Thom H. confirms my observation that hair spray and deoderant are better propellents for a potato gun than starting fluid or propane. Why is this? Not enough oxygen for the starting fluid? or is the flash point not as important as the volume of gass produced by the reaction?

-- Anonymous, April 06, 2000

Answers

We always used old tennis balls lubricated with shaving foam. Lighter fluid was the fuel source, though afficionados always liked rolling the firing chamber (last beer can in the string) in their hands to warm it and make sure that fluid was well vaporized.

We were too chicken to use potatoes as started to approach a lethal impact level (as well as pushing the limits of our beer can cannon) because we mostly deployed them in the winter time on campus. A frozen potato would have the cushiness of an rock impacting a head.

There was an ongoing debate as to effectiveness of snow balls - seemed that they possess an almost dangerous component of ice in order to survive the firing of the gun.

All of us engineering types had hair that was too short to require hairspray in the late '70's, and I'm not even sure we used spray on deodorant much... Ugh-Ugh

-- Anonymous, April 06, 2000

Ok, Dave knew he would sucker me in with this question, the Spudzooka being my latest playtoy. I think the problem with the starting fluid is that the spray is not a fine enough mist. It might work better if I waited a bit for it to evaporate. I did try rubbing alcohol spritzed from a spray bottle and it worked some times and not others. The evaporation factor may have been involved there too. If I could find a good atomizer, I would try other volatile liquids: naptha, lacquer thinner, gasoline. I have now mounted the canon on a cradle and can spin the spark igniter with a long piece of string (a lanyard) wrapped a few times around the knob. That way I don't have to hold it in my hands.

-- Anonymous, April 06, 2000

We had beer cans and duct tape. And a used tennis ball will slip-fit in the beer can. It was about 5-6 beer cans long, the first four or five having both ends removed. The last can had a hole in it for squirting in the lighter fluid and applying a flame to; more advanced models had a spin-flint for ignition. There was two U-shaped pieces of coat hanger that sat in the last most can so as to define the firing chamber - the tennis ball would fetch up against these (the ends of the U rested on the bottom end of the cannon and the U portions were placed as an X so as to define a platform for the ball to hit). The tennis ball was rolled in a pair of hands with shaving cream on them, pushed down the cannon (muzzle loader of course). The lighter fluid was squirted in and the firer would wrap his hands around the last beer can and roll it slightly back and forth for a few seconds. Another person would bear the cannon across his shoulder as with a bazooka, and do the aiming (struck me as the braver of the two as it was upside his head) then the match would be applied and there would be a long thumping whoosh. Lots of duct tape, coupled with the ductility of the aluminum cans probably is what allowed the whole thing to work without turning into a pipe bomb. It was useful for the initial salvo in a snowball fight, or when someone wanted to participate from a 2nd story window, but was very slow to reload and without the projectile spinning it would not shoot very straight. Was more of a surprise thing, if it hit a winter jacket (the ones we where up here) it had about the force of a snowball. Could knock the front wheel of a bike out of someones hands though (witnessed an ambush while I was walking home on the bike path - tennis ball hit the tire ahead of the axle and spun the wheel out of the rider's hands. Rider went over the handlebars and sustained scrapes etc. Not so funny...) Now, what I liked was where you took two 12 foot lengths of rubber surgical tubing, a large funnel, two friends, and a bucket full of water balloons. Much faster reload and the deformation of the water balloon as it morphed through the air as it came at you seems to have the same psychological effect as when you have men in wool skirts coming at you heralded by musicians biting on cats' tails (okay - kilts and bagpipes).

-- Anonymous, April 07, 2000

An interesting site, scroll to the bottom and click on the last link for some interesting stuff

http://www.servtech.com/public/wkimler/links/links.html

-- Anonymous, April 10, 2000