THE INFLUENCE OF DESIGN PARAMETERS ON GLIDER TRAILER TOWING BEHAVIOR

Abstract

A computer engineering model simulation can predict the dynamic lateral-sway behaviors of various combinations of tow vehicles (trucks, autos, vans, motorhomes, etc.) and trailers. A model has been developed to analyze various combinations of trucks and trailers owned by the U.S. Forest Service and operated by a diversity of personnel. A method of selecting the correct combinations of trucks and trailers was needed by, and developed for, the U.S. Forest Service to make trailer use and selection most efficient within the limits of safety and practicability. This model has also been used by the author to analyze the in-motion lateral-sway behavior of vehicle/trailer configurations typically used to convey and store gliders and is the subject of this paper. The effects of the key design parameters (such as trailer wheelbase, weight and yaw inertia, weight distribution, hitch weight, tire lateral stiffness, and tow vehicle weight and geometry) have been analyzed to determine their influence on trailer lateral-sway behavior. These may be used to provide a rational basis for the decisions that are eventually made in the trailer design process. Recommendations for changes of current designs of trailers are made which will enhance the safety and dynamics of trailer towing. Glider trailer configurations with weights over 800 Kg. and hitch-to-CG lengths of less than 5m (which includes most of today's configurations) are marginally safe when towed by medium and small vehicles (under 1800 Kg.), regardless of whether front-wheel or rear-wheel drive. Improvements of lateral sway dynamics will result from the following changes to the trailer: (1) Increase: Hitch length, hitch weight, tire size, or (2) Reduce: Speed, yaw inertia, weight.