This report presents the Phase 2 results of a three-phase study to identify criteria to minimize the potential for rudder overcontrol, leading to structural failure of the vertical stabilizer in transport aircraft in up-and-away flight. Rudder sizing and travel are typically defined by requirements for minimum-controllable airspeeds following an engine failure and crosswind limits for takeoff and landing. The rudder authority that results from these requirements can impose excessive loads on the vertical stabilizer at high airspeeds. Therefore, rudder travel is limited as airspeed increases. The method used to limit rudder travel can have an impact on the tendency to overcontrol and varies significantly among and within manufacturers. The objective of this program is to collect data that allows the Federal Aviation Administration to develop criteria for rudder flight control systems that ensure safe handling qualities by minimizing the tendency for overcontrol. A piloted simulation was conducted on the National Aeronautics and Space Administration Ames Research Center Vertical Motion Simulator. The results of that simulation showed that the primary factor leading to a tendency for rudder overcontrol was short pedal throw. All other factors were less significant. Specifically, increasing the pedal force did not compensate for short pedal throw, and nonlinearity in the load-feel curve, such as would result from high breakout and low maximum pedal force, was not a significant factor for overcontrol. Rudder overcontrol results in very high vertical stabilizer loads only if accompanied by a large sideslip angle. This piloted simulation showed that there is a tendency to achieve slightly higher sideslip angles for configurations with short pedal throw, but other factors must be present to accomplish the magnitude of sideslip that could cause failure of the vertical stabilizer. Preliminary analysis suggests that these factors consist of complete loss of yaw damper functionality when saturated and high rudder control power in combination with low effective dihedral. Phase 3 will focus on quantifying these factors to complete the development of criteria to prevent overcontrol and consequent overstressing the vertical stabilizer.
Piloted Simulation Study to Develop Transport Aircraft Rudder Control System Requirements, Phase 2: Develop Criteria for Rudder Overcontrol
2010
115 pages
Report
No indication
English
Criteria to Mitigate Rudder Overcontrol in Transport Aircraft
British Library Conference Proceedings | 2011
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