Vortex ring state protection flight control law.
Abstract
The current and future trend towards fly-by-wire (FBW) control architectures on helicopters is aimed at bringing improved handling and enhanced safety. By giving a direct input through electrical signals, commands are much more precise enhancing overall safety. Furthermore, the pilot commands are monitored by the FBW control system to ensure the helicopter is kept within the flight protection envelope. As a result, the pilot always can get the maximum performance out of the helicopter without running the risk of exceeding safety margins. Vortex Ring State (VRS) conditions are among adverse flight conditions which mostly occur within a boundary confined to a part of the flight envelope at low forward airspeeds and at steep angles of descent or high rates of descent. The contribution of the present paper is to incorporate VRS boundaries inside a FBW flight control law in order to prevent the helicopter from entering the VRS region. The stability margin given by the heave mode damping is used as a metric to quantify the safety margin. Simulations show the good performance of the VRS-protection function.
Origin : Files produced by the author(s)
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