Air cannons used in the Rolling Stones' Bigger Bang tour fire 30-m fabric ribbons skyward using compressed air. To accomplish the effect, a rotary actuator instantly opens a ball valve to transfer air from a pressurized reservoir to the barrel of each cannon. (Click on image for larger view.)
Summarizing the solution
As part of the finale, 36 air cannons — accompanied by explosive sounds — fire hundreds of 30-m ribbons into the air from the top of the stage set. Each cannon consists of a 20-l reservoir charged with up to 4 to 6 bar of compressed air. Upon command, a rotary actuator opens a ball valve, which instantly routes compressed air from the reservoir into the barrel of the cannon. This 1-m long, 15-cm bore cannon barrel is packed with the multicolored ribbons. Therefore, when the command is given to fire each cannon, a blast of air propels thousands of multi-colored ribbons skyward.
Parker Hydraulics & Pneumatics specified Festo components for all the pneumatic control functions. They are an approved Festo Premier Stockist and knew that Festo's electropneumatically actuated ball valves offered an ideal means of controlling the output from the cannons' air reservoirs.
Ball valves were chosen for their high flow capacity — when fully open, they provide an open flow path — so air can flow unrestricted from the reservoir to the cannon barrel. Ball valves also can accommodate high pressure, so they easily accommodate the 6-bar maximum charge pressure of the reservoirs. Furthermore, Festo's ball valve design features an inherently safe, blow-out proof shaft that is assembled from the inside of the component.
Each ball valve is driven by a quarter-turn pneumatic actuator, which provides rapid response time, from a NAMUR series solenoid valve. NAMUR is an international mounting configuration that allows the solenoid valve to be bolted over the supply ports of a single-acting spring-return or double-acting pneumatic actuator.
The actuator itself features a scotch yoke mechanism* that produces high initial torque for rapid shifting of the ball valve. The solenoid for each valve is wired back to the stage set's main sound and effects management desk and triggered manually when required. Pilot pressure to operate the actuator comes from a tee in the line between the reservoir and the ball valve. The amount of compressed air for actuating the valve is negligible compared to that needed to launch the cannon.
According to Tony Bowern, General Manager of Brilliant Stages, "The performance of our new air cannons has far exceeded expectations. The sound they make is quite incredible, and the visual affect is superb! The system provides a dramatic audio-visual finale for each concert and has proved remarkably robust, having performed flawlessly on every occasion."
For more information, contact Parker Hydraulics & Pneumatics at www. parkerhydraulics.co.uk. Contact Festo Corp. in the U. S. at (631) 4350800 or visit www.festo.com. Brilliant Stages can be reached at www.brilliant stages.com
* Click here for details on scotch yoke and other types of rotary actuators from the Fluid Power Basics section of our website.
