Optimization of Balanced Field Length Performance of Multi-Engine Helicopters

摘要

The main objective of the study is to develop a tool that computes completetrajectories, addressing the rejected (RTO) and continued (CTO) flight simultaneously and including the all-engines-operating phase, so that complete balanced field lengths (BFL) may be optimized directly. The attention is focused on the optimization of Category A runway takeoff operations of multi-engine helicopters according to FAR Part 29. For this purpose, a direct optimization method, based on discretization using collocation, is applied. First, the results of some helicopter take-off optimizations from earlier studies were reproduced using the direct collocation method, using two software packages, DOVNLPAC and Xgesop. Then, an optimization system was developed, using the software package XGesop. An alternative optimization system was developed as well, that handles both continued take-off and rejected take-off in a more efficient way, so that computation time is reduced and the achievable accuracy, increased. A study on aerodynamic helicopter models has also been conducted, to determine an adequate model as a starting point for the optimization systems; possibilities for modifications are also indicated. For the balanced field length optimizations conducted in this study, a two-dimensional point-mass model including rotor rotational dynamics was used as aerodynamic model.