Definition
A small vertical aerodynamic surface mounted at the tip of an aircraft wing. Tip fins reduce induced drag by limiting the spanwise flow of air around the wingtip, and on some aircraft they also contribute to directional stability.
Plain English
A small upright surface at the end of the wing that helps stop air from spilling around the wingtip, which makes the wing more efficient.
Context Anchor
Seen in aircraft design, stability discussions, and inspections of tail surfaces on aircraft that use fins at the ends of the horizontal tail.
Derivation
Tip refers to the end of the wing. Fin comes from the Old English finn, meaning a thin projecting surface, like the fin of a fish, used for stability or steering. Together the term describes a small fin-shaped surface fitted at the wingtip.
Why Pilots Care
Reduces the size needed for the main vertical tail, lowering weight and drag while preserving yaw control.
Intuition Check
Do not read “tip fin” as a decorative tip or a fish-like fin. In aviation, it means a fixed aircraft surface placed near the tip of another surface to help with stability.
Example Sentence 1
The aircraft's tip fins helped reduce induced drag during long cruise flights.
Example Sentence 2
During preflight the pilot checked the tip fins for damage that could affect yaw response.