Fly loft

A fly system, flying system or theatrical rigging system, is a system of lines (e.g., ropes), blocks (pulleys), counterweights and related devices within a theater that enables a stage crew to quickly, quietly and safely fly (hoist) components such as curtains, lights, scenery, stage effects and, sometimes, people (e.g., in Peter Pan). Systems are typically designed to fly components between clear view of the audience and out of view, into the large opening, fly loft, above the stage.

Fly systems are often used in conjunction with other theatre systems, such as scenery wagons, stage lifts and stage turntables, to physically manipulate the mise en scène.

Theatrical rigging is most prevalent in proscenium theatres with stage houses designed specifically to handle the significant dead and live loads associated with fly systems. Building, occupational safety, and fire codes limit the types and quantity of rigging permitted in a theatre based on stage configuration. Theatrical rigging standards are developed and maintained by organizations such as USITT and ESTA (now PLASA).

The line set is the fundamental machine of a typical fly system.

The function of a typical line set is to fly (raise and lower) a slender beam (typically a steel pipe) known as a batten (or a bar in the UK) by hoisting it with lift lines (typically synthetic rope or steel cable). By hanging scenery, lighting, or other equipment to a batten, they in turn may also be flown. A batten is said to be "flying in" when it is being lowered toward the stage, and "flying out" when it is being raised into the fly space. Battens may be just a few feet in length or may extend from one wing (side) of the stage to the other. A batten is suspended from above by at least two lift lines, but long battens may require six or more lift lines.

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