Definition
A force applied to a spinning gyroscope that attempts to change the orientation of its spin axis. Because of gyroscopic precession, the gyro responds to a deflective force not at the point where the force is applied, but at a point 90 degrees ahead in the direction of rotation.
Plain English
A push or pressure on a spinning gyro that tries to tilt it. Instead of tilting where you push, the gyro reacts a quarter-turn later around its spin.
Context Anchor
Seen in discussions of gyroscopic precession, especially how a spinning propeller can affect aircraft handling when its angle is changed.
Derivation
From Latin 'deflectere,' meaning 'to bend aside' or 'turn away.' A deflective force is one that tries to bend or turn the gyro's spin axis away from its current orientation.
Why Pilots Care
Pilots must anticipate instrument lag or errors during rapid maneuvers so they can interpret attitude and heading indications correctly.
Grounding Statement
Picture the propeller as a spinning disk: if something tries to tilt that disk, the response appears about a quarter-turn later, not exactly where the force was applied.
Intuition Check
Deflective force does not mean any force that bends or damages something. Here it means a push or pull on a spinning object that tries to change where its spinning disk is pointed.
Example Sentence 1
When the pilot pitches the nose up sharply, the deflective force on the spinning propeller produces a yawing tendency due to precession.
Example Sentence 2
During a rapid turn, the heading indicator reacts to the deflective force by precessing the gyro 90 degrees from the yaw input.