Most of use are familiar with the Airzooka: A kid-powered vortex generator, or in layman's terms, a big ol' air gun.
Find a pair of D-cells, and have a small mechanism (I'm guessing my Lego set could do the prototyping) replace the kid.
Whammo! Fully-automatic blasts of air. Scare your cats! Clean the leaves off your lawn! Knock things off your desks -- at fully automatic speeds!-- Almafeta, Dec 23 2003 Airzooka Website http://www.airzooka.com/(Just in case you haven't heard of it...) [Almafeta, Oct 04 2004] How fast could it be fired? How much kinetic energy is needed to move a small ball of air? So how long would the bateries last?-- RobertKidney, Dec 23 2003 Having played with one of these in the "gadget shop" I came to the conclusion that the fun is in shooting it at somebody then looking away innocently. The thing is so directional and the sound of it to the victim is so much like a loud bang that they invariably turn around and clearly can't believe that nobody else heard the explosion. This guerrilla tactic would probably work less well if they turned to see me brandishing an automatic airzooka at them. Overall a fishbone for scaring cats.-- dobtabulous, Dec 23 2003 Croissant for the cat-scaring application .... can you make the thing actually fire the D cells at them ?-- 8th of 7, Dec 23 2003 <aims cat at 8th of 7>Kill pus! kill! Oh okay just sit and clean yourself then - I give up</blah>-- dobtabulous, Dec 23 2003 My traditional airzookas are on back order. I'm not crazy about an idea that obsolesces my new toy before it arrives.
as for cats I did think my friends would enjoy 'zooking stuff near the cats to animate them with an unseen hand. I'm not kept by a cat and so am not sure if this application would be fishboned. Any thoughts [dobtabulous]?-- DadManWalking, Dec 23 2003 Leaf blower? Its louder sure, but its the flamethrower of Airzookas.-- Letsbuildafort, Dec 23 2003 Well, you have ~20 newtons * ~.075 meters = 1.5 J so, power supply is not too much of a problem... however, you'll have problems with turbulent airflow in the thing. You won't get the quality of vortexes you'r used to (at high rates of fire).-- my-nep, Jan 08 2005 random, halfbakery