Flue pipe
An organ pipe that produces sound through an air stream at the mouth, unlike a reed pipe.
What it means
A flue pipe is an organ pipe in which sound arises because a stream of air is split against an edge, the languid and lip, setting the air column inside the pipe body into vibration. It works much like a recorder or a panpipe.
In the notation
Pipe construction does not appear in the score itself but in stop lists, where registers are classed as flue or reed stops.
Musical use
Most organ stops, such as principals, flutes and strings, are flue stops. They are distinct from reed pipes such as the trumpet or oboe, where a beating metal tongue produces the tone and the pipe body merely acts as a resonator. Flue pipes therefore sound rounder and steadier, while reed stops are sharper and richer in overtones.