Challenge:
A 15 ft 6 inch circular rotating “whirlygig” mechanism will be used for a production in California and New York. The mechanism suspends the performer over the stage via eight (8) winches which move the performer up and down. The performer stands on a diamond shaped deck which is suspended from the winch cables. The whirlygig system was built by others and required a complete structural evaluation and stamped drawings by a registered professional engineer in both California and New York before the mechanism could be used in the venues.
Resolution:
Our engineering team created a math model of the main structural support system from the winch cable drum shafts to the aluminum tube support frame to the upper rotating gear up to the two manual “F” type trolleys. These trolleys are supported by and roll along heavy-duty horizontal track trusses above which are suspended from the building structural steel above. The model was analyzed for various orientations, dynamic loads, and possible single-point failures.
