DOCSLIB.ORG

Asphalt Pavement Inspector's Manual

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Asphalt Pavement Inspector's Manual ASPHALT PAVEMENT INSPECTOR'S MANUAL Prepared by Matthew Reckard, P.E. & John Ryer, P.E Alaska Department of Transportation & Public Facilities May 1990 Revised by Gary L. Eddy, P.E.; Alaska DOT/PF Statewide Design & Engineering Services Division Design & Construction Standards July 2002, Third Edition FOREWORD The information currently available on asphalt paving would fill a small library. Furthermore, DOT&PF's Alaska Construction Manual describes procedures for the Department's staff to use on all aspects of construction projects. This manual draws on the Alaska Construction Manual and other sources but does not attempt to replace them as a reference for official Department policy. It is intended to present portions of this information needed by laydown and asphalt plant inspectors in a convenient form. It also presents information of value to paving materials inspectors. Material test procedures are so detailed, however, and test requirements so variable between projects, that this manual presents only rather general information about them. More information on asphalt and paving is available in the publications listed in Appendix F (Further Reading). Many of these are available at your construction project office or the regional materials office. A copy of the Alaska Construction Manual should also be at the project office. The Alaska Transportation Technology Transfer Center can provide a wealth of videotapes and publications dealing with paving and other transportation issues. Their address and phone number are listed in Appendix F. Many individuals and agencies assisted in the preparation of this manual by reviewing draft versions and by making photographs and figures available. Ed Schlect of the Asphalt Institute is notable in this regard. Nicole Greene and Sheree Warner spent many hours preparing the text for publication. The authors appreciate and acknowledge this help. _____________________________________________________________________ The third revision of this manual was accomplished with the help of Myles A. Comeau, Paving Inspector for Northern Region for reviewing the manual for changes and recommendations. Jack Phipps, Transportation Maintenance Manager for Northern Region added the section on Necessities for a Successful High Float Project that was presented at the Asphalt Summit in 1997. R. Scott Gartin, Statewide Materials, Pavement Management Engineer for his paper on Pavement and Surface Treatments used in Maintenance, Rehabilitation, and construction. John S. Ball, III for his article Like Night and Day courtesy The Asphalt Contractor. Gary L. Eddy, P.E., Construction Standards Engineer, for reformatting, making corrections, printing and placing the Manual on the ADOT & PF Design & Construction Standards Home Page. Readers should consult the Asphalt Institute MS-19, a Basic Emulsion Manual for information regarding High Float and Chip Seal surface treatments. In October 2001, the “Asphalt Surface Treatment Guide” by Robert L. McHattie, P.E. was completed for the Department. This is not a Design Guide, it covers materials selection and quality, construction methods, and troubleshooting three types of asphalt surface treatments used in Alaska. III Table of Contents 1. BACKGROUND ......................................................................................................................................................... 1 1.1. HOT ASPHALT CONCRETE PAVING: A BRIEF DESCRIPTION ................................................................................ 2 1.2. AIRPORT, HIGHWAY, AND MARINE FACILITY PAVEMENTS................................................................................. 2 1.3. SAFETY ............................................................................................................................................................... 3 1.3.1 Safety Equipment Checklist............................................................................................................................ 3 1.3.2 Safety on the Paving Project.......................................................................................................................... 4 1.3.3 Documenting Accidents ................................................................................................................................. 7 1.4. PLANS AND SPECIFICATIONS ............................................................................................................................... 7 1.4.1 Airport Projects ............................................................................................................................................. 7 1.4.2 Highway Projects........................................................................................................................................... 7 1.5. TRAFFIC CONTROL .............................................................................................................................................. 8 1.5.1 Air Traffic Control......................................................................................................................................... 8 1.5.2 Air Traffic Control Checklist ......................................................................................................................... 8 1.5.3 Avoiding Accidents ........................................................................................................................................ 8 1.5.4 Highway Traffic Control................................................................................................................................ 8 1.5.5 Highway Traffic Control Checklist................................................................................................................ 9 2. GENERAL GUIDELINES FOR THE INSPECTOR ................................................................................................ 11 2.1. INTRODUCTION.................................................................................................................................................. 12 2.2. ASPHALT PAVING INSPECTION .......................................................................................................................... 12 2.3. GENERAL RESPONSIBILITIES OF THE INSPECTOR ............................................................................................... 12 2.4. RECORD KEEPING.............................................................................................................................................. 12 2.5. AUTHORITY OF THE INSPECTOR......................................................................................................................... 13 2.6. RELATIONSHIP WITH THE CONTRACTOR............................................................................................................ 14 3. MATERIALS............................................................................................................................................................. 15 3.1. RESPONSIBILITIES OF THE MATERIALS INSPECTOR............................................................................................ 16 3.1.1 Materials Testing Requirements .................................................................................................................. 16 3.1.2 Test Categories ............................................................................................................................................ 16 3.1.3 Testing Procedures ...................................................................................................................................... 16 3.1.4 When toTest ................................................................................................................................................. 17 3.2. BRIEF DESCRIPTION OF TESTS........................................................................................................................... 17 3.2.1 Acceptance Testing ...................................................................................................................................... 17 3.2.2 Quality Requirements and Documentation.................................................................................................. 22 3.2.3 Check Marshall Tests................................................................................................................................... 22 3.2.4 Materials Handling...................................................................................................................................... 23 3.3. MARSHALL MIX DESIGN: AN OVERVIEW............................................................................................. 23 3.3.1 Marshall Method ......................................................................................................................................... 24 3.3.2 The Mix Design Report................................................................................................................................ 24 3.4. THE 0.45 POWER CHART................................................................................................................................... 26 4. ASPHALT PLANT.................................................................................................................................................... 31 4.1. INTRODUCTION.................................................................................................................................................. 32 4.2. BATCH
Load more

Recommended publications
  • PASER Manual Asphalt Roads
    Pavement Surface Evaluation and Rating PASER ManualAsphalt Roads RATING 10 RATING 7 RATING 4 RATING PASERAsphalt Roads 1 Contents Transportation Pavement Surface Evaluation and Rating (PASER) Manuals Asphalt PASER Manual, 2002, 28 pp. Introduction 2 Information Center Brick and Block PASER Manual, 2001, 8 pp. Asphalt pavement distress 3 Concrete PASER Manual, 2002, 28 pp. Publications Evaluation 4 Gravel PASER Manual, 2002, 20 pp. Surface defects 4 Sealcoat PASER Manual, 2000, 16 pp. Surface deformation 5 Unimproved Roads PASER Manual, 2001, 12 pp. Cracking 7 Drainage Manual Patches and potholes 12 Local Road Assessment and Improvement, 2000, 16 pp. Rating pavement surface condition 14 SAFER Manual Rating system 15 Safety Evaluation for Roadways, 1996, 40 pp. Rating 10 & 9 – Excellent 16 Flagger’s Handbook (pocket-sized guide), 1998, 22 pp. Rating 8 – Very Good 17 Work Zone Safety, Guidelines for Construction, Maintenance, Rating 7 – Good 18 and Utility Operations, (pocket-sized guide), 1999, 55 pp. Rating 6 – Good 19 Wisconsin Transportation Bulletins Rating 5 – Fair 20 #1 Understanding and Using Asphalt Rating 4 – Fair 21 #2 How Vehicle Loads Affect Pavement Performance Rating 3 – Poor 22 #3 LCC—Life Cycle Cost Analysis Rating 2 – Very Poor 23 #4 Road Drainage Rating 1 – Failed 25 #5 Gravel Roads Practical advice on rating roads 26 #6 Using Salt and Sand for Winter Road Maintenance #7 Signing for Local Roads #8 Using Weight Limits to Protect Local Roads #9 Pavement Markings #10 Seal Coating and Other Asphalt Surface Treatments #11 Compaction Improves Pavement Performance #12 Roadway Safety and Guardrail #13 Dust Control on Unpaved Roads #14 Mailbox Safety #15 Culverts-Proper Use and Installation This manual is intended to assist local officials in understanding and #16 Geotextiles in Road Construction/Maintenance and Erosion Control rating the surface condition of asphalt pavement.
    [Show full text]
  • Ayc Fleets Rise to the Challenge
    AUSTIN YACHT CLUB TELLTALE SEPT 2014 AYC FLEETS RISE TO THE CHALLENGE Photo by Bill Records Dave Grogono w/ Millie and Sonia Cover photo by Bill Records IN THIS ISSUE SAVE THE DATE 4th Annual Fleet Challenge Social Committee News Sep 7 Late Summer #1 Oct 18-19 Governor’s Cup Remebering Terry Smith Ray & Sandra’s Sailing Adventure Sep 13-14 Centerboard Regatta Oct 23 AYC Board Mtg Sep 20-21 ASA 101 Keelboat Class Oct 25-26 ASA 101 Keelboat Class Board of Directors Reports Message from the GM Sep 21 Late Summer #2 Oct 25 Women’s Clinic Fleet Captain Updates Scuttlebutt Sep 25 AYC Board Mtg Oct 26 Fall Series #1 Sep 28 Late Summer #3 Nov 2 Fall Series #2 Sailing Director Report Member Columns Oct 5 Late Summer #4 Nov 8-9 TSA Team Race Oct 10 US Sailing Symposium Nov 9 Fall Series #3 Oct 11 US Sailing Race Mngt Nov 16 Fall Series #4 2014 Perpetual Award Nominations Recognize those that have made a difference this year at AYC! You may nominate a whole slate or a single category – the most important thing is to turn in your nominations. Please return this nomination form to the AYC office by mail, fax (512) 266-9804, or by emailing to awards committee chairperson Jan Thompson at [email protected] in addition to the commodore at [email protected] by October 15, 2014. Feel free to include any additional information that is relevant to your nomination. Jimmy B. Card Memorial Trophy: To the club senior sailor, new to the sport.
    [Show full text]
  • Experimental Study on the Dynamics of Washboard Road on Various Surfaces
    Experimental Study on the Dynamics of Washboard Road on Various Surfaces Teeranai SRIMAHACHOTA Candidate for the Degree of Master’s Degree Supervisor: Prof. Shunji KANIE Division of Engineering and Policy for Sustainable Environment Introduction Washboarding is the spontaneous formation of transverse ripple on dirt road. It is usually found on unpaved heavy- traffic road under dry weather condition. Driving over washboard road may increase risk of traffic accident since ripples reduce the contact area of the wheel to the road. Mitigating washboard road has long been a challenge for the road maintenance [1]. In addition, spontaneous formation of ripple pattern similar to washboarding can be found on other physical system; for examples, rail corrugation [2, 3], sand dune [4], lubricated disks [5], and periodic ripples on snow covered road [6]. The mechanism of washboarding was first studied in 1962 Fig. 1. Schematic illustration of the experimental apparatus. by Mather [7], and he concluded that it caused by the (a) top view of the self-rotating track showing several ripples bouncing motion of the wheel excided by random formed on the track. (b) diagram of the seesaw-shaped perturbation on road surface. Recent studies have shown that oscillator. washboard road can be formed using rolling wheel [8] and inclined plowed dragged on a granular surface [9, 10]. measure original height of the surface. Then we place the Washboarding can be described by theoretical models which oscillator to touch gently on the flat surface. The oscillator is determine the effect of lift and drag forces to the time in the balance of force so that almost no compression force variation of surface geometry.
    [Show full text]
  • Asphalt Concrete Pavement Design­ a Subsystem to Consider the Fatigue Mode of Distress
    Asphalt Concrete Pavement Design­ A Subsystem to Consider the Fatigue Mode of Distress D. A. KASIANCHUK, Associate Professor of Engineering, Carleton University, Ottawa; C. L. MONISMITH, Professor of Civil Engineering, Institute of Transportation and Traffic Engineering, University of California, Berkeley; and W. A. GARRISON, Materials Testing Engineer, Contra Costa County Public Works Department, Martinez, California In this paper a working model is presented for a subsystem to consider the fatigue mode of distress for asphalt concrete pavements. The de­ sign subsystem is divided into three general sections-(a) preliminary data acquisition, (b) materials characterization, and (c) analysis and evaluation. In developing a particular design with this subsystem, use is made of traffic and wheel load distributions, environmental condi­ tions based on available weather records for the vicinity of the pro­ posed design, multilayer elastic theory, resilient response of untreated granular materials and fine-grained soils, stiffness and fatigue char­ acteristics of the asphalt concrete, and a cumulative damage hypothesis based on the simple linear summation of cycle ratios. To expedite the design process, the majority of the design computations have been pro­ grammed for use with a high-speed digital computer. An example shows the use of the design procedure for a structural pavement section consisting of asphalt concrete resting directly on the subgrade soil. The design developed is shown for conventional mate­ rials and traffic to result in a thickness that is quite reasonable based on comparisons with other design methods. This particular subsystem would appear to have some advantages, however, in that it can be ex­ tended to consider loading conditions and material characteristics for which experience is not available.
    [Show full text]
  • Caltrans Proves Effectiveness of Pavement Renewal Approach 14
    TR NEWS NUMBER 232 MAY–JUNE 2004 3 Get In, Get Out, Stay Out! Caltrans Proves Effectiveness of Pavement Renewal Approach Kirsten R. Stahl and Mario A. Gutierrez Six years ago, a national workshop convened to discuss and develop innovative 3 approaches to the timely repair of crowded freeways. The California Department of Transportation, host of the workshop, immediately set out to apply the most workable concepts. Here is a report on the successful results with asphalt concrete and portland cement concrete projects. 4 Renewal Program Awaiting Launch Ann M. Brach 5 Birth of the Accelerated Construction Technology Transfer Team Frederick D. Hejl 6 Accelerated Construction Technology Transfer Workshops: 14 Completing Projects Faster, Safer, and Better Bill Bolles 8 Mix and Structure of I-710’s Long-Lasting Pavement Carl L. Monismith 12 CA4PRS Software Generates Pavement Rehabilitation Strategies Eul-Bum Lee, John T. Harvey, and Michael M. Samadian 14 The AASHO Road Test: Living Legacy for Highway Pavements 35 Kurt D. Smith, Kathryn A. Zimmerman, and Fred N. Finn The AASHO Road Test, conducted more than four decades ago, established many standards and protocols and helped define many pavement design, construction, and evaluation practices for rigid and flexible pavements. How did the pioneering project originate, gain support, develop, proceed, and produce such long-lasting, influential results? 23 Withstanding the Test of Time Fred N. Finn 24 Smithsonian to Archive Road Test Records Linda Mason 25 TRANSIT COOPERATIVE RESEARCH PROGRAM REPORT Cover: The new Transit Capacity and Quality of Service Manual assists The New Transit Capacity and Quality of Service Manual: planners in setting transit service Tour of the Expanded Guide for Transit Planners and Operators goals for a community.
    [Show full text]
  • The Road Inventory of Mackay Island National Wildlife Refuge Knotts Island, NC
    The Road Inventory of Mackay Island National Wildlife Refuge Knotts Island, NC Prepared By: Federal Highway Administration Central Federal Lands Highway Division October, 2010 Report Generated: 10/05/2010 TABLE OF CONTENTS SECTION PAGE I. INTRODUCTION 1 - 1 II. SUMMARY INFORMATION Summaries by Condition, Surface Type and Functional Class 2 - 1 III. REFUGE ROUTE LOCATION MAPS 3 - 1 IV. ROUTE IDENTIFICATION LIST 4 - 1 V. ROUTE CONDITION RATING SHEETS 5 - 1 VI. PARKING LOT CONDITION RATING SHEETS 6 - 1 VII. BRIDGE INVENTORY INFORMATION 7 - 1 VIII. PHOTOGRAPHIC SHEETS 8 - 1 IX. ACCIDENT SUMMARY 9 - 1 APPENDIX Funcitonal Classification Table i Description of Rating System ii INTRODUCTION The Transportation Equity Act for the 21st Century (Public Law 105-178) created the Refuge Roads Program. Refuge roads are those public roads that provide access to or within a unit of the National Wildlife Refuge System and for which title and maintenance responsibility is vested in the United States Government. Funds from the Highway Trust Fund are available for refuge roads and can be used by the station to pay the cost of: (a) Maintenance and improvements of refuge roads. (b) Maintenance and improvements of: (1) Adjacent vehicle parking areas (2) Provision for pedestrians and bicycles and (3) Construction and reconstruction of roadside rest areas that are located in or adjacent to wildlife refuges (c) Administrative costs associated with such maintenance and improvements. The funds available for refuge roads are to be disbursed based on the relative needs of the various refuges in the National Wildlife Refuge System, and taking into consideration: (a) The comprehensive conservation plan for each refuge; (b) The need for access as identified through land use planning; and (c) The impact of land use planning on existing transportation facilities.
    [Show full text]
  • Standard Specifications for Street and Drainage Construction
    STANDARD SPECIFICATIONS FOR STREET AND DRAINAGE CONSTRUCTION 2 of 114 DIVISION 100. GENERAL PROVISIONS ................................ 6 Section 101. Definitions and Terms........................................................................ 6 Section 102. Control of Material ............................................................................. 9 Section 103. Quality Control Requirements.......................................................... 11 Section 104. Measurement and Payment............................................................. 15 Section 105. Roadway Construction Control........................................................ 18 Section 106. Trench and Excavation Safety Systems .......................................... 20 DIVISION 200. EARTHWORK ............................................... 21 Section 201. Clearing and Grubbing .................................................................... 21 Section 202. Excavation and Embankment.......................................................... 22 Section 203. Subgrade Preparation ..................................................................... 27 Section 204. Select Grading................................................................................. 28 DIVISION 300. STORM DRAINAGE..................................... 30 Section 301. Storm Drainage Pipe ....................................................................... 30 Section 302. Drop Inlets and Junction Boxes....................................................... 33 Section 303. Concrete
    [Show full text]
  • Table of Contents INTRODUCTION City of Lubbock Street Department
    TABLE OF CONTENTS TABLE OF CONTENTS Introduction • Brief Summary of the Pavement Preservation Strategy and Assessment of Current Conditions Pavement Preservation Overview • What is Pavement Preservation? iVIaintenance Strategies and Practices • strategies for Asphalt Paving • Strategies for Concrete Paving • Strategies for Brick Paving Test Sections of Streets • List of Test Sections • Test Sections Evaluations PAVER • Overview of MicroPAVER • Sample Inspections Sheets • Sample Report Sheets Pavement Distresses • Paved Asphalt Distresses • Paved Concrete Distresses • Paved Brick Distresses Paver Aids in Implementing GASB 34 • PAVER Aids in Implementing GASB 34 • Current Estimated Value of City of Lubbock Streets • Current Estimated Value of City of Lubbock Streets by Council District • Articles briefly explaining GASB 34 Glossary • Pavement Preservation Glossary of Terms Appendix • November 1983, APWA Reporter Article on PAVER • Asset Management and Innovative Finance Page 1 of 1 Pavement Preservation Strategies Table of Contents INTRODUCTION City of Lubbock street Department August 22, 2003 Brief Summary of the Pavement Preservation Strategy And Assessment of Current Conditions The City of Lubbock has over 2600 lane-miles of paved streets with a replacement value of approximately $250,000,000. Street Department is charged with the responsibility of effectively preserving this extensive portion of the City's infrastructure. Although the overall pavement preservation strategy has many aspects, the following is a brief summary of the typical scenario. A. History: The City of Lubbock since 1984 has been a subscriber to the American Public Works Association (APWA) PAVER Project. This computerized street maintenance program, as well as an associated Microsoft Access database program, provides such information on each block of paved street as; 1.
    [Show full text]
  • Chapter 3 : Transportation (V1)
    Town of Aberdeen - Development Guide Chapter 3 : Transportation (v1) Chapter 3 : Transportation 3.1. - Traffic Impact Analysis 3 3.1.1. - Purpose 3 3.1.2. - Threshold 3 3.1.3. - Review 4 3.1.4. - Format 4 3.2. - Driveway Design Standards 7 3.2.1. - Non-residential Driveways 7 3.2.2. - Residential Driveways 7 3.3. - Separation Standards 8 3.4. - Street Construction Standards 9 3.4.1. - General Standards. 9 3.4.2. - Trench Backfill Standards 10 3.4.3. - Subgrade Standards 11 3.4.4. - Proof Roll 11 3.4.5. - Other Standards 12 3.4.6. - Fire Apparatus Requirements 13 3.4.7. - Intersections 13 3.5. - Sight Distances 15 3.5.1. - Intersection Sight Distance 15 3.5.2. - Minimum Stopping Sight Distance 15 3.5.3. - Intersection Sight Distance 15 3.5.4. - Greenway Sight Distance 17 3.6. - Right-of-way Design 17 3.6.1. - Arterial Streets 17 3.6.2. - Collector Streets 18 3.6.3. - Sub-Collector Streets 19 3.6.4. - Local Streets 20 3.6.5. - Alleys 21 3.7. - Dead-End Streets 22 3.7.1. - Dead-End Street Standards 22 3.7.2. - Turnaround Standards 22 3.8. - Street Signs 23 3.8.1. - Street Name and Traffic Control Signs. 23 3.8.2. - Street Name Sign Fees 23 3.8.3. - Standards for All Street Signs 23 3-1 Town of Aberdeen - Development Guide Chapter 3 : Transportation (v1) 3.8.4. - Specialty Street Signs 24 3.8.5. - Standards for Street Name Signs 25 3.8.6.
    [Show full text]
  • Pavement Preservation How: Arizona, Texas, Utah, and New Mexico Edc-4 Peer-To-Peer Exchanges
    Tech Brief PAVEMENT PRESERVATION HOW: ARIZONA, TEXAS, UTAH, AND NEW MEXICO EDC-4 PEER-TO-PEER EXCHANGES PAVEMENT INTRODUCTION PRESERVATION HOW On May 2nd and 3rd, 2019, an FHWA-sponsored EDC- The fourth round of Every Day 4 “How” Pavement Preservation State Peer-to-Peer Counts (EDC-4) innovations promoted quality construction Exchange was conducted in Phoenix, Arizona. State and materials practices that department of transportation (DOT) participants included apply to both flexible and 28 DOT representatives from Arizona, 1 from Texas, 2 rigid pavements. For flexible pavements, these include using from Utah, and 1 from New Mexico. Additional participants included improved specifications for thin 4 FHWA representatives, 1 consultant, and representatives from 5 county asphalt surfacings such as chip governments, 24 municipalities, and 9 tribal communities. Larry Galehouse seals, scrub seals, slurry seals, with the National Center for Pavement Preservation and Larry Scofield with the micro surfacing, and ultrathin bonded wearing courses; following International Grooving & Grinding Association and American Concrete Pavement improved construction practices; Association facilitated the day-and-a-half-long meeting. Arizona was the host state and and using the right equipment provided meeting room facilities. Antonio Nieves of the FHWA introduced the meeting to place these treatments. Rigid pavement treatments include the background and kicked off the meeting. rapid retrofitting of dowel bars to The meeting format consisted of each of the states identifying their current procedures, reduce future faulting; the use of new, fast-setting partial- and full- issues, and successes for each of the topics discussed. Table 1 indicates the depth patching materials to create discussion topics.
    [Show full text]
  • Pavement Marking Handbook
    Pavement Marking Handbook August 2004 © 2004 Texas Department of Transportation All rights reserved Pavement Marking Handbook August 2004 Manual Notices Manual Notice 2004-1 To: Recipients of Subject Manual From: Carlos A. Lopez, P.E. Traffic Operations Division Manual: Pavement Marking Handbook Effective Date: August 2004 Purpose and Content This handbook provides information on material selection, installation, and inspection guidelines for pavement markings. It is targeted for two audiences — engineering personnel and field personnel. The portion for engineering personnel provides information on selecting pavement marking materials for various applications. The portion for field personnel provides information on pavement marking installation and inspection. Additional information about TxDOT specifications, procedures, and standards applicable to pavement markings are included in an appendix. The manual may be used by designers to help with pavement marking material selection and inspectors in the field. Instructions This is a new manual, and it does not replace any existing documents. Content Cover Table of Contents Chapters 1 through 3 Appendix A & B Review History This manual is the product of a Texas Department of Transportation (TxDOT) research project. The TxDOT project director is Greg Brinkmeyer of the Traffic Operations Division. The research supervisor is Gene Hawkins of the Texas Transportation Institute (TTI). Tim Gates and Liz Rose of TTI developed most of the material in the handbook. Wade Odell was the research liaison engineer for the TxDOT Research and Technology Implementation Office. (continued...) Review History (continued) This handbook became a reality because numerous individuals were willing to contribute their time, ideas, and comments during the development process. Special credit should be given to a group of TxDOT staff who meet on a regular basis to review drafts and develop material for the handbook.
    [Show full text]
  • Further Devels'nent Ofthe Tunny
    FURTHERDEVELS'NENT OF THETUNNY RIG E M H GIFFORDANO C PALNER Gi f ford and P art ners Carlton House Rlngwood Road Hoodl ands SouthamPton S04 2HT UK 360 1, lNTRODUCTION The idea of using a wing sail is not new, indeed the ancient junk rig is essentially a flat plate wing sail. The two essential characteristics are that the sail is stiffened so that ft does not flap in the wind and attached to the mast in an aerodynamically balanced way. These two features give several important advantages over so called 'soft sails' and have resulted in the junk rig being very successful on traditional craft. and modern short handed-cruising yachts. Unfortunately the standard junk rig is not every efficient in an aer odynamic sense, due to the presence of the mast beside the sai 1 and the flat shapewhich results from the numerousstiffening battens. The first of these problems can be overcomeby usi ng a double ski nned sail; effectively two junk sails, one on either side of the mast. This shields the mast from the airflow and improves efficiency, but it still leaves the problem of a flat sail. To obtain the maximumdrive from a sail it must be curved or cambered!, an effect which can produce over 5 more force than from a flat shape. Whilst the per'formanceadvantages of a cambered shape are obvious, the practical way of achieving it are far more elusive. One line of approach is to build the sail from ri gid componentswith articulated joints that allow the camberto be varied Ref 1!.
    [Show full text]