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Tennis Ball Mortarby Tetranitrate on May 31, 2007
Table of Contents
intro: Tennis Ball Mortar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Video . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
step 1: Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
step 2: Building the mortar tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
step 3: Firing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Advertisements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
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Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
http://www.instructables.com/id/Tennis-Ball-Mortar/
intro: Tennis Ball Mortar..................................................................................................................................................................................
The tennis ball mortar is a great project for many reasons: all the materials are cheap and readily available, its construction is extremely simple, and it gives off a niceloud *pop* which the video doesn't do justice.
Quick and dirty explanation on how it works: The mortar is composed of three sections of Pringles cans duct taped together. The metal bottoms of the top two cans arecut to form baffles, which will focus the force of the expanding hot gas created by the burnt vaporized naptha, onto the center of the tennis ball. Thanks to the near exactmatch in diameter of the ball and can, the force of the compressed gases is trapped behind the tennis ball for the whole length of the top can.
As you can probably guess this design has room for improvements. For example, if the length of the top can were extended, the ball would have a longer time toaccelerate and thus achieve a faster speed, but at what point does the downward air pressure on the ball overpower the structural integrity of cardboard and duct tape?How does increasing the volume of the cans affect overall performance? What effect would adding a few more baffled cans have? I'm sure the answer is only a simplemath problem or two away, but you look bored and like your enjoying a few too many fingers. (More after the video)
Video
Today (June 1st) I am beginning a contest (Shhh! Its not an official contest so don't tell my bosses Eric and Christy) to see who can come up with the best tennis ballmortar design. No one characteristic defines "best", it is a combination of performance, creativity, adn 1's aBiLiTy 2 not tlak LIEK Dis!!!1!1 I am judge and jury of thiscontest, and my decision is final.
How to enter: Join the group Tennis Ball Mortars (Its moderated) If you feel your design is truly innovative, and that you are making great advances in the field of tennisball mortarology, write a new instructable and post it in the group. If you just have some pictures, or if the only difference between your mortar and someone else's is thecolor of the duct tape, post it in the forums, and then add it to the group.
Now for the good part *THE PRIZE*. I'm sure your dieing to know what sacrificing several fingers, gaining numerous pounds, and clogging all your arteries will win?::Drum roll:: The ULTIMATE SUPER GRAND PRIZE is .........a cookie, thats right you win a cookie (Specifically: (1) Entenmann's chocolate chip cookie mailed in plain white envelope to any address in the world ( Its internationallydelicious!! )). I know what your thinking "Damn Tetranitrate you cheapskate, even Fred, the guy who sits in his van by the playground is more generous with sweets thenyou", to which all I reply is "After all those Pringles you don't need anymore junk food, and you should probably tell a trusted adult about Fred."
**DISCLAIMER: By entering this contest, thinking about entering this contest, or even just reading this, you retain all liability should you happen to blow up or injureyourself in an attempt to build this.
(edit: I ate the cookie)
http://www.instructables.com/id/Tennis-Ball-Mortar/
Image Notes1. Office warfare 2.0
Image Notes1. You can eat all the chips at once, or if you feel like your going to vomitdehydrated potato and processed cheese flavoring turned nuclear orange by justthe right amount of stomach acid... you can put them in a bag.
step 1: Materials1. (3) Pringles Cans2. Duct tape3. Lighter fluid4. Tennis balls (edit: or aerosol hairspray)
(Told you it was simple)
http://www.instructables.com/id/Tennis-Ball-Mortar/
step 2: Building the mortar tubeStep 1: Eat the chips. Vomit when necessary. Repeat. (I was making a joke about the flavor of the chips, but it also works nicely as a beginners guide to bulimia)
Step 2: Wash out the cans with soap and warm water. Do not get the cans too wet or the cardboard will lose some of its integrity. Dry cans.
Step 3: Cut out a circle in the center of two of the cans metal bottoms. The diameter of the hole should be equal to the radius of the metal bottom.
Step 4: Stack the two cans with baffles (holes) on top of the solid bottomed one, and duct tape heavily ( 7 - 12 times around) at the seams.
Step 5: Completely cover the cans in duct tape at least three times (three layers of duct tape thick)
Step 6: Poke a 1/4" hole 1" from the bottom of the mortar
http://www.instructables.com/id/Tennis-Ball-Mortar/
Image Notes1. 7-12 layers thick
http://www.instructables.com/id/Tennis-Ball-Mortar/
Image Notes1. You can eat all the chips at once, or if you feel like your going to vomitdehydrated potato and processed cheese flavoring turned nuclear orange by justthe right amount of stomach acid... you can put them in a bag.
Image Notes1. 1" from bottom
http://www.instructables.com/id/Tennis-Ball-Mortar/
step 3: FiringSafety first: Lighting the mortar without a stand (like I did in the first shot of the video) is asking for trouble. A simple and fast stand can be made from PVC pipe and coathanger as demonstrated in the photo. If no stand materials are available at least lean the mortar against something (bench, rock, etc.) so it isn't at risk of falling when youare trying to light it.
Tip: 3" PVC pipe will fit perfectly around Pringles cans with just the right amount of duct tape on them. A hole can be drilled through the PVC and cans for lighting. Thisprovides extra structural reinforcement to the cans lessening the chances of a blowout.
Tip 2: Use a barbecue lighter, or like in the video a quick & easy torch (made by bending coat hanger around paper towel). This will put distance between your fingers andthe bottom of the tube, in case of a blowout.
Generic safety stuff: Use adequate eye, ear, nut-sack, and various other body part protection.
To prepare for firing: Set up the mortar in a large open area where you have little risk of hitting someone. Squirt about 1-2 teaspoons of lighter fluid down the barrel of themortar, making sure to aim for the bottom can. Spray a little extra through the hole in the bottom, to help aid in lighting, or, if using hairspray, you can spray hairspraydown the mouth of the barrel for a few seconds. Drop the tennis ball down the barrel. The mortar is now loaded, and from now on no one should pass in front of it.
To fire: Wait about two minutes after pouring, to give the chamber enough time to fill up with the evaporating lighter fluid (Pouring the perfect amount of fluid, and waitingtill exactly the right time to light are the two things to master when it comes to tennis ball mortars). Light the barbecue lighter or torch, and hold it close to the hole on thebottom. If all goes well you should hear a loud bang, and see the ball sail off into the distance.
Image Notes1. Stand made from thin PVC pipe and a bent coat hanger.
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http://www.instructables.com/id/Tennis-Ball-Mortar/
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Comments50 comments Add Comment view all 225 comments
chloride says: Sep 29, 2008. 10:06 AM REPLYWhat is the second baffle for exactly? I get the first baffle is to make sure the ball doesn't get to the bottom of the tube but what's the second one for andwhat would happen if I used more than two baffles?
andrew13 says: Aug 12, 2008. 6:56 PM REPLYYa think you can put airsoft BBs in it?
Kendallkip says: Sep 7, 2008. 5:52 PM REPLYno, they would all fall down the hole thingy
andrew13 says: Sep 8, 2008. 8:37 PM REPLYok... my friend and i made one, and we made somthing to carry the bbs, it only flew a few feet, but it ws a start!
darth acexxacer says: Jan 12, 2008. 12:21 PM REPLYi made this into a RPG-7 out of this its sick as hell
PS heres a real RPG-7
darth acexxacer says: Jan 25, 2008. 9:21 PM REPLYhere it is rough model not quite done as of yet
http://www.instructables.com/id/Tennis-Ball-Mortar/
bomberman3 says: Jul 5, 2008. 3:07 PM REPLYwhat did you use for the grip?
darth acexxacer says: Jul 5, 2008. 3:13 PM REPLYan mm's tube
Kendallkip says: Sep 7, 2008. 5:54 PM REPLYXD
darth acexxacer says: Sep 7, 2008. 9:27 PM REPLYlol yup
spleinman says: Jan 14, 2008. 5:11 PM REPLYDang, that thing looks fun to play w/!
darth acexxacer says: Jan 14, 2008. 9:47 PM REPLYya totaly
James (pseudo-geek) says: Jan 13, 2008. 2:57 PM REPLYThose things are nasty powerful too, I'd hate to get hit with one.
darth acexxacer says: Jan 13, 2008. 3:27 PM REPLYi saw a show about someone who was 15 feet away from one when it exploded and he lost his right arm and half of his right leg
RFilyaw says: Jan 29, 2008. 9:14 AM REPLYUnless you're using some sort of high explosives like C4, nitroglycerin or black powder, salt peter, etc, you're not going to lose any limbs,especially from 15 feet away.
The worst this might do is break your nose or a few teeth when the ball hits you.
darth acexxacer says: Jan 29, 2008. 5:11 PM REPLYi was talking about a REAL RPG-7
James (pseudo-geek) says: Jan 13, 2008. 3:35 PM REPLYouch.
darth acexxacer says: Jan 14, 2008. 3:52 PM REPLYtell me about it but its cool because he got some prosthetic limbs
darth acexxacer says: Jan 12, 2008. 12:47 PM REPLYcan i enter it in to the contest when im done building it?
Scythica says: May 3, 2008. 8:13 PM REPLYi made this and fired it using a storm drain as a bunker i worked once but then the mortar court fire lol i tred it at a mates again but we re-enforced it andused a more power put propelent (Av gas (jet fuel) vapour)and we fired tennis balls filled with very fun stuff if you want to know what those fun stuff wasemail me and i'll be glad to share
thinker says: Aug 10, 2008. 3:07 PM REPLYmessage me with it, im intrigued
http://www.instructables.com/id/Tennis-Ball-Mortar/
magician13134 says: Mar 23, 2008. 4:59 PM REPLYLighter fluid didn't work for me, it just hissed a little bit. Does anyone know why this is or how to fix it? Thanks!
katanakreater says: Aug 10, 2008. 2:05 PM REPLYYou may have been using charcoal lighter fluid... it took me about 2-3 mortars to realize therew was a difference. Hair-spray can work if you spray downthe barrel and in the hole that you light at.
geewizartcool says: Apr 7, 2008. 3:18 PM REPLYyou may not be using the correct fuel or tour combustion chamber is not sealed well.
Geoffrito says: Apr 5, 2008. 10:04 AM REPLYmake sure its naptha (naptholene) lighter fluid, as opposed to kerosene lighter fluid. I"m not sure what anyone uses naptha for any more, but you canbuy it under the name 'ronsonol'. Kerosene lighter fluid is the common stuff used for lighting grills. it doesn't vaporise as easily and needs differentparameters to burn.
beechy says: Jul 24, 2008. 2:21 AM REPLYget a 500ml coke bottle take off the lid spray butane inside and then stick it in the mortar and fire it. it makes the botlle go further !
i tried it and it doubled the range on my weapen
gamerguy314 says: Jul 15, 2008. 4:40 PM REPLYwhats the "Cut out a circle in the center of two of the cans metal bottoms. The diameter of the hole should be equal to the radius of the metal bottom." for? isit like a chamber for the evaporated lighter fluid?
Admiral Puffinfresh says: Jun 30, 2008. 4:07 AM REPLYHahaha love the bulimia joke. Very tasteful. =] Also, try using this as an over-the-shoulder rocket launcher? =]
four_eyes954 says: Feb 3, 2008. 2:15 PM REPLYif i were to fill about a quarter of the tennis ball with match heads and put in about 200 air soft bbs could i have an air soft mortar
coolcaleb says: Jun 26, 2008. 6:05 PM REPLYread my comment above i could make an instructable about how to make an airsoft mortor/bazooka
dUc0N says: Apr 21, 2008. 5:24 AM REPLYNah, that's not likely. The match heads would go as it leaves the tube thanks to the concussion from the gas exploding. Real mortars have timed fuzingfor that.
greenupkid says: May 14, 2008. 9:49 AM REPLYhey use pvc pipes and pipe glue it works better and shoots farther
NapoleanDynamite says: May 27, 2008. 12:53 PM REPLYYeah, PVC pipes work better. They don't get obliterated after firing them a few times. I made one out of pringle cans, and after firing about 3-4 times, Ihad to throw it away.
coolcaleb says: Jun 26, 2008. 6:03 PM REPLYYa use pvc thats what i do SOOOO much better also try using a flicker thing that makes sparks i made a bazooka that u hold over ur shoulder andlaunch anything but my favorite ic putt ing a cup filled with airsoft bb's and using it like a shotgun
Arzon says: Jun 25, 2008. 10:28 PM REPLYEver thought about making a triple barreled cannon? Use 9 Pringles cans, tape them together real good and fire one at a time? Fire, rotate, fire rotate, fire,rotate, reload? When I first saw this, thats what I was going to do, but I'm underage, so I can't.
Oh and one more thing, Could you use those tubes at those clubs that can hold up to 6 to 9 at once? Obviously can't fire that many at once, but the tubemight work out..Allot tougher than those Pringles cans.
http://www.instructables.com/id/Tennis-Ball-Mortar/
Arzon says: Jun 26, 2008. 5:23 PM REPLYYou could angle the hole on Step 2 part 6 so they all face the same direction, up. That way you don't need to rotate it.
rawdog33 says: Jun 20, 2008. 1:49 PM REPLYI built this cannonthng and when fire it the cannon makes a shwoop type bang noise but the tennis ball wont leave the barrel. What am i doing wrong?
thedog458 says: Apr 19, 2008. 4:42 AM REPLYhey really good Instructable. now this is gona be a really dumb question but do u have to use the lighter fluid?(coz where I live they don't sell it):(
pyromanizak says: Jun 14, 2008. 12:00 AM REPLYspray some butane in there
Tetranitrate says: Apr 19, 2008. 9:19 AM REPLYYeah, you kinda do need the lighter fluid. Where do you live that they don't sell it, North Korea?
thedog458 says: Apr 19, 2008. 11:20 PM REPLYlol no I live no coober pedy. but thanks any way.
irish meatball says: Jan 2, 2008. 11:14 AM REPLYi love this thing! i almost lit my neighbors house on fire with it though.... when i shot it the ball came out on fire and landed on their roof! (thank god it rolledoff)
paintballer111 says: Mar 13, 2008. 6:54 PM REPLYhey you can soak the ball in water and it'll still shoot
pyromanizak says: Jun 13, 2008. 11:58 PM REPLYits better to soak it in petrol
solidacid says: Apr 22, 2008. 6:53 AM REPLYbecause you liked the pain Hmm?
XI3 says: Feb 1, 2008. 9:13 AM REPLYlol thats hilarous. i made a mini one out of some small pvc pipe, (shoots mini marshmallows and marbels)and the bottom blew off of it and sent burning lighterfluid onto my pant leg. i almost didnt put it out,.
Kendallkip says: Jun 19, 2008. 5:39 PM REPLYperfect for mini smores lol
i do crazy stuff says: Jun 9, 2008. 8:58 PM REPLYmaby if you shacke the liquid it could makevapour easier too and if u head it up using blueice you can heat that up and then it will make it combustable hint:put the blue ice around the propelant cartage and let it head up awesome for shooting and if you play airsoft you can use it to make covering fire
i do crazy stuff says: Jun 9, 2008. 8:56 PM REPLYlolz i have the stuff to make it my parents are strict though so i cant make one but i can make a modle
lighterkid19 says: Jun 4, 2008. 11:56 AM REPLYwould it work better if you put the lid on the top can when the fuid was evaporating so the gas couldnt come out?
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