Separation simulation for helicopter external stores and generation of safe separation envelopes

Kapulu, Özge
In many aerospace applications, simulations are used to predict the behavior of the flight vehicle and reduce the number of flight tests required. In this thesis modeling and development of separation simulation tool for helicopter external stores is carried out. Detailed explanations of mathematical modeling, procedure of store separation analysis and collision detection approach from flight dynamics point of view are presented. The nonlinear mathematical model of armed configuration of Black Hawk helicopter is developed in FLIGHTLAB Simulation environment. 2.75-inch diameter rocket and 19-tube rocket launcher are also modeled to simulate store behavior after separation from the helicopter. A simulation code is written to trim the mathematical model at a desired flight condition; then simulate store separation at that trim point. The trajectory of helicopter and store are recorded during simulation. Store distance to critical helicopter points are calculated until the store leaves the helicopter neighborhood. Collision detection routine checks whether the store has contact with the helicopter components or exceeds the clearance margins. Using the simulation tool many points in the flight envelope are investigated to obtain safe separation and safe jettison envelopes. These envelopes represent the maneuvers that the store separates safely without endangering the aircraft or crew. The main rotor interference on external stores is investigated using different main rotor inflow methods. The effect of launcher loading is also studied to determine the most critical launcher configuration at jettison. The simulation tool is validated with jettison of external fuel tanks. The jettison envelope generated based on simulation results is consistent with the safe jettison limits defined by flight test data.
Citation Formats
Ö. Kapulu, “Separation simulation for helicopter external stores and generation of safe separation envelopes,” M.S. - Master of Science, Middle East Technical University, 2015.