Taming Left Turning Tendencies: Part One, Torque

Pilots notice early in their training that single‑engine, propeller‑driven airplanes seem to
“want” to turn left, especially during takeoff and climb. This isn’t sloppy flying or bad trim
work — it is physics at work. Four primary forces gang up on the airplane to create
these left‑turning tendencies: torque, slipstream, P‑factor, and gyroscopic precession. In
this and the next three CFI Care columns, each force will be unpacked in turn (pun
intended), starting with torque.

Torque comes straight from Newton’s Third Law: for every action, there is an equal and
opposite reaction. When the engine spins the propeller clockwise as seen from the
cockpit, the airplane experiences a reactive tendency to roll to the left. The more power
that is applied and the slower the airplane is moving through the air, the stronger and
more noticeable this rolling tendency becomes.

At the start of the takeoff roll, the airplane cannot actually roll left because the wheels
are still firmly on the ground. Instead, the rolling moment transfers more weight to the
left main wheel, which increases drag on that side of the landing gear. Think of the
difference between pushing an empty wheelbarrow and one loaded with concrete: it is
much more difficult to push when it is heavier. Conversely, the airplane’s wheel with
more effective weight on it resists motion and “drags” you in that direction, causing the
airplane to veer left. Once airborne, the airplane is free to roll, so the pilot counters the
torque‑induced roll with right aileron, which has its own aerodynamic consequences.

Whenever an aileron is deflected downward, it behaves much like the flaps: it increases
lift on that wing but also increases drag. That added drag causes the nose to yaw in the
opposite direction of the roll, a behavior known as adverse yaw. This tradeoff between
more lift and more drag is the same reason flaps are so useful on landing — they let the
airplane fly slower and descend more steeply. The key difference is that flap systems
add the same lift and drag to both wings, keeping the nose pointed straight ahead.

When only one aileron is deflected downward, it is as if a flap were lowered on just one
side, and the airplane tends to yaw and “pull” left. This is the moment when the CFI’s
voice echoes in the cockpit: “Right rudder!”

Torque is most noticeable early in the takeoff roll, and it becomes apparent as soon as
the airplane starts moving. A simple experiment during the runup illustrates the effect:
smoothly add power while holding the brakes and watch for a slight drop of the left wing.
That subtle dip is torque in action. Then, as the brakes are released and the airplane
accelerates, the left‑turning tendency from torque becomes easier to feel through the
rudder pedals and yoke. And if you are already wondering whether the spiraling
slipstream is joining the party during this phase of flight, that is exactly where the
discussion is headed next month.