UBC Theses and Dissertations
Helicopter logging productivity in dispersed and aggregate partial retention systems Lyons, Charles Kevin
This study evaluated several factors that affect helicopter logging productivity in partial cutting operations. The harvest treatments applied to the 4 units in this study were 75% aggregated retention, 40% dispersed retention, 40% aggregated retention, and 15% dispersed retention. The flight record data included turn time, turn mass, and the number of logs per turn for each unit, while there was only limited detailed sampling of the in-unit turn time elements, and of turn merchantable volume to mass ratios. The treatments applied in this study did not appear to have a dramatic effect on helicopter productivity. There was little correlation detected between turn time and turn mass, turn time and the number of logs per turn, and turn mass and the number of logs per turn. The distance to the unit from the landing appeared to have the greatest affect on total turn time, while the lifting component of the in-unit time dominated the variation of the in-unit timing. The turn cycles with choker drops and aborts increased the average total turn time in units 2 and 5 by less than 7 %. Turn mass did not vary greatly between the units, and this is attributed to the ability of the hooktenders to compensate for the varying conditions. Regression equations were developed to estimate total turn time and turn volume. These equations demonstrate that productivity increases with reduced horizontal distance to the unit, increased log size, and increased volume of merchantable wood per unit mass. However, more detailed sampling is required to identify nonlinear relationships between log volume and turn volume, and horizontal distance and turn time. Also more research is needed to identify factors that link turn time and turn volume to stand conditions at higher levels of retention.