forest U . See also: Economics Watershed engineering Timber Quality * ** ***** * * ** *HelicoptersforLoggingCharacter- Contents Page istics, Operation, and Safety Consid- Bibliography 107 erations, by P.M. Stevens and Edward H. Clarke (2) *** ** * * ** * ** * * *** * *** This report presents an overview of factors Helicopter Logging: Advantages and relevant to the productive and safe use of Disadvantages Must Be Weighed, by helicopters for timber harvesting. The load Doyle Burke (1) characteristics of approximately fiftyheli- copters are discussed along with factors such Helicopter logging may have advantages as operating costs, productivity, and safety where road access is restricted or the use of considerations. conventional logging systems is prohibited. Disadvantages related to cost, slash disposal, cull material handling, and post-harvest land An Analysis of Production and Costs in Soil Surface Conditions Following Sky- management may outweigh the advantages, High-Lead Yarding, by M.E. Tennas, line Logging, by C.T. Dyrness (5) however. Helicopter logging is especially ex- R.H. Ruth, and C.M. Berntsen (3) pensive and therefore may be restricted to The results of a study to compare soil dis- the removal of scattered trees or pockets of Factors influencing production and costs on turbance caused by tractor, high-lead, and high-value timber. a high-lead yarding operation in a 100-year- skyline logging are reported. Both soil sur- old stand on the Cascade Head Experi- face disturbance and slash density were re- mental Forest were isolated and analyzed. corded at about 1,750 different points on Industrial engineering techniques and statis- one watershed. The most surprising result tical analyses were used to estimate how of the study is that soil disturbance caused crew size, haul-in distance, volume per turn, by high-lead and skyline logging were about slope, length of yarding road, and number of the same. logs per acre affected production and costs. The influence of these variables is illustrated by a series of curves which demonstrate, for GLOSSARY example, that choker-set time increases with increasing distance from the spar tree. Skyline Tension and Deflection Hand- book, by Hilton H. Lysons and Charles N. Mann (4) The need for additional information on the capabilities of multispan skylines led to this study of skyline tensions. The report begins with a discussion of the general characteris- Glossary of Cable Logging Terms, by ticsof skyline logging systems.It then Pacific Northwest Forest and Range Ex- progresses to a detailed investigation of both periment Station (6) single-span and multi-span skylines. Prob- lems, such as the rigging of a 1-5/8-inch- Did you know that a "top guy" is one of diameter skyline on a convex slope, are several lines tied to the top of a spar tree, or posed and then solved by the authors. that a ''triple drum" is found on a three- drum yarder?If you had a copy of the Graphs related to load factors and tensions Glossary of CableLogging Terms you under varying conditions are presented in a would have a comprehensive sourceof general manner to allow the solution of all dozens of terms used throughout the log- practical problems. ging industry. 100 The Forester's Almanac Mechanics of Skyline Anchoring, by density. Holding power also increases with Charles 0. Campbell (7) the square of the stump diameter. A 48- inch stump will hold approximately four Good anchoring cannot be overemphasized times as much as a 24-inch stump. in planning a skyline operation. In the past, there have been many instances when car- Methods of rigging stump anchors and cal- riagesand other equipment havebeen culating load are presented in this paper. TAMING THE TUSSOCK MOTH damaged or destroyed because of anchor by Thomas Michael Baugh failures.Stumps are the most common anchor, and although there are no definite June 9, 1974, dawned clear in the moun- methodsofpredictingtheload-bearing tains of eastern Washington and Oregon. As capacity of stumps, a few general observa- the light of the new day spilled into the dark tions hold true. The holding power of a canyons, the quiet was broken by the puls- ing whir of helicopters. stump tends to increase with soil depth and Slump anchor at ridgetop. The ungainly airshps, carrying long pljes A Technique for the Solution of Sky- slung from their undercarriages, were part line Catenary Equations, by Ward W. of the largest all-helicoptet insect control Carson and Charles N. Mann (8) project ever to take place in the forests of the Pacific Northwest. When their work The designer of a skyline logging operation was finished, a month and a half later, they must determine the load-carrying capability had sprayed DDT over 426,000 acres of cf his system in order to establish mechan- tussock moth-infested forest land. ical and economic feasibility. Because of the complexity of the mathematical equations The control project was the culminating act which describe these cable systems, this can in a debate and drama which had involved be a computationally difficulttask. This much of the preceding 2 years. The contro- report proposes an efficient method of com- versy over theuse of DDT had raged Schematic of snubbed carriage. puting load-carrying capabilities. throughout the United States. Final approval had been given by the Environmental Pro- tection Agency in an attempt to save as Digitizing Topographic Data for Sky- eophotographs through the use of a Kelsh- line Design Programs, by W.W. Car- type stereoplotter and a digital scaler or much forest as possible from the moth. son, D.D. Studier, and W.M. Thomas digitizer. (9) At the same time that the helicopters were First, the skyline designer prepares equip- spreading their loads of insecticide, planning This research note discusses a procedure for ment information and specific road descrip- was taking place in the offices of the United the collection of topographic data from ster- tions on photographs. Then the person States Department of Agriculture in Wash- Spar 1 operating the stereoplotter uses the digitizer ington, D.C. Concerned public officials and 11, lint: and a keypunch to take terrain point data natural resource managers were in the pro- 4 7 directly from the stereophotograph model. cess of structuring a major scient/ic effort Data cards are then prepared that describe to investigate the ecological factors related Corr1ae each skyline road. to tussock moth outbreaks and to find their control methods. Companion investigations Inner were also planned for two other forest in- Skyline Spar 2 sects, the gypsy moth in the Northeast and Uthe southern pinebeetleintheSouth. Terrain point I Height (feet) I.As is true of all native insect pests, the tus- sock moth is "endemic," meaning always present, but in very low numbers. Occasion- Standing skyline Oater yarding limit ally, however, the tussock moth population Igets out of balance with its environment and a population explosion occurs. The result An Analysis of Running Skyline Load can be severe defoliation and death of many Path, by Ward W. Carson and Charles trees over thousands of acres. Tussock moth N. Mann (10) outbreaks occur in the West on the average of about every 7-10 years, although not This paper is intended for those who wish usually in the same location. For example, to prepare an algorithm to determine the another serious outbreak may not occur load path of a running skyline. The mathe- until about 1980, but not necessarily in the matics of a running skyline design problem Blue Mountains of Oregon where defolia- are presented. The approach employs as- tion was severe in 19 72-74. sumptions which reduce the complexity of the problem to the point where it can be Ward Carson solved on desk-top computers of limited capacities. ir. Forest Engineering 101 The authors show how to apply the for- Running Skyline Design With a Desk- mulas developedinthepreviouspaper Running Skylines Reduce Access Road Top Computer/Plotter, by W.W. Car- (Running Skyline Design With a Desk-Top Needs, Minimize Harvest Site Impact, son, D. Studier, and H.H. Lysons (11) Computer). by Doyle Burke (17) The running skyline system is being used A well-planned running skyline system can by an increasing number of timber operators substantiallyreduceaccessroad mileage for thinning and clearcutting. It is a system while providing almost unlimited flexibility of two or more suspended moving lines, in meeting timber harvest requirements. generally referred to as main and haulback, The running skyline, one of the most ver- that when properly tensioned will provide satile yarding systems ever developed,is lift and travel to a suspended load. The designed around the three-line interlocked desk-top computer approach presented in yarder with tracked or wheeled undercar- this paper allows the planner to determine riage. deflection and load path for a specified load. Calculator, printer, and plotter combination. Running skylines can be matched to almost Determination of Skyline Load Capa- any timber harvest situation. They provide bility with a Programable Pocket Skyline Logging Profiles From a Digital for extended yarding up to 2,000 feet. Road Calculator, by W.W. Carson (12) Terrain Model, by Doyle Burke (15) spacing can be increased to almost twice that of systems with uphill yarding capability For planning purposes, logging engineers A digital terrain model based on input from need tools and methods to determine the only. Running skylines allow lateral yarding improved topographic and orthophoto maps up to 150 feet, reduce average yarding dis- load-carrying capability of skyline cable sys- can help to accurately evaluate alternatives tance, and can he rapidly set up and moved. tems. Both computerized and hand compu- for skyline logging operations. A digital ter- tation methods are available for these deter- rain model program is available to transcribe minations; however, no approach has been data from maps into profile plots.