SpudFiles Wiki - User contributions [en]

Copper pipe

2006-03-04T22:43:35Z

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Copper pipe and fittings are rising in popularity as a spudgun construction material. It is more expensive than [[PVC]] (especially larger dimensions) and much heavier, and is therefore mostly used for small caliber cannons (1" or less). Copper pipe is also rated to much higher pressures than PVC, which makes it well suited for high pressure [[pneumatic cannon]]s and [[hybrid cannon|hybrid]]s. It is is also often used for making [[fuel meter]]s. Copper pipe is usually joined by [[sweating]], or by using [[compression fitting]]s. The latter are more expensive, and may slip under high pressure unless braced correctly, but they require no tools other than a wrench for mounting. Threaded fittings for copper pipe are usually made of brass.

Copper pipe comes in two tempers, annealed and drawn. Annealed copper pipe is very soft, and can usually be bent by hand. Drawn copper pipe is rigid, and will flex rather than bend (to a certain limit). Drawn pipe is the most useful in spudgun construction, since it will keep its shape and not get damaged easily. It is also rated to about twice the pressure as an annealed pipe of the same size.
[[category:construction materials]]

History

2006-03-04T22:42:26Z

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A Brief History of Spud Guns

A loooonnngggg time ago, fabled to be about 40 years, somewhere (in America of course) some middle-aged guys were bored so gathered up a bunch of beer cans (they were steel back then), duct tape, gasoline, and at least one tennis ball. Both ends of all cans were removed save one, from which only the bottom was removed; the peel-top hole end was left as is.

Legend has it the idea was struck that if all these cans were securely taped together to make a long tube, the tennis ball could be stuck down it muzzle loader style and fired by putting a small amount of gasoline in the bottom can (with the hole lid as the breech) and one brave soul (the one that had consumed the most beers) holding a lit match or lighter near the peel-top hole. Miraculously the tennis ball was expelled with great velocity. Much whooping and hollering ensued, and the device was promptly reloaded to verify the first one was not a 'fluke.' Hence the backyard cannon was born.

Sourced from the [http://spudtech.com/content.asp?id=3 Spudgun Technology Center]

Muzzle velocity

2006-03-04T22:41:53Z

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'''Muzzle velocity''' is the velocity of the projectile immediately after leaving the barrel, and other than a few hypothetical situations, is the fastest the projectile will ever go. Muzzle velocity is typically measured by a chronograph, a device that measures the time it takes the projectile to travel between 2 sensors, although less accurate results can be gathered from a [[ballistic pendulum]] or the quite inaccurate [[hang time]] test.

==Muzzle energy==

This is muzzle velocity's companion, and can be calculated as following:
1/2MassVelocity^2 , where mass is in kilograms, velocity is in meters/sec, and output is in joules.
For instance, a 100g potato going 150 meters/sec (a large [[combustion launcher|combustion]] is capable of this) would have a muzzle energy of:
1/2*.1*150^2=1125 J

1.5 joules is approximately 1 foot pounds, the traditional imperial (US) unit of energy for firearms.

It should be noted that in the case of saboted projectiles being simulated with the [[GGDT]], the acctual muzzle energy is equal to GGDT muzzle energy * projectile mass/projectile mass+sabot mass.

The following is a table of misc, rim, and centirfire ammunition muzzle energies, for comparison.
<table><tr><td>'''projectile'''</td><td>'''energy, J'''</td></tr>
<tr><td>typical paintball</td><td>17</td></tr>
<tr><td>.22 rimfire</td><td>180j</td></tr>
<tr><td>.45 colt</td><td>675</td></tr>
<tr><td>.223</td><td>1900</td></tr>
<tr><td>30-06</td><td>4500</td></tr>
<tr><td>410 slug</td><td>1000</td></tr></table>

EVBEC

2006-03-04T22:40:30Z

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EVBEC stands for "Energy & Volume Based Estimator for Combustions", and is intended to calculate the muzzle velocity of [[combustion launcher]]s.
The latest version (V 1.2) can be downloaded from [[spudfiles]] right [http://www.spudfiles.com/forums/viewtopic.php?t=1212& here]

==Physics model==
EVBEC assumes that:
*Energy produced from combustion is directly proportional to chamber volume.
*The portion of this energy utilized in a launcher is directly derivable from the [[Chamber to barrel ratio]].
*The [http://www.burntlatke.com/launch.html latke tests] are accurate.

From these assumptions, one can get the driving equation of EVBEC:
vsimulation=vtest/SQRT((Stest/Ssimulation)/(Mtest/Msimulation))

Where:
*v is velocity
*S is chamber volume
*M is mass

Using this, the velocities are calculated for all the ratios tested by latke, and the proper ratio to use to find the velocity is indicated on a graph.

==limits of the physics model==
The physics model does not account for the following:
*Differing burn times
*Variations in efficiency caused by different projectile masses. (which is why the 1.5" data is "out there")
*Odd effects caused by launcher design (ie; breach restrictions).

Several of these problems are likely to be alleived when the results of some recent tests being carried out by pimpmann22 of the spudfiles forums are released.

==use==
Directions for use are provided in the documentation of the program.

Butterfly valve

2006-03-04T22:39:30Z

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[[Image:Butterfly_valve.jpg|frame|A typical butterfly valve]]
A '''Butterfly valve''' is a type of flow control device, used to make a fluid start or stop flowing through a section of pipe. The valve is similar in operation to a [[ball valve]]. A flat circular plate is positioned in the center of the pipe. The plate has a rod through it connected to a handle on the outside of the valve. Rotating the handle turns the plate either parallel or perpendicular to the flow of water, shutting off the flow. It is a very robust and reliable design. However, unlike the ball valve, the plate does not rotate out of the flow of water, so that a pressure drop is induced in the flow.

These valves are typically used in applications where a very large valve is needed, such as pumpkin chucking and dams, and are available on ebay in sizes from roughly 2" to 10+". These are very cheap, with a 4" metal valve often selling for 50-20$ or less. Unfortunately, most butterfly valves use bolts to attach to the pluming system, requiring one to buy a flanged adapter or use flanged metal pipe.

There are three types of butterfly valve:
# '''Resilient butterfly valve''' which has a flexible rubber seat. Working pressure up to 1.6 Mpa (232 psi)
# '''High performance butterfly valve''' which is usually double eccentric in design . Working pressure up to 5.0 Mpa (725 psi)
# '''Tricentric butterfly valve''' which is usually with metal seated design. Working pressure up to 10.0 Mpa (1450 psi)

== See also ==
* [[Ball valve]]
* [[Gate valve]]
* [[Globe valve]]

[[category:valves]]

Pilot valve

2006-03-04T22:38:56Z

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A '''pilot valve''' is the valve used to release the air from behind a [[diaphragm valve|diaphragm]] or [[piston valve]], causing it to open. It can vary in flow from a [[schrader valve]] to a 2" [[ball valve]] and above. Small diaphragm and piston valves are also sometimes used as pilots for bigger valves.

[[Blowgun]]s are commonly used as pilot valves since they are easy to open by hand, and many have a trigger grip that fits well into the design of a gun. [[Ball valve]]s are sometimes used since they have much better flow than blowguns, though they are less ergonomical.

[[Slide valve]]s and [[three-way valve]]s are sometimes used as pilots for semi-automatic cannons, in one position the chamber is filled through the pilot, in the other the pilot is exhausted and the main valve triggered.

Some problems that indicate the need for a higher flow pilot valve:
* "[[honking]]" of the valve. This loud noise indicates that your valve is oscillating open and closed.
* A 'dull' sounding launch. (note that this does not apply in the case of a [[chamber to barrel ratio]] near optimum, because there isn't much energy left over to make a loud "crack".)
* [[GGDT]] simulation indicates that your performance would be improved with a larger valve.

[[category:valves]]

Butane

2006-03-04T22:38:34Z

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[[Image:Butane.gif|frame|The butane molecule]]Butane is quite similar to [[propane]], but with a slightly lower [[stoichiometric]] value of 3.23%. Pure butane is found in lighter refill canisters.

Butane has a lower vapor pressure than propane, and its boiling point is -0.5°C (31.1°F), so it won't work well in low temperatures. It is most easily used the same way as [[aerosol]] fuels.

Disposable canisters with mixtures of butane, propane and (sometimes) isobutane is sold for camping gear and blowtorches, this gas evaporates at lower temperatures and can be used in cold weather.

[[category:fuels]]

Safety

2006-03-04T22:37:23Z

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Spudguns can be very dangerous if built or used improperly. However, if they are respected, they can be great fun.

==Launcher safety==

*Use good, safe [[cannon construction|construction methods]] and materials.
*Follow the rules of basic gun safety: never point the cannon at anything you don't want to destroy, and treat it as if it's loaded at all times. Never look down the barrel.
*Always make sure you are firing in a safe direction that is free of people, pets, livestock, cars, houses and other property. Use a solid backstop or make sure you have a clear landing area.
*Don't look into the chamber of a [[combustion cannon]] that has failed to fire. Fresh air can make a rich gas mixture lean enough to ignite.
*Don't use PVC cannons in cold weather. Sub-freezing temperatures makes PVC brittle and increases the chances of catastrophic failure.
*Don't use a cannon that is cracked or heavily scratched, or has been dropped on a hard surface. Joints may be weakened and the pressure ratings on damaged parts cannot be trusted.
*Don't use excessive pressure in a [[pneumatic cannon]]. [[PVC]] pipe is not rated for pressurized air because of the shrapnel risk, so use in a pneumatic gun is considered to be outside pipe specifications in the first place. Never exceed the pressure rating of the lowest rated part.
*Don't use overly powerful fuels in a [[combustion cannon]]. Solid fuels and very reactive gases such as [[hydrogen]] or [[acetylene]] are not suitable for use in spudguns. Don't use oxygen to enrich the mix in a PVC cannon.
*Use hearing protection when firing loud combustion and hybrid cannons, especially in an enclosed space. Use eye protection if there is a chance of splinters or other debris from the projectile hitting the target.

==Don't shoot living things==
A typical spudgun is capable of launching a potato weighing 50-150 grams a couple hundred yards with the muzzle energy of a powerful handgun. Longer distances are easily achieved with rocks,PVC darts,golf balls, and other aerodynamic projectiles.

This energy, carried by a projectile as fragile as the humble tuber is easily capable of killing someone, or at least breaking bones or putting out eyes. As to property damage, a thrown potato is capable of destroying windows, smashing decorations, and the like.

Most launchers can put a vegetable through a piece of 1/2" plywood, and many can put it through 3/4".

Firing a sock at a door can puncture the door from 10 feet away.

Firing a sock at a friend can (and will) puncture the friend causing hospitalization or death.

The same applies to short/and or small-bore launchers too.

Despite their great potential to do harm, it is not looked upon well if you (attempt) to use your launcher as a hunting instrument. They are often hard to aim, leading to a low probability of a clean (humane) kill - plus, it is illegal to do so.

Some people don't take the extreme danger of a projectile fired from a potato cannon seriously enough. There are frequent news articles about people injured by potato guns firing projectiles other than vegetables, or people being accidentally shot while handling the gun.

Accidental discharges are the most likely cause of injury however some individuals lack the mental capacity to keep their guns pointed away from others at all times. When a potato gun is pointed at a human being the dangers are extreme. Do not under any circumstances let the barrel of a potato gun point towards another human, even if the gun is not loaded.

The bottom line is: don't aim a spudgun at anyone, at any time, even if you think it's not loaded.

==Ammo Safety==
Some advise against shooting bolts, coke cans full of concrete, and other hard objects out of your gun; saying things along the lines of:
"Anything that is much harder than a spud can cause grievous bodily harm if shot at another person, or any animal for that matter."
...in actuality, even a tater will cause "grievous bodily harm" if shot at another living being. The danger lies in an increased chance of ricochet when using sturdy ammo - use common sense, and don't fire non-shattering ammo at close targets.

Some caution should be taken with shooting loose sub-munitions, specifically gravel or stones, with a [[sabot]] behind them - there is a significant probability of them jamming up, and the barrel being overstressed when the sabot tries to keep moving through the blockage, leading to a failure. Always wrap your lose projectiles in something - paper towels, old socks, and plastic bags are all acceptable.

Sleeving

2006-03-04T22:36:22Z

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==Reasons==
Sleeving is a method of reinforcing pipe, typically thinwall [[PVC pipe]], by placing it inside a larger diameter pipe. For sleeving to be efficient, the outer diameter of the inner pipe needs to closely match the inner diameter of the outer pipe.

Another reason for sleeving barrels is to create more appropriate diameters for specific projectiles. For instance, if the barrel inside diameter is 2.00" and you have a slightly smaller projectile, another PVC barrel could be inserted inside the 2.00" diameter barrel. The resulting smaller diameter barrel would be an appropriate size for a golf-ball or other unusual projectile.

==Methods==
===Direct insertion===
Sometimes, there is a pipe diameter that matches the pipe you want to sleeve close enough to directly insert it. For instance, 1.5" nominal fits very well in 2" sch 80. Often it it glued, normally with a relatively slow-curing glue. However, the force required to cause the pipe to move sometimes makes this overkill.

===modified insert===
This is used in the situation that the pipe you want to insert is too big to do so.
Simply, a lengthwise section of the pipe is removed, allowing the diameter of the insert to be reduced. With much effort, it is then possible to shove this into the outer pipe; the effort required to do so is great enough that gluing it is unneeded.

{{stub}}

Computer Applications

2006-03-04T22:35:57Z

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The certain members of the spudding community have written computer programs pertaining to spudguns:

==the [[GGDT|Gas Gun Design Tool]]==
Written by David Hall (Dhalls of the [[SGTC]]), it is the most commonly used program to predict [[pneumatic cannon]] performance, and is free for the download at Hall's [http://www1.iwvisp.com/thehalls/ggdt/index.html website].

Accuracy of the predictions is typcialy within 5-10% of the actual value, although there has not been much testing of very long where the (unaccounted for) flow resistance due to barrel length is significant, or very high pressure launchers where the non-modeled liquification of the propellent gas(ses) may take place.

==[[CALM]]==
Standing for Compressed Air Launcher Model this is a Pneumatic Launcher simulator program by AKB of the [[SGTC]]. Since it is written in the Python programming language you can read the code and see how it works. It is not graphical, but produces tables of pressure, velocity, height, etc.

CALM can be downloaded at http://www.qsl.net/wb6zqz/calm.html .

==[[EVBEC]]==
EVBEC stands for Energy & Volume Based Estimator for Combustions. Written by boilingleadbath, it is based on [http://www.burntlatke.com Latke's] chamber:barrel test data.

==Works in progress==

Gas Gun Design Tool

2006-03-04T22:34:39Z

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Hall Consulting's '''Gas Gun Design Tool''' is a simulation program to aid the design of [[pneumatic cannon]]s. It is available [http://www1.iwvisp.com/thehalls/GGDT/index.html here].

==Physics model==
As of version 4.2, in modeled the fol owing features:

# Valve configuration and opening times. In fact, GGDT models five different types of valve: chamber sealing pilot (see [[piston valve]]s), barrel sealing pilot (ie, barrel sealing [[diaphragm valve]]s and [[piston valve]]s, [[burst disk]], [[hammer valve]], and "generic." Each of these valves have different behaviors and GGDT accounts for these behaviors (more on that below).
# Pressure drop across the valve oriface.
# Temperature (and thus pressure) increase in the valve pilot due to work performed by gun gases on the valve piston/diaphragm.
# Gas leakage from the main valve body into the upper valve chamber ([[pilot]]).
# Performance differences due to different gases.
# Temperature effects on gas properties (and thus, performance).
# Performance limitations due to flow choking in the valve or the barrel.
# Valve effective oriface increases due to lowered valve throat Mach number.
# Temperature (and thus pressure) drop in the barrel due to work performed by the gas accelerating the projectile.
# Gas leakage around the projectile in the barrel.
# Compressibility (Mach) effects on air pressure both in front of and behind the projectile to include the creation of shocks. (see [[shock heating]])

However, it does not consider:

# Energy losses associated with turbulence or frictional forces between the gas and the gun's reservoir/barrel walls. In other words, pressure drops due to bends or rough edges in the gun's plumbing.
# Reservoir fineness ratio's effect on performance.
# Freezing or liquification of gun gases.

However, these are not a major concern in most launchers, as they require very long barrels or very high pressures to notice.
Typically, the GGDT outputs numbers within 5-10% of the measured value, although this is somewhat clouded by not knowing the proper input numbers.

==Use==
See Hall's [http://www1.iwvisp.com/thehalls/ggdt/index.html page] on use
{{stub}}

Launcher configuration

2006-03-04T22:32:57Z

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== Chamber-Barrel position ==
The possibilities are limitless, but these are the most common ways to position the chamber and barrel:

*[[Linear]] or inline
*[[over/under]]
*[[co-axial]]
* "multiple tanks and Ts"
Like the setup used on the [http://www.spudtech.com/images/products/mega-II-ov2.jpg megah-launcher]. However, the multiple bends results in slightly reduced flow. [[GGDT]] simulations typically don't show much improvement from the increased chamber volume.

== Projectile delivery ==

* [[Muzzle loading]]
The basic option. Projectile loads from the front, and reload time is quite slow. If there's any significant friction between the projectile and barrel, a ramrod must be used to push the projectile down the barrel.

* [[Union]] loading
A step up. Allows you to load the projectile from the breech, but requires alignment and twisting afterwards. A union can also hold a [[burst disk]]. [[Cam lever coupling]]s are similar to unions, but faster to open and close. They are usually rated for less pressure than unions.

* [[Breech loading]]
Allows you to load a projectile from the breech (end of gun towards user). Mechanism and loading time varies by construction technique.

* [[Vogt-pattern]]
A tube holds the ammo, about around half a dozen balls. Upon firing, the balls are sucked one-by-one into the airflow, resulting in a tight grouping of balls fired a few dozen milliseconds apart. Suitable for large-caliber weaponry (has been tested with as large as [http://forums.spudtech.com/topic.asp?TOPIC_ID=11012 tennis balls]) Named after the late [[Bill Vogt]], who came up with the design.

Stun gun

2006-03-04T22:31:49Z

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[[Image:Stun-open.jpg|frame|A stungun being modified for use in an ignition system]]'''Stun guns''' create a large high voltage spark, and are therefore useful as [[ignition source]]s. They are one of the simplest to set up, the [[spark gap]] is simply connected to the main electrodes. Stun guns provide the highest voltage of the common ignition sources, 50-900kV, but spark length is limited by the default gap. They are typically powered by one or more 9V batteries, and the trigger switch only carries battery voltage, so it can be replaced a remote trigger switch in a more convenient place. The entire stun gun circuit can also be removed from the original enclosure and mounted in a project box or similar, though the default gap should always be left intact to prevent overvoltage and arcing. The spark gap needs to be smaller than the default gap for the circuit to function.

Stun guns are relatively cheap and very reliable ignition sources, but they are not dimensioned to be powered on for more than a few seconds at the time and could break. Most often it is the main switching transistor that dies, it can usually be replaced with any model of similar or higher ratings.

Tasers and cattle prods also contain similar high voltage sources, but are less well suited as ignition sources. Tasers are expensive and have a lot of superfluous components, cattle prods have a lower voltage and can only drive small spark gaps.

Stun guns are illegal in several countries, so alternate ignition sources are more commonly used outside the US. The design of a [[camera flash]]+[[ignition coil]] ignition is very similar to that of a stun gun.
[[Category:Ignition sources]]

Starting fluid

2006-03-04T22:31:08Z

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'''Starting fluid''' is normally known as ether, diethyl ether, or ethyl ether. All types are powerful, some people believe they produce more power than propane. Ethers are incredibly easy to over-fuel however. the upper flammability limit is about the same as the LOWER flammability limit of propane.

Some starter fluids contain oil, which can gunk up the chamber and disable [[lantern sparker]]s. It may also be corrosive to certain plastic and rubber materials. The fluid can be tested for oil by spraying some on a piece of paper, any oil will leave a grease stain after the ether has evaporated.

[[category:fuels]]

Stoichiometry

2006-03-04T22:30:24Z

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[http://en.wikipedia.org/wiki/Stoichiometric Stoichiometry] is an important concept in [[combustion cannon|combustion]] and [[hybrid cannon|hybrid]] launchers, since they use the energy from combustible fuels. A stoichiometric mixture is one where the ratio of fuel and oxygen molecules is balanced, so all the fuel and oxygen in the chamber is (in optimal conditions) consumed in the reaction. A [[fuel meter]] system is usually designed to achieve this mixture, which will yield the most power out of the combustion reaction.

===Calculations===

The stoichiometric ratio for gaseous fuels can easily be calculated. When the hydrogen and carbon in a fuel burns, it combines with oxygen as follows:

C + O2 --> CO2 
4H + O2 --> 2H2O 
CxHx + O2 --> CO2 + H2O

If the fuel molecule contains oxygen atoms, they will replace oxygen atoms from the air in the reaction. So for each oxygen atom the fuel contains, one less atom of atmospheric oxygen is needed. To begin calculating the stoichiometric ratio of a fuel, first find the chemical formula for the fuel, and count how many hydrogen, carbon and oxygen (if any) atoms it contains.

Since hydrogen combines with oxygen to make water (H2O), and two hydrogen atoms combine with every oxygen atom, four hydrogen atoms will consume one O2 molecule. Conversely, it can be said that one hydrogen atom will consume 0.25 O2 molecules.

Carbon atoms combine with oxygen to form CO2, so each carbon atom will consume one entire O2 molecule.

Any oxygen in the fuel will lead to one less oxygen atom being consumed from the air. Two oxygen atoms will prevent one O2 molecule from being consumed, so each oxygen atom "saves" 0.5 O2 molecules.

Now we need to find how many O2 molecules are consumed by each fuel molecule, which is calculated as follows:
*for each hydrogen atom, add 0.25 to the amount of oxygen molecules needed
*for each carbon atom, add 1
*for each oxygen atom, subtract 0.5
The resulting number is the oxygen to fuel ratio. To find the fuel to oxygen ratio, divide 1 by the oxygen to fuel ratio. The amount of oxygen in air is 21%, so to find the fractional fuel to air ratio, the fuel to oxygen ratio is multiplied with 0.21. To find the ratio in percent, multiply this value by 100.

To find the volume of fuel needed for a particular chamber, the fractional ratio is multiplied by the chamber volume.

===Concrete example===

Formula of [[propane]]: C3H8

*number of carbon molecules: 3
*number of hydrogen molecules: 8
*number of oxygen molecules: 0

number of oxygen molecules needed = 3*1 + 8*0.25 = 5 molecules 
the actual combustion reaction is as follows: C3H8 + 5O2 --> 3CO2 + 4H2O

fuel/oxygen ratio = 1/5 = 0.2 
fuel/air ratio = 0.2*0.21 = 0.042, or 4.2% 
fuel volume in a 3000 cc chamber = 3000*0.042 = 126 cc

Single formula for fractional fuel to air ratio: (1/(C+(H/4)+(O/2)))*0.21

Piston valve

2006-03-04T22:28:47Z

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A '''piston valve''' is a [[pilot valve|pilot]] operated valve. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphram with a rigid cylinder. There are 2 varieties; barrel sealing and chamber sealing.

== Construction, barrel sealing ==

The piston is often a well fitting cup-shaped object, such as a endcap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. Equalization is accomplished by simply allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].

Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "F" in the "use, barrel sealing" diagram.

These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put coaxially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.

== Use, barrel sealing ==
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]
Operation:
<ol><li>Air is added by filling behind the piston (C).
<li>The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the pressure to equalize] from the chamber.)
<li>More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.
<li>The pilot valve (D) behind the piston is opened, the pressure in the [[pilot|pilot volume]] (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.
<li>The air flows around from the chamber, and into the barrel, propelling the projectile.</ol>

The performance of these valves can be calculated with the [[GGDT]].
If your valve [[honking|honks]], it is probably a good idea to invest in a better [[pilot valve]].
[[category:valves]]

Linear

2006-03-04T22:27:34Z

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A type of cannon where the barrel is directly in front of, and pointing in the same direction, as the chamber. It's slightly cheaper than the over/under configuration, but only by the cost of 2 90* elbows. The linear design is most often used in [[combustion launcher]]s, and this is considered the most basic launcher design. It's also the simplest to assemble, requiring no special tools or fittings.

Bulk tank regulator

2006-03-04T22:26:49Z

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[[Image:Pressure-regulator.jpg|thumb|right|300px|A high-pressure bulk tank regulator]]
A '''bulk tank regulator''' is used to regulate down the output pressure of bulk gas tanks, such as CO2 or scuba tanks. They are made in many different designs for use in welding, cutting, scuba diving, carbonization of beverages etc.

Some regulators regulate flow instead of or in addition to pressure, a pure flow regulator is not useful in most spudgun applications, since it doesn't drop the output pressure from the tank to a safe level.

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Muzzle loading

2006-03-04T22:25:31Z

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The standard way of doing things, because it is the cheapest and easiest to make; in fact, it is not possible to make a launcher that cannot be muzzle-loaded.

To muzzle-load a spudgun:
* Get a (strait) stick, and preferably mark it where it is flush with the muzzle when the pushing end of it is at the desired projectile depth.
* Cut your projectile to size, by either pushing your projectile over your muzzle knife or your separate spud cutter. Paring knifes are not recommended.
* Ram that projectile home. Firm, steady pressure works best. If you cannot get the projectile go down, you may need to scratch it; this is done to allow the air to leak past.

Some design their launchers to be easier to muzzle load by making a small (like 1/16") vent hole at the base of their barrel for air to escape. This air would otherwise prevent the nearly airtight ammo from being rammed down there. Some, however, prefer to install a small valve of sorts. This prevents air or hot combustion gasses from shooting out and decreasing performance and/or burning the operator.

It is recommended that you sharpen your muzzle if you are planing upon shooting produce. Such a modification is called a "muzzle knife". If you do not feel safe having a cutter on the end of your gun, you can instead keep your [[spud cutter]] as a separate instrument.

Flyback circuit

2006-03-04T22:24:54Z

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[[Image:flybackdriver.gif|frame|right|basic flyback driver circuit]]A '''flyback circuit''' uses the flyback transformer from a TV or computer monitor to generate high voltage for ignition. It's one of the more complex ignitions to build, but the hot, continuous arc makes it very reliable.

The image on the right shows perhaps the most basic flyback driver that can be built. There are a few improvements that can be made though:
*Remove the 27Ω resistor, it gets very hot and also seems to limit the output voltage.
*Use a better transistor, the 2N3055 is not well suited for this.

The circuit ''can'' be powered by a 9V battery, but it will be weak and won't last long. It's better to use a RC battery pack or other rechargeable batteries. 12V is a good input voltage.

{{stub}}
[[Category:Ignition sources]]

Compressor

2006-03-04T22:24:30Z

70.31.208.207: spelling

A '''compressor''' is basically an electrical pump that compresses air. They range from small 12V compressors with relatively high pressure but very low volume, to shop compressors with big air tanks for storage, and scuba compressors that can deliver thousands of [[psi]] to fill portable air tanks.

types of compressors:
*'''Reciprocating''' - Uses a reciprocating piston to draw air in through a valve and force the drawn air into a storage tank or through a smaller orifice. They are available with single or multiple cylinders, depending upon the pressure and volume required. Reciprocating compressors are referred to as positive displacement compressors. (1)
*'''Rotary Screw''' - Two intermeshing helical rotars in a twin bore case are used to compress between one convex and one concave rotor. The trapped volume of air is decreased while the pressure is increased. Rotary screw compressors are referred to as positive displacement compressors. (1)
*'''Centrifugal Compressor''' - Unlike the reciprocating and rotary screw compressors, centrifugal compressors do not make use of positive displacement. Air or gas enters the center of rotation of an element and is forced outward. The element can use curved blades, radial blades, or backward blades. The acceleration of the air causes the pressure to rise. (1)

sources:
(1) http://www.ctrlsys.com/library/applications/compressors-2.php

{{stub}}

Breech loading

2006-03-04T22:23:16Z

70.31.208.207: spelling

Many types of breech loaders are employed. The most common methods are to use male and female adapters to connect the barrel to the chamber, as seen here: http://www.spudfiles.com/forums/viewtopic.php?t=183

A method favored due to speed is to use a type of [[Cam lever coupling|cam lock]] fitting to connect the barrel and chamber. one such example is here: http://www.spudfiles.com/forums/viewtopic.php?t=311

One method that is one of the more challenging to make is a bolt action, which can be seen here:
http://pneumaticsniper.mypicgallery.com/

A internal "twist n' lock" can be also used, which is an "inside-out" version of the above sniper, to load a projectile, twist the barrel and pull it from a fitting to open, put in the projectile, push the barrel back into the fitting and twist to close and lock, this takes good measurements to be done correctly, as it may need [[o-ring]] grooves will be fitted inside a coupling very tightly(or else a blow-out will happen, making a whistle like noise), a "L" shaped groove and a bolt in a coupling to lock it.
One advantage this loading method offers is that it looks like a normal muzzel loading spudgun.

[[Category:Accessories]]

Pneumatic cannon

2006-03-04T22:22:06Z

70.31.208.207: spelling

[[image:pneumatic ballvalve cannon.jpg|right|thumb|300px|Pneumatic ball valve cannon]]
A '''pneumatic cannon''' is a cannon powered by pressurized gas, usually air or CO2. They are more complex than [[combustion cannon]]s but also more powerful, and their performance is more consistent.

Pneumatic launchers consist of five basic elements:

*Compressed gas storage reservoir ([[chamber]] for short)
*Filling valve (bicycle [[Schrader valve]]s, [[quick disconnect]]s, etc.)
*Firing valve ([[ball valve]]s, [[sprinkler valve]]s, [[piston valve]]s, [[quick-exhaust valve]]s, and [[burst disk]]s are the most common)
*[[Barrel]]
*[[Pressure gauge]] (for safety & repeatable launches)

In order to fire, the operator loads a projectile into the barrel, fills the chamber with a compressed gas (air [[compressor]]s, hand pumps, [[Pressure regulator|regulated]] bottled gas, and 12 gram [[CO2 cartridge]]s are common filling methods), and activates the main valve thus dumping the air in the chamber to the barrel.

The expansion of the compressed gas propels the projectile down the barrel. The barrel length determines the amount of energy transferred to the projectile and ultimately the velocity of the projectile.

High performance launchers use techniques such as [[sprinkler valve modification|modifying valves]] for faster opening times, using homemade valves, and maximizing the amount of airflow through the valve.

The [[GGDT]] (gas gun design tool) is highly recommended to those interested in pneumatic launchers.

Help:Contents

2006-02-22T22:43:11Z

70.31.208.207: spam removed...

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]

Safety

2006-02-10T01:16:23Z

70.31.208.207: this artical is not dumb, reverted to last change by 68.235.179.129

Spudguns can be very dangerous if built or used improperly. However, if they are respected, they can be great fun.

==Don't shoot living things==
A typical spudgun is capable of launching a potato weighing 50-150 grams a couple hundred yards with the muzzle energy of a powerful handgun. Longer distances are easily acheived with rocks,PVC darts,golf balls, and other aerodynamic projectiles.

This energy, carried by a projectile as fragile as the humble tuber is easily capable of killing someone, or at least breaking bones or putting out eyes. As to property damage, a thrown potato is capable of destroying windows, smashing decorations, and the like.

Most launchers can put a vegtable through a peice of 1/2" plywood, and many can put it through 3/4".

Firing a sock at a door can puncture the door from 10 feet away.

Firing a sock at a friend can (and will) puncture the friend causing hospitalization or death.

The same applies to short/and or small-bore launchers too.

Despite their great potential to do harm, it is not looked upon well if you (attempt) to use your launcher as a hunting istrument. They are often hard to aim, leading to a low probability of a clean (humane) kill - plus, it is illegal to do so.

Some people don't take the extreme danger of a projectile fired from a potato cannon seriously enough. There are frequent news articles about people injured by potato guns firing projectiles other than vegetables, or people being accidentally shot while handling the gun.

Accidental discharges are the most likely cause of injury however some individuals lack the mental capacity to keep their guns pointed away from others at all times. When a potato gun is pointed at a human being the dangers are extreme. Do not under any circumstances let the barrel of a potato gun point towards another human, even if the gun is not loaded.

The bottom line is: don't aim a spudgun at anyone, at any time, even if you think it's not loaded. Also, make sure you are firing in a safe direction that is free of people, pets, livestock, and property.

==Ammo Saftey==
Some advise against shooting bolts, coke cans full of concrete, and other hard objects out of your gun; saying things along the lines of:
"Anthing that is much harder than a spud can cause grevious bodily harm if shot at another person,or any animal for that matter."
...in acctuality, even a tater will cause "grevious bodily harm" if shot at another living being. There may be an increased chance of ricrochet when using sturdy ammo - use common scence, and don't fire non-shattering ammo at close targets.

Some caution should be taken with shooting loose sub-munitions, specificaly gravel or stones, with a [[sabot]] behind them - there is a significant probability of them jamming up, and the barrel being overstressed when the sabot tries to keep moving through the blockage, leading to a failure. Always wrap your lose projectiles in something - paper towls, old socks, and plastic bags are all acceptable.

Help talk:Contents

2006-02-09T02:27:57Z

70.31.208.207: deleted spam

Burst disk

2006-02-09T02:26:54Z

70.31.208.207: 13$ to $13

A '''burst disk''' consists of a thin disc of airtight material that will rupture at a certain pressure, held in place inside a [[union]] or cam lever coupling.

Since the burst disk ruptures almost instantly when the pressure gets to a certain point, they have the fastest [[opening time]] of any valve in existence. Since they are pressure-triggered they are nearly always used in [[hybrid cannon|hybrids]], they are also occasionaly used as the main valve in a [[pneumatic cannon]] because of their superior performance.

Burst disks are a very close rival to a ball valve in cost, at roughly $13 for a 2" [[union]] in sch 40 PVC. More expensive (but conveinent) devices exist, such as [[cam lever coupling]]s.

To use, [[solvent welding|solvent weld]] your chamber to one half of your union or cam coupling. One then 'loads' the valve by putting one or more layers of [[burst disk material]] (such as aluminum foil, or a piece of a beverage container) in between the two halves of the union or coupling. The union or cam coupling is then tightened down, locking the burst disk in place.

In a hybrid cannon, burst disks fail when the pressure builds due to the combusting gasses. Prior to this, the chamber was containing the flammable gasses at a relatively low pressure. They are also sometimes used on [[combustion cannon]]s - for their noisemaking capabilities, and/or their ([http://www.advancedspuds.com/burstdisk.htm debated]) performance improvement.

In a pneumatic cannon, they can be used in the same way, simply pointing the cannon in the correct direction and filling it until it fires. However, many opt to use another system because of the inherent safety issues with this. Such systems include puncturing it with a pointy object (such as a nail) attaced to the end of the projectile, melting it with an electrically heated wire, or having a pneumatically [[triggered burst disk]] system using dual burst disks.

[[category:valves]]

Burst disk

2006-02-09T02:25:36Z

70.31.208.207: typo

A '''burst disk''' consists of a thin disc of airtight material that will rupture at a certain pressure, held in place inside a [[union]] or cam lever coupling.

Since the burst disk ruptures almost instantly when the pressure gets to a certain point, they have the fastest [[opening time]] of any valve in existence. Since they are pressure-triggered they are nearly always used in [[hybrid cannon|hybrids]], they are also occasionaly used as the main valve in a [[pneumatic cannon]] because of their superior performance.

Burst disks are a very close rival to a ball valve in cost, at roughly 13$ for a 2" [[union]] in sch 40 PVC. More expensive (but conveinent) devices exist, such as [[cam lever coupling]]s.

To use, [[solvent welding|solvent weld]] your chamber to one half of your union or cam coupling. One then 'loads' the valve by putting one or more layers of [[burst disk material]] (such as aluminum foil, or a piece of a beverage container) in between the two halves of the union or coupling. The union or cam coupling is then tightened down, locking the burst disk in place.

In a hybrid cannon, burst disks fail when the pressure builds due to the combusting gasses. Prior to this, the chamber was containing the flammable gasses at a relatively low pressure. They are also sometimes used on [[combustion cannon]]s - for their noisemaking capabilities, and/or their ([http://www.advancedspuds.com/burstdisk.htm debated]) performance improvement.

In a pneumatic cannon, they can be used in the same way, simply pointing the cannon in the correct direction and filling it until it fires. However, many opt to use another system because of the inherent safety issues with this. Such systems include puncturing it with a pointy object (such as a nail) attaced to the end of the projectile, melting it with an electrically heated wire, or having a pneumatically [[triggered burst disk]] system using dual burst disks.

[[category:valves]]

Help:Contents

2006-02-04T18:21:02Z

70.31.208.207: ! Spam Again !

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]

Butterfly valve

2006-01-27T22:48:07Z

70.31.208.207: copied from wikipedia

[[Image:USPatent6518683.png|right|150px]]
A '''Butterfly valve''' is a type of flow control device, used to make a fluid start or stop flowing through a section of pipe. The valve is similar in operation to a [[ball valve]]. A flat circular plate is positioned in the center of the pipe. The plate has a rod through it connected to a handle on the outside of the valve. Rotating the handle turns the plate either parallel or perpendicular to the flow of water, shutting off the flow. It is a very robust and reliable design. However, unlike the ball valve, the plate does not rotate out of the flow of water, so that a pressure drop is induced in the flow.

There are three types of butterfly valve:
# '''Resilient butterfly valve''' which has a flexible rubber seat. Working pressure up to 1.6 Mpa
# '''High performance butterfly valve''' which is usually double eccentric in design . Working pressure up to 5.0 Mpa
# '''Tricentric butterfly valve''' which is usually with metal seated design. Working pressure up to 10.0 Mpa

== See also ==
* [[Ball valve]]
* [[Gate valve]]
* [[Globe valve]]

{{tech-stub}}

[[Category:Plumbing valves]]

[[de: Drosselklappe]]
[[it:Valvola a farfalla]]

Help:Contents

2006-01-27T22:45:11Z

70.31.208.207: Page Protected By SaladTossser

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]
Page Protected By SaladTo''sss''er

Help:Contents

2006-01-26T23:24:37Z

70.31.208.207: ****in same spam over and over again, help me ppl plz

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]

Talk:Current events

2006-01-14T23:30:07Z

70.31.208.207: damn those spammers

Help:Contents

2006-01-11T00:03:20Z

70.31.208.207: ****in spam

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]

Talk:Stoichiometry

2005-12-29T01:25:14Z

70.31.208.207: damn ad again

Is this an okay format for presenting calculations, or should there be more/less info, or ordered in a different way? I tried to make an explanation of how everything is done so someone not familiar with the calculations involved can get to understand how the formula is derived and works, as well as providing a short answer for those just looking for the hard math. I'm interested to know if someone has problems understanding something in the article, so that it can be improved upon. --GalFisk 19 October 2005 05:28 (CDT)

I think including the actual chemical formulas (both a generic example of a hydrocarbon combustion, and the specific propane reaction) would help, mainly to clarify the concept of balancing the equation.--Wesman987 19 October 2005 11:18 (CDT)

Edited according to suggestions. Any further comments welcome. If anybody has something concrete to add/remove/change/fix, just go ahead and do it. It's easy :) --GalFisk 19 October 2005 13:12 (CDT)

Some of the information here could be moved/duplicated to combustion process. --GalFisk 25 October 2005 08:04 (CDT)

Help:Contents

2005-12-29T01:23:59Z

70.31.208.207: damn ad again

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]

Help:Contents

2005-12-06T01:15:15Z

70.31.208.207: Darn Spammer

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]

Help:Contents

2005-11-27T19:22:58Z

70.31.208.207: reposted original info due to spam

[http://meta.wikimedia.org/wiki/Help:Contents The WikiMedia Handbook]

User:70.31.208.207

2005-10-22T01:44:02Z

70.31.208.207:

Its Me!!!

Ball valve

2005-10-22T01:43:41Z

70.31.208.207:

These valves open with a 90* twist of lever. They are the cheapest valve you can get, but also yeild the worst preformance. (due to the slow [[opening time]])

Openning time can be shortened, by the use of a spring, or a pneumatic ram.

A ballvalve offeres better air flow compared to a sprinkler valve, thus can be used in large cannons for good performance. For better performance, use a butterfly valve, piston valve, or a burst disk.

To make it easier to open, one can apply dish soap to the moving parts. It is not recomended to use oil, because it can damage the seals.

Combustion process

2005-10-22T01:37:42Z

70.31.208.207: added br tags

1. A cap is opened to the chamber 
2. Fuel is sprayed or injected 
3. The cap is shut and sealed 
4. The fuel is mixed with the air 
5. The mixture is ignited 
6. The mixture burns rapidly until the fuel or air is all used up, increasing pressure, shooting the projectile out 
7. The cap is openned again, to vent the exhaust fumes and load in fresh air

Combustion process

2005-10-22T01:37:09Z

70.31.208.207: first edition

1. A cap is opened to the chamber
2. Fuel is sprayed or injected
3. The cap is shut and sealed
4. The fuel is mixed with the air
5. The mixture is ignited
6. The mixture burns rapidly until the fuel or air is all used up, increasing pressure, shooting the projectile out
7. The cap is openned again, to vent the exhaust fumes and load in fresh air

Breech loading

2005-10-22T01:32:21Z

70.31.208.207: added twist-lock method

Many types of breech loaders are employed. The most common methods are to use male and female adapters to connect the barrel to the chamber, as seen here: http://www.spudfiles.com/forums/viewtopic.php?t=183

A method favored due to speed is to use a type of [[Cam lever coupling|cam lock]] fitting to connect the barrel and chamber. one such example is here: http://www.spudfiles.com/forums/viewtopic.php?t=311

One method that is one of the more challenging to make is a bolt action, which can be seen here:
http://pneumaticsniper.mypicgallery.com/

A internal "twist n' lock" can be also used, which is an "inside-out" version of the above sinper, to load a projectile, twist the barrel and pull it from a fitting to open, put in the projectile, push the barrel back into the fitting and twist to close and lock, this takes good measurements to be done correctly, as it may need o-ring grooves will be fitted inside a coupling very tightly(or else a blow-out will happen, makeing a whistle like noise), a "L" shaped groove and a bolt in a coupling to lock it.
One advantage this loading method offers is that it looks like a normal muzzel loading spudgun.

Cannon construction

2005-10-22T00:25:17Z

70.31.208.207:

It is important to construct your launchers with care. This includes:

* Using pressure rated (NSF-PW or NSF-61) fittings and pipe, especialy in a [[pneumatic cannon]].
* [[Solvent welding]] [http://www.burntlatke.com/weld.html correctly]
* Using pipe of the proper pressure rating, eg. sch 80 in a [[Hybrid Cannon]].
* Only [[tap]] though a double layer of pipe where the pipe and a fitting is joined(for bolts, pressure gauges) .

Under no circumstances WHAT SO EVER should you use [[cell-core]] or unsleeved thinwall pipe.

Cannon construction

2005-10-22T00:24:49Z

70.31.208.207:

It is important to construct your launchers with care. This includes:

* Using pressure rated (NSF-PW or NSF-61) fittings and pipe, especialy in a [[pneumatic cannon]].
* [[Solvent welding]] [http://www.burntlatke.com/weld.html correctly]
* Using pipe of the proper pressure rating, eg. sch 80 in a [[Hybrid Cannon]].
* Only [[tap]] though a double layer of pipe(for bolts, pressure gauges) .

Under no circumstances WHAT SO EVER should you use [[cell-core]] or unsleeved thinwall pipe.

History

2005-10-21T23:53:32Z

70.31.208.207:

A Brief History of Spud Guns

A loooonnngggg time ago, fabled to be about 40 years, somewhere (in America of course) some middle-aged guys were bored so gathered up a bunch of beer cans (they were steel back then), duct tape, gasoline, and at least one tennis ball. Both ends of all cans were removed save one, from which only the bottom was removed; the peel-top hole end was left as is.

Legend has it the idea was struck that if all these cans were securely taped together to make a long tube, the tennis ball could be stuck down it muzzle loader style and fired by putting a small amount of gasoline in the bottom can (with the hole lid as the breech) and one brave soul (the one that had consumed the most beers) holding a lit match or lighter near the peel-top hole. Miraculously the tennis ball was expelled with great velocity. Much whooping and hollering ensued, and the device was promptly reloaded to verify the first one was not a 'fluke.' Hence the backyard cannon was born.

plagerized from SGTC by none other than SaladTossser