To start lets consider what each term means; a stall is a breakdown of the smooth airflow over the wing into a turbulent one, resulting in a decrease in lift. The lift will no longer fully support the aeroplane’s weight, and the aeroplane sinks; “Yaw” is the rotation around the vertical access – to dampen this is to simply control it so the aircraft does not “hunt” left and right in flight all the time.
The Boeing 737-600/700/800/900 ng series incorporates a Stall Management Yaw Damper (SMYD) system, providing critical flight safety enhancements. This system includes two key elements: stall warning and yaw damper functionalities.
The SMYD system uses input from various airplane sensors and systems to compute commands for the stall warning system, elevator feel shift, leading edge (LE) autoslat system, primary yaw damping, Wheel to Rudder Interconnect System (WTRIS), and performance data for display on the Common Display System (CDS).
Stall warning is critical for indicating the approach of a stall, allowing pilots to take corrective action.
The yaw damper function helps in maintaining smooth and coordinated turns by controlling unwanted yaw motions.
This is achieved by a series of inputs form the aircraft systems and then outputs also from the SMYD.
Inputs: The SMYD receives data from multiple sources, including Air Data Inertial Reference Unit (ADIRU), Flight Management Computer System (FMCS), control wheel position sensors, Angle of Airflow (AOA) sensors, and more.
Outputs: It provides data to Flight Control Computers (FCC), Ground Proximity Warning Computer (GPWC), Cabin Pressure Controllers (CPC), and others for coordinated airplane operations.
The SMYD integrates with various airplane systems, managing performance data crucial for flight operations. It ensures appropriate stall warnings, coordinates yaw damping, and interfaces with other systems for safe and efficient flight control.
The SMYD plays a pivotal role in stall management, enhancing flight safety by actively managing and monitoring critical parameters like airspeed, pitch attitude, and rudder movements.
This system exemplifies advanced aeronautical engineering, blending multiple inputs to enhance safety and performance of the Boeing 737 series. It underlines Boeing’s commitment to integrating complex systems for flight safety and operational efficiency.
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