) FIGURE PAGE 50 Dry Brake Test Runs Tires Code Numbers 22-N and 1-R-2 Tire Load, 16,000 Lbs (Test Wheel/Tire Speed, Brake Pressure and Brake Torque vs Time) Friction Coefficient vs Speed, Wet Track Tests, KC-135 Tire - Standard Tread Friction Coefficient vs Speed, Wet Track Tests, KC-135 Tire - 1/4 Inch Deep Sipe Friction Coefficient vs Speed, Wet Track Tests, KC-135 Tire - 1/8 Inch Deep Sipe Friction Coefficient vs Water Depth, Wet Track Tests, KC-135 Tire Friction Coefficient vs Speed, Wet Track Tests, KC-135 Tire, Water Depth (Damp) Friction Coefficient vs Speed, Wet Track Tests, KC-135 Tire, Water Depth (0.05 Inch) Friction Coefficient vs Speed, Wet Track Tests, KC-135 Tire, Water Depth (0.10 Inch) Friction Coefficient vs Speed, Wet Track Tests, KC-135 Tire, Water Depth (0.15 Inch) 99 C-1 S/N 0870(18-N), Cyc. 49, 0.5 gpm 101 C-2 S/N 0870(18-N), Cyc. 50, 1.0 gpm 102 C-3 S/N 0870(18-N), Siped N/A Cyc. 51, 2.0 gpm 103 C-4 S/N 0870(18-N), Siped N/A Cyc. 52, 0.5 gpm 104 C-5 S/N 0870(18-N), Siped N/A Cyc. 53, 1.0 gpm 105 C-6 S/N 0870(18-N), Siped N/A Cyc. 54, 2.0 gpm 106 C-7 S/N 0870(18-N), Siped 3/i6" x 8/32" Cyc. 55, 0.5 gpm 107 C-8 S/N 0870(18-N), Siped 3/16" x 8/32" Cyc. 56, 1.0 gpm 108 C-9 S/N 0870(18-N), Siped 3/16" x 8/32" Cyc. 57, 2.0 gpm 109 x

14 AFWAL-TR LIST OF ILLUSTRATIONS (Continued) FIGURE PAGE C-1O S/N 0870(18-N), Siped 3/16" x 8/32" Cyc. 58, 0.5 gpm 110 C-l S/N 0870(18-N), Siped 3/16" x 8/32" Cyc. 59, 1.0 gpm Ill C-12 S/N 0870(18-N), Siped 3/16" x 8/32" Cyc. 60, 2.0 gpm 112 C-13 S/N 1174(20-N), Siped N/A Cyc. 61, 0.5 gpm 113 C-14 S/N 1174(20-N), Siped N/A Cyc. 62, 1.0 gpm 114 C-15 S/N 1174(20-N), Siped N/A Cyc. 63, 2.0 gpm 115 C-16 S/N 1174(20-N), Siped 3/16" x 8/32" Cyc. 64, 0.5 gpm 116 C-17 S/N 1174(20-N), Siped 3/16" x 8/32" Cyc. 65, 1.0 gpm 117 C-18 S/N 1174(20-N), Siped 3/16" x 8/32" Cyc. 66, 2.0 gpm 118 C-19 S/N 1185(21-N), Siped N/A Cyc. 67, 0.5 gpm 119 C-20 S/N 1185(21-N), Siped N/A Cyc. 68, 1.0 gpm 120 C-21 S/N 1185(21-N), Siped N/A Cyc. 69, 2.0 gpm 121 C-22 S/N 1293(22-N), Siped N/A Cyc. 70, 0.5 gpm 122 C-23 S/N 1293(22-N), Siped N/A Cyc. 71, 1.0 gpm 123 C-24 S/N 1293(22-N), Siped N/A Cyc. 72, 2.0 gpn 124 C-25 S/N 1185(21-N), Siped 3/16" x 5/32" Cyc. 73, 0.5 gpm 125 C-26 S/N 1185(21-N), Siped 3/16" x 5/32" Cyc. 74, 1.0 gpm 126 C-27 S/N 1185(21-N), Siped 3/16" x 5/32" Cyc. 75, 2.0 gpm 127 C-28 S/N 1293(22-N), Siped 3/16" x 8/32" Cyc. 76, 0.5 gpm 128 C-29 S/N 1293(22-N), Siped 3/16" x 8/32" Cyc. 77, 1.0 gpm 129 C-30 S/N 1293(22-N), Siped 3/16" x 8/32" Cyc. 78, 2.0 gpm 130 C-31 S/N 1293(22-N), Siped 3/16" x 8/32" Cyc. 90, DRY 131 C-32 S/N 6A0013 (#1-R-2), Siped N/A Cyc. 96, 0.5 gpm 132 C-33 S/N 6A0013 (#1-R-2), Siped N/A Cyc. 97, 1.0 gpm 133 xi

15 AFWAL-TR LIST OF ILLUSTRATIONS (Continued) FIGURE PAGE C-34 S/N 6A0013 (#1-R-2), Siped N/A Cyc. 98, 2.0 gpm 134 C-35 S/N 6A0013 (#l-r-2), Siped N/A Cyc. 99, 3.0 gpm 135 C-36 S/N 6A0013 (#I-R-2), Siped N/A Cyc. 100, 3.0 gpn 136 C-37 S/N 6A0013 (#1-R-2), Siped N/A Cyc. 101, 0.5 gpm Water on After Landing 137 C-38 S-/N 6AO012 (#1-R-2), Siped N/A Cyc. 102, 1.0 gpm Water on After Landing 138 C-39 S/N 6A0013 (#1-R-2), Siped N/A Cyc. 103, 2.0 gpm Water on After Landing 139 C-40 S/N 6A0013 (#l-r-2), Siped N/A Cyc. 104, 3.0 gpm Water on After Landing 140 C-41 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32" Cyc. 105, 0.5 gpm Water on After Landing 141 C-42 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32", Cyc. 106, 1.0 gpm Water on After Landing 142 C-43 S/N 6A0013 (#1-R-2), Siped 3/16 x 7/32", Cyc. 107, 2.0 gpm Water on After Landing 143 C-44 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32, Cyc. 108, 3.0 gpm Water on After Landing 144 C-45 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32", Cyc. 109, 0.5 gpm 145 C-46 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32", Cyc. 110, 1.0 gpm 146 C-47 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32", Cyc. 111, 2.0 gpm 147 C-48 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32", Cyc. 112, 3.0 gpm 148 C-49 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32", Cyc. 113, 4.0 gpm 149 C-50 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32, Cyc. 114, 7.5 gpm 150 C-51 S/N 6A0013 (#1-R-2), Siped 3/16" x 7/32", Cyc. 115, DRY 151 xii

16 AFWAL-TR LIST OF ILLUSTRATIONS (Continued) FIGURE PAGE D-1 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate Code Number 18-N 153 D-2 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 1. (GPM) Flow Rate Code Number 18-N 154 D-3 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 2 (GPM) Flow Rate Code Number 18-N 155 D-4 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate Code Number 18-N Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 1 (GPM) Flow Rate Code Number 18-N 157 D-6 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 2 (GPM) Flow Rate Code Number 18-N 158 D-7 Velocity vs. Brake Distance F-4 MLG. Siped Tire Evaluation 25,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate -,ode Number 20-N Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 1 (GPM) Flow 160 Rate Code Number 20-N D-9 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 2 (GPM) Flow 161 Rate Code Number 20-N D-10 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 0.5 (GPM) Flow 162 Rate Code Number 21-N 0-11 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 1 (GPM) Flow 163 Rate Code Number 21-N 0-12 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 2 (GPM) Flow 164 Rate Code Number 21-N xiii

17 AFWAL-TR LIST OF ILLUSTRATIONS (Continued) FIGURE PAGE D-13 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate Code Number 22-N 165 D-14 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 1 (GPM) Flow Rate Code Number 22-N 166 D-15 Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 2 (GPM) Flow Rate Code Number 22-N 167 D-16 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate Code Number I-R D-17 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 1.0 (GPM) Flow 169 Rate Code Number 1-R-2 D-18 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 2.0 (GPM) Flow Rate Code Number 1-R D-19 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 3.0 (GPM) Flow 171 Rate Code Number l-r Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 3.0 (GPM) Flow 172 Rate Code Number l-r-2 D-21 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate Code Number I-R-2 Water on After Landing 173 D-22 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 1.0 (GPM) Flow 174 Rate Code Number I-R-2 Water on After Landing 0-23 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 2.0 (GPM) Flow 175 Rate Code Number l-r-2 Water on After Landing 0-24 Veloctiy vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 3.0 (GPM) Flow Rate Code Number I-R-2 Water on After Landing 176 xiv

18 AFWAL--TR LIST OF ILLUSTRATIONS (Ccncluded) FIGURE PAGE D-25 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate Code Number l-r-2 Unsiped 177 D-26 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 1.0 (GPM) Flow Rate Code Number l-r-2 Unsiped 178 D-27 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 2.0 (GPM) Flow Rate Code Number l-r-2 Unsiped 179 D-28 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, 3.0 (GPM) Flow 180 Rate Code Number l-r-2 Unsiped 0-29 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Siped, 7/32" Depth 181 (Const) 0.5 (GPM) Flow Rate, Code Number l-r-2 D-30 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Siped, 7/32" Depth 182 (Const) 1.0 (GPM) Flow Rate, Code Number I-R-2 D-31 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Siped, 7/32" Depth 183 (Const)2.0 (GPM) Flow Rate, Code Number l-r-2 D-32 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Siped, 7/32" Depth (Const) 3.0 (GPM) Flow Rate, Code Number 1-R D-33 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Code Number l-r D-34 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Code Number l-r Water on After Loading/Before Braking D-35 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Siped, 7/32" Depth 187 (Const) Code Number l-r-2 D-36 Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation 16,000 (LBS) Tire Load, Siped, 7/32" Depth 188 (Const) Code Number l-r-2 Water on After Loading/Before Braking xv

19 AFWAL-TR LIST OF TABLES TABLE PAGE I F-4 MLG, 30X /24 PR Tire, Marcy Tread Sipe 30 Configurations 2 F-16 MLG, 25.5X8.0-14/18 PR Tire, Marcy Tread Sipe 31 Configuration 3 KC-135 MLG, 49X17/26 PR Tire, Marcy Tread Sipe 31 Configurations 4 Tire Contact Area Data, F-4 MLG 30X /24 PR 32 Tire 5 Tire Contact Area Data, KC-135 MLG, 49X17/26 PR Tire 6 High Speed Tread Integrity Test Data Inch 34 Dynamometer 7 Quasi-Static Lateral Force Test Matrix - TFM Tire Load (25000 Lbs), Tire Inflation (243 PSI) 8 High Speed Lateral Force Test Matrix-120 Inch Dynamometer, Tire Code Number 24-N, Siped 8/32 Inch Deep by 3/16 Inch Spacing, Tire Load (25,000 LBS), Tire Inflation (268 PSIG), Curved Smooth Steel Surface - Average Texture Depth 36 (0.002 IN) 9 Brake Stop Data, 30X /24 PR Unsiped vs Siped Tire Brake Stop Data, 30X /24 PR Unsiped vs Siped Tire, Tire Code Number 1-R Brake Stop Comparison Data, 30X /24 PR Unsiped vs Siped Tire, 25,000 LBS Load, 245 PSIG Pressure, Water 39 Applied Before Tire Lands 12 Brake Stop Comparison Data, 30X /24 PR Unsiped vs Siped Tire, 16,000 LBS Load, 145 PSIG Pressure, Water 40 Applied Before Tire Lands 13 Brake Stop Comparison Data, 30X /24 PR Unsiped vs Siped Tire, 16,000 LBS Load, 245 PSIG Pressure, Tire Code Number 1 R-2, Siped 7/32 Inch Deep by 3/16 Inch Spacing 41 xvi

20 i1 AFWAL-TR SECTION I INTRODUCTION 1. BACKGROUND Aircraft adverse weather ground operations (wet or icy runways with high gusty cross winds) have been a primary concern since the introduction of jet aircraft as their landing speeds are usually well above the hydroplaning speed of their tires. In addition, with the continued improvement in flight instruments and instrument landing systems, more landings are attempted under adverse weather conditions. This increase in adverse weather ground operations coupled with the higher landing speeds of new aircraft has led to increases in adverse weather landinq accidents. In order to reduce hydroplaning accidents, researchers have continually sought to improve the traction of aircraft tires during adverse weather ground operations. Researchers have defined three types of hydroplaning; viscous hydroplaning (thin film lubrication), reverted rubber hydroplaning, and dynamic hydroplaning. Viscous hydroplaning is defined as thin film lubrication (water and/or contaminants) between the tire and the runway causing a degradation in braking and steering capability. Viscous hydroplaning is normally associated with aircraft operation on damp, wet, or icy runways. This research effort deals with the evaluation of tread configurations which promise a reduction in viscous hydroplaning. Dry reverted rubber hydroplaning is defined as tire skidding caused by reverted rubber build-up between the tire and the runway which can occur during rapid tire spin-up at the time of touchdown or during heavy braking (wheel lock-up). Changes in rubber compounding by the tire manufacturers is one known way of reducing dry reverted rubber hydroplaning. This type of hydroplaning was not considered in this research effort. I

21 AFWAL-TR Dynamic hydroplaning is defined in two degrees or levels of hydroplaning. Partial dynamic hydroplaning is defined as a partial loss of the tire's contact (footprint) area due to a sufficient increase in the ground hydrodynamic pressure which is caused by a film of water being trapped between the tire and the runway. This loss in contact area causes a degradation in traction capabilities. Total dynamic hydroplaning is defined as a complete loss of contact between the tire and the runway as the ground hydrodynamic pressure has been increased sufficiently to support the entire wheel load and the tire rides on a layer of water of distinct thickness causing a complete loss of braking and steering capability. Past research has determined that the predominant parameters which affect dynamic hydroplaning are aircraft speed, tire inflation pressure, water depth, the runways surface texture, the tire contact area (footprint), and the tire's tread pattern. Subsequent research has also determined that as an aircraft's speed is increased, there exists a critical speed (dynamic hydroplaning speed), unique for each tire inflation pressure, in which the runway surface micro texture and the tire's tread pattern are no longer important in reducing dynamic hydroplaning. Total dynamic hydroplaning was not considered in this research effort as runway grooving is considered a much more effective means of reducing total dynamic hydroplaning than changes in tire tread patterns. Partial dynamic hydroplaning was considered during the flooded track tests at the Navy's Lakehurst facility. NASA defined three levels of runway water depth in the joint USAF-NASA program, "Combat Traction" (Reference 1); damp, wet and flooded as determined by the NASA water depth gage. These were defined as: damp - water depth less than 0.01 inch wet - water depth between 0.01 inch and 0.10 inch flooded - water depth greater than 0.10 inch - t...., "[" '' " a ra I il I i l i.....

22 AFWAL-TR A comparison of the various water depths that were used in the Marcy siped tire traction program, the water depths used in previous traction tests on transverse groove (rain) tires at the NASA track, and the water depths used in actual aircraft traction tests on various runways in the combat traction tests, is shown in Figure 1. The effects of runway texture on traction and hydroplaning have been studied by researchers in various ways. NASA has measured numerous runways and defined a typical operational runway in Reference 2 as having an average texture depth of the order of 201 jm (0.008 in) as determined by the grease sampling technique described in Reference 3. In Reference 4, roads and runways have also been classified in very general qualitative terms with respect to their macro and micro texture in four classes of surfaces as: MACRO MICRO SURFACE TEXTURE TEXTURE A Rough Harsh B Rough Polished C Smooth Harsh 0 Smooth Polished A quantitative measure of runway texture is the skid number as defined in Reference 5. Typical measured skid numbers of various wet concrete and asphalt pavements ranged from 25 to 65. In several cases it was observed that for any particular textured surface, the skid number decreased with increasing water depth until 0.01 inches of water depth was reached at which point the skid number remained constant regardless of additional increases in water depth. This fact undoubtedly led to NASA's criteria for distinguishing damp surfaces from wet surfaces. A means of changing runway texture is that of adding runway transverse or longitudinal grooves. Runway grooving is recognized as the most effective way of reducing dynamic hydroplaning by providing adequate water drainage between the tire and the pavement; however, it 3

23 AFWAL-TR requires a large initial capital investment with high recurring maintenance costs and has the detrimental side effects of increased tire wear and tire damage (chevron cutting). The addition of a porous friction course over worn runways has been reported as being effective in reducing hydroplaning but this method has not been universally accepted. A comparison of the texture depths of the various test surfaces used in the Marcy siped tire traction program, the test surfaces used in previous traction tests at the NASA track, and the test surfaces of actual runways is shown in Figure 2. The effect of changing a tire's tread pattern to reduce hydroplaning has been studied many years with various small improvements being developed. Previous studies have shown that the most effective way of reducing hydroplaning through tread design is circumferential grooves of adequate cross sectional area to sufficiently drain the water trapped between the tire and the pavement. However, any increases in the number of grooves or increases in the width or depth of the grooves compromises tread wear. Consequently, the tire companies have traditionally established a tradeoff between tread life and the tire's hydroplaning tendencies. Subsequent studies have also indicated that the benefits provided by runway grooving and circumferential tire tread grooving for reducing dynamic hydroplaning on flooded runways far exceed any benefits which could be achieved by other tread design changes, such as transverse tire grooving. Therefore, this program primarily addresses viscous hydroplaning with a cursory look at the phenomenon of dynamic hydroplaning. In References 2, 6, and 7, it is reported that adding more circumferential grooves and/or transverse grooves in the tire tread is an effective way of improving tire traction and reducing aircraft stopping 4

24 AFWAL-TR distances. This was demonstrated through track testing and actual aircraft tests on damp and wet runways. However, previous testing also determined that tread wear and tread integrity during high speed operation have been limiting factors in past tread alterations and, therefore, these factors must always be evaluated for new tread designs. In August 1977, a different method of reducing viscous hydroplaning and improving the wet traction of tires was developed by Marcy Inc. This method, unlike previous transverse groove designs, did not remove tread material but rather sliced transverse cuts into the tire tread. A photograph of the Marcy Inc machine siping an F-4 main tire is shown in Figure 3. A close up of the helix sipe-cutting blade is shown in Figure 4, while a close up of an F-4 main tire with Marcy transverse cuts or sipes is shown in Figure 5. This process conceivably promises improvements in wet surface traction without compromising tread wear or high speed tread integrity. Therefore, an agreement was made between the Air Force and Marcy Inc in which the Air Force would provide and test F-4 main gear tires which had been siped by Marcy Inc in order that the Marcy siping process could be evaluated by the Air Force for improved wet surface tire traction and the tread integrity of the tires could be verified. The tread integrity tests and laboratory wet surface traction tests were performed by Air Force, AFWAL/FIEM personnel at the Landing Gear Development Facility (LGDF), WPAFB, while the wet concrete track tests were performed by Federal Aviation Administration (FAA), National Aviation Facilities Experimental Center (NAFEC) personnel at the Naval Air Engineering Center (NAEC) Facility in Lakehurst, New Jersey. Potentially, this siping process can provide a means to significantly improve aircraft safety and increase adverse weather operating capability when operating on damp or wet ungrooved runways. 5

25 AFWAL-TR OBJECTIVE The objective of this program was to laboratory test, track test, and evaluate the improvements in viscous hydroplaning or wet surface traction (aircraft directional control and stopping capability) offered by the Marcy Inc tire tread siping process and to determine if this process compromised the tread integrity of the tire. 6

26 AFWAL-TR-S SECTION II SUMMARY 1. Based on the results of the high speed tread integrity tests conducted on the LGDF 120 inch dynamometer, the Marcy tread siping process did not adversely affect the tread integrity of either the F-4 or F-16 main gear tires that were tested at sipe depths up to 9/32 inch deep for the F-4 tire and 7/32 inch deep for the F-16 tire. 2. During the flooded quasi-static lateral force and braking tests on the Tire Force Machine (TFM) aluminum (flat) surface, the Marcy siped tread F-4 tires showed large improvements in lateral force and developed brake torques over the standard tread F-4 tire. It is believed, however, that these improvements are much higher than can be expected for typical runways due to the extremely low textured aluminum surface and can only be correlated with aircraft operation on extremely icy or snow covered runways. 3. During the flooded quasi-static lateral force and braking tests on the TFM tungsten carbide (flat) surface, the Marcy siped tread F-4 tires showed significant improvements in lateral force over the standard tread F-4 tire. These results are considered more realistic since the texture of the tungsten surface is within the range of measured runway textures. 4. During the damp high speed lateral force tests on the steel (curved) surface dynamometer, the Marcy siped tread F-4 tire demonstrated significant improvements in lateral force over the standard tread F-4 tire at all test speeds and at all tire slip angles. This data relates to viscous hydroplaning and can be correlated with aircraft operation on damp runways or track tests on damp test surfaces since the estimated water depth achieved on the dynamometer flywheel surface was less than inch at speeds greater than 80 mph and less than 0.01 inch for all test speeds. The amount of improved lateral force obtained during these tests is also considered somewhat high since the flywheel surface texture falls slightly below the range of typical runway textures. 7

27 AFWAL-TR During the damp high speed braking tests with the Mark III anti-skid on the steel (curved) surface dynamometer, the Marcy siped tread F-4 tire demonstrated significant improvements in deceleration rates, developed brake torques and stopping performance when compared to the unsiped tire. The trend for improvement in stopping performance provided by the Marcy sipe tire correlated with actual aircraft data obtained during previous F-4 rain (transverse groove) tire performance flight tests at Edwards AFB (Reference 7). The amount of demonstrated improvement, however, was much higher for the laboratory tests, presumably, due to the low surface texture of the steel flywheel. 6. The F-4 Marcy siped tread tire also demonstrated significant improvements over the standard tread tire in tire spin-up times on the damp flywheel surface during the high speed brake anti-skid stops. 7. During the high speed traction tests at the NAEC (Navy) test track, the Marcy siped (1/4 inch deep by 3/16 inch spacing) tread KC-135 main tire showed a significant increase in friction coefficient over the standard (unsiped) tread tire when tested on the damp (no measurable water depth) portland cement surface at all test speeds. The improvement in friction coefficient demonstrated by the 1/8 inch deep by 3/16 inch spacing Marcy siped KC-135 main tire, however, was insignificant when compared to the standard tire during the wet track tests. On portland cement track surfaces containing standing water (average water depth of 0.05, 0.10 and 0.15 inch), neither the 1/8 inch deep nor 1/4 inch deep siped tire prevented dynamic hydroplaning or showed an improvement in friction coefficient over the standard (unsiped) tire. 8

28 AFWAL-TR SECTION III DESCRIPTION OF TEST TIRES The tires used in TFM dynamometer brake stop tests, and the dynamometer tread integrity tests were F-4 main gear 30X , 24 ply rating, type VIII aircraft tires. These tires were the standard three grooves (circumferential) design currently in the US Air Force inventory. The specified minimum mold skid depth of these tires is 0.26 inch per Reference 8. The Marcy sipe configurations tested with this size tire are listed in Table 1. A Marcy sipe configuration of 5/32 inch deep by 3/16 inch spacing is shown in Figure 6. Additional dynamometer tread integrity tests were performed on siped F-16 main gear 25.5X8.0-14, 18 ply rating, aircraft tires for possible F-16 application. These tires were the standard three groove (circumferential) design currently in the US Air Force inventory. The specified minimum mold skid depth of these tires is 0.20 inch per Reference 9. The Marcy sipe configuration tested with this size tire is listed in Table 2 and shown in Figure 7. The tires tested at the NAEC test facility located at the US Navy Lakehurst, New Jersey test track were KC-135 main gear 49X17, 26 ply rating, type VII aircraft tires. These tires were the standard four groove (circumferential) design currently in the US Air Force inventory. The specified minimum mold skid depth of these tires is 0.40 inch per Reference 6. The Marcy sipe configurations tested with this size tire are listed in Table 3 and the 4/32 inch deep by 3/16 inch spacing sipe configuration is shown in Figure 8. The F-4 main gear tire with the Marcy sipes was not track tested sin-e the FAA test track fixture could not be readily adapted to accept & t ~re with a 30 inch outside diameter. In addition, the FAA was currently conducting wet traction tests on a commercial six groove 49X17/26 ply rating tire and their set up and fixturing was compatible with the Air Force four groove tire. 9

29 I AFWAL-TR In urder to eliminate errors caused by tire-to-tire variability when comparing unsiped tire to siped tire configurations, the unsiped tire was tested to completion, removed from test, siped, and then retested to identical test conditions. This procedure, however, was not used during the track tests at the Navy facility.. 10

30 AFWAL-TR SECTION IV TEST EQUIPMENT The laboratory tire tests were conducted by AFWAL/FIEM personnel in the Flight Dynamics Laboratory (FDL) Landing Gear Development Facility using the flat surfaced TFM, the 192 inch conventional dynamometer and the 120 inch programmable dynamometer, while the track tests were conducted by FAA-NAFEC personnel and NAEC personnel at the NAEC test track facility in Lakehurst, New Jersey. 1. TIRE FORCE MACHINE (TFM) The TFM was used for the quasi-static flooded flat surface traction cornering and braking tests. The force-measuring system consists of six load cells (3 vertical, 2 fore-aft and 1 lateral) instrumented to measure all six force-and-moment components developed by the tires. The machine is designed to permit low speed (0.17 mph) tests at yaw angles between +20 degrees and any desired value of longitudinal slip. A photograph showing an F-4 sipe tire being set-up in the TFM is shown in Figure 9. Flooded traction tests of an F-4 siped tire are shown in Figure 10. The TFM testing was performed on a smooth aluminum surface with an average texture depth of inch and a tungsten carbide surface with an average texture depth of inch as measured by the grease smear technique developed by NASA (Reference 3) INCH CONVENTIONAL DYNAMOMETER The 192 inch dynamometer was used for the F-4 normal energy damp surface brake stops and the tire spin up tests. The flywheel had an average texture depth of inch as measured per Reference 3. i1

31 AFWAL-TR INCH PROGRAMMABLE DYNAMOMETER The 120 inch dynamometer, incorporating a force measuring system similar to the TFM, has the capability of programmable yaw, camber, radial load, wheel velocity, wheel acceleration, and sink rate. The high speed tread integrity tests and the high speed cornering tests on a damp surface were performed on the 120 inch dynamometer. The measured texture depth of the flywheel was inch as measured per Reference 3. Descriptions and capabilities of the TFM, 192 inch, and 120 inch dynamometers are listed in the FDL Landing Gear Development Facility Brochure (Reference 10). 4. NAEC TEST TRACK FACILITY Test track number 1 at the NAEC facility in Lakehurst, New Jersey was developed jointly by the FAA and the US Navy and it has the capability of simulating a jet transport tire-wheel assembly at touchdown and rollout. A 4000 lb steel yoke housed the tire-wheel assembly, applied the loading and braking to the wheel, and contained the instrumentation system which measured the loading, angular motion, and linear motion of the wheel. The dynamometer or steel yoke was an adaptation of a NASA design. The dynamometer and tire-wheel assembly shown in Figure 11 were contained in a 60,000 lbs deaa load fixture. The dead load fixture was accelerated to speeds between 70 and 130 knots by four J-48 jet engines, each capable of 6000 lbs of thrust. The dead load fixture was arrested by a cable-fluid brake system at the recovery end of the mile long track. The loading was applied to the wheel through two hydraulic cylinders activated by pressurized nitrogen. The vertical load applied in these tests was lbs. The braking system was activated in a manner similar to the loading system. Vertical strain-gauged load links measured the vertical load applied to the wheel while horizontal strain-gauged load links measured the braking force between the tire and the surface tested. 12

32 AFWAL-TR The test bed surface shown in Figure 12 was a slab 200 feet long, 30 inches wide, and 5 inches thick consisting of Portland cement concrete of 5000 psi crushing strength, with a broomed surface finish shown in Figure 13. The average texture depth of the test surface as determined by the grease smear technique described in Reference 3, was inch based on the average of eight grease smear measurements. The test surface was diked by rubber strips into five 40 foot test sections. Dimensional tolerances of the surface, for each section, were held to within inch from a horizontal plane. The first 40-foot section was kept dry to insure that all load transients had stabilized prior to entering the wet test sections. The second 40-foot section was damp but contained no measurable water depth. The three remaining 40 foot test sections contained average water depths of 0.05 inch, 0.10 inch and 0.15 inch, respectively. 13

33 AFWAL-TR SECTION V TEST REQUIREMENTS AND PROCEDURES 1. STATIC TESTS Tire Contact Area F-4 Tire: The contact area prints (footprints) were obtained for the F-4 MLG, 30X /24 PR tire when loaded against a flat surface and the 120 inch diameter dynamometer surface at three loads, lbs, lbs (rated), and Ibs; and at two inflation pressures, 145 psig and 245 psig. The gross contact area of the tire footprints was measured and is defined as the total area of the print including the tread ribs and the spaces (tread grooves) between the tread ribs. The net area of the tire footprints was also measured and is defined as the summation of the individual tread rib areas where tread material contacts the test surface. KC-135 Tire: The contact area prints (footprints) were obtained for the KC-135 MLG, 49X17/26 PR tire when loaded against a flat surface at two loads, lbs and lbs (rated), and at an inflation pressure of 170 psig (rated). The gross and net contact areas of the tire footprints were measured. 2. DYNAMIC TESTS a. High Speed Tread Integrity Tests Inch Dynamometer F-4 Tire: In order to check the tread integrity of the Marcy sipe configurations, F-4 main tires with various sipe depth and sipe spacing configurations were tested to the dynamic test conditions specified by USAF Drawing 62J4031, Exhibit "B" (Reference 11), which included 25 taxi takeoffs, 25 landing taxis, 25 inboard camber taxis, 25 outboard camber taxis, and 3 straight taxi rolls. 14

34 AFWAL-TR F-16 Tire: In order to check the tread integrity of a Marcy sipe configuration for F-16 application, an F-16 main tire, siped 7/32 inch deep and at a 3/16 inch spacing, was tested to the dynamic test conditions specified by the General Dynamics Drawing 16VLO02A (Reference 9) which included 47 taxi takeoffs, 47 landing taxis, and 3 straight taxi rolls. b. Quasi-Static Lateral Force and Braking Tests - TFM F-4 Tire: Lateral force data was obtained for unsiped (standard) and siped F-4 tires on the dry and flooded (1/2 inch water) aluminum surface and on the dry and flooded (1/2 inch water) tungsten carbide surface of tile TFM at a rated vertical load of lbs and at a rated inflation pressure of 243 psig and at tire slip angles of 3, 6, and 9 degrees with and without braking. The braked lateral force tests on the flooded TFM were performed by pre-determining the brake pressure required to produce maximum braking without incurring circumferential tire slip (rotational tire slip) for each set of test conditions. This brake pressure was then held constant for both the unsiped and siped tire configurations for each unique test condition. c. High Speed Lateral Force Tests Inch Dynamometer F-4 Tire: Lateral force data was obtained for unsiped (standard) and siped F-4 tires on the dry and damp flywheel surface at water flow rates of 1/2 gpm, I gpm, 2 gpm, 3 gpm, and 6 gpm, at constant flywheel speeds of 5 mph, 10 mph, 30 mph, and 60 mph, at a rated vertical load of Ibs, at an inflation pressure of 268 psig, and at tire slip angles of 00, 30, 60, and 90. The 268 psig inflation pressure represents the test inflation pressure required for flywheel curvature correction per Reference 8. The various degrees of dampness were regulated with a valve, measured in gallons per minute (gpm) with an in line flow meter and applied evenly to the flywheel surface immediately in front of the tire/flywheel contact patch with a variable opening nozzle. Calculations were made to estimate the approximate water depths on the flywheel which were represented by the various flow rates as a function of the flywheel surface speed. Sample calculations are given in Appendix E. These results are plotted in Figure

35 AFWAL-TR d. High Speed Braking Tests With Mark III Anti-Skid Inch Dynamometer F-4 Tire: Normal energy brake stops per USAF Drawing 62J4031, Exhibit "A" (Reference 11), were conducted using unsiped (standard) and siped F-4 tires on a dry and damp flywheel surface at water flow rates of 1/2 gpm, I gpm, 2 gpm, 3 gpm, 4 gpm, and 7.5 gpm. The same valve, flow meter, and nozzle arrangemnt were used for the brake distance stops as were used and described for the high speed lateral force tests. The specific brake energy parameters and normal energy requirements are: Kinetic Energy - 14,780,000 ft-lbs Inertia Equivalent - 13,527 lbs Initial Velocity mph 2 Deceleration Rate ft/sec Braking Distance - 3,300 ft Braking Time - 25 sec Brake Torque - 56,000 in-lbs Tire Load (Heavy GW) - 25,000 lbs Tire Load (Light GW) - 16,000 lbs Rolling Radius in The normal energy brake stops were conducted using a complete F-4 brake hydraulic system mock-up with the actual brake system hardware which included a fully functioning Mark III anti-skid system, anti-skid box, anti-skid valves, wheel speed sensor, brake valves, restrictors, check valves, actual hydraulic line lengths, and the emergency brake system. Brake stops were conducted at two loads representing a heavy gross weight F-4 aircraft and a light gross weight F-4 and at two tire inflation pressures to evaluate tire inflation pressure effects. e. High Speed Traction Tests - NAEC Test Track The NAFEC and NAEC personnel were not able to readily adapt the test track fixtures to accept the F-4 MLG tire size. For the sake of expediency, it was decided to conduct track tests on the KC-135 MLG. 49X17/26 PR Marcy siped tires since this tire size fit into the existing equipment with minor fixturing changes. In addition, baseline traction data was available for this tire size from previous FAA traction studies. 16

36 AFWAL-TR The unsiped and siped tires were accelerated down the test track at constant tire speeds of 70 knots, 90 knots, 110 knots, and 130 knots, a tire pressure of 170 psig and at a vertical tire load of lbs. At the end of the test track, the 200 foot test section was divided into five 40 foot test sections. The system was launched with the tire in contact with the ground (concrete surface) and in a state of free roll supporting only the 4000 lbs weight of the test fixture for the full mile-length of the test track. Several hundred feet before the test bed was reached, the pusher cart was braked and separated from the test fixture with the test tire assembly. One hundred and fifty feet before the test bed was reached, the lb vertical load was applied to the test wheel. The tire/wheel assembly was braked approximately 30 feet before reaching the test bed. The fully loaded and braked aircraft tire/wheel assembly then entered the 200 foot test section at the desired speed. The tire encountered increasing water depths at each successive 40 foot test section. The first 40 foot test section was kept dry and used as baseline data. The second 40 foot test section was damp and contained water but no measurable depth. The last three 40 foot sections contained average water depths of 0.05 inch, 0.10 inch and 0.15 inch, respectively, as measured by the NASA water depth gauge (Reference 1). Brake pressures were varied, depending on the traction capability of the tire-surface combination, in order to achieve maximum braking for each set of operating conditions. Maximum braking was not attempted on the dry surface. f total of 64 tes.ts were conducted in this series. The friction coefficient, the horizontal force between the tire and the concrete surface divided by the vertical load on the wheel, was measured over the entire length of the 200 foot test section. 17

37 AFWAL-TR SECTION VI TEST RESULTS AND DISCUSSION 1. STATIC TESTS Tire Contact Area F-4 Tire: In order to establish baseline contact area data for the different size tires that were tested, contact area prints were obtained and measured for both the F-4 MLG tire and the KC-135 MLG tire. The contact area (footprints) data on the F-4 tire is tabulated in Table 4. The gross and net contact area vs normal load are plotted in Figure 15. The relationship between tire contact area, tire inflation pressure and dynamometer flywheel curvature is also shown in Figure 15. In Figure 16, the gross and net contact areas are plotted vs tire inflation pressure at three tire loads on both a flat and a curved surface. The gross and net contact areas of the F-4 tire are plotted vs percent tire deflection at a tire load of 25,000 pounds and at tire inflation pressure of 245 psig (Figure 17) and 145 psig (Figure 18) on both the flat and curved surfaces. KC-135 Tire: The contact area prints (footprints) obtained on the KC-135 MLG tire were measured and the data is tabulated in Table 5. The gross and net contact areas are plotted vs normal load and percent deflection in Figures 19 and 20, respectively. 2. DYNAMIC TESTS a. High Speed Tread Integrity Tests Inch Dynamometer F-4 Tire: In order to determine if the Marcy sipe configurations adversely affect the tread integrity of the F-4 tire, five tires with various sipe configurations were subjected to the dynamic test conditions specified in the F-4 tire qualification specification. Three of the five tires successfully completed the 103 dynamic test cycles with only a slight or negligible amount of tread chunking visible at the test completion. The tread chunking is shown in Figure 6. The carcasses of 18

38 AFWAL-TR the remaining two tires failed at depths below the tread sipes. None of the failures was considered to be caused by the Marcy siping process. The results of the tread integrity tests on the F-4 tires are tabulated in Table 6. The carcass failures of the F-4 tires were not considered a cause for alarm due to the severity of th_ -4 qualification test and the Laboratory's historical failure data on the F-4 tire. F-16 Tire: The tread integrity of an F-16 main tire with a 7/32 inch deep by 3/16 inch Marcy sipe was checked by subjecting the tire to the F-16 main tire qualification test. The tire, shown in Figure 7, successfully completed the 97 dynamic test cycles with a negligible amount of groove cracking and slight rib undercutting. None of the tread damage was considered caused by the Marcy siping process. The results of the tread integrity test on the F-16 tire are listed in Table 6. b. Quasi-Static Lateral Force and Braking Tests - TFM F-4 Tire: Quasi-static - flat surface - lateral tire force data was obtained for both unsiped and siped F-4 tires on the dry and flooded aluminum and tungsten carbide surfaces of the TFM. The test configurations and results are listed in Table 7. The 8/32 inch deep by 3/16 inch spacing sipe configuration demonstrated over 200 percent improvement in lateral force and a 30 percent improvement in developed brake torque for the flooded aluminum surface during maximum braking as shown in Figure 21. The 9/32 inch deep by 3/16 inch spacing siped configuration demonstrated improvements in lateral force for the flooded aluminum surface which ranged from 64 percent to Ill percent for unbraked runs and from 128 percent to 440 percent during maximum braking as shown in Figure 22. The 9/32 inch deep by 1/8 inch spacing siped configuration showed improvements in lateral force for the flooded aluminum surface which averaged about 78 percent for unbraked runs and 100 percent during maximum braking as indicated in Figure 23. The 5/32 inch deep by 3/16 inch spacing configuration showed an average improvement of 61 percent for unbraked runs on the flooded aluminum surface and an average improvement of 9 percent 19

39 AFWAL-TR for unbraked runs on the flooded tungsten carbide surface as indicated in Figure 24. During dry runs on both the aluminum surface and the tungsten carbide surface, there was a slight increase in lateral force for the siped tire configuration as shown in Figure 25. c. High Speed Lateral Force Tests Inch Dynamometer F-4 Tire: High speed - curved surface - lateral tire force data was obtained for both unsiped and siped F-4 tires on the dry and damp steel surface of the 120 inch dynamometer. The test matrix and results are listed in Table 8. The 8/32 inch deep by 3/16 inch spacing siped configuration demonstrated significant improvements in lateral force over the unsiped tire for all speeds and tire slip angles during the high speed runs as shown in Figures 26 through 29 and listed in Table 8. In an attempt to maintain a constant water depth on the flywheel for the various speed runs, flow measurements and calculations were made to generate a family of curves relating flywheel water depth vs dynamometer flywheel speeds for the various water flow rates. The results are shown in Figure 14 and listed in Table 8. An approximate water depth of inch was maintained for the runs. In order to check the effect of slightly changing the water depth, a second set of 60 mph runs were made at a flow rate of 2 gpm (0.001 inch water depth). The percent improvement of the siped over the unsiped tire was reduced by approximately 10% when compared to the 6 gpm (0.002 inch water depth), 60 mph runs as shown in Figure 30. Attempts to significantly increase the water depth for the higher speed runs were halted due to the large flow rates and water volumes required. During the dry high speed runs, there was an insignificant increase in lateral force at all tire slip angles as indicated in Table 8 and Figures 31 through

40 AFWAL-TR-81-3U68 d. High Speed Braking Tests with Mark III Anti-Skid Inch Dynamometer F-4 Tire: Normal energy high speed brake stops were conducted on unsiped (standard) and siped F-4 30X /24 PR tires on the dry and damp flywheel surface of the 192 inch dynamometer. The brake stops were conducted with a complete mock-up of the F-4 brake hydraulic and Mark III anti-skid systems which used actual F-4 brake system hardware. These tests were performed to study the interaction between the anti-skid system and the tread sipes which affects the traction at the tread/flywheel interface. Measurements and data were obtained to determine if the various tread sipe configurations provided increases in deceleration rates and brake torques resulting in decreased braked stop distances when compared to the unsiped tire. The brake stops were conducted at two different tire loads representing a heavy and light gross weight aircraft configuration and at two different tire inflation pressures. Most of the brake stops were conducted with the water applied before the tire was loaded against the flywheel, however, some were conducted with the water applied after fully loading the tire but prior to braking in order to determine what effect this might have on braking performance. The test sequence and test data for the dynamic anti-skid brake stops are tabulated in Tables 9 and 10. The analog data for the brake stops on the tires code numbers 18-N (cycles 49 through 60), 20-N (cycles 61-66), 21-N (cycles 67 through 69 and 73 through 75), and 22-N (cycles 70 through 72 and 76 through 90) is shown in Figures Cl through C31 of Appendix C. Actual tire spin down or tire slip data was recorded on channel 2 (test wheel speed) while the antiskid action or brake pressure and brake torque response was recorded on data channels 3 and 4. Analog plots of flywheel speed vs stopping distance comparing the unsiped and siped tire at each water flow rate for the above cycles is shown in Figures DI through D15 of Appendix D.. 21

41 AFWAL-TR The 8/32 inch deep siped tires (18-N, 20-N, and 22-N) and the 5/32 inch deep siped tire (21-N) demonstrated significant improvements in damp surface traction for the heavy gross weight aircraft condition at applied water flow rates greater than 1/2 gpm by developing greater brake torques which resulted in higher deceleration rates and much shorter brake stop distances than the unsiped tires as shown in Figures 35, 36, 37, and 38 and tabulated in Table 11. The results of these tests did not indicate a significant difference in traction performance on the damp surface between the two sipe depths (8/32 inch vs 5/32 inch). The 8/32 inch deep siped tire (18-N) also demonstrated significant improvements in damp surface traction for the light gross weight aircraft conditions and at the reduced tire inflation pressure conditions at applied water flow rates greater than 1/2 gpm as shown in Figure 39 and Table 12. In the preceding tests, the water was applied to the flywheel prior to loading the tire on the flywheel surface. The water was sprayed on the flywheel by means of the variable opening nozzle shown in Figure 40. The analog data for the brake stops on the tire code number l-r-2 (cycles 96 through 115) is shown in Figures C32 through C51 of Appendix C. Analog plots of flywheel speed vs stopping distance comparing the unsiped and siped tire, code number l-r-2, are shown in Figures D16 through D24 of Appendix D. The 7/32 inch deep siped tire (l-r-2) demonstrated significant improvements in damp surface traction over the unsiped tire for the light gross weight aircraft conditions (Table 13) both in the case in which water was applied to the flywheel before the tire was landed (Figure 41) and the case in which water was applied after the tire had landed with full load but prior to brake application (Figure 42). In case I, water applied 22

42 AFWAL-TR before the tire landed, the unsiped tire failed to fully spin up and incurred total hydroplaning or total tire spin down during the 2 gpm bra'.e stop (Figure C34). During two case I, 3 gpm, brake stops, the unsiped tire failed to fully spin up and incurred total hydroplaning (Figures C35 and C36). In case II, water applied after the tire landed, the unsiped tire fully spun up to the flywheel speed after landing on the dry flywheel but started immediately to spin down after water application and incurred partial hydroplaning during the 2 gpm stop (Figure C39) and total hydroplaning during the 3 gpm stop (Figure C40). During case I and case II brake anti-skid stops, the 7/32 inch siped tire (l-r-2) did not incur total tire spin down or total hydroplaning at water flow rates of 1/2, 1, 2, 3, 4, and 7.5 gpm as shown in Figures C41 through C50. The application of the water to the flywheel at a flow rate of 4 gpm during a brake anti-kid stop is shown in Figure 43. The flywheel and tire had decelerated from 181 mph to 40 mph when this photograph was taken. In Figure 44, the test wheel/tire speed is compared for the unsiped and siped configuration of the tire code number 18-N when tested to the heavy gross weight aircraft conditions for water flow rates of 1/2, 1, and 2 gpm. It is interesting to note the increased traction of the siped tire during initial tire spin up as the unsiped tire took longer than the siped tire to spin up to the synchronous flywheel speed. This difference in initial tire spin-up is even more prevalent in the light gross weight aircraft test runs as shown in Figure 45. In Figures 46 and 47, a large difference is noted between the case I (water before tire load) and case II (water after tire load) tire spin ups. During the case I tests, the unsiped tire was unable to spin up to the synchronous flywheel speed at the high water flow rates while the siped tire was able.o spin up to the flywheel speed (Figure 46). During the case II tests, both the unsiped and siped tire immediately reached the 23 L - " J m,.... m, - -, a,, l n ni I - I I I l

43 AFWAL-TR flywheel synchronous speed (Figure 47) since the surface was dry. As far as braking performance (decreased stop Gistance) was concerned, it did not appear to make much difference whether the water was applied before (case I) or after (case II) the tire was landed for either the unsiped or siped tire. Analog plots of flywheel speed vs stopping distance comparing case I and case II stops are shown in Figures D25 through D28 for the unsiped tire and Figures D29 through D32 for the siped tire. A comparison of the tire spin up of the 3 gpm brake stops for the unsiped and siped tires for case I and case II is shown in Figures 48 and 49. Analog plots of flywheel speed vs stopping distance for case I and case II test runs at the various water flow rates are shown in Figures D33 and D34 for the unsiped tire and Figures D35 and D36 for the siped tire. Brake anti-skid stops were conducted on a dry flywheel surface on the tires code numbers 22-N and I-R-2 in order to establish baseline (dry surface) data. The analog data is shown in Figures C31 and C51. During the dry stop on 22-N (Figure C31), it was interesting to note the torque peaking which occurred in the middle of the braked run. Torque peaking which normally occurs at the end of a stop is thought to be caused by excessive localized non-uniform heating in the brake friction surfaces which results in rapid change in the friction coefficients of the rubbing surfaces and a rapid increase in the developed brake torques which in turn can cause the tire to spin down or skid. However, since the anti-skid system was operative, it cycled preventing a complete tire/wheel lock up as shown in cycle 90 (Figure C31). The tire'wheel speer', brake pressure, and brake torque data for the two dry stops are compared in Figure

44 AFWAL-TR e. High Speed Traction Tests - NAEC Test Track KC-135 Tire: High speed damp, wet, and flooded track tests were conducted at the NAEC facility by NAFEC and NAEC personnel on braked standard tread (unsiped) and siped 49X17/26 PR KC-135 main gear tires to evaluate the traction capability of a siped tire when tested on wet portland cement at various water depths and test speeds. The NAFEC test results at the NAEC facility are reported on in Reference 12. These results of the wet track tests are replotted in Figures 51 through 58. In Figures 51 through 53, the friction coefficient vs speed is plotted at the various water depths for the standard (unsiped) tire, the 1/4 inch deep by 3/16 inch spacing siped tire and the 1/8 inch deep by 3/16 inch spacing siped tire, respectively. Friction coefficient vs water depth is plotted in Figure 54 and the siped and unsiped tires are compared. Friction coefficient vs speed is plotted for the siped and unsiped tires for the damp, 0.05, 0.10, and 0.15 inch test conditions in Figures 55 through 58, respectively. During the damp condition (no measurable water depth) track tests, the 1/4 inch deep siped tire produced a significant increase in friction coefficient over the standard tread tire while the 1/8 inch deep siped tire showed only a slight improvement in friction coefficient over the standard tire (Figure 55). During the track tests on surfaces containing standing water (average water depths of 0.05, 0.10 and 0.15 inch), neither siped tread tire showed a significant increase in friction coefficient over the standard tread tire and in most cases produced less traction (Figures 56, 57, and 58). 25

45 AFWAL-TR SECTION VII CONCLUSIONS 1. The Marcy tread siping process does not appear to adversely affect the tread integrity of the F-4 or the F-16 main gear tires if the sipe depths and sipe spacing is constrained to those configurations tested. 2. The 1/4 inch deep by 3/16 inch spacing Marcy siped tread configuration reduced viscous hydroplaning and demonstrated significant improvements over the standard (unsiped) tread tire in lateral force, in developed brake torque and in stopping performance during laboratory tests and improved the friction coefficient during track tests. 3. The improvement in traction, however, is negligible on the wet portland cement surface when the sipe depth is reduced by tire wear to depths less than 1/8 inch. The Marcy siping machine, however, does allow for resiping a tire if sufficient tread material exists. 4. None of the Marcy sipe configurations prevented dynamic hydroplaning or demonstrated traction improvements during the track tests when the tire encountered standing water. 5. Since tread wear effects and chevron cutting effects can not be evaluated for the Marcy sipes through laboratory or track tests, these effects must still be evaluated before the overall payoffs can be determined. 26

46 AFWAL-TR SECTION VIII RECOMMENDATIONS The testing to date indicates that the Marcy 1/4 inch deep by 3/16 inch spacing siped tread configuration reduces viscous hydroplaning and offers significant improvements in friction coefficient, lateral force, developed brake torque, and stopping performance when encountering damp or wet ungrooved runway surfaces without adversely affecting the tread integrity of the tire. Since this demonstrated improvement can only be verified through aircraft tests on damp or wet runways, it is recommended that this effort be followed by flight demonstration tests. Also, the US Navy has recently shown considerable interest in the Marcy siped tire based on the results of the Air Force wet traction tests, therefore, it is recommended that a joint US Air Force, US Navy flight test program be pursued in order to share the flight test costs. During these aircraft tests, additional questions such as what effects tread siping has on tread wear and chevron cutting can be addressed. 27

47 AFWAL-TR APPENDIX A TABL ES h1ee AM ha3m-k=o 71 LJ 29

48 AFWAL-TR TABLE 1 F-4 MLG, 30X /24 PR TIRE, MARCY TREAD SIPE CONFIGURATIONS TIRE SIPE SIPE CODE NR DEPTH (IN) SPACING (IN) TYPE TEST 1-N 5/32 3/16 Tread Integrity - Dynamometer 6-N 9/32 1/8 8-N 5/32 1/8 11-N 5/32 3/16 12-N 5/32 3/16 3-N 8/32 3/16 Quasi-Static Cornering - TFM 5-N 9/32 3/16 6-N 9/32 1/8 11-N 5/32 3/16 18-N 8/32 3/16 Brake Distance - Dynamometer 20-N 8/32 3/16 21-N 5/32 3/16 " " 22-N 8/32 3/16 " 1-R-2 7/32 3/16 24-N 8/32 3/16 High Speed Cornering - Dynamometer 30

49 AFWAL-"IR I TABLE 2 F-16 MLG, 25.5X8.0-14/18 PR TIRE, MARCY TREAD SIPE CONFIGURATION TIRE SIPE SIPE CODE NR DEPTH (IN) SPACING (IN) TYPE TEST I-N 7/32 3/16 Tread Integrity - Dynamometer TABLE 3 KC-135 MLG, 49X17/26 PR TIRE, MARCY TREAD SIPE CONFIGURATIONS TIRE SIPE SIPE CODE NR DEPTH (IN) SPACING (IN) TYPE TEST 1-N 4/32 3/16 Traction Tests - Test Track 2-N 8/32 3/16 "

50 AFWIAL-TR cjc CO cm m'~ (I~ U- U-J W.- - r- COW CD C U)1--C-- I.- L r I.-I 10 LUIU4 &- -W - -a z -- CL~.j' NNN rxi CN 32ULi

51 AFWAL-TR Cj -C %- CDC U~eJ I. 0 u. Le I- j o 33

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53 AFWIAL-TR zu M LU~C L C. -j0 ILU 1 ~ * t Lu *4 - IU - 00 cli 0 0 = LU o - ~ C C C C; CI LUEc Z -0 -L.Cr4 P U. M I ~I J- 4, J 4- C,,t CI A C')) ui w I.- L3, cu1 -j.- 0: w 10 a- LU L LU CD~ u@ :z ui. "0 'o 0 cm R i C, C j LIc LA,~ ' A3 353

54 AFWAL-TR 'n CD L L M. -I C O 1.. u _ji C D <a 4, 4) w6 cu Q) 0) _j m a C) o C, I CD a C ZC Ca C C a. I-Li u- Do -o co-a -o uz Ln 0 FS a. C! Z c w L Lu wi c\j m4 CSj(' (J' c'j - ('4a w - xa. (>C )0 ) D 0c DC -j ZL. LU LZcr LU x -v z.. cc 5- I.- in LUco Li uj. _ Uf 0 CD:. - ' I.- 4n C> LU u-.0 V) 2C - 7z _j LU "' LU0 U L. joaj Liuu cl In In L-.L3 I.- clt0 m amc E EE L c MLi 'o v V v V V Vu v Q 46 w6 G 0) u cu W) 0) a) ua mz. mza lvo 1)50 a )0 V 6)60 'a.a ca. M0V i-i- W~ C.- a K" C. m~ C- c- 04/6 ~ I zo I 460n0n SI ti 0I) _j IU La in0 DC Dc n nc >C )c. 36

55 AFWAL-TR TABLE 9 BRAKE STOP DATA, 30X /24 PR UNSIPED VS SIPED TIRE INITIAL FINAL FLOW BRAKE BRAKE CYC CODE LOAD PRES SPEED SPEED RATE DECEL 2 TORQUE DISTANCE TREAD NR NR LBS (PSIG) (MPH) (MPH) (GPM) (ft/sec (in-bs) (ft) CONFIG N Unsiped N Unsiped N Unsiped N Unsiped Unsiped Unsiped N N N Siped 8/32" N Siped 8/32" Siped 8/32" N Siped 8/32" N N Siped 8/32" N Siped 8/32" N ' Unsiped N Unsiped N Unsiped N Siped 8/32" N Siped 8/32" N Siped 8/32" N Unsiped N N Unsiped Unsiped N Unsiped N Unsiped N Unsiped N Siped 5/32" N Siped 5/32" N Siped 5/32" N Siped 8/32" N Siped 8/32" N Siped 8/32" N DRY Siped 8/32" 37

56 AFWAL-TR TABLE 10 BRAKE STOP DATA 30X /24 PR UNSIPED VS SIPED TIRE, TIRE CODE NUMBER 1-R-2 INITIAL FINAL FLOW BRAKE BRAKE CVC CODE LOAD PRES SPEED SPEED RATE DECEL 2 TORQUE DISTANCE TREAD NR NR LBS (PS1G) (MPH) MPhj) (GMP) (ft/sec) (in-bs) (ft) CONFIG 96 I-R Unsiped 97 I-R I-R Unsiped Unsiped 99 I-R Unsiped R Unsiped 101 I-R * Unsiped 102 I-R * Unsiped R * Unsiped R I-R * * Unsiped Siped 7/32" 106 I-R * Siped 7/32" R * Siped 7/32" 108 I-R * Siped 7/32" 109 I-R Siped 7/32" 110 I-R Siped 7/32" R Siped 7/32" 112 I-R Siped 7/32" R rf Siped 7/32" R Siped 7/32" R DRY Siped 7/32" *Water applied to flywheel after tire was landed and at full load. cycles,the water was applied before tire was landed. All other test 38

57 AFlIAL-Tit I- a.. I- o n Lq'c 0o 0D 0) ac~ o -T a. c,.0." a. cjc c!li a. LnL V) ) n 0 cl w ur 4o-" V c, -: aec~ (C\J C o 'n C7 M' In co. 1 m In - en a - m -.m v) C U~ LLJ U U 0 fln r-no VC c--l 0 t 0 c-l!n a. 'z a. j 3. w ~.5- w ml. V M V a. wn WOw co CC L) 'A (D C oq L na -o M c 0 r-c) 0n r 0x - ~ c.cr uu ma -e -o W :2CJj u * C) 4' U; =u 1;Lill C) u C) a QA j C>.00 -z eq 0 0 ). 0j C I- _ i j In *no o-.4 IQ lo j. w co ~ C, I m U.) "P Vwt M. be m f-. co o. u. >C. a. -N. C C)O NJ)- CO 4)O I C>C II I C) e LO ~j ( m ' VJ -n en -m- w - - -n-o 41o V ON9JO. N'o. (L) (L) 4) a) IA 7; 4. V V cn (D cl I C) r )i a.q a. aaa V Il L.. In r : u >.c*. I- *C'J.r~N 2F a -0-r a I -D n NJ% n % -D NJ 04 m cm m 1) 2: 2C11 - C 4-2: &A 4-) ta a, 2:I Q ui Li CD LU u~c al 41U~ r S al (Dc.)a,a -. %IGO..- = l-- 0 a 39

58 AFW~AL-TR C. U., LUD 0 4-, % 0Y (U, - 40 Ucl0 cfl -j a. CL C'. La ul cm CD0 CD ;; ;:: =0 -i U' I. Ci CLC. u LU LLJ uu. C OC'. 0 -~ o"0 a. C 4D IM4 cujc Ci 11.S a)i o.3.a coc D c Col W fla)0 10 4).j d -SO. LU, ac' Im 41 1 IV t- W v.. W) u, a =a *40

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60 AFWAL-TR APPENDIX B FIGURES AND PHOTOGRAPHS 42

61 I; \ AFWAL-TR " FLOODED 43 U FLODED! l ' 15" 0.1" W I0" 0.02 O.05" IWET IWET.002F DAMP DAMP 1DA P A B C n E A - High speed 120 (in) dynamometer tests at LGDF. WPAFB (Marcy siped tire) B - Low speed TFM tests at LGDF, WPAFB (Marcy siped tire) C - High speed track tests at Navy track, Lakehurst (Marcy siped tire) o - High speed track tests at NASA track, Langley (rain tire tests) E - High speed aircraft tests on various runways (combat traction tests) Figure 1. Water Depth Comparison for Various Facility Traction Tests 43

62 AFWIAL-TR S 4-1 4, *1 o> 4-1 CD-- - %a - 4, 4 -C u '4, 4, 0L mc. 4,1 ~ oj CD 0 W 4J 'a o. 0s- S.- 1- '- 4 M ; s- m, %-(D r=, U~,~ W EC E C.40 c M -. U S LW w S CD ) E m 4,4a4-'' m -- 4 C Cl _ m >4), 4z -I'C xu I-4 'Urn 444

63 S. Q)

64 A FWATP -I-U~ FlJiure 4. Marcy Hlel ix Si peurt j i ~ air

65 Lilr t-. Ma rcy Troa, I p. m r i ifi( - 7 i

66 LO t_

67 AFWAL-TR Figure 7. Marcy Tread Sipe, F-16 Tire, 7/32 Inch Deep by 3/16 Inch Spac ing 49)

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69 H- r H- I-- I I

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71 Cr 0n 0j CZ I-j

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73 ANWA L-T--21Tt L-( C LL. 55O

74 AFWAL-TR C)A ccc C(4- LC!, CD m <>0CD - i >a.( S 06 - cm o) Li. j a- 0) LLi o) M R Q) od >- a-- 4-) a (sjhjni)~c -) Mi3 M3LM13M1 561

75 AFWiAL-TR w 49. < L =u - M8 Lu L 9 01 U. U *c S! a CL.~ 000 L C., LuO * CA LUn Go C~ a el zt NO- 'CV13IO 57

76 AFWAL-TR LJ L.J w I.- I.- I.- (0404 C I-s n!. I C=zz ac in C' U, Ui 404 ::t Ut 0 c- u- I- vi &Ac. Li0-4 C w- w0 0 U ~el 0 n'g o. C- c;- i-q. I a -3V NO) i3vn ~ '8

77 AFWAL-TR LIS La J C) C LO 00 tz L00 w I.- n LLJ -I to 0 CD o0 %0 r UJV NY) - 41N 59.

78 AFWAL-TR Lo 4- ix2 % In c WLU0 00i G* CL U U 0 C'.. a, -j us 0 u- C i 0 '.r4 z 0 u cc U J~ 3 8- _ -0 Z L W Ln LLU ~LU O L LU, 83. CO1.0.p zz NO MY OVN 600

79 AFWAL-TR ui 2,0 U- -0 =0 9 cc~i -j I o, LJ - UJ.j v - -4A c cc I.- LL 0 - CA w~ U, 0% 2C -r C,, UD CJ cn0 4A I I 0 C-4 Nlj - - (NO) V3NV IDWI.N03 61

80 AFWAL-TR L.J u- 4?Z 2c: 0ZL u - ow r- IA U UJu 0 0 fl In )( I.- ~c a 0- OI~~.Iin L'5 * to CC.) CDC2 (Z NOV39Y 3YINO 0l 62a

81 AFWdAL-TR TFM DATA SIPED TIRE EVALUATION 3OX /24 PR AIRCRAFT TIRE ALI.IINU?4 SURFACE-AVERAGE TEXTURE DEPTH ( IN) FLOODED (112 IN WATER DEPTH) 25,000 LBS VERTICAL LOAD, 243 PSIG PRESSURE TIESIPAGE(DGES _IED(A 600USIED(AXBRKIG o IAIG 63 6

82 AFWAL-TR TFT4 DATA SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE ALUMINUM SURFACE-AVERAGE TEXTURE DEPTH ( IN) FLOODED (112 IN WATER DEPTH) 25,000 LBS VERTICAL LOAD, 243 PSIG PRESSIODE Im T3 6 9 TIRE SLIP ANGLE (DEGREES) 0 - SIPED (NO BRAKING) 0 - SIPED (MAX BRAKING) *- UNSIPED (NO BRAKING) *- UNSIPED (MAX BRAKING) Figure 22. Lateral Force vs Slip Angle, Flooded Test Surface, Tire Code Number 5-N (Siped g/32' Deep X 3/16" Spacing) 64

83 AFWIAL-TR TFM DATA SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE ALUMINUM SURFACE-AVERAGE TEXTURE DEPTH ( IN) FLOODED (1/2 IN WATER DEPTH) 25,000 LBS VERTICAL LOAD, 243 PSIG PRESSURE z~3000. P " T3 6 9 TIRE SLIP ANGLE (DEGREES) od - o - SIPED (NO BRAKING) SIPED (MAX BRAKING) *- UNSIPED (NO BRAKING) *- UNSIPED (MAX BRAKING) Figure 23. Lateral Force vs Slip Angle. Flooded Test Surface, Tire Code Number 6-N (Siped 9/32" Deep X 1/8" Spacing) 65

84 AFWAL-TR TFI4 DATA SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE TUNGSTEN CARBIDE SURFACE - AVERAGE TEXTURE DEPTH (0.004 IN) AND ALU14ZNUM SURFACE-AVERAGE TEXTURE DEPTH ( IN) FLOODED (1/2 IN WATER DEPTH) 25,000 LBS VERTICAL LOAD, 243 PS16 PRESSURE 9000' S6000 ~j TIRE SLIP ANGLE (DEGREES) O-SIPED (NO BRAKING-TUNGSTEN SURFACE) *-UNSIPED (NO BRAKING-TUNGSTEN SURFACE) CI- SIPED (NO BRAKING-ALUMINUM SURFACE) S - UNSIPED (NO BRAKING-ALUNiNUM4 SURFACE) Figure 24. Lateral Force vs Slip Angle, Flooded Test Surface, Tire Code Number 11-N (Siped 5/32" Deep X 1/8" Spacing) 66

85 AFWAL-TR TFM DATA SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE TUNGSTEN CARBIDE SURFACE-AVERAGE TEXTURE DEPTH (0.004 IN) AND ALUMINUM SURFACE-AVERAGE TEXTURE DEPTH ( IN) (DRY SURFACE) 25,000 LBS VERTICAL LOAD, 243 PSIG PRESSURE 10000" 9000.m " TIRE SLIP ANGLE (DEGREES) 0 - SIPED (NO BRAKING-TUNGSTEN SURFACE) 0- UNSIPED (NO BRAKING-TUNGSTEN SURFACE) 0 - SIPED (NO BRAKING-ALUMINUM SURFACE) S- UNSIPED (NO BRAKING-ALUMINUM SURFACE) Figure 25. Lateral Force vs Slip Angle, Dry Test Surface, Tire Code Number 11-N (Siped 5/32" Deep X 1/8" Spacing) 67

86 AFWAL-TR DYNANONETER DATA INCH DIAMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) 25,000 LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 5 MPH CONSTANT SPEED DAMP (1/2 GPM) 1400" _ I,,' 400 " 2oo TIRE SLIP ANGLE (DEGREES) (- SIPED (NO BRAKING) P- UNSIPED (NO BRAKING) Figure 26. Lateral Force vs Slip Angle, Damp Test Surface, 5 MPH, 1/2 GPM, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) 68

87 AFWAL-TR DYNAMIOMETER DATA INCH D3IMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) 25,000 LOS RADIAL LOAD. 268 PSI6 INFLATION PRESSURE 10 MPH CONSTANT SPEED DAMP (1 GPM) 1200" S ' TIRE SLIP ANGLE (DEGREES) 0 - SIPED (NO BRAKING) N - UNSIPED (NO BRAKING) Figure 27. Lateral Force vs Slip Angle, Damp Test Surface, 10 MPH, 1 GPM, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) 69

88 AFW~AL-TR DYNANONETER DATA INCH DIAM4ETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT T[RE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) 25,000 LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 30 M4PH CONSTANT SPEED DAMP (3 GPM) * I.- 3 n TIRE SLIP ANGLE (DEGREES) Figure 28. ~-SIPED (NO BRAKING) A-UNSIPED (NO BRAKING) Lateral Force vs Slip Angle. Damp Test Surface, 3D MPH, 3 GPM. Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) 70

89 AFWIAL-TR DYNIAMOMETER DATA -120 INCH DIAMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 60 MPH CONSTANT SPEED DAMP (6 6PM) u' SOO. 00 LII TIRE SLIP ANGLE (DEGREES),-UNSIPED (NO S-SIPED (NO BRAKING) BRAKING) Figure 29. Lateral Force vs Slip Angle, Damp Test Surface, 60 MPH, 6 6PM, Tire Code Number 24-N (Slped 8/32" Deep X 3/16" Spacing) 71

90 OW AFWdAL-TR DYINAMOMETER DATA INCH DIAMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 60 MPH CONSTANT SPEED DAMP (2 GPM) j I TIRE SLIP ANGLE (DEGREES) Q-SIPEO (NO BRAKING) UNSIPED (NO BRAKING) Figure 30. Lateral Force vs Slip Angle, Damp Test Surface. 60 MPH, 2 GPM, Tire Code Number 24-N (Siped 8/32" Deep X 3116" Spacing) 72

91 AFWAL-TR DYNAMOMETER DATA INCH DIAMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) 25,000 LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 5 MPH CONSTANT SPEED DRY SURFACE 9000'' " _j 6000" i S TIRE SLIP ANGLE (DEGREES) o - SIPEC (NO BRAKING) 0 - UNSIPED (NO BRAKING) Figure 31. Lateral Force vs Slip Angle, Dry Test Surface, 5 MPH, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) 73

92 AFWAL-TR DYNMOMETER DATA INCH DIAMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) 25,000 LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 10 MPH CONSTANT SPEED DRY SURFACE Z _j Z 4000 LU TIRE SLIP ANGLE (DEGREES) CD - SIPED (NO BRAKING) N - UNSIPED (NO BRAKING) Figure 32. Lateral Force vs Slip Angle, Dry Test Surface, 10 MPH, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) 74

93 AFWAL-TR DYNAMOMETER DATA INCH DIAMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IN) 25,000 LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 30 MPH CONSTANT SPEED DRY SURFACE " ',j 4000 w TIRE SLIP ANGLE (DEGREES) 6- SIPED (NO BRAKING) A- UNSIPED (NO BRAKING) Figure 33. Lateral Force vs Slip Angle. Dry Test Surface. 30 MPH, Tire Code Number 24-N (Siped 8/32" Deep X 3/16" Spacing) 75

94 AFWAL-TR DYNAMOM4ETER DATA INCH DIAMETER SIPED TIRE EVALUATION 30X /24 PR AIRCRAFT TIRE STEEL CURVED SURFACE-AVERAGE TEXTURE DEPTH (0.002 IM) 25,000 LBS RADIAL LOAD, 268 PSIG INFLATION PRESSURE 60 MPH CONSTANT SPEED DRY SURFACE ~ S5000. u TIRE SLIP ANGLE (DEGREES) I JPED (NO BRAKING) UNSIPED (NO BRAKING) Figure 34. Lateral Force vs Slip Angle, Dry Test Surface, 60MPH. Tire Code Number 24-Nt (Siped 8/3Z" Deep X 3/16" Spacing) 76

95 AFWAL-TR BRAKE STOP DATA 30X /24 PR SIPED VS UNSIPED TIRE LBS LOAD, 245 PSIG PRESSURE u ', CY ""- o t.12000" < 8000" ' ' I I 1 2 APPLIED WATER FLOW RATE (GPM) Q- SIPED TIRE 0- UNSIPED TIRE Figure 35. Brake Stop Data vs Water Flow Rate, Tire Code Number 18-N 77

96 AFWAL-TR BRAKE STOP DATA 30X /24 PR SIPED VS UNSIPED TIRE LBS LOAD, 245 PSIG PRESSURE L.) APPLIED WATER FLOW RATE (GPM) 0 - SIPED TIRE 0 - UNSIPED TIRE Figure 36. Brake Stop Data vs Water Flow Rate, Tire Code Number 20-N 78

97 AFIWAL-TR BRAKE STOP DATA 30X /24 PR SIPED VS UNSIPED TIRE LBS LOAD, 245 PSIG PRESSURE B.- -J APPLIED WATER FLOW RATE (GPM) )"SIPED TIRE -UNSIPED TIRE Figure 37. Brake Stop Data vs Water Flow Rate, Tire Code Number 22-N 79

98 AFWAL-TR BRAKE STOP DATA 30X /24 PR SIPED VS UNSIPED TIRE LBS LOAD, 245 PSIG PRESSURE :i I 0* APPLIED WATER FLOW RATE (GPM) 0-SIPED TIRE 0-UNSIPED TIRE Figure 38. Brake Stop Data vs Water Flow Rate, Tire Code Number 21-N... I- 80

99 AD-A AIR FORCE WRIGHT-AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH FIG, 1/3 WET TRACTION TESTS -MARCY SIPED TIRE.U FEB 82 P C ULRICH UNCLASSIFIED AFWAL-TR 'NL E~h~hhEE~Sol

100 IL

101 AFWAL-TR BRAKE STOP DATA 30X /24 PR SIPED VS UNSIPED TIRE LBS LOAD, 145 PSIG PRESSURE N A 8, w 4- LU 30000' LJ L~a " LU 100 BOOO APPLIED WATER FLOW RATE (GPM) 0- SIPED TIRE 0- UNSIPED TIRE Figure 39. Brake Stop Data vs Water Flow Rate, Tire Code Number 18-N 81 L t

102 L..0 CL CD LL.

103 AFWAL-TR BRAKE STOP DATA 30X /24 PR SIPED VS UNSIPED TIRE LBS LOAD, 245 PSIG PRESSURE WATER APPLIED BEFORE TIRE LANDS L" II." Lu C 32000' I.- ~ 000- Wu I, UNSIPED TIRE HYDROPLANED AT 147 MPH DRING 2 GPM BRAKE STOP APPLED IdA-: FLOW RATE (GP1) 0 - SPED TIRE TIRE - UNSIPED * Figure 41. Brake Stop Data vs Water Flow Rate, Tire Code Number 1-R-2, Case I Tests 83

104 AFWAL-TR BRAKE STOP DATA 30X /24 PR SIPED VS UNSIPED TIRE LBS LOAD, 245 PSIG PRESSURE WATER APPLIED AFTER TIRE LANDS ca &, UNSIPED TIRE HYDROPLANED AT MPH FOR 2 GPM BRAKE STOP 4-. S S S APPLIED WATER FLOW RATE (GPM) 0 - SIPED TIRE 0 - UNSIPED TIRE Figure 42. Brake Stop Data vs Water Flow Rate, Tire Code Number 1-R-2. Case 11 Tests 84

105 Al W!\I - C- F- C- 'C L r C- -z Cm a' C' -c U- C 4-, U as -c 4-' ~ (0 ~ a -n o ~-' o F- 4-' I 01~ S a c cz ~s C,-' C' 1- C Cm U- 2 r,

106 AFWAL-TR CYC NR 49 C GP1 UNSIPED SEC 7 CYC NR 55 IT, GPM SIPED 200 I WL100 CYC NA 50 CI 1 GP I loo ] / I TPMN-L CYC NR 56," 200- I GPM.UV- SIPED :; ti I X.O CYC NA 51 Cr SIPEO I II NEV ",.492 C UNSIPED 4v 200- I I I 1 4, 100 I I I I CYC NR G2 '.G I1l Figure 44. Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Nuber 18-N. Tire Load 25,000 Ibs, Test Wheel/Tire Speed vs Time, 1/2, 1 and 2 GPM Water Flow Rates, Case 1-Water Applied Prior to Landing Tire 86

107 AFWAL-TR CYC NR 52 a. GPM 200- UNSIPED T CYC NR GPM H u 200 SIPED -, n.5 I I -r CYC NR 53 I1GPM4 UNSIPED v 3c vz2oo- - "I,.-,.,. 3V I si~w CYC NR 59 c- - - IGP.M 1 SIPED 200- " r yrv, CYC NR 54 c o 2 GPM UNSIPED 3z /i / Vp CYC NR SIPED.! -" P ' *-,,. 4jt 100-_ Figure 45. Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number 18-N, Tire Load 16,000 Lbs. Test Wheel/Tire Speed vs Time, 1/2, 1 and 2 GP Water Flow Rates, Case I-Water Applied Prior to Landing Tire 87

108 AFWAL-TR CYC NR6 GPM UNSIPED S T CYC NR 109 CL GPM f SIPED ( " I.( I CYC NR 98 2 GPH ' 200- UNSIPED 4 1 I. _ IO CYC NR GPM " '7,n vv+nv SIPED 2= J 4J 100. CYC NR 99-3 GPM 2002 UNSIPEO v 0 CYC NR 112-W 3 GPM SIPED " 2 Figure 46. Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number l-r-2, Tire Load 16,000 Lbs. Test Wheel/Tire Speed vs Time, 1/2, 2 and 3 GPM Water Flow Rates, Case I-Water Applied Prior to Loading Tire 88

109 i- 100llh1 AFWAL-TR CYC NR s - 1; UNSIPED 3c I - 10 I, I I CYC NR 105 C, G P M u " - - SIPED "' - CYC HR 103 "- 2GPM - UNSIPED I - -! I - -, 7 - i, - CYC NR 107-; SIPED. W..200 A 2 GPM In,. f CYC NR 104, UNSIPED 200" GPM CYC HR GPM -j200 SIPED I 'T U~L100 Figure 47. Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number I-R-2, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 112, 2 and 3 GPTr Water Flow Rates, Case 2-Water Applied After Loading Tire 89

110 AFWAL-TR CYC NR 99 3 GPM 200- ls UNSIPED ' I- v 100- CYC NR SIPED 100- I- Figure 48. Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number l-r-2, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 3 GPM Water Flow Rate, Case 1-Water Applied Prior to Landing Tire CYC NR 104 [ 3GPM UNSIPED." ' 200 OS0 100 CYC NR GPM 20 SIPED jl tp * 100 t iifi Figure 49. Tire Spin Up Comparison, Siped vs Unsiped, Tire Code Number l-r-2, Tire Load 16,000 Lbs, Test Wheel/Tire Speed vs Time, 3 GPM Water Flow Rate, Case 2-Water Applied After Loading Tire 90

111 AFWAL-TR CYC NR 90 DRY L SE SIPED U I CODE NR 22-N "' - m L 1 CYC NR k+ h -,..L DRY -'" 4 i tii CODE NR 1-R-2 0- ",-.t,. a- - - CYC NR 90 I 71IL I1-- DRY. 2- SIPED -, CODE NR 1-R-2 U C. CYC NR 90 " DRY _ I SIPED T --.-,,. - CODE NR 22-N.. ~ j ~ ' CODE NR 1-R-2." Figure 50. Dry Brake Test Runs Tires Code Numbers 22-N and 1-R-2 Tire Load, 16,000 Lbs (Test Wheel/Tire Speed, Brake Pressure and Brake Torque vs Time) 91

112 AFWdAL-TR C C. L OL'J LL C5n -j D I-- C0 0- ) LU In C) L, cxa CL0 0 ou Col.- ao. 0 INLJ30 AJIH o 92 === Mo

113 AFWAL-TR I/ 3E a -LU 3D IC)i 0 In I il z " - - I - i Li I s K.,, *,--I " / I- LaL )/U I Li I I- I III 4) co I I I 5/ -I~ C3-0 I I I SM-C 1 I11- ii4 L 0 I01/1I II C 4 OD 0 ) la U i 9C9 C; c2 C in3131a303 OrD-H I I I 93

114 AFWIAL- TR C> In 0-0 La c Q. 1 1 C =D I U. 0 U I0.. oc Ii / 940

115 AFWAL-TR BRAKING PERFORMANCE OF FOUR GROOVE 49X17 AIRCRAFT TIRES ON PORTLAND CEM4ENT CONCRETE AT VARIOUS SPEEDS AND WATER DEPTHS I J(DAMP) J(DAMP) s WdATER DEPTH (IN) WATER DEPTH (IN) w KNOTS 130 KNOTS 3 IT 0.20kLONT. C.N' S0.10 J(DAMP) j(damp) WATER DEPTH (IN) WATER DEPTH (IN) 0 -STANDARD TREAD -- 1/8 " X 3/16 -SIPED TREAD Q -1/411 X 3/16" SIPED TREAD Figure 54. Friction Coefficient vs Water Depth, Wet Track Tests, KC-135 Tire 95

116 AFWAL-TR c -C L-- W uu I 0,.Li 0 x w 2! Li o -T- t '. - LaU iow 3. wc C> in Lo" 0 =,, i, I=, cy. LM La C C0 D 96

117 AFWAL-TR I "ID L.a I. S I NC 0 0 I k^ 0 w 0 0 C o II L; 1K /,I I CD IN3131JJ3-.0 ~ 9.,a,

118 AFWAL-TR /1 - ', I- - - C, c-. c-ii o=,,, 0 3 t" I" w 0 too -D Co. = w LU c 0 IQ -l o - - I, LU ~~ - CD C) -c 4- C C, coc 0. / Ix - '' a.! o i o, CD c0) L-. IflIn LAJ 98

119 AFWAL-TR aj w uja z "ja Li LaL tooi - coi3 La I-I- l.r( CDU3 IN313JA30 M01131Is ID ~ft I - -I~99

120 AFWAL-TR APPENDIX C ANALOG TRACES HIGH SPEED BRAKE ANTI-SKID STOPS 192 INCH DYNAMOMETER 100

121 AFWAL-TR X Dab 6 fls _.oo - ='D : -1-' L IO -- " - ii -I:.:2 a-.7 "- I ' j -. i ii i.... 4)-. { : :] I i : I " ' A4I 4.' ~~t 4,6 ft._;ii 12 Figure C1 S/N0870(18-N), Cyc. 49, 0.5 gpm 101

122 Al WAI -Ik-h I - ol u-i DOr.13.~ P' 3r I ti 'I v- -ri---1i 010

123 AFWAL-TR ".-.,: -00- I -,?. - a r HoD Z , *t I _ ~ _ i [++t -f ' ttl 103 e / y. 5, 2 0 g - i Fi g ur C3. S/-7 (1 ) r... I II -m~ m

124 AFWAL-TR S o0- w - h , %I I 30-I X -- FIE-- 1~ 1- q.: LL _

125 AFWAL-TR CL " E g U L! -: ' L- -f-i iz. LL IL L} Figure C5. S/NO870(18-N), Siped NIA Cyc. 53, 1.0 gpm 105

126 AFWAL-TR " D L DI C %' ; CL lu 2 1 L o a - 11, 30- I-I " -,--- I ILA Dist - -, f -- " 8- I -ii I-I -- niii Figure C6. S/NO870(18-N), Siped N/A Cyc. 54, 2.0 gpmn 106

127 AFWAL-TR e el: E ' SI I _.... r i i i i '- 100o- - I _ I -0,_ 2 I I I " I L R _ 44- z oo - ~ t....- XIiL I i -I A4L -~ -I--L cc--i- -. L A ~-1- -o -t E _L ii { Ii i _I _.,3. i....,."o-a.-- L -, -~:Ii 2 ~ ~-tz i!i I I ft - -I M.- - -,.J Figure C7. S/N0870(18-N), Siped 3/16" X 8/32", Cyc. 55, 0.5 gpm 107

128 AFWJAL-TR '0 200 SE-Lo E I-W ;;' i'-ii~ DO rl A w zz z4- zx ziziiii 'I co * - 4ii - Al Figure C8. S/N0870(18-N), Slped 3/16" X 8/32", Cyc. 56, 1.0 gpmn 108

129 AFWAL-TR d-o _ i - -" ' r...- [ a. I1 T, ] - I -,, ' - ( i i I I I I, - - i, i :i ' 10 0' i t V- - ~ 2 I-... -o i -- l - i-- i F, I I I - J, l-,_; 12 - I ' D st:.i 8... III u" 4 i! -,. " II.., n - -' I I I II I I l I1 Figure C9. S/NO870(18-N), Siped 3/16" X 8/32", Cyc. 57, 2.0 gpm 109

130 AFWAL-TR JE I I-T t i; +~ ow 3 -- r v v - { l.. i. i. - do 2 - if 1 I _-_: _ zt I

131 AFWIAL-TR U COD i 'Sii S-o j~ i 0 -- t ' t C3-4n L Figure C-11. S/N0870(18 N). Siped 3/16" X 8132", CyC. 59, 1.0 gpm

132 AFlAL-TR " -.,' AI- sicf s - 1FSC * 30 [ 0 [ - r = -. o- ' !t , - i 112 i.i I 3I- L. - S \ I riur C-2 S/O7(1-) Sie 3/6: /2,Cy.6.20g 0* - -,. "" " --. s , no i l / i ni- -i

133 AFWAL-TR ILI L t - z - -- IL Figure C-13. S/N1174(ZO-N). Siped N/A. Cyc. 61, 0.5 gpe

134 AFWAL-TR " -r ]-r - S200 l) oo a, - -L i-- - J T :F :j :{ - _ I.. L -l i : ' 38 - VI 4-[ 3 I C-1 [.. N 62, a _ '- 1 - m 104 -J " 10.. f.. I I I IIl IIl I Il

135 AFWAL-TR T I I "-La SE i ~ U. 100~ L I oi.: 'A J 4.M H ic0-)i Cyc. 63,. 2 ga I - 15 U, 4-0, ~~ UT,---I1 Figure C-15. S/Nl174(20-N), Siped N/A, Cyc gpm 115

136 AFWAL-TR CL ii ni 0 t :! '- - -K '6-, 3 a G. 2- -A 4U 44 IL ( f I f 4-" ,4 Ei i, Figure C-16. S/N1174(20-N), Stped 3/16" X 8/32", Cyc. 64, 0.5 gpm 116

137 AFIAL-TR _200-.I m loo -!L-t L " I f I I I I I I I I I L_ i 0-1- U ' ,, USl,I t T I I Figure C-17. SINl174(2O-N), Stped 3/16" X 8/32", Cyc. 65, 1.0 gpm

138 AFWAL-TR U- 7 t X.3 - w w 2 2 'C1L ~ ~ ~ -.-- f I I -_ -- ijiz 1i Fiur -1., S/I1420N ipd3/6 X8/2. y. 6,20 p ~111

139 AFWAL-TR CL L T -----V Th i4-1219

140 AFWAL-TR CL '1 SE0-SE 300- CL~ c M an llll jil -4 - il j~ * i~. 4-' Figure C-20. S/N1185(21-N), Siped N/A. Cyc. 68, 1.0 gpn 120

141 , AFWAL-TR I, In w -L~ --- L..0 * 4. o-- =[ IL L 0kca if- ii ' I I I i t - Fgr C-; N6 Il2 Figure C-21. S/N1185(21-N), Siped N/A, Cyc. 69, 2.0 gpm 121I... " I I l l i I.....H I l

142 AFWAL-TR : '* III T co Cl "- l ft ro Hem ma m

143 AFWAL-TR (.. "ec L fs I o SEC c -o X1 I '- - lo..1-i '-,,.. co _ I~ _ 1 1, ' - I [ I. ~ :! ' :: 123 '~1.- : ,,., FA g SN 9( y.41, Ogp 4-23, * a i.-... I I i l l i I

144 AFWAL-TR II r I " -- i "---- DII i,$ljf E * - -, *., o-s L o [ L o T I- -{ -. - Figure C-24. S/NI293(22-N), Stped N/A, Cyc. 72, 2.0 gpm 124

145 AFWdAL-TR ) il 0* o i -I Figure C-25. S/N1185(21-N), Siped 3/16" X 5/32", Cyc. -3, 0.5 ggxn 125

146 S4 ii AFWAL-TR o -.LPs D ee - 100o Dee: _. fps -- C~~~ S C-JE I] loo -... it - -- J ' [,. i I F..' L , a I I-T - ii- c T - P1 - -o ""~.- -i-j +--'- - i-ij ', Figure C-26. S/N1185(21-N), Siped 3/16" X 5/32", Cyc gpm 1?6

147 AFWAL-TR Z - I - _ ' + j + ' - T- }oo I.... a), o- - [w 1 " ] t o z -, - :l-1: i~~ ~ t I;; Figure C-27. S/Nl185(21-N), Siped 3/16" X 5/32", Cyc. 75, 2.0 gpm 127

148 AFWAL-TR VI Q. ~~-0. ~ 10 SE-C Iii c"-2 ca o, t -4,4-i-- 1/8

149 AFW4AL-TR r -Z.20. -F ii 200- s S100-4, 4 w VX. CLca ~ C 30-0g i:zt 10 {I JJ i 12

150 AFWAL-TR tol.- el :Z----.u~10--*--- 3 _ :

151 AFWAL-TR 'el & 12.6 (f 5 sic4- I',0- ' I ! 30C 20-- i- - w Il - 4J -- - _ ~ i ]--i -- ca LL I u 200-3&- 20- cx4-... II I ii1111nini - - -I IS I:- 1-f4- Figure C-31. S/N1293(22-N), Siped 3/16" X 8/32", Cyc. 90, DRY gpmi 131

152 AFWAL-TR it-a 1 - # t I-.- ~ A T I fl Figure C-32. S/N6A0013C#I-R-2), Siped N/A, Cyc. 96, 0.5 gpn

153 AFWAL-TR Dece 1.87 fps f I = ' ~ -- i z -- I I I... L ,L_ 30(r -I L'-' t 200- : : Ilt I ] E. t La Figure C-33. SIN6AOOI 3(#lI-R-2), Si ped N/A, Cyc. 97, 1. 0 gpm 133

154 AFWAL-TR el T.8 W v I, ~~Ir II a,- I- * S12- -t i-- Tt v) J-1~ Figue C34. S/NAO03(0-R-), i pdnacc 9,2. m ztz~l

155 AFWAL-TR CLC 2 - I I: -'300,- I i Ii CLL I. L. 0-3 _' ft I I I I it 4-j U, I... 4.' " 4 - II ''[d, 1 11 Figure C-35. S/N6AOOI3(E1-R-2), Siped N/A, Cyc gpni 135

156 AFWAL-TR S J , f s20 10% /i I S CD " 4-8 Figure C-36. S/N6A0013(#I-R-2), Siped N/A, Cyc. 100, 3.0 gpni 136

157 AFWAL-TR IL S 00_ "' V ' ii i I mj 4) i-- -, -....I _ L_ 00 i, i [, i - 0- '-- n Li "- 20 r- -]I- ]z ' 4- o- id W UL ft. U 4 -- T Figure C-37. S/N6AOO13(#].R-2), Siped N/A, Cyc. 101, 0.5 gpm Water on After Landing 137

158 AFIAL-TR M--.-4 S ' - I ~.- i -l 200I -0 i.j AL-!!,, gvv II!. v I: _l.,, I.0I oo I..m. a [_. 0, Figure C-38. S/N6AOO13(#1-R-2), Siped N/A, Cyc. 102, 1.0 gpm Water on After Landing 12S I9 Iifit 138

159 AFWiAL-TR C ca ' oo L - 100i URsc i \.2 o, : t Lc C i- 300 " - II I ' - - -I,- Mc1 ' -- IZ 0 I l 4-A, ini 8 CL _ I A0 4 Figre SNA03- R-) Sie N/A ~139 Wae nate adn 123

160 AFWIAL-TR I, I I - 0 SE 30-r C- 20I- CLI- 0r ; j ~ CLDSIt Figure C-40. S/N6A0013(01-R-2), Siped N/A, Cyc. 104, 3.0 gpm Water on After Landijng 140I

161 AFWAL-TR ~ V) U7 I-4 w {.1I ~T.4- di Wate on Afe Landuin7i 141 -

162 AFWAL-TR C. *, 200 -I CI _ ---- u L--4- Z ' 2 3 " co - I-- I -I ) '4. Figure C-42. SIN6AOOI3(#I-R-2), Siped 3/16" X 7/32", Cyc. 106, 1.0 gpm Water on After Landing 142

163 AFWAL-TR o I~..-a i % i - -.' , u L l L M E I kail i' L - I 1 1L 4,a, ', Ez- -I ** _ M J z-- Figure C-43. S/N6A0013(#1-R-2), Slped 3/16" X 7/32". Cyc. 107, 2.0 gpnm Water on After Landing 143

164 AFWAL-TR V) CL 200- L 4-00 w/ I I -ooi ] 4) a-, -- L' - - II v CL M 1 IIO0 :1- tu 1111IlI~ -- -, E i Vi I.I * 12 S i i,ol l J - -TT1PT 4 - Figure C-44. S/N6A0013(#]-R-2), Siped 3/161, X 7/32", Cyc. 108, 3.0 gpei Water on After Lanrlinq 144

165 AFWAL-TR U- I C-*.,-,, E, -,. -. i.. Si i i -IL lo - -i _ ~~,, - ' ! 4D 2--- f --- 1T F -- z- CD _ -I- Figure C-45. S/N6AOO13(#I-R-2}, Siped 3/16" X 7/32", Cyc. 109, 0.5 9pi. 145

166 AFWAL-TR S200-.4, C. U, ~~~~~~ I- 0~ U, 4 Figure C46. S/N6A0013(#1-R-2), Siped 3/16" X 7/32', Cyc. 110, 1.0 gprll 146

167 AFWAL-TR ~1 f CL , Us c 07-3c -C 200s- 1. Uoo_ I -L H - *Am pm w % - lul LS i-- 0* o -' iti J I.. I.. a ].~ Figure C47. SIN6AOOI3(#1-R-2), Siped 3/16" X 7/32", Cyc. 111, 2.0 gpm 147

168 AFWAL-TR o m loo 00 o., =I I I f s (F - a o I to j I- I. J i,.... i J 100 -V : toi I I CL Figure C48. S/N6A0013(#l-R-2), Siped 3/16" X 7/321, Cyc. 112, 3.0 gpm 148

169 AFlAL-TR C. 200, jo20o- Ml'--i-- ~A WU ] 4 - f l - 2I : i-i I 7 GI., I : - i i ;II -i i in a 2- Figure C49. S/N6A0013(#1-R-2), Siped 3/16' X 7/32', Cyc. 113, 4.0 gpmn 149

170 AFWAL-TR I -' L , c , - I A.1 SI I I I ME M I - -I li Figure C-50. S/N6AO013(#1-R-2), Siped 3/16" X 7132", Cyc. 114, 7.5 gpm 150

171 AFWAL-TR S U ~ ii -I T j 2-4E Figure C51. S/N6A0013(01-R-2). Slped 3/16" X 7/32", Cyc. 115, DRY gpm 151

172 AFWAL-TR APPENDIX D X-Y PLOTS FLYWHEEL VELOCITY VS BRAKE STOP DISTANCE HIGH SPEED BRAKE ANTI-SKID STOPS 192 INCH DYNAMOMETER 152

173 AFWAL-TR ) UNSIPED, CYC. #49 () SIPED, 8/32" DEPTH (CONST) CYC. #55 a- Cz Q C) C U'I STPPN DITAC (T FiueD.Vlct s rk itnef4mg ie ieeauto 2500(B)Tr od. GP)FoUaeCd ubr1- L153

174 AFWAL-TR UNSIPED, CYC. #50 0 SIPED, 8/32" DEPTH (CONST) CYC. # C) 0 0 z 0-C 0 LU W 0 LD C) co 0000 \ \0 STOPPING DISTANCE (FT) Figure D2. Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, 1. (GPM) Flow Rate Code Number 18-N 154

175 AFWAL-TR UNSIPED, CYC. #51 C)SIPED, 8/32" DEPTH (CONST) CYC. #57 C*1 01 CD U4 00 a CD 0 ('155

176 AFWdAL-TR UNSIPED, CYC. #52 0 SIPED, 8/32" DEPTH (CONST) CYC. #58 oi 0L ObD T20 STPIGDSTNE(T FiueD. Vlct0s rk itnef4mg ie ieeauto 1600 (LS iela,05(p)fo0aecd ubr1- a~. 15j

177 AFMAL-TR UNSIPED, CYC. #53 0 SIPED, 8/32" DEPTH (CONSr) CYC. #59 I" C STPIGDSTNE(T Fiue0. Vlct s BaeDsac.- L, ie ieeauto 1600(B)Tr od GM)Fo aecd ubr1- a157

178 AFWdAL-TR (D UNSIPED. CYC. #54 0SIPED. 8/32" DEPTH (C0NST) CYC. #60 9 a-0 CD 0 D , STP.N DITNE(T Fiue06 s eoct BaeDitne - L, ie Tr vauto 1600(LS ir od 2 GM Fo at oenbr1-15

179 AFMAL-TR ouesiped, CYC. #61 0 SIPED, 8/32" DEPTH (CONST) CYC. #64 Q C; C5 C0i 0"CO 0L NU STPIGDSTNE(T Fiue07.Vlct s rk itnef4mg i ieeauto 25000B)Tr od. GP)Fo aecd ubr2- bi159

180 AFWlAL-TR UNSIPED, CYC. #62 () SIPED, 8/32" DEPTH (CONST) CYC. #65 C3 C'. U.' Uj CL I.' C)0 0eC 0 o Figure D8. STOPPING DISTANCE (FT) Velocity vs. Brake Distance F-4 MLG. Siped Tire Evaluation 25,000 (LBS) Tire Load, 1 (GPM) Flow Rate Code Number 20-N 160

181 AFWIAL-TR UNSIPED, CYC SIPED, 8/32" DEPTH (CONST) CYC. #66 01 C0 co 0LC 0n 0i 0; STPIGDSTNE(T FiueD.Vlct s rk itnef4kg ie ieeauto 2500(O)Trood GM)Fo aecd ubr2-16

182 AFWAL-TR UNSIPED, CYC. # 67 SIPED, 5/32" DEPTH (CONST) CYC. # 73 ct 0, STOPPING DISTANCE (FT) Figure 0I0, Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 2 5,000 (LBS) Tire Load, 0.5 (GPM) Flow Rate Code Number 21-N me - 162

183 AFIEAL-TR UNSIPED, CYC SIPED, 5/32H DEPTH (CO#4ST) CYC. *74 CD L.J STOPPING DISTANCE (FT) Figure D-11. Velocity vs. Broke Distance F-4 NIG, Siped Tire Evaluation 25,000 (IBS) Tire Load, 1 (GPM) Flow Rate Code Number 21-N 163

184 AFWAL-TR UNSIPED, CYC. f 69 SSIPED, 5/32" DEPTH (CONST) CYC. # 75 CLi o , STOPPING DISTANCE (FT) Figure D ti0l " "m Velocity vs. Brake Distance F-4 MLG, Stped Tire Evaluation 25,000 (LBS) Tire Load, 2 (GPM) Flow Rate Code Number 21-N 164.

185 AFWAL-TR UNSIPED, CYC. f970 SIPED, 8/32' DEPTH (CONST) CYC. # L CL 0 C! STPPN DITNE(T FiueD30eoiyv.BaeDsaneF4.G ie ieeauto 2500(B)Tr od. GP)Fo aecd ubr2- w165

186 AFWAL-TR UNSIPED, CYC. # 71 SIPED, 8/32" DEPTH (CONST) CYC. # 77 CD i LU L6 -- CD STOPPING DISTANCE (FT) Figure 014. Velocity vs. Brake Distance F-4 MLG, Siped Tire Evaluation 25,000 (LBS) Tire Load, I (GPM) Flow Rate Code Number 22-N 166 Eb,_

187 AFMiAL-TR UNSIPED, C'fC. f 72 0 SIPED, 8/32" DEPTH (CONST) CYC. f*78 Va STOPPING DISTANCE (FT) Figure 015. Velocity vs. Brake Distance F-4 MiD, Siped Tire Evaluation 25,000 (LBS) Tire Load, 2 (GPM) Flow Rate Code Number 22-N 167

188 AFWAL-TR CYC# 96, UNSIPIED 0 CYCi 109, SIPED, 7/32" DEPTH (CONST) a 0C 09 zz(d STPIGDSTNE(ET 0 iued6 eoiyv rk itnef4mg ie ieeauto 1600LSTr od,05(p)fo at oenme --

189 AFMAL-TR CYCO 97, UNSIPED 0CYC# 110, SIPED, 7/32' DEPTH (CONST) C 0 j us0 ~~0 0 Figure :17 STOPING DISTANC(E0ET i10li0: Figue D7. Vlocty s. BakeDisanceF-4MLGSipd Tre Ealutio

190 AFWAL-TR CYC# 98, UNSIPED CYC# 111, SIPED 7/32" DEPTH (CONST) a STOPPING DISTANCE (FEET) Figure 018. Velocity vs. Brake Distance F-4 MLG. Siped Tire Evalution 16,000 (LBS) Tire Load, 2.0 (GPM4) Flow Rate Code Number 1-R-2 170

191 AFWAL-TR CYC# 99. UNSIPED CYC# 112, SIPED, 7/32" DEPTH (CONST) C2 0D S A~000. 4~ STOPPING DISTANCE (FEET) Figure 019. Velocity vs. Brake Distance F-4 NIG, Siped Tire Evaluation (LBS) Tire Load, 3.0 (GPM) Flow Rate Code Number 1-R-2 171

192 AFWAL-TR CYCE 100, UNSIPED CYC# 112, SIPED, 7132" DEPTH (CONST) 10 0 c'j 0D 6 C D STPPN DITNE(ET Fiur D2.Vlct sork itnef4mg ie ieeauto 0LS 1600 iela,30(p)flwrt oenme

193 AFWAL-TR SCYC# 101, UNSIPED 0 CYC# 105, SIPED, 7/32" DEPTH (CONST) V , ITNE(ET STPPN FiueD10 oiyv.baedsanef4mg ie ieeauto 16,00 0L iela,05(p)flwrt oenme -- 0nAtr Wae adn u17

194 AFWAL-TR CYC# 102, UNSIPED 0 CYC# 106, SIPED, 7/32" DEPTH (CONST) C- CD- C' Am00. olooo STOPPING DISTANCE (FEET) Figure D22. Velocity vs. Brake Distance F-4 MIG, Siped Tire Evaluation 16,000 (IBS) Tire Load, 1.0 (GPM4) Flow Rate Code Number 1-R-2 Water On After Landing 174

195 AFWAL-TR CYC# 103, UNSIPED CYC# 107, SIPED, 7/32" DEPTH (CONST) 00 0t10 CD C ITNE(ET STPPN Fiur D2. Vlct0s rk itnef4mg ie ieeauto 0600(B)Tr od. GM lwrt oenme -- Wae O ftr-adn 07

196 AFWAL-TR CYC# 104, UNSIPED CYC# 108, SIPED, 7132" DEPTH (CONST) c 0' Ooo ITNE(ET STPPN Figur D2. Vlct0s rk itnef4mg ie ieeauto LS iela,3 GM lwrt oenme -- 0nAtr Wate adn 07

197 AD-A AIR FORCE WRIGHT.AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH FIG 1/3 WET TRACTION TESTS -MARCY SIPED TIRE.(U) FEB 82 P C ULRICH UNCLASSIFIED AFWAL- TR ML HEND

198 II L25 6I1

199 AFMAL-TR CYC# 96, WET LANDING 01 CYC# 101, WATER ON AFTER LANDING 0 0C MDM i, D ! STOPPING DISTANCE (FEET) Figure D25. Velocity vs. Brake Distance F-4 NLG, Stped Tire Evaluation 16,000 (LBS) Tire Load. 0.5 (GP14) Flow Rate Code Number 1-R-2 Unsitped ~~" '-. I...I.... ".. :!, : 177

200 AFWAL-TR CYC# 97, WET LANDING 0o Y#12 WATER ON AFTER LANDING 0 CL 0 0t & STPIGDSTNE(ET FiueD60eoiyv.BaeDsaneF4MG ie ieeauto 1600(B)Tr oa,10(p)fo at oenme -- Unspe U-7

201 AFWAL-TR CYCe 98. WET LANDING CYC. 103, WATER ON AFTER LANDING Ct ~0 C) La &OO STPIGDSTNE(ET FiueD7 eoiyv.boedsanef4hg ie ieeauto 1600 (LS iela,20(p) I-Ct oenme -- Uz o 17

202 AFWAL-TR CYC# 99, WET LANDING CYC# 104. WATER ON AFTER LANDING 10 ' 0D I.- C0 000O dI000. A Figure D28. STOPPING DISTANCE (FEET) Velocity vs Brake Distance F-4 MIG. Siped Tire Evaluation 16,000 (LOS) Tire Load, 3.0 (GPM') Flow Rate Code Number 1-R-2 Unsiped 180

203 AFWAL-TR CYCO 105, WATER ON AFTER LANDING 0 CYCE 109, WET LANDING NA , STOPPING DISTANCE (FEET) it105 Figure 029. Velocity vs Brake Distance F-4 MLG, Siped Tire Evaluation (LOS) Tire Load, Sipad, 7/3i. Depth (Const) 0.5 (GP14) Flow Rate, Code Number I1-R-2 z 181

204 AFWAL-TR OCYCO 106. WATER ON AFTER LANDING ocyc# 110. WET LANDING 00 I t-1,0 "A C Q. Q Q OO Oo 1o. Ioo STPIGDSTNE(ET FiueD0 eoiyv rk it-c - L ie ieeauto 16000B)Tr od ie, /i et Cnt. GM Flo Rae oenme -- uj182

205 AFMAL-TR CYC# 107, WATER ON AFTER LANDING 0 CYCO 111. WET LANDING ~0 cj Q C C; La C STOPPING DISTANCE (FEET) Figure D31. Velocity vs Brake Distance F-4 NLG. Siped Tire Evaluation 16,000 (LBS) Tire Load, Siped, 7/32" Depth (Const) 2.0 (GPM4) Flow Rate. Code Number 1.R-2 183

206 AFWIAL-TR CYC# 108. WATER ON AFTER LANDING CYC# 112. WET LANDING Q- 00) STPPN DITNE(ET FiueD2-eoiyv J, BaeDsac - ie ieeauto 1600(I)TreLa.Spd 73"Dph(ont. GM FlwRtCdeNme -- sa1 4

207 AFWAL-TR C FLOW RATE (GPiq) UNSIPEO DRY SIPED, 7/32" DEPTH (CONST) 968 I9 I I I STOPPING DISTANCE (FEET) Figure D33. Velocity vs Brake Distance F-4 NLG, Siped Tire Evaluation (LBS) Tire Load. Code Number 1-R-2 185

208 AFWAL-TR CYC# FLOW RATE (GPM) UNSIPED DRY SIPED, 7/32 DEPTH (CONST) C:, Li 0. w STOPPING DISTANCE (FEET) tl i Figure D34. Velocity vs Brake Distance F-4 MLG, Sipe Tire Evaluation (LBS) Tire Load, Code Number 1-R-2 Water On After Loading/Before Braking uj --

209 AFWAL-TR CYCO FLOW RATE (GPN4) o l0g 0.5 o ill ' STOPPING DISTANCE (FEET) Figure 035. Velocity vs Brake Distance F-4 NLG. Siped Tire Evaluation (LBS) Tire Load, Siped. 7/32" Depth (Const) Code Numnber I1-R-2 187

210 AFWAL-TR CYC# FLOW RATE (GPM4) o DRY ~~ STOPPING DISTANCE (FEET) Figure 036. Velocity vs Brake Distance F-4 MIG, Siped Tire Evaluation 16,000 (185) Tire Load, Siped. 1/32" Depth (Const) Code Number l-r-2 Water On After Loading/Before Braking 188

211 AFWAL-TR APPENDIX E CALCULATION SHEET Wateerr/ r V Dnamometer Volume Q --F lyw h ee l i F lyw hee l - o -Tire 1,; t' t,1 I.W'. Patchr Pt : L- -_ <Tire, Qin TtContactw Calculations For Water Wedge Thickness: Granted the following calculations and assumptions are not a rigorous attempt at describing the system, the calculations and assumptions made are considered adequate enough to establish trend curves of water wedge thickness as a function of water flow rate, tire contact patch size and dynamometer flywheel speed. Assumptions: 1. All water passes between tire and flywheel and forms water wedge olume i.e., Qin = Qout 2. Water wedge width = tire contact patch width = w = 10 inches (0.833 feet) 3. Water wedge depth = t inches (unknown) 4. Water wedge area = a = w x t 5. Water Velocity, V = tangential velocity of flywheel, Vfw 6. Water Flow Rate, Q = V x a 7. Since Q = V x a = V x w x t t= Q V xw Calculation 1: Q = 7.5 gpm = feet 3 /sec V = 55 mph = 80.7 feet/sec w = 10 inches = feet t = w feet inches V x w 80.7x Calculation 2: Q = 7.5 gpm = feet 3 /sec V = 140 mph = feet/sec w = 10 inches = feet t =--- Q V x w x = feet = inches 189

212 AFWAL-TR REFERENCES 1. Thomas J. Yager, W. Pelhahm Phillips and Walter B. Horne, NASA LRC, and Howard C. Sparks, USAF, ASD, WPAFB, A Comparison of Aircraft and Ground Vehicle Stopping Performance on Dry, Wet, Flooded, Slush-, Snow-, and Ice- Covered Runways - Project Combat Traction, NASA-TN-D- 6098, November Robert C. Dreher and John A. Tanner, NASA LRC, Experimental Investigation of the Braking and Cornering Characteristics of 30X , Type VIII Aircraft Tires With Different Tread Patterns, NASA TN D- 7743, October Trafford J. W. Leland, Thomas J. Yager and Upshur T. Joyner, NASA LRC, Effects of Pavement Texture on Wet- Runway Braking Performance, NASA TN D-4323, January Sam K. Clark (Editor) University of Michigan, Mechanics of Pneumatic Tires, NBS Monograph 122, November ASTM, 1976 Annual Book of ASTM Standards, Part 38, F-9 Committee Standards On Tires, Robert W. Palmer and W. W. Macy, McDonnell Aircraft Company, Effects of Skid Control, Tires and Steering on Aircraft Ground Performance (Rain Tire), MDC A2683, February Larry K. McCallon, Major, USAF, AFFTC, Edwards AFB, F-4 Rain Tire Performance Flight Tests, AFFTC-TR-74-3, March MIL-T-5041G, Military Specification - Tires, Pneumatic, Aircraft, 12 September General Dynamics Drawing Specification SCD 16VL002, Tire Assembly 25.5X8.0-14/18 PR Type VIII, Revision "A", March Mechanical Branch, Landing Gear Test Facility Brochure , Air Force Flight Dynamics Laboratory, Wright-Patterson Air Force Base, Ohio, AFWAL/FIEM. 11. USAF Drawing Specification 62J4031, Exhibit "A", F-4 Main Wheel and Brake Assembly and Exhibit "B", Tire Assembly 30X /24 PR Type VIII, Revision "4", September Hector Daiutolo and Charles Grisel, Airport Development Division, ACT-400, Federal Aviation Administration (FAA) Technical Center, Braking Performance of USAF Four-Groove 49X17 Aircraft Tires With and Without Sipes, FAA-RD , June NASA Conference, NASA LRC, Pavement Grooving and Traction Studies, NASA SP-5073, November

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