A detailed three‐dimensional model of a twin‐lift system has been derived. The system includes two helicopters, spreader‐bar, load and cables, connecting all the bodies. Nonlinear equations of motion of the entire system were used to obtain a system of nonlinear
algebraic equations describing trim. Another system of linear differential equations described small perturbations about that trim. It is shown that the equations of trim form an undetermined system, and so additional conditions are required to define a single solution. This presents an interesting
problem of optimizing trim. Stability analysis of the trim positions indicates that the root locus of the various modes is complicated and requires physical insight into the system's behavior. The flight of the system is complicated by unstable modes across the entire range of air speeds.
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Document Type: Research Article
Faculty of Aerospace Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
Publication date: 2005-04-01
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