From brett@sr.hp.com Thu Mar 17 16:48:59 1994
Date: Thu, 17 Mar 94 12:34:40 PST
Subject: The Ancient Art of Cannonry
Date: 26 Jul 1993 19:26:06 GMT
..
——————————–
.. The Ancient Art of Cannonry v1.0
…. by
…
jdolske@andy.bgsu.edu
…. 7/23/93
.. ——————————–
===
0.0 Index
Section Title
0.0 Index
1.0 Introduction and
Disclaimer
1.1 Equipment list
1.2 Credits
2.0 Tennis Ball Cannon v1.0
2.1
Tennis Ball Cannon v2.0
2.2 Tennis Ball Cannon v2.5
3.0 Other Designs and Ideas
3.1 Alternative Fuels
3.2 Alternative Designs
3.3 Assorted Ideas
===
1.0 Introduction and Disclaimer
So you wanna build a cannon? I think nearly everybody
is familiar with the
basic idea of the Tennis Ball Cannon — some type of device that, when
making a cannon
that can shoot long distances (E.g., 100+ yards) can be a bit
tricky. The purpose of this
document is to guide the reader through the
production of a number of different types of
cannons.
Section 2.0, 2.1, and 2.2 deal with the three types of cannons I’ve
built to date. If you just want to build a cannon, these are the sections
for you. These
cannons are probably not the most powerful that can be made,
but they have all been built and
tested. They’re easy to build and easy to
fire, unlike some of the vague net-info I’ve seen
floating around. Hopefully
I’ve been precise enough that anyone with some a little talent and
time can
successfully build a cannon that can fire impressive distances. If you’re
interested in theory or experimentation with unproven designs (by this
author, at least),
check out later sections.
While I’ve never had any serious accidents with my cannons, I
recognize
that this it *not* a harmless sport! I feel that although the simpler cannons
are fairly safe (assuming standard precautions are taken), the more advanced
models can
generate TREMENDOUS pressures in the barrels. The power of such
simple devices still amazes
me. With this said, keep these points in mind:
.* Don’t build and use any of these
cannons if you’re not willing to
.take a risk. If you feel wary of setting off large fire
crackers,
.this sport isn’t for you.
.
.* I’m not perfect person, and this isn’t
a perfect guide. Just
.because I don’t mention something or I leave a point out doesn’t
mean
.it isn’t important. Use some common sense.
.
.* Play it safe! Wear
eye-protection (e.g., impact resistant goggles)
.and ear-protection. These things can blow up
and can make VERY loud
.bangs. A sturdy pair of gloves is also a must. I’m not kidding — I
.is recommended
also for use as a "blast shield" around the cannon.
.If these cannons explode,
you’ll be glad for 1/4" or more of PVC
.between it and you.
.
.* Read
through this entire document before building or buying
.anything.
.* I take no
responsibility for your actions and/or stupidity. If you
.get hurt, it’s not my fault. Use
this information at your own risk.
Please email me with any
suggestions/ideas/experiences. The quest for the
bigger, better, farther, safer cannon never
ends!
===
1.1 Equipment list
Here are some basic items you’ll want
to have on hand when building cannons.
Don’t run out and buy everything at once — Not all of
it is used in every
cannon.
.* Duct Tape — Used to reinforce cannon. Plan to use
at least 1/2
.. of a roll for every cannon.
.* Glue — Wood Glue (a.k.a. Carpenter’s
Glue) and Super Glue are handy
.* Cardboard tubes — About 2.5" diameter. Pringles cans
are easiest.
… For future reference, a Pringles can is 9.5"
… long.
.*
Tennis Balls — Your projectile!
.* Pop Cans — Can function as a both barrel components and
as a tip
.. to firmly hold tennis ball.
.* Lighter or Matches — Used to ignite cannon.
Long matches are a
….good idea…
.* Knives — A good sharp knife for cutting
cardboard/tape. A cheap
.. knife can be used to cut cans and other thin metal.
.*
Lighter Fluid — Used as a fuel. Don’t use butane! You want the
… liquid stuff, also known
as Naphtha. "Zippo" is
… a common name brand.
.* Tape Measure — If you’re
interested in exactly how far your cannon
… can *really* fire.
.* SAFETY EQUIPMENT —
See Section 1.0!
===
1.2 Credits
This document was created as a
summary and guide to cannonry after spending
the summer of 1993 building and improving
cannons.
Ideas, suggestions, etc. were also contributed by the following people:
.Kevin Parsley
.brad@slammer.UUCP (Brad Isley)
.dale@unislc.slc.unisys.com (Dale
Clark)
.david@baervan.nmt.edu (Davis Fritchman)
.farb@ecr.mu.oz.au (William_Cuming
FARROW)
.gt5876b@prism.gatech.edu (Rick Farmer)
.i919802@redgum.ucnv.edu.au (Douggie)
.henlib@nevada.edu (Carroll Gardner)
.
.Tidbits gathered from other UseNet rec.pyrotechnics readers
.The Big Book of Mischief v1.3
(TBBOM13.TXT)
===
2.0 Tennis Ball Cannon v1.0
This is the first type
of cannon I built, and it’s also quite simple to
build. This design can fire a tennis ball
about 45 feet. It’s also quiet –
the "whoosh" sound of this cannon probably doesn’t
require hearing protection
unless you’re sensitive to sound. I’d encourage anyone who’s never
built a
cannon before to build this one first; it can later be modified to a
"v2.0"
cannon.
The design of this cannon is extremely simple. The
barrel is made from
between 2-5 Pringles cans (I found that more that 5 has no effect).
Just
empty the cans, and cut off the metal bottoms on all but 1 can. When you
cut off
the bottoms, cut the cardboard sides as evenly as possible to ensure
a good fit. Tape/glue all
the cans together as securely as possible. The one
can with the metal bottom intact should be
the bottom can, everything else
goes on top. Make sure all joints and the bottom are
reinforced especially
strong.
At the base of the bottom can, make a small hole. It
should be no bigger
than 1/4 inch, and no smaller than 1/8 inch. A hole in the metal instead
of
the cardboard should also work, but I found a hole in the side to be less
awkward to
light.
All that needs to be done now is to make a fitting for the tennis ball to
sit in.
The easiest fitting is to cut a circle out from the plastic Pringles
can lid so that a tennis
ball can be snugly wedged into it. You may wish to
run a wire or string through the sides of
the can near the top so your tennis
ball will not fall all the way into the cannon! An
alternative to the lid is
to use a pop can with the top and curved-part of the bottom
removed. The pop
can fitting may shorten the range of the cannon, however.
Now
would be a good time to make sure your safety gear is on!
The cannon is now complete
and ready to be fired. To fuel it, put a squirt
or two all the way down the *side* of the can.
Don’t just dump it all on the
bottom or it won’t work! Do put a few drops on the bottom to
make sure that
there is plenty of fuel by the ignition hole. It doesn’t take very much
lighter fluid at all. Between 1/2 teaspoon and 1 teaspoon is PLENTY. We’re
only interested in
burning the *vapors* of the lighter fluid.
As soon as you’ve put in the fuel, stick the tennis
ball in the top. Wait
5 to 10 seconds to be sure the lighter fluid has vaporized. Now point it
in
a direction that won’t injure anyone or anything, and ignite the cannon with
your
lighter or match.
If all goes well, you will be rewarded with a "whump" and the
tennis ball
will shoot out the top. At a 45-degree angle, the cannon should throw the
ball about 45 feet.
* If your cannon would not ignite:
.- Your hole may be too
small. Try making it a little bit bigger.
.- Make sure the fuel was squirted evenly down the
side, with a little
. extra near the ignition hole.
.- If you’ve fired it before, make
sure you blow out the exhaust
. gasses — the lighter fluid must have fresh air in the cannon
to
. burn.
* If your cannon ignites but is very weak:
.- Your hole may be too
large. Use tape to shrink the size. A large
. hole allows the pressure to vent through the
hole instead of pushing
. the tennis ball.
.- The tennis ball may need to be wedged in
firmer to allow pressure to
. build up before launch. use a smaller circle in the Pringles lid
or
. push in the side of the cola can a bit.
.- If you’ve fired it before, all of the
exhaust fumes may not have
. been blown out. A hairdryer can be used to quickly perform
this.
.- A 2 can cannon will not fire nearly as far a larger cannon. Roughly
. expect
about 20 feet for 2 cans, 30 for 3, 40 for 4, and 45 for 5.
===
2.1 Tennis Ball
Cannon v2.0
Well, the first cannon was a good start, but it just wasn’t impressive.
hand. Now
enter the exciting world of the "baffle." By placing an obstruction
across half of
the diameter of the cannon at regular intervals, the pressure
produced by the cannon is
GREATLY increased. I suspect the baffles slow down
the combustion of the vapor, allowing for a
more complete burn, but that may
not be correct. In any case, you can at least triple the
range of a v1.0
cannon by just adding a few baffles.
WARNING! This is where
these cannons become much more dangerous! The noise
produced is now much, much, MUCH louder —
ear protection is a MUST! I can’t
stress this enough. I personally lost hearing for a few
minutes after my first
shot — stupid, but I’m much more careful now. The pressures involved
are
also tremendous. The bottom end of a Pringles can is always dented and warped
after
the first firing, and you’ll always get seams blown out. The baffles,
which are made from
metal, have the potential to produce shrapnel. And, of
course, the tennis ball has much more
energy. I’ve heard these can cause welts
at close ranges.
I strongly suggest
first building a cannon of no more than 2 cans. It’s
fairly simple to add on one can at a time
– this will give you a feel for
just how much reinforcement to use when constructing cannons.
Use of a PVC
"blast shield" is strongly encouraged!
The range on these
cannons is impressive. A 3-can cannon can fire over
120 feet, and a 4-can cannon can reach 100
yards! Beware of blow-outs. The
first time a baffled cannon is fired, you will probably find
areas around
seams where the cannon has split the duct tape. After securely taping these
up you can easily add 100 feet of range. Thus, the second shot is always more
impressive than
the first.
A baffled cannon is also harder to fuel and ignite. Your first few attempts
may not work well at all, or may be very weak. Don’t be fooled!
Construction of this
type of cannon is similar to that of a v1.0, except
for the baffles. The best material for
baffles I’ve found are the sides of
pop cans. Use some sort of cutting instrument to cut off
the top and
bottom to a can, and slice down the side to create one sheet of metal.
Flatten this sheet out.
For baffles in the middle of a can, simply make a straight cut
through
half of the can. Then insert the metal sheet, and cut so that it extends
about
1.5" from the side of the can. Baffles on a seam between cans just
need to be cut to
shape.
….. Sheet of metal
.(Top view) /
….. /
.
.—————————-.
. | |
. | |
. | |
. | |
. | __—__
|
. | /’ `\ |
. | .’ `. |
. |______|_____________|_______|
.. `. .’
…\ /
… `–___–’
…. \
…. \
…. Pringles can
Using the
extra metal on the sides, use a pair of old scissors to cut
flaps. These will be used to
secure the baffle to the can to prevent them from
being blown out. The ASCII pic below shows 6
crude flaps. One-by-one, bend
the flaps down and tape them securely to the can. You may wish
to use some
wood glue here to help get a tighter fit. The baffles should alternate sides
so that you cannon see more than 2 baffles as you look into the cannon.
.
.—————————-.
. | \ | / |
. | \ | / |
. | \ | / |
. | \ | /
|
. | \ __—__ / |
. | \/’ `\/ |
. |——.’ `.——-|
.
|______|_____________|_______|
.. `. .’
…\ /
… `–___–’
Once all the cans are baffled, you’ll have a cannon with a side view
something like this:
(Cutaway view)
..__________________________________
. | | |
.
|_____________|_____________|______
Make sure you use LOTS of tape to reinforce
the cannon. On the last cannon
like this I made (4 cans), I used about 3/4 roll before the
first shot, and
more afterwards to patch blow-outs. You can’t use too much. Pay special
attention to the seams and cuts for the baffles. Make sure you’ve got plenty
holding on the
back or it will blow off! If you’ve been firing from a hole on
the bottom instead of the
side, consider putting the hole on the side so if
the back blows off it won’t hit your
hand.
Now would be a good time to put on your safety gear!!!
Fueling
baffled cannons is a bit trickier because you don’t have a clear
route down the side. Get the
lighter fluid as far down as you can by
squirting down the top, then flip the cannon over and
squirt some through the
ignition hole. Rotating and tilting the cannon will help the fluid get
to the
middle. Stick in the tennis ball, and let the fuel evaporate for about 20
seconds. Make sure you’re wearing a glove when you ignite this! You’ll burn
any fingers near
the ignition hole if you’re not wearing gloves…
Hopefully you’ll hear a loud boom
(muffled, of course, through your ear
protectors) and the tennis ball will shoot about between
100 feet and
100 yards. Now take a look at your cannon. Patch any blowouts with plenty
of tape. Observe the denting done to the bottom of the Pringles can and
damage done to the
baffles. These cannons are good for about 5 shots before
the baffles are completely destroyed.
Now go find your tennis ball. 
* If your cannon would not ignite:
.- Check
fixes listed under Cannon v1.0
.- Baffled cannons take much longer to vent exhaust fumes from
. previous firings. Always blow through the ignition hole to push
. out the exhaust.
. area?
* If
you cannon performed weakly:
.- Did you allow the lighter fluid to evaporate?
.- See
caution above about exhaust fumes.
.- On larger cannons, vapors may not be reaching the middle
of the
. cannon. Try putting fluid in the bottom first, and blowing though
. the
ignition hole to force vapors into the middle.
.- Check your baffles. After 4 or 5 shots they
are badly damaged or
. destroyed.
.- Refuel and try again. Sometimes they seem to fix
themselves.
===
2.2 Tennis Ball Cannon v2.5
This section is
still "under construction." As of this writing, I have not
completed or tested this
cannon, but I will describe it’s construction. This
cannon is basically the same as v2.0, but
is designed with strength and
durability in mind.
The barrel of this cannon is no
longer made from Pringles cans — an
important benefit to those of you sick of eating Pringles
by this point!
Instead, use a thick cardboard tube of about the same diameter. These are
the kinds of tubes used for mailing things, storing blueprints/drafting plans
in, etc. A good
art store, mailing store, or office supply store should have
something like this in stock. I’m
using the shipping tube from 1960’s vintage
M518 (?) 2.5" rockets, but other cardboard
tubes will work just as well. I’ve
seen cardboard tubes with walls in the 1/4" range, so
these should hold up
much longer than a Pringles can.
The tube I’m using already has a
metal end on it, but most others don’t.
I should think a PVC end-cap or tin-can of the
appropriate diameter would
work well. Be sure to use extra tape to hold the end on and to help
prevent
shrapnel!
Unfortunately, these cardboard tubes lack the smooth foil/plastic
coating
that the Pringles can had. I plan to use a polyurethane (The type in a
spray-paint type can) to coat the inside to prevent the fuel from soaking
into the
cardboard.
The baffles are made from sheet metal, the type used in air duct work is
with pliers.
===
3.0 Other Designs and Ideas
The following sub-sections are, unless
noted, untested by this author. Some
designs/ideas were submitted by other
"cannonists," some are just theories
or thoughts. I’ll try to note which the case
is. Experiment at your own risk!
===
3.1 Alternative Fuels
The fuel
used by most cannons is just lighter fluid (naphtha), but other
fuels are available — some
are reported to be much more powerful.
.* Fuels that don’t work: (experience)
.
-Gasoline: I thought this would be great, but I just wasn’t
.. able to get the cannon to
light. This may just
.. be tricky to use properly.
. -White Gas, a.k.a. Coleman Fuel:
Same thing, wouldn’t ignite.
.* Propane: (experience)
. This worked quite well,
it’s as good or slightly better than
. naphtha. Propane is certainly worthy of further
study…
.* Alcohol: (submission)
. Also known as denatured ethyl alcohol. This
is supposed to be
. more powerful than naphtha, but is also supposed to be much harder
.
to reliably measure/ignite.
.* Engine starting fluid: (submission)
. Also known
as ether (one brand is diethyl ether), this seems to
. be second in popularity. One drawback
is it’s higher cost. Be sure
. to only use with STURDY cannons! This is supposed to be
quite
. powerful.
.* Acetylene: (submission)
. Also known as welding gas.
Acetylene/air mixtures can be
. *extremely* powerful, and have the potential to be ignited
from
. even tiny amounts of static electricity. Use caution with this!
.* Calcium
Carbide: (submission)
. When mixed with water, this produces a gas closely related to
.
Acetylene — follow similar precautions.
.* Hair spray: (submission)
. Commonly
available, but I would imagine that other fuels would
. produce better results. I would also
think this would leave a
. sticky residue in the cannon.
.* Hydrogen/Oxygen:
(untested)
. This should produce some impressive results, but has the potential
. to be
dangerous. A hydrogen/oxygen mix (66%/33%) will produce the
. best results, but a hydrogen/air
mix should also work (air is 20%
. oxygen). A cannon filled with pure hydrogen will not
work.
. A fairly simple way to produce a hydrogen/oxygen mix is by
. electrolysis of
water. This has the advantage of producing the
. gasses in the exact ratio.
. Hydrogen
alone can be collected as the byproduct of dissolving a
. metal in an acid. Aluminum foil in
muratic acid (usually about
. 9M HCl) works fine.
.* Acetone: (untested)
.
Acetone evaporates quickly, but I’m not sure how explosive the
. vapors are.
.*
Propylene Oxide: (untested)
. This is what the military uses in Fuel-Air Explosives. I bet
this
. stuff would be great to use, but I have no idea on where to get
. some, and it’s
probably highly toxic.
===
3.2 Alternative Designs
.* A cannon made
from pop cans: (submission)
. This design is basically a cannon using 1 can as a combustion
. chamber, and 4-5 cans as a barrel. This design may not be practical
. today due to
pop cans being pressed/molded rather than rolled steel
. with ends put on. In any case, the
tops and bottoms of 4-5 cans are
. removed and the cans are taped together. I suggest using
plenty of
. tape on the sides to prevent blowouts and (especially) shrapnel.
. The
"chamber" can has holes punched on top — a LOT of holes — and
. a small hole at
the bottom to ignite the cannon.
. With a few drops of lighter fluid in the combustion
chamber, shake
. the cannon to help the fuel vaporize. This cannon is supposed to
.
fire about 100 yards.
.* Another pop can cannon: (submission)
. This is similar
to a v2.0 cannon. Cut the tops off of 4 cans, and
. 1/2 the bottom on 3 of those cans.
Securely glue and tape these
. cans together, using the can with only the top removed as the
base
. for the cannon. Again, use plenty of tape on the sides.
. Use a few drops of
lighter fluid for fuel. No ranges given, but
. it is claimed to have a "significant"
kick.
.* Yet another pop can cannon: (submission)
. Same as "Another pop can
cannon" but a soup can was used for the
. base. With ether as a fuel, this cannon is said
to fire 200 yards.
.* Juice can cannon: (submission)
. Simple construction. A
3-liter metal juice can with a 2-foot
. length of natural gas pipe stuck in the top. A
weighted 35mm film
. canister was used as a projectile instead of a tennis ball.
.* Propane cylinder cannon: (submission)
. This one certainly sounds sturdy! Cut the top off
of two empty
. propane cylinders, and the bottom off from one of them. These are
. the
thinner kind used for handheld torches, not the squat/fat ones
. used for camping. Weld the
two cylinders together, and weld a nut
. over the ignition hole for a spark plug to screw into
for remote
. ignition. This cannon was used with acetylene gas.
.* Aerosol can
cannon: (submission)
. Barrel:
. Take a tall aerosol can of correct diameter.
Most paint cans are
. just right. The large Gunk engine cleaner cans are great. Make
.
sure the can is EMPTY. This means punch a hole in it in a
. location that is to be discarded.
This is to be sure there is no
. pressure remaining. With a dremel tool or other grinder, cut
off
. the top completely. This includes removing the crimp. Leave a
. smooth end. Then
take a can opener and remove the bottom. Leave
. the crimp ring on the bottom of the can.
. Chamber:
. Smaller aerosol can of same diameter. Large WD40, etc. With same
. dremel tool or similar cut off the very top of the dome. The hole
. you cut will need to be
about 1/3 to 1/2 the diameter of the can.
. This will form a stop for the ball as it is
loaded. Punch a small
. hole in the side near the bottom. If you want more power, use a
. tall can for the chamber. I’m quite pleased with the medium sized
. can for a chamber.
. Ignition source and handle:
. Get one of those trigger operated butane lighters that
has a piezo
. electric trigger. Zippo makes the one I use. The lighters I use
. are red
and white with a long chrome-plated steel extension for
. lighting fireplace starters. Remove
the coil thingie behind the
. trigger. Unfortunately the coil thingie will vary quite a bit.
. Some are not usable - they have a brass cap on the end. I was
. unable to solder a
wire to the brass cap. Solder a wire to each
. post on this piezo thingie and insert it in a
handle of sorts.
. I made a pistol-shaped handle attached to a flat board like so:
….. \
. ——————————-=——————
.
| /| |
. | Dome -> | | |
barrel -> | \| | <- chamber
.
——————————-=——————
….. ================== <- flat
board
…… \ \
… piezo thingie trigger -> [####]=\== <- wires
…….\
\
……. \ \ <- handle
……. —–
. Construction:
. Using duct
tape, tape the ringed end of the barrel to the dome
. end of the chamber. Be sure the fit is
tight. Drill a hole in the
. handle where you want the trigger. Arrange for the wires to go
in
. first and allow for an exit where you want it. Attach the handle
. to the flat
board with screws. Duct tape the handle to the
. chamber. Run the wires around to the hole
you punched. Twist the
. ends of the wires together for about an inch so they will stay in
. close proximity. Strip the ends about 1/8" and make a gap about
. 1/8".
Test the spark by pulling the trigger. Get as long a spark
. as the piezo will make. Insert
the wires into the hole such that
. the gap is close to the center of the rear of the
chamber. Test
. spark with no fuel to make sure you get good ignition. If you
. can,
weld the cans together. The tape is slowly dissolved by
. fuel.
. Use:
.
Denatured alcohol is difficult to measure into a proper combustible
. mixture. It is also much
more powerful than naphtha and caused the
. handle to be ripped off the chamber in our tests.
Two layers of
. duct tape solved this. We have had excellent repeatability with
. the
following fueling method with naphtha. If recently fired you
. should sling the gun around in
large arcs to get a fresh charge of
. O2. Holding the barrel upright using a standard lighter
filler
. squirt for 1 second or a little less straight through the hole in
. the dome
of the chamber. Make sure that approximately 1 second’s
. worth goes through the hole in the
dome. Fuel in the barrel is
. useless. IMMEDIATELY insert a tennis ball into the barrel ALL
THE
. WAY to the dome. Wait about 5 seconds and pull the trigger.
. Don’t get in the
way of the ball. I have a hole in the ceiling of
. my garage from a shot. If you use alcohol,
I’d stick to the
. smaller chambers because it’s a lot more powerful than naphtha.
3.3 Assorted Ideas
.* Try a nighttime firing. These cannons, especially
with starting
. fluid for a fuel, as supposed to produce a decent sized flame/flash.
.*
Aluminum powder sprinkled in the end of the barrel is supposed to
. produce a bright flash.
(Probably best viewed at night)
.* Try using one of the infamous dry-ice bombs in the bottom
of a
. larger chamber instead of a fuel that is ignited.
.* I’d really like to make a
reliable system for remote ignition. Any
. ideas on this? I’ve had no success using
model-rocket igniters or
. steel wool. (Steel wool will sortof burn when a current is
passed
. through it) A spark plug may work well…
.* If you get a reliable remote
ignition system, sealing off both ends
. of the cannon would probably produce a rather loud
bang. (And
. probably shrapnel)
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