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

Download
2015
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.

Suggestions

Design and analysis of fixed load crushable column type energy absorbing mechanism for a helicopter seat
Öztürk, Gülce; Kayran, Altan; Department of Aerospace Engineering (2018)
Crashworthiness is the survivability of occupants inside a vehicle during a crash. In helicopters, crashworthiness is ensured by three subsystems; the landing gear, floor structure and the seats. Because of the critical role of the seats in helicopter crashworthiness evaluation, dynamic performance of the seat has to be studied in depth. There are different regulations in which requirements of survivable loads and crash conditions are defined. In this respect, a seat that is used in helicopter should be cer...
Development of a comprehensive and modular modelling, analysis and simulation tool for helicopters
Yücekayalı, Arda; Kutay, Ali Türker; Department of Aerospace Engineering (2011)
Helicopter flight dynamic, rotor aerodynamic and dynamic analyses activities have been a great dispute since the first helicopters, at both design and test stages. Predicting rotor aerodynamic and dynamic characteristics, helicopter dynamic behavior and trimmed flight conditions is a huge challenge to engineers as it involves the tradeoff between accuracy, fidelity, complexity and computational cost. Flight dynamic activities such as; predicting trim conditions, helicopter dynamic behavior and simulation of...
A Comparison of model following control systems for helicopter flight control near hover
Okçu, Ilgaz Doğa; Kutay, Ali Türker; Department of Aerospace Engineering (2015)
Helicopters are complex, coupled dynamic systems with unstable behavior. Countless studies have shown that decoupling the helicopter flight dynamics greatly reduces pilot work load and increases the handling qualities. Design guidelines such as Aeronautical Design Standard 33E-PRF (ADS-33E), which are developed as a means of measuring the handling qualities of a given helicopter, emphasizes that coupling between pitch, roll, yaw and heave degrees of freedom are undesired. ADS-33E also gives flight dynamics ...
Control of a helicopter during autorotation
Şansal, Kaan; Konukseven, Erhan İlhan; Nalbantoğlu, Volkan; Department of Mechanical Engineering (2018)
Autorotation is a maneuver that requires no power and it is used in rotorcrafts when last operating engine is lost. It is an extremely complex state of flight and landing successfully after total power loss requires considerable skill. Main idea behind autorotation is that, by descending with a controlled rate, available potential energy is used as a source that turns main rotor at desired speed for providing thrust and flight control. Just before touchdown, ground speed and descent rate must be reduced for...
Fatigue and fracture analysis of helicopter fuselage structures
Özcan, Rıza; Dağ, Serkan; Department of Mechanical Engineering (2013)
In this study a methodology is developed for the fatigue and fracture analysis of helicopter fuselage structures, which are considered as the stiffened panels. The damage tolerance behavior of the stiffened panels multiaxially loaded is investigated by implementing virtual crack closure technique (VCCT). Validation of VCCT is done through comparison between numerical analysis and the studies from literature, which consists of stiffened panels uniaxially loaded and the panel with an inclined crack. A program...
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.