Counter Weight Flying

This type of flying allows scenery to be counter balanced by a vertically travelling cradle which is attached to steel wires which run over a series of pulleys in the grid which all terminate on a fly bar. To operate the system control lines are tied off to each end of the cradle, this allows the operator to move the bar either in or out. By pulling the rope down the bar will move towards the stage and by pulling the rope up the bar will move towards the grid.

Single Purchase

The simplest form of counterweight flying is single purchase. On a single purchase set the weight in the cradle should be equal to that of the weight on the bar. At RSAMD one 'whole weight' is equal to 12Kg one 'half weight' is equal to 7.5Kg. For every foot of control line moved the bar will also move one foot. In order for a single purchase system to work the cradle would have to have the same travelling distance of the bar however this is not always possible and so double-purchase systems are installed.

Double Purchase

Double Purchase sets are installed when the cradle cannot have the same travelling distance as the fly bar. With the cradle only travelling half the distance and the control line having to travel through an extra set of pulley blocks then the weight in the cradle must be double that of which is on the bar in order for it to be balanced. Although the travelling relationship between the bar and the cradle is doubled the control line still operates on a 1:1 ratio due to it's double drop above and below the cradle.

Rigging

The safe procedure for rigging a counterweight flying bar is as follows;

The bar# is called to flyperson by whomever is running/calling the rigging from stage level and asks for it to be brought in.

Flyperson then calls bar in eg. "Heads on stage bar 10 coming in" brake is then released and rope is pulled down to lower the bar to stage, flyperson will be listening for a call to stop bar when it is at working height.

Flyperson will then apply brake and then attach rope clip which will stop any vertical movement in the cradle they will then call to stage that "Bar 10 is braked and clipped".

When bar is at working height flying piece is then attached, eg. a black gauze.

When all ties are complete on gauze the stage will then call to loading gallery "Can we have 4 weights in cradle 10 please" normally at this point the gallery may ask (if it's possible) for the bar to be brought right in to stage level so they can reach the cradle.

When loading gallery have loaded the cradle they will respond with "Bar 10 weighted"

The stage will then ask for the bar to be unclipped and for the flyperson to take the weight of the bar. The flyperson will then call the bar out eg. "Heads on stage black gauze going out". They must slowly let the brake off and let the rope slip through the brake as it will be cradle heavy. This can be assisted by some crew easing the weight off the cradle by applying weight to the bar. When the bar is to high off the ground for them to reach hemp lines can be thrown over and held to take the strain off the cradle heavy bar.

When the flyperson has flown the piece off the ground the stage will tell them that they are "Floating" and ask them how the weight is, if it is bar heavy then more weight will need to be added to the cradle or if it is cradle heavy then some weight will be removed. If the cradle is relatively light then this can usually be done from the fly floor if not then it should be done from the loading gallery or intermediate fly floor.

When the flyperson is happy with the weights and the bar and cradle are balanced then the bar can be gridded until it is next required.

Parts of the system

Grid

The highest area in the fly tower, this is where all the loft and header blocks send the steel wires which are attached to the cradle down through the grid floor to the bar.

Loading Gallery

This is where the cradle is at its highest point of travel and so is weighted here.

Intermediate Fly Floor

Level between fly floor and loading gallery this area is used for balancing out cradles and giving assistance with heavy hemp lines.

Fly Floor

Where all the fly bars are operated from.

Flying Bar

Metal bar onto which flown pieces of scenery, lighting, speakers, pyrotechnics etc. are attached to.

Short, Short Mid, Long Mid, Long

The steel lines which are attached to the flying bar, tavel up to the grid, go through a series of pulleys and attach to the cradle.

Cradle

A metal frame into which counterweights are placed to counter-balance the weight of a flying bar.

Weights

Weights used to balance out heavy scenery which are placed into a cradle usually in two sizes 'whole' and 'half' weights.

Control Line

The line which is hauled either up or down to move the cradle and move the flying bar.

Brake

The brake has the control line passing through it and when applied is designed to stop any movement in the cradle or bar however they are not designed to, and should never be, holding any of the weight.

Blocks

The header block is always the first block on the grid which the lines will pass through, each block after that is known as a loft block.

Hardware

Drifts

These are lengths of steel wire rope which are used to hold scenery to fly bars.

Barrel Clamps

Double sided clamp with circular hole designed to fit round fly bar and hold scenery in place.

Turnbuckle

Double ended twisting screw which allows small altertions in the height and level of a flying piece by either raising or lowering it.

Shackles

Used as a joining piece between drifts, turnbuckles and barrel clamps. Usually in two different types:

D-Shackle Can only have force applied on each end of shackle. Good for straight up/down rigging.

Bow Shackle Can have force applied in several directions. Good for multi-angle/directional rigging.

Flying Irons

Attachement between the scenery and the drift, usually bolted to back of flat and then turnbuckled and shackled to drift.