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What Causes a Flat Spin?

Published in Aircraft Aerodynamics 2 mins read

A flat spin is primarily caused by an aircraft's center of gravity (CG) shifting too far aft (towards the tail), which fundamentally alters its aerodynamic behavior.

The Core Mechanism of a Flat Spin

When an aircraft's center of gravity moves significantly towards the rear, it creates an unstable condition that can lead to a flat spin. As noted, this critical shift in weight distribution results in a scenario where:

  • The aircraft's rotation becomes more horizontal, rather than maintaining a conventional nose-down or slightly nose-down attitude characteristic of a typical spin. This horizontal alignment is a key differentiator of a flat spin.
  • In this highly unusual and unstable orientation, the aircraft's wings aren't producing enough lift. The airflow over the wings is disrupted to such an extent that they can no longer generate the necessary aerodynamic force to keep the aircraft aloft.
  • Consequently, the aircraft essentially falls out of the sky while spinning. It descends rapidly, rotating on a largely horizontal axis, due to the severe lack of effective lift.

This combination of an aft center of gravity, horizontal rotation, and insufficient lift defines the dangerous condition known as a flat spin, where the aircraft loses its ability to control its descent effectively.