A plane’s rudder is the trailing portion of its standing tail fin, and controls the plane’s vertical axis.

The rudder is vital for controlling the plane’s movement, especially during crosswinds.

The rudder is often used with the plane’s ailerons, which control the longitudinal axis.

These two systems are often used in conjunction, since movement by one often causes unintended movement in the other axis.

The rudder is also used to prevent adverse yaw and P-factor.

As a result, the rudder is one of the most important components of a plane.

Without a rudder, most planes, especially during high winds, would be unable to fly straight. 

What is a Rudder on a Plane?

The rudder is a moveable surface that’s attached to the edge of the airplane’s standing tail fin.

The rudder is used to control the airplane’s rotation around its vertical axis, which is called the plane’s ‘yaw.’  Unlike the rudders on boats, the ones on airplanes don’t steer the aircraft.

An airplane’s rudder is only to control its vertical rotation, and is located on the trailing edge of the tail’s standing tail fin.

How a Plane’s Rudder Works

The pilot controls the rudder with a left and right rudder pedal in the cockpit.

The pilot deflects the corresponding rudder pedal, and the rudder deflects in the same direction – i.e. pushing the left rudder pedal causes the rudder to also deflect to the left. 

In most planes, the rudder is connected to the cockpit mechanically.

Larger airplanes sometimes also use hydraulic actuators to overcome mechanical loads on the rudder.

A Plane’s Rudder Purpose

The rudder is used to control the plane’s vertical rotation and performs these two practical functions:

1. The rudder helps during crosswinds when landing

The pilot uses the plane’s rudders and ailerons together to turn the plane.

The ailerons impact roll and the rudder imparts yaw.

The rudder alone could turn the plane, but it’s more efficient with ailerons.

During crosswinds, the pilot will use the rudder and ailerons in opposite directions to maintain the plane’s fuselage in line with the runway. 

2. The rudder helps keep the plane straight

The rudder can compensate for the yaw effect of engine failure in a multi-engine plane, keeping the plane straight.

Pilots also use the rudder to keep the plane straight during landings and take off if there’s high winds.

What Controls the Rudder?

The pilot controls the plane’s rudder through the left and right rudder pedals.

The rudder deflects in the same direction as the rudder pedal that’s pushed.

Pushing the right pedal deflects the rudder to the right. 

Larger planes sometimes use a more sophisticated system of hydraulics instead of pedals to control the plane’s rudder. 

Can a Plane Fly Without a Rudder?

Most planes can fly without a rudder through the use of the ailerons to control the plane and by making small adjustments by adjusting engine thrust on either side. 

However, with a rudder, the pilot loses most control over the vertical, or yaw, axis.

If there are low winds, the pilot could stably fly the plane, but control at low speed will be poor. In high wind conditions, it’d be extremely difficult for the pilot to control the airplane.

In fact, the pilot would most likely lose control over the yaw axis.

What is the Difference Between a Rudder and an Aileron?

Ailerons are located on the trailing edges of the plane’s wings, while the rudder is located at the trailing edge of the plane’s standing tail fin.

Ailerons control the plane’s movement around its longitudinal axis.

In contrast, the rudder controls the plane’s vertical axis. 

Both systems are frequently used together, since a rotation in one axis normally causes an unwanted rotation in the other axis.

So pilots control both systems to ensure there’s no unwanted rotation on either axis.

Rudder and Adverse Yaw

The rudder is used to counter the effects of adverse yaw, a phenomenon caused by lowering the ailerons.

After a pilot lowers the ailerons, an increased lift is generated, which raises the airplane up.

But, this increased lift also increases drag on the plane, which specifically slows the aircraft on the upper wing side. 

The result is an adverse yaw movement that pushes the plane in the other direction.

The pilot uses the rudder to decrease adverse yaw and keep the plane aligned in the desired direction.

Using both the rudder and ailerons is known as a ‘coordinated turn.’ 

Rudder and P-Factor

The rudder is used to counter the adverse yaw effect caused by P-factor, an aerodynamic phenomenon.

A P-factor is when a moving propeller’s center of thrust moves off-center due to a high angle of attack.

This shift in the center of thrust causes an adverse yawing movement that causes the aircraft to yaw to one side.

The pilot uses the rudder to prevent P-factor in the opposite direction to which the P-factor yaws the aircraft.

The pilot may also change engine power or pitch in coordination with changing the rudder to decrease the P-factor.

In conclusion:

  • The rudder is the trailing edge of a plane’s standing tail fin.
  • The rudder is used to control the plane’s vertical axis.
  • The rudder works through two pedals located in the cockpit: the left and right pedals.
  • The pilot pushes the desired pedal, and the rudder deflects in the same direction, changing the plane’s yaw.
  • The rudder is frequently used with ailerons, which control the plane’s longitudinal axis.
  • Movement by one of these systems usually causes undesired rotation in the other one. So the rudder is extensively used to prevent undesired yaw.

Helen Krasner holds a PPL(A), with 15 years experience flying fixed-wing aircraft; a PPL(H), with 13 years experience flying helicopters; and a CPL(H), Helicopter Instructor Rating, with 12 years working as a helicopter instructor.

Helen is an accomplished aviation writer with 12 years of experience, having authored several books and published numerous articles while also serving as the Editor of the BWPA (British Women Pilots Association) newsletter, with her excellent work having been recognized with her nomination of the “Aviation Journalist of the Year” award.

Helen has won the “Dawn to Dusk” International Flying Competition, along with the best all-female competitors, three times with her copilot.