Театральные подъемные механизмы и системы оснастки сцены.

Rigging above a theater stage

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. 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 , , or 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). 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, 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, 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.

A pin rail, originally a wood beam, is typically a large diameter round steel tube with vertical through holes that accept belaying pins used in a hemp rigging system. Depending on the pin rail design, the pins may be removable or permanently fixed to the rail. Pin rails are typically installed permanently at the onstage edge of the fly gallery(ies), extending from the proscenium wall to upstage wall, sometimes in a stacked (rail over rail) arrangement. Mobile pin rails may also be used and are bolted down to the stage deck where needed.

A locking rail is typically a steel angle or rectangular tube to which the rope locks of a counterweight system are mounted. Locking rails are located on the stage deck and/or fly gallery and typically extend from the proscenium wall to the upstage wall. A stage level locking rail may be provided with an engaging bar for a portable capstan winch.

Arbor pits, where provided, are troughs at the stage edge that provide additional vertical travel to a counterweight system's arbors. Providing a counterweight arbor pit can help compensate for height limitations of a fly tower. The trough depth typically ranges from 2 to 10 feet. Shallower pits may be accessible only from above at the stage deck. Deeper pits are sometimes accessible from a trap room or orchestra pit.

Because fly systems involve large amounts of weight, and particularly because the weight is usually suspended above people, there are a number of common precautions taken to ensure safety and prevent injuries. Communication, inspection, and loading procedure are key to the safe operation of a fly system.

Except for during performances and some rehearsals, a standard practice in theatre is for the flyman to always call (shout) out a warning before moving a lineset so as to alert personnel (e. g., rehearsing performers and technicians) who are on the stage. People on stage typically acknowledge the operator's warning by yelling out a confirmation that the warning was heard. The flyman's warning specifies what is moving and its direction of movement. For example, a particularly verbose call might be something like "lineset three, first electric flying in to the deck, downstage" (in USA) or "Heads onstage, Bar 3, LX 1 coming in." (in UK). In many theaters, all people on stage are expected to respond with "thank you." Upon completion of the lineset motion, some operators may call again (e. g., "lineset three locked") to announce that the lineset has stopped moving.

Unbalanced loads are of great concern in manual rigging. Minor imbalance is sometimes desirable, for example so that as an operating line is let out a line set will fly in of its own accord. However, as it is common for many thousands of pounds of equipment and scenery to be flown above cast and crew, major imbalance is a grave hazard, and, if left unaddressed, can result in runaways. The use of block and tackle or capstan winch is common to handle line sets that have significantly unbalanced loads. Block and tackle sets use the mechanical advantage (e. g., 6 : 1) of multi purchase blocks to enable a crew to manually raise an imbalanced line set. The standing block is secured at the grid level and the running block to the batten or arbor (whichever is overloaded). Where an engaging bar has been designed into the stage level locking rail, a portable electric capstan winch may be used to counteract an imbalanced counterweight line set. Pulling on (constricting) a rope wrapped a few times around the capstan, a drum spinning at a constant rate, generates enough traction (through friction) to tug the imbalanced load. Especially tall fly towers pose a balance problem for standard counterweight line sets. As a line set is lowered to the stage, the weight of the lift lines is added to the total weight of the line set that a rigger must be able to control. For example, a batten with 6 lift lines of ¼" aircraft cable that travels 50 feet effectively weighs about 40 pounds more when flown in than when it is flown out. To address this issue, a compensating mechanism may be added to the counterweight system. Either chain or thick wire rope may be used. One end of a compensating chain (typically roller chain) is suspended from the underside of the counterweight arbor, the opposite end mounted to the adjacent wall, at a point corresponding to half the travel of the arbor. The compensating chain is about half the length that the arbor travels, and sized to weigh twice as much as the combined weight of the lift lines per linear foot. At arbor low trim, the compensating chain is fully supported by the wall. At arbor high trim, the chain is fully supported by the arbor. Paying out at half the speed of arbor travel, a compensating chain effectively eliminates imbalance along the full path of travel. A compensating wire rope line is attached to the top and to the underside of an arbor and runs through sheaves near those for the operating line. This wire rope line follows a similar path to the operating line. The compensating line is made of two lengths of wire rope: a thick heavy wire rope (e. g. 1" diameter), and a thin wire rope (e. g. 1/4" diameter). One end of each length is attached together. The free thick end of the compensating line is attached to the underside of the arbor and the free thin end is attached to the top. As fly pipe lowers and the arbor rises, more of the thick heavy wire rope hangs beneath the arbor and compensates for the additional weight of the fly lines. This mechanism works well with T track counterweight systems.

A runaway is a moving lineset that cannot be safely controlled by its operator. Runaways can occur when the weight on the arbor is not equal to the weight of the batten and its load. Linesets are often intentionally unbalanced to facilitate quick flying in one direction and, in such cases, runaways are more likely to occur. In the rare event that an unbalanced lineset gains so much momentum that the operator cannot stop it, a specified safety procedure is usually followed. Venues typically establish a standard call for this event, which might sound something like "Runaway 47, upstage, heads." (It is unlikely that a flyperson will have enough time to utter all of that. More likely they will just scream "Heads! Heads! ". Acceleration due to gravity is 9.8 metres per second per second; if there's a front heavy runaway batten heading for the deck from 20m overhead there will only be a couple of seconds to give a warning to those below. For this reason, it is standard operating procedure in most venues to for crew to be clear from directly underneath of battens when they are being loaded/unloaded and flown unbalanced. "Heads" is a standard call but runaway cradles are, thankfully, not a standard event; they can kill.) Operators are trained not to attempt to stop a runaway lineset but rather to warn others and safely escape. The reason for this is that it is unlikely that they will be able to stop it, and very likely that they will burn their hands or be lifted by the lineset, potentially injuring themselves on structure above and/or from a subsequent fall. Furthermore, this might position the operator in the path of the batten, arbor, or sandbag as they accelerate downward. Spreader plates are used in counterweight arbors to keep the arbor's vertical rods from bending and releasing the counterweights in the event of a runaway, while the locking plate prevents the counterweights from bouncing out of the arbor.

When loading a batten, or arbor in a counterweight system, it is imperative to control the balance of a set. The lineset should be balanced before loading begins, then the batten flown in, the set added, and then the counterweight added from the loading bridge. The specific order is important because it keeps the set from being unbalanced in a position where it could run away. When it is batten heavy (after the set is added, but before the counterweights) the arbor does not have anywhere to run away to as it is already at its grid stop (the upper end of the track). In cases where the set is too tall for the batten to be all the way in, it should be kept as far down as possible. It is always best to add the load in pieces as small as practical and counterweight them one at a time so the system can never get too out of balance. Improper loading procedure is a common cause of accidents in many theaters.