Definition
The phase of a spin in which the aircraft's rotation rate, airspeed, and vertical descent rate have stabilized. The airplane is fully stalled, autorotating about a vertical axis, and the forces acting on it (aerodynamic and inertial) are in approximate balance, producing a steady, repeating motion until recovery inputs are applied.
Plain English
It's the middle, settled-in part of a spin. The airplane has stopped winding up and is now rotating, descending, and holding speed at a steady rate.
Context Anchor
Seen in stall and spin training, spin recovery discussions, and accident reports describing what happened after a spin entry.
Derivation
"Developed" comes from the Latin developare, meaning to unwrap or unfold. A developed spin is one that has fully unfolded from its entry phase into a steady, established motion.
Why Pilots Care
Recognizing when a spin has developed tells the pilot exactly when to apply the standard recovery procedure, since the aircraft behaves differently once rotation and descent stabilize.
Grounding Statement
After the entry, if the airplane keeps rotating and descending in a steady pattern, the spin has become developed.
Intuition Check
Do not read developed as meaning intentional or advanced. Here, developed means established: the spin has settled into a steady rotating descent.
Example Sentence 1
Once the spin became fully developed, the instructor demonstrated the standard recovery procedure.
Example Sentence 2
Recovery from a developed spin begins by reducing power and applying opposite rudder to stop the yaw.