Definition
A type of engine cooling device in which the outer surface (skin) of the aircraft itself acts as the heat-exchanging surface. Coolant from the engine is circulated through passages built into or beneath the skin, releasing heat to the airflow passing over the aircraft.
Plain English
A cooling system that uses the airplane's own outer surface to get rid of engine heat, instead of a separate radiator hanging in the airstream.
Context Anchor
Seen in aircraft engine cooling-system descriptions, especially for older or specialized liquid-cooled aircraft.
Derivation
From 'skin' (the outer surface of the aircraft) and 'radiator' (a device that radiates, or gives off, heat). The name describes exactly what it is: the skin doing the job of a radiator.
Why Pilots Care
Skin radiators reduce drag because there is no bulky external radiator hanging in the airflow, but they are vulnerable -- a small puncture in the skin can cause coolant loss and rapid engine overheating.
Analogy
It is like spreading a car’s radiator flat into part of the airplane’s outer surface so the passing air can carry heat away.
Intuition Check
“Skin” does not mean human skin here; it means the aircraft’s outer covering. A skin radiator is not a separate radiator hanging in the airflow; it uses the airplane’s outside surface to remove engine heat.
Example Sentence 1
Some early racing aircraft used skin radiators along the wings to minimize drag while still cooling the engine.
Example Sentence 2
During inspection the mechanic checked the skin radiator for dents that could reduce cooling airflow.