Rotor blade-airframe strikes are rare but they do occur. Three areas of the airframe are particularly vulnerable: the tail boom, canopy and, in the case of the underslung, teetoring rotor, the rotor shaft. This latter case is known as mast bumping. This report studies a system to prevent a helicopter rotor blade from striking any part of the airframe. Essentially, the system continuously predicts ahead the rotor blade flapping in response to an input such as pilot control or an atmospheric disturbance. If a blade strike is predicted to occur then an appropriate feedback control is applied to alter the future flapping. The prediction is then begun again with the altered control. In the actual system, an enunciator might warn the pilot at the time that he is attempting a control input which could be hazardous. Two somewhat independent approaches to the design of the controller are taken. One of the programs is entirely numerical in its approach. The other uses modern control theory and considers the preliminary aspects of implementing the controller in digital hardware. Both methods indicate the feasibility of preventing excessive flapping, although the question of implementation in a dedicated microprocessor is not fully resolved. Helicopter rotor control systems. (edc)
Analysis of a System to Prevent Helicopter Rotor Blade-Airframe Strikes
1989
126 pages
Report
No indication
English
Aircraft , Air Transportation , Helicopter rotors , Rotor blades(Rotary wings) , Aerodynamic loading , Airframes , Atmospheric disturbances , Aeronautical booms , Aircraft canopies , Control systems , Control theory , Digital systems , Feedback , Flight control systems , Helicopters , Input , Load control , Masts , Microprocessors , Pilots , Predictions , Prevention , Shafts(Machine elements) , Tail assemblies , Time , Warning systems , Mast bumping , Flapping(Rotor blades)
UNMANNED MULTI-ROTOR TYPE HELICOPTER AIRFRAME GUARD DEVICE
European Patent Office | 2016
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