3
PLANNING AND CONSTRUCTING ARRAYS
3.1
Planning
A site survey should be conducted before arriving on site and a rigging plan
prepared. The rigging plan should include details of the number and type of
cabinets to be flown, their position in the array as well as the angles
needed to best cover the audience areas of the venue. The plan should
also include the weight, intended height and position of the load(s) to allow
the venue riggers to select the rigging points needed to suspend the flying
system from the roof of the building.
3.1a
Load limits
To maintain the 7:1 safety factor of the flying system, the above hook
rigging - roof structure, rigging and motor chain hoists - should all be
capable of supporting loads 7 times that of a fully loaded flying system.
3.1b Rigging, loading and motor hoists
The rigging plan allows users to determine the exact position of the rigging
points needed for the array described. The chains or steels suspended
from the rigging points should hang vertically with the array attached - if
they do not, then the horizontal shearing forces introduced by misalignment
will reduce the load safety margin of the flying system. Because of this
factor, users must ensure the correct position and spacing of the rigging
points. But the most obvious result of mispositioning will be that the whole
system will not array in the intended manner.
Normally, a W8L system is flown from two separate rigging points. However
a bridle chain can be used to fly a system from a single rigging point or
crane hook. For bridled, single point suspension the load ratings of the
motor hoist above hook rigging and the rigging point will all need to be
double that used for normal twin point suspension. To ensure that the rated
load safety factor of the W8L flying system is maintained, always check the
actual total load of the flying system, rigging and loudspeaker cabinets.
In calculating the total load on each rigging point remember to include the
weight of the motor, cables and any additional rigging. Always consult the
W8L data sheets for cabinet weights.
See Section 2.3 for more information
Martin Audio – W8L Flying System
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