Counterweight Systems

The flying system consists of a number of elements:

The Fly Tower extends the stage height beyond the proscenium arch, ideally 1.5 times higher than the proscenium opening. This enables the scenery to be flown out of view, and a theatre with this arrangement is said to have Full Flying Height. The horizontal bars on which scenery and lighting equipment are suspended or attached

Scenery is attached to or hung from a flying bar (or barrel), or stage lighting equipment is rigged on lighting bars which are hung from the flying bar. The lighting bars are often internally-wired, which means lighting equipment can be easily plugged into existing sockets on the bars, which are then connected to dimmers via connection points at the end of the lighting bar. 
Wire Ropes are connected to the flying bars, and run vertically from the bar up towards the Grid, which is an arrangement of girders or slats which provide a stable support for a series of Pulleys, around which the wire ropes are run. There are (at least) 3 ropes connected to each bar, known as Long, Middle and Short, each running vertically to a pulley, known as a Loft Block. The wires then run to the side of the stage where the Fly Gallery is located, where they pass over a Head Block down to the Counterweight Cradle or Arbor. This is loaded with Counterweights on the Loading Gallery by the Fly Crew. 
The cradle / arbor travels vertically up and down the counterweight frame. Attached to the cradle/arbor is a purchase line, made from rope, which passes through a rope lock / brake, and is controlled by the Fly Crew. 

There are (at least) two types of counterweight system: 

  • Single Purchase: The cradle travels the same vertical distance as the fly bar, from the grid, to a few feet above the stage floor. The counterweight frame therefore occupies the full height of the side wall of the stage. The counterweight cradle / arbor needs to contain weights equal to the load on the flying bar. 
  • Double Purchase: Counterweighted flying system where the cradle/arbor travels half the distance of the fly bar, leaving the side wall of the stage under the fly floors clear of flying equipment. The cradle of a double purchase system needs twice as many counterweights as that of a single purchase system balancing the same weight.

Single Purchase Counterweight systems


Keywords: Flying Systems, Counterweight Flying Systems, How does a flying system work?