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The forces of multiple ventilatons can be superimposed, creating stacked ventilators or ''stacked ventilatorspusfans''. A double ventilator will life a paper ball faster than a single ventilator. A sextuple ventilator 6-pusfan can slowly lift the [[wooden ball]] with a mass of 1.9 tons (when increasing the number of ventilator to around 10, the rising speed is similar to the rising speed provided by 1 ventilator to a paper ball), and a 32 stacked ventilators -pusfan can lift a [[stone ball]] with a mass of 10 tons. The force of the stacked ventilators pusfans on the paper ball will also increase accordingly, so that it can produce the effect of "flying into the sky".