You know, it hit me, this is the toroidal 'wind cannon' developed by the
Germans...take any cylinder, like one of those large plastic trash
barrels, cut out one end so it is basically a large hollow cylinder,
cover one end with a membrane with a hole in the middle, cover the over
end with another membrane with a string attached to the middle.
Pull the string to stretch the membrane out and suck in air into the
plastic enclosed cylinder, then let go of it...when it pushes in very
rapidly, a rotating vortex of high pressure air is ejected from the end.
The harder you push it, the faster the doughnut ring of the toroid
rotates on itself, the farther it will go and the harder it will hit....
The Germans claimed they could knock down a brick wall at 2 miles with
their 'wind cannon'. I've seen it demonstrated with air, snuffing a
candle at about 20 feet and flowing these very tight smoke rings that
let you SEE the things being projected.
-- Jerry W. Decker / jdecker@keelynet.com http://keelynet.com / "From an Art to a Science" Voice : (214) 324-8741 / FAX : (214) 324-3501 KeelyNet - PO BOX 870716 - Mesquite - Republic of Texas - 75187