Fly system
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A fly system is a system of ropes, counterweights, pulleys, and other tools designed to allow a technical crew to quickly move set pieces, lights, and microphones on and off stage quickly by 'flying' them in from a large opening above the stage known as a fly tower/flyspace.
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[edit] Types of fly systems
There are many types of systems that are made of different materials and operated in different fasions. The most common type in permanent theaters is the counterweight system. Other types include the pin-rail system which relies on sand bags as counterweights and uses a single main pulley to hold the control line, and motorized system which use electrical motors to move a load.
[edit] Counterweight Flysystem
[edit] Structure and Operation
In a typical counterweight line set, a counterweight-carrying arbor moves up and down a track parallel to a wall. The arbor is attached to several steel cables which weave around a series of pulleys at the very top of the fly tower (above the stage) and attach to a long pipe, or batten that is the length of the stage. The combined weight of the arbor and the counterweight inside it initially matches that of the batten, so both are equally balanced on the series of pulleys above the stage. A long rope or operating line, attached to both the bottom and the top of the arbor feed through two pulleys underneath and above the arbor's entire movement track, allowing an operator to pull the rope up or down and move the arbor and pipe batten with ease.
As more weight is added to the pipe batten (in the form of curtains, scenery, lighting equipment, and rigging hardware), it is counter-weighted by adding more steel weights to the arbor. This enables an operator to "lift" the load on the pipe off the ground and fly it "out" (meaning "up" in theatrical terms) sometimes as high as 70 feet (clear above the stage and above the proscenium). A typical counterweight fly system will sometimes have 50 or more individual parallel sets of lines running up the length of an off-stage wall in a theatre.
[edit] Arbor
An arbor is a steel frame which holds counterweights and is moved vertically opposite of the batten. The bottom attaches to the purchase (control) line, which runs around the tension sheave, through the lockrail, up over the head sheave and back down with the hoisting cables (or lift lines typically made of galvanized aircraft steel cable) to attach at the top of the arbor. The hoisting cables run from the top of the arbor, up around the head sheave, across the stage to the loft sheave (attached to the gridiron (grid) over the stage) and down to the batten. When the arbor is raised (via the purchase line) the hoisting cables slacken, which causes the batten over the stage to lower. Complementary to this process, when the arbor is lowered, it pulls the hoisting cables down causing the batten over stage to raise up.
[edit] Weights
Counterweights are a key part of the fly system. They are placed on the arbor and balance the load being flown; they counterweight it. Weights are usually made of lead or steel and vary in thickness from 1 to 3 inches. Weights are usually loaded from the loading bridge, but can also be loaded from the fly gallery or locking rail. It is customary to paint the weights that counterweight the batten (pipe) yellow; these weights should not be removed. When draperies are flown permanently, their respective weights are also painted yellow. Finally, weights usually have a a flat corner for easy removal. It is customary to stack weights in an alternating manner, with the flat corner opposite to the opposite side as the previous weight.
[edit] Batten
A long steel pipe which moves up into the flyspace and down onto the stage, usually parallel to the proscenium arch and to the stage floor.
[edit] Locking rail
A locking rail is located on the stage deck, or on a backstage catwalk, usually perpendicular to the proscenium arch, generally extending from the proscenium line to the back wall. It has a rope lock for each lineset, a built in lever-operated clamp which keeps a balanced load from drifting, as well as a safety lock. There is also usually a headset system or a cue light system to signal the flyrail crew. It is possible to load (add counterweights) from this rail, but it is considered more proper to load weight at the loading bridge.
[edit] Loading bridge
The loading bridge is a catwalk located directly above the locking rail(s) at grid level and allows a technician to add or remove counterweights from a lineset to keep the arbor and batten balanced. The floor of the loading bridge holds a large amount of counterweights (usually made of steel) stored for use.
[edit] Grid
A grid is a steel lattice floor at the top of most flyspaces, which allows technicians to walk over the fly loft, and configure lift lines and loft-blocks (the final pulley which lets the horizontal lift line coming from the head block to hang vertically and move a batten. Not all fly systems have a grid due to height limitations. In these theaters, the battens are generally in permanent locations.
[edit] Hazards
Conterweightfly systems can be very dangerous if not operated by a competent and trained technician. Runaway situations can occur when the weight on the arbor is not equal to the weight of the batten and its load. When this happens, gravity could lift a person off the ground and up several feet in the air, creating both a drop and collision risk. Communication and inspection is key to maintaining and operating a safe fly system. A standard practice in theatre is for the flyman to always call out a warning before flying anything in. This alerts any rehearsing performers or working technicians on stage to be aware that an object is being flown in and to be alert. People on stage generally acknowledge the operators warning by yelling out a confirmation that the warning was heard.
[edit] Pin-rail
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A pin-rail is a pipe with holes drilled at common intervals with a belaying pin inserted in the holes.
[edit] Motorized flysystem
There are two varieties of motorized fly-systems. One incoporates the above arbor and lineset group through use of a winch motor located below the locking rail. The other is more similar to an elevator winch using a cable drum between it and the counterweights with no control rope involved. The first can be attached or detached from the linesets depending on use. Winches are helpful when it comes to moving linesets that are extremely heavy, such as an electric, which with the pipe, circuit raceway, and lighting instruments can weigh close to 1,500 lbs. However, many motors can only move the linesets about half as fast as a flyman at a decent pace, and thus are not used without need of horsepower or remote operation. Additionally, a chain winch can be hung from the grid or a pipe and uses lengths of chain to fly objects out without using an entire batten.
[edit] Common fly system uses
[edit] Electrics
Electrics are special battens with raceways built across them allowing lighting instruments to be hung and connected to remote dimmers. These battens often can also support microphones or special effects equipment. Electrical battens are permanent fixtures with cables hanging from the grid.
[edit] Sets
Soft painted drops can be flown in to depict a background. Solidly constructed sets can also be flown in and hung above the stage or set in contact with the deck. It is not uncommon to see an orchestra shell being flown using the fly system. Larger, multi-use theatres that must convert the stage from a drama theatre to a concert hall make use of the fly system in this way. A batten could also be used to hang pieces of a set, such as a moving stairway or bridge.
[edit] Drapery
Teasers, travelers, legs, cycs and scrims are all commonly flown in drapery used to mask the stage or provide a background.
