Rudder Control Loading and Trim

For accurate large jet simulation it is essential to have control loading (force feedback) of the rudder pedals. Rudder forces are important in crucial stages of flight (take off, landing), manual hand flying operation and failure scenarios such as engine failure. The Airbus has flybywire characteristics but the rudders remain mechanically (hydraulically) operated and are augmented when the autopilot is engaged:

Source: Aeroflot Aviation School – Aircraft Type Course Airbus A320 Category B1

Simulation of rudder behaviour is complex and different scenarios have previously been discussed (see Impressions of the Airbus A320 Rudder System).

By utilising the BFF Control Loader boards control loading of the rudder pedals can be achieved. A servo motor connected to a planetary gear reducer drives the horizontal rod motion of the pedals. The rudder trim function can also be used to manually trim the rudder at 1° second. Using the BFF Control Loader software, forces can be tuned and the rudder pedals can self-centre appropriately with variable spring tension.

The control loading system – 80ST-M02430 Servo Motor connected to a 16:1 Yun Duan Planetary Reducer; attached SHF20 flanged shaft and flat plate

The following components (obtainable on e-commerce platforms such as e-Bay and Aliexpress) have been used to build this BFF Control Loader system:

• 80ST-M02430 Servo Motor and 80ST Mounting Bracket
• Angle Aviation Plug Socket (YD18 15P, YD18 4P)
• Yun Duan 90mm Flange 16:1 Speed Ratio 16 Planetary Reducer 19MM Input Shaft Gearbox Reducer (calculations performed by Richard Long, CockpitSOLID)
• SHF20 Flanged Shaft Support or QTX20MM Bushing
• 24V 15 amp Power Supply Unit
• Flat plate aluminium profile for rudder rod attachment

Resources

80ST-M02430 Motor Specifications
SHF20 Flanged Shaft Support 20 mm
QT20MM Brushing

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