Aerial Logging Research

Research on aerial logging by helicopter and balloon is described. Research on free lift helicopter logging by the U.S. Forest Service in 1961 showed this type of logging to be independent of timber volume per acre. Cost and safety factors were listed as disadvantages. Additional research toward reducing costs indicated a reduction could be accomplished by increasing the size of turns, reducing round trip time per turn, reducing helicopter costs, and reducing cost of support facilities. A helicopter trial held in Thomaston, Connecticut over level ground investigated the possibility of increasing payload by yarding instead of free lifting logs. Time and payload weight were the important factors. A 3900 pound log was free lifted 100 feet in the air over a 450 foot range in a time of 47 seconds from hook-up to delivery and back to the hook-up site. By yarding over the same range, the time was increased to 55 seconds, but the payload was a 7100 pound log. A trial at Carlton Lake, Oregon, was for the purpose of determining over water, mud, and swamp the maximum weight of log a certain sized helicopter could yard, the maximum speed possible for yarding the log, and air and ground problems encountered. It was concluded that other means would be better in water, and since the helicopter could not get close enough to the ground for safety reasons, yarding over mud and swamp would not be successful. A trial at McMinnville, Oregon, was conducted to test hook-up and unhook procedures and rigging. A non-spin wire eliminated log roll-up. A way of picking up a log without a choker operation was concluded to be an important research problem. Other areas for future research include wood weight, drag resistance, and operations. Trials in balloon logging in Sweden showed gas leakage and difficulty in balloon control during windy weather as problems. In Canada, two barrage balloons having 7,000 pounds of lift capacity each were used with a common high lead system. Turns of 10,000 pounds were yarded over a 2,200 foot range. It was considered that this method showed the greatest promise over any other aerial method. Cost for the balloon was low and maintenance of the balloon was considered reasonable even with the gas leakage problem. A longer range bringing a significant reduction in spur road construction costs is probable. Disadvantages are difficulty in balloon control during adverse weather periods, difficulty in unhooking chokers at the landing, and frequent changes of tail blocks.

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