A fly system, or theatrical rigging system, is a system of ropes, pulleys, counterweights and related devices within a theater that enables a stage crew to fly (hoist) quickly, quietly and safely components such as curtains, lights, scenery, stage effects and, sometimes, people. Systems are typically designed to fly components between clear view of the audience and out of view, into the large space, the 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.[1]
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 on 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.
In manual rigging, a line set's lift lines support weights opposite their connections to the batten in order to balance the weight of the batten and whatever it carries. The lift lines are reeved through a series of pulleys, known as blocks, that are mounted above the stage to fly loft structure. An operating line (a.k.a. hand line or purchase line) allows riggers on the fly crew to raise and lower the batten.
Automated rigging sometimes uses weights to help balance line set loads in a manner similar to manual counterweight rigging. Otherwise it relies solely on the motor power of an electric hoist to fly a line set.
Together, a series of parallel line sets regularly spaced up and down stage, commonly at 6 in (150 mm), 8 in (200 mm), or 9 in (230 mm) centers, comprise the bulk of most fly systems. Theatrical rigging systems are made up of hemp, counterweight and/or automated line sets able to serve various functions.
Line sets are typically general purpose in function, meaning they can perform any number of functions which vary depending upon the requirements of a particular theatre production. For example, a general purpose line set can usually be quickly transformed into a drapery or scenery line set, but converting a general purpose line set into an electrical line set is more involved.
When a line set has a predetermined, relatively permanent, function it is known as a dedicated line set. Line set functions include:
Line sets often suspend theater drapes and stage curtains such as travelers, teasers (a.k.a. borders), legs, cycs, scrims and tabs, as well as associated tracks, in order to mask and frame the stage and provide backdrops. Line sets are sometimes dedicated to particular draperies, such as the main (grand) curtain and main border (valance) that mask the proscenium opening, but drapery locations can often vary.
In many stage productions, theatrical scenery is mounted to line sets in order to be flown in and out so as to quickly change set pieces during the course of a performance. For example, painted soft and hard flats (e.g., muslin drops) and are commonly used to depict settings. Also, three-dimensional sets (e.g., box sets) may be flown.
Electrical line sets, commonly called electrics, are used to suspend and control lighting instruments and, in many cases, microphones and special effects equipment as well. Electrics may be temporarily "wired" with drop boxes (electrical boxes with outlets) or multicable fanouts dropped from the grid or draped from a fly gallery, or permanently wired with connector strips (specialized electrical raceways).[2]
There are normally at least three electrical line sets provided above the stage, with one just upstage of the proscenium wall, one mid-stage, and one just downstage of the cyclorama. Additional electrics are typically desirable.
Permanently wired electrical line sets are known as dedicated electrics, fixed electrics or house electrics. In addition to providing dimmed and switched outlets for lighting fixtures, connector strips may provide low-voltage controls (e.g., via DMX512 and Ethernet taps), for data being sent to lights and other devices, as well as microphone jacks. Power often is fed to fixed electrics from terminal boxes at the grid deck via multicable. Single and double-purchase cable cradles mounted to lift lines can be used to drape the multicable, prolonging its lifespan and reducing the likelihood of conflict with adjacent line sets or lighting instruments. Pantographs are also used to drape the multicable feeding dedicated electric line sets.
Dedicated electrics typically employ truss battens (pipe over pipe) to facilitate cable snaking and to maximize lighting positions. In large professional theatres, such as the Philadelphia Academy of Music, an electric may take the form of a flying bridge (catwalk) that provides a walkable platform for electrician access to fixtures and effects. Flying bridges may also be used for followspot positions.
It is not uncommon for the panels, known as clouds, of an orchestra shell to be flown. Larger, multi-use theaters that cannot have a static shell often make use of the fly system in this way. Before being flown the cloud is sometimes pivoted to a vertical orientation to minimize the space it requires for storage in the fly loft.
A less common use for the fly system is the use of a focus chair system. This is a system where a small chair with fall protection equipment is suspended from a track that runs the length of a batten to which it is mounted. An electrician sits on the chair, and is flown out to the height of the electrics, to focus lighting instruments.
Flying rigs are used to fly scenery or performers in a more elaborate fashion than typical line sets. A flying rig typically allows horizontal as well as vertical movement by paying out individual lift lines to varying lengths and/or through the use of tracks. Flying rigs usually involve specialized equipment and techniques operated by a relatively experienced crew. Peter Foy is known for his innovations in manual flying rigs, especially those used in theatrical productions of Peter Pan. Automated flying rigs, which synchronize multiple point hoists, are becoming more common as motor control systems become safer and more sophisticated.
A permanently installed fire curtain line set, though not used for productions, is a typical element of a theatrical rigging system installation. Building and fire codes typically require that either a fire/safety curtain or water deluge system be installed to separate an audience from the stage in the event of a fire.
Fly systems are broadly categorized as manual or automated (motorized). Manual fly systems are more specifically categorized as "hemp" (a.k.a. rope line) or "counterweight" systems.
"Hemp houses" (a reference to the manila hemp once most commonly used to make the ropes) exclusively use the centuries-old tradition of ropes, pulleys and sandbags to fly theatrical scenery in and out. Hemp rigging incorporates many nautical rigging techniques and equipment (e.g., block and tackle), and was once thought to have stemmed from the nautical rigging. However, recent research has shown that this is not the case,[3] Counterweight rigging evolved separately from hemp rigging [3] and generally handles scenery in a more controlled fashion.
Counterweight rigging replaces the hemp rope and sandbags of rope line (hemp) rigging with wire rope (steel cable) and metal counterweights, respectively. Those substitutions permit the flying of greater loads with a high degree of control, but with a loss of flexibility inherent to most hemp systems. Flexibility is lost because most components of a hemp system may be repositioned, while counterweight system components are relatively fixed. Old "hemp houses" lacked counterweight rigging, but today most manual rigging houses use a combination of counterweight rigging and, at least some, hemp rigging. For example, theaters that incorporate built-in, grid-based counterweight fly systems often will also support additional, spot hemp system line sets for spot-rigging (to spot something, in theatre jargon, simply means to (re)position something).
Manual rigging is also possible with hand (and drill-operable) hoists (winches), but relatively limited operating speeds preclude their use for most running applications.
Automated systems are becoming more prominent. They have the potential advantages of relatively high precision, speed and ease of control, but tend to be significantly more expensive than manual systems. Hoists of various types (e.g., line shaft, chain motor, etc.) are used. A conventional counterweight system may be automated by the incorporation of a motor and controls, in what is commonly called a motor-assist system. By using counterweight in such a manner, motor sizes can be kept relatively small.
The use of a particular type of fly system in a theater usually does not preclude the use of other rigging methods in the same theater.
A hemp fly system, so named for the manila hemp rope that was once common in theatrical rigging, is the oldest type of fly system, certainly the simplest type of system. Recent research shows that the hemp system, although known for centuries, was not much used. The hemp system gained popularity first in the United States in the mid nineteenth century. It soon gained popularity in England, as it was inexpensive and provided a great deal of flexibility for moving scenery.[4] Hemp systems are also known as rope line systems, or simply as rope systems.
Stage rigging techniques draw largely from ship rigging, as the earliest stagehands were actually sailors seeking employment while on shore leave. Because of this, there is common terminology between the two industries. For example, the stage is referred to as a deck in the manner of a ship's deck. Other expressions and technology that overlap the nautical and theatrical rigging worlds include: batten, belay, block, bo'sun, cleat, clew, crew, hitch, lanyard, pinrail, purchase, trapeze, and trim.
In a typical hemp system, a "line set" consists of multiple hemp lines running from a batten above the stage up to the grid, through loft blocks to a headblock and then down to the fly floor, where they are tied off in a group to a belaying pin on the pin rail. The lift lines and hand (operating) lines are one and the same. Typically, a lift line runs from the sand bag (counterweight) assigned to a specific line set, up to "a single loft block" above the fly floor and back down to the fly floor. A trim clamp or a "Sunday" (a circle of wire rope) is used to attach this sandbag to the "line set" to balance the load placed on the batten. The sandbags are usually filled to weigh slightly less than the load, making the line set "Batten Heavy". When the flyman wishes to fly a batten (scenery or lights) "In" (i.e., to the floor/deck), the flyman unties the "High" trim and allows the batten to travel "In" while the sandbags travel "Out" toward the grid. When the flyman wishes to fly the batten "Out", he pulls down on the operating lines (leaving them tied off at the pin rail at "Low" trim) and the batten flies out as the sand bag descends to the fly floor. This arrangement allows the flyman to control the speed of ascent and/or descent and provides greater safety for people on the stage below. The proper "Out/High" trim for the batten is set when the sand bag reaches the fly floor in its descent (adjustable) and the proper "In/Low" trim for the batten is established when the line set (previously tied off to the pin rail) is fully extended (adjustable). This makes it unnecessary to "spike" or "mark" either the line set or the lift line. The Hemp system relies on being slightly "batten heavy" to allow the load to travel to the floor/deck. Because the ropes are flexible there is physically no way to move/push the sandbags "Out" if the weight on both sides is equal.
Another hand line, known as a jack line, may be used to lift the sandbags if they are heavier than the batten load. (UNSAFE condition) The jack line, which runs up to a loft block and back down to the trim clamp, is tied off to a belaying pin adjacent to the one used for the line sets lift lines, either at the same, or a secondary, pin rail.
Pulling on the hand lines of a hemp set flies a line set out. Pulling on the jack line flies a line set in.
Hemp systems can be easily configured for spot rigging, where lift lines must be frequently relocated. They are much less expensive and easier to install than counterweight fly systems, though somewhat more difficult to operate.
First introduced in Austria in 1888,[3][5] counterweight rigging systems are the most common fly systems in performing arts facilities today.
In a typical counterweight fly system, an arbor (carriage) is employed to balance the weight of the batten and attached loads to be flown above the stage. The arbor, which carries a variable number of metal counterweights, moves up and down vertical tracks alongside an offstage wall. In some lower-capacity fly systems, cable guide wires are used instead of tracks to guide the arbors and limit their horizontal play during vertical travel (movement).
The top of the arbor is permanently suspended by several wire rope lift lines, made of galvanized steel aircraft cable (GAC). The lift lines run from the top of the arbor up to the top of the fly tower, around the head block, across the stage to evenly spaced loft blocks, then down, terminating at the batten, a load-bearing pipe that spans much of the width of the stage.
If the loft blocks are mounted to the grid deck, at the loft block wells, the system is called a grid-mount, or upright counterweight rigging system. If the loft blocks are mounted to roof beams (loft block beams), the system is called an under-hung counterweight rigging system. Under-hung systems have the advantages of maintaining a clear grid deck surface for spot rigging and facilitating crew movement across the grid.
The arbor's vertical position is controlled by means of a rope known as the operating line, hand line, or purchase line. The operating line forms a loop by running from the bottom of the arbor down to and around the tension block, through the rope lock, up and over the head block and back down (alongside the lift lines), where it terminates at the top of the arbor. The head and tension blocks are located above and below the full extent of the arbor's travel (movement), respectively, thereby enabling an operator to pull the operating line up or down to move the arbor. When the arbor is raised via the operating line, the lift lines slacken, which causes the batten to lower under its own weight (and the weight of its load, if any). Conversely, when the arbor is lowered, the lift lines increase in tension, which in turn causes the batten to rise.
The combined weight of the arbor and its counterweights initially matches that of the batten so that when the batten is not being raised or lowered, it will tend to remain motionless at any arbitrary elevation above the stage. As more weight is added to the batten (in the form of curtains, scenery, lighting equipment, and rigging hardware), the system is rebalanced by adding more counterweights to the arbor. When the system is properly balanced, an unassisted operator (flyman) can lift the batten and its arbitrarily heavy load from the stage ("fly it out", in theatrical jargon), completely above the proscenium and out of view of the house, sometimes to heights in excess of 70 feet (21 m).
Some large theatres, such as the Metropolitan Opera House (Lincoln Center), have more than 100 independent, parallel counterweight line sets, while smaller venues may only have a few line sets for the most frequently adjusted loads, such as electrics.
Double purchase counterweight systems are sometimes used where the vertical travel of the counterweight arbor would be inadequate due to limited fly space or stage-level wing space. In systems of this type, the operating and lift lines are double-purchased so that the batten will travel twice the distance of the arbor. In other words, for every foot of arbor travel, the batten travels two feet. This often results in the arbors remaining well above the stage deck, leaving the otherwise occupied wing space usable for cast and crew.[6]
In a conventional counterweight system the operating and lift lines terminate at the top of the arbor after passing over the head block. In a double-purchase system, however, after passing over the head block the operating and lift lines pass through another block, which is mounted to the top of the arbor, before rising back up and terminating below the head block. In addition, the opposite end of a double-purchase operating line terminates at the fly gallery, off-stage wall, or stage deck, instead of the underside of the arbor, after passing through a block mounted at the underside of the arbor.[6] The additional blocks result in the arbor moving at half the rate of the lift and operating lines.
In order to compensate for the reduced arbor travel, the loaded arbors must weigh twice as much as the batten load, resulting in arbors that are twice as tall. The additional mass on the arbor increases inertia, and the additional blocks increase friction, resulting in linesets that are more difficult to operate. In addition, double-purchase linesets are more expensive to install and maintain. For those reasons, double-purchase line sets are generally avoided, or limited to a few sets within a counterweight system, unless space issues preclude the use of a single-purchase system. The use of an arbor pit is an alternative approach to dealing with limited space for arbor travel.
Electrical hoists (also referred to as winches) can facilitate coordination with cues, move extremely heavy line-sets, and significantly limit the required population of the fly crew. Despite those potential benefits, most hoists can fly line sets at only a fraction of the speed that an experienced flyman can achieve manually.
There are two general categories of motorized fly systems, motor-assist and dead-haul.
Motor-assist systems very closely resemble standard counterweight fly systems described above, however a drum winch, typically mounted behind the locking rail below the arbor, is used to drive a steel cable purchase line. The purchase line is still terminated at the top and bottom of the arbor, but a rope lock is not used on the motor-assist line set. Weight on the arbor helps balance the batten load so that hoist motor size can remain relatively small. It is often feasible to retrofit a standard counterweight line set to become a motor-assist set.
Dead-haul systems fly the entire load placed on a line set without the assistance of counterweight. Therefore, dead-haul motor sizes are relatively large.
Hoist (winch) motors are either fixed speed or variable speed. Fixed speed motors are used at heavy-load and/or slow-speed line sets (e.g., electrics and orchestra shell line sets). Variable speed motors are used at line sets requiring dynamic motion that may be viewed by the audience (e.g., drapery and scenery line sets). Scenery hoists commonly allow travel at rates of hundreds of feet per minute.
Digital control systems incorporating computers or programmable logic controllers (PLCs) have become commonplace as well, bringing their advantages of high accuracy, safety and repeatability to fly systems.
Battens are linear members to which live loads may be attached for flying. Battens were made of wood originally, but today they are typically steel pipe. Loads mounted to battens include lights, curtains and scenery so they may travel vertically, be raised up into the fly space (flown out) or lowered near to the stage floor (flown in) by its associated line set. Battens typically stretch the width of the stage, parallel with the proscenium wall, and are maintained level (parallel to the stage deck) regardless of elevation. When a batten is flown all the way out (close to the grid) it is at high trim. When it is flown all the way in (usually to about 4 feet (1.2 m) above the stage deck) it is at low trim.
Loads are attached to the batten in various ways. Most lighting fixtures, for example, utilize a C-clamp to rigidly secure the light onto the batten, in conjunction with a safety cable that is looped around the batten to prevent the light from falling should the C-clamp connection fail. Non-traveling curtains (e.g., borders) often employ cloth ties, similar to shoestrings, that are hand tied onto the batten.
Battens are suspended by evenly spaced lift lines, with pick points generally 9 to 12 feet (3 to 4 m) apart. The unsupported, cantilevered, ends of a batten, beyond the last lift line pick points, are generally no longer than 3 feet (0.9 m) unless a bridle is used to effectively limit the cantilever.
Battens were originally made from wood, but have been replaced by steel pipe. In the United States they are typically fabricated from 21-foot (6.4 m) sections of 1.5-inch (38 mm) nominal diameter, 1.9-inch (48 mm) outside diameter, schedule 40 steel pipe that are spliced together (with internal pipe sleeves and bolts) to provide a continuous member that stretches the width of a stage. Schedule 80 pipe is also used. Standard pipe battens are typically designed to support 15 to 30 pounds (6.8 to 13.6 kg) of live load per foot of length.
Truss battens, sometimes referred to as double battens, use a pipe-over-pipe arrangement (often 12 inches (300 mm) center-to-center), with vertical struts welded between the upper and lower pipes to provide rigidity. Truss battens generally permit greater loads than single-pipe battens and may not require as many lift lines due to improved ability to span between lift lines. Truss battens are typically designed to support 25 to 50 pounds (11 to 23 kg) of live load per foot.
An electric batten, a.k.a. lighting batten, may be a single-pipe or truss batten. Electric battens typically incorporate steel straps that are used as brackets for the support of electrical equipment such as connector strips (raceways). The same straps supporting electrical equipment may also connect the two-pipe arrangement of a truss batten. The center-to-center spacing of electric truss pipe, often from 1.5 to 2.5 feet (0.46 to 0.76 m), is typically greater than for a standard truss batten to allow for the proper mounting and focusing of lighting instruments. It is typical for an electric batten to support thousands of pounds of live load.
Light ladder battens are a special type of electric batten oriented perpendicular to and beyond the proscenium opening, at the stage wings. They suspend light ladders (pipe frames) to which lighting fixtures may be attached. When provided, light ladder battens are usually of the truss type and may be fitted with heavy-duty track to permit repositioning of the light ladders up and down stage.
Tab battens are oriented perpendicular to the proscenium opening, parallel to and just off stage of light ladder battens. When provided, they are single-pipe or truss battens for the support of tab draperies, which are used to mask the stage wings.
