Reducing Control Forces

081-05-06Pablo Asensio Martínez2026-04-011 min

The Problem

As aircraft size and speed increase, the force required to deflect a control surface becomes too great for a pilot to handle manually.

Aerodynamic Balance

Methods to use airflow to help move the control.

  1. Horn Balance: A portion of the control surface (the "horn") projects ahead of the hinge line at the tip.

    • When deflected, the horn produces a force that assists the movement.
    • Also acts as a Mass Balance weight.

  2. Inset Hinge: The hinge is set back into the control surface.

    • Part of the surface area is ahead of the hinge line, reducing the moment arm of the aerodynamic load.

  3. Balance Tab: (Covered in Trimming). Moves opposite to the control surface.

  4. Frise Aileron: (Covered in Roll). The nose of the aileron projects into the airflow, assisting the deflection (and adding drag).

Artificial Feel

In fully powered controls (hydraulics/FBW), the pilot feels no aerodynamic load.

  • Springs/Q-Feel: Artificial resistance must be added so the pilot receives feedback proportional to deflection and airspeed.