How do airplanes manage to stay straight on the runway during takeoff?

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Answer by Thomas Zerbarini:

Most large aircraft have two methods of steering on the ground. For slow speeds and ground maneuvering we use the "tiller". The tiller is a hand control that sends steering commands to the nose wheel. The tiller usually commands approximately 60 to 75 degrees of direction left or right. The second method of steering is the rudder pedals. The rudder pedals have a smaller amount of deflection than the tiller, about 8-12 degrees of deflection left or right.

The rudder pedals also have independent brakes systems for their appropriate side (left brake system for left pedal, right brake system for right brake pedal.) Having independent brake systems allow the pilot to use differential braking to control direction. this can be used as a back up method for on the ground steering if the hydraulics to the nose wheel or other steering electronics failure occurs.

During take-off roll, the tiller is initially used to align the aircraft with the runway centerline. Once aligned, the rudder pedals are used to maintain directional control as the aircraft accelerates during the take-off roll. As airspeed increases, the flight controls become more affective and are used for directional control at higher speeds. Once the aircraft has reached a safe speed for flight (We call it Velocity Rotate or Vr,) the flight controls are the primary method of controlling the aircraft. The pilots will use flight control input to "Rotate" or fly the aircraft off the ground. As a positive rate of climb is established, the landing gear is commanded raised and the nose wheel steering system is deactivated.

Thomas Zerbarini

How do airplanes manage to stay straight on the runway during takeoff?


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