A flame holder is a component of a jet engine designed to help maintain continual combustion.
The design of the flame holder is an issue of balance between a stable eddy and drag.
The simplest design, often used in amateur projects, is the can-type flame holder, which consists of a can covered in small holes.
Much more effective is the H-gutter flame holder, which is shaped like a letter H with a curve facing and opposing the flow of air.
Even more effective, however, is the V-gutter flame holder, which is shaped like a V with the point in the direction facing the flow of air.