As Multistage were already supplying and installing the counterweight flying system an amount of preliminary design work on the acoustic shell was carried out following the guidelines set out by the Architect and the Acoustic Consultant.
- .The back wall would be a flown framework with the upstage sections of the side stage wall frameworks hinged from the two ends.
- The two downstage sections of the side stage wall frameworks would be hinged-out from the leading edge of the existing Proscenium Towers and would track on and off with them when not in use.
- The two mid stage side wall sections, each incorporating a set of double access doors, would comprise back-braced, frees-standing wagons with a complete winch down top section, enabling it to be stored in the scenery dock.
- The ceiling would require to be split up into two flown sections, one upstage and one downstage. The upstage, flown section being split into four, individual, swivelling frameworks. The frameworks would clip into position for vertical storage and be held at the connect inclination by adjustable stay-wires when deployed.
- The triangular profiling and density of the timber cladding required, led to the concept of utilising fabricated aluminium frameworks and suspension trusses in order to keep the weights of the various elements down to a manageable level.
- The intention would be to provide an Acoustic Shell that a minimum of 2 operatives (preferably3) could deploy or store in under 3 hours with only the use of a stepladder.
Construction Design & Fabrication
- Suspension of the back wall from a modified square truss with hanging adjustment to allow for weight compensation after cladding is fitted.
- General usage of "turtle" castors rather than single swivel castors.
- Having the individual frames in each of the flown ceiling sections swivel alternately upstage and downstage of the ladder truss when being stored vertically to balance the weight.
- Utilising a substantial "drop-in" bracing frame across the back of the mid stage wagon to help stabilise the two winch sections when travelling. The same bracing frame being relocated across the top of the doorway, when the wagon is in position, to stabilise the front structure before winching up the top section.
- Addition of small castors to the bottom of each door to allow operation without recourse to a bottom door sill.
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Installation in Cyprus was due to start straight after the Epiphany holiday on the 8th January 2017, which would require the equipment to be loaded into a container at Total Solutions ‘ Birmingham works the week before Christmas 2017; not the best timing for local weather conditions, as it turned out.
The complete side wall structures were erected easily; however it soon became apparent that the counterweight flying set nominated for the suspension of the back wall would be too far downstage and the whole set, including the longer cradle would require moving. Once the counterweight set was relocated and the truss hung, the back wall was assembled and joined to the two side wall frameworks using blind bolts. The completed shell framework was checked dimensionally and then marked up on the stage.
Modifications to the steel frameworks of the existing Proscenium Towers were made to allow the downstage Acoustic Shell frameworks to be permanently hinged from the on stage leading edges and to fold back into the towers, when not deployed, whilst still allowing the towers to track on and off stage as before. An additional, heavy duty, wheeled carrier was added to each of the over stage tracks supporting the towers to compensate for the additional weight.
The completed side walls were detached from the back wall and moved apart to allow the assembly and rigging of the ladder trusses used to suspend the ceiling panels. Once the two ladder trusses were in place the various pre-assembled frames were pinned into position; the panels then being set at the required angle using the pre-installed stay wires.
Once the deployed ceiling units were flown out, the side wall frameworks were moved back into position and the ceiling angle checked against the tops of the wall frames and adjusted as required. The whole Acoustic Shell framework was now ready for the timber cladding to commence.
The cladding work proved relatively easy and progressed quickly; the exception being the mid stage wall frameworks requiring much more exacting work to cater for the close tolerances for the moving door and top framework sections.
Each of the mid stage sidewall sections were set back into their storage formats, with the doors retracted and the top sections winched down, to check the clearances with the cladding now in place. They were then wheeled into the Scenery Dock to check that they would fit into the designated storage areas. No problems were encountered in doing this.
Some last minute concerns about the overall loading imposed when flying the back wall with both upstage side wall frameworks on the same counterweight set, resulted in a decision to store the two side frameworks, separately, flat against the rear structural wall of the stage area. The original hinges between the rear and up stage side frameworks were replaced with new, fabricated, hinges with removable pins.