SpudFiles Wiki - User contributions [en]

Barrel

2006-12-25T23:26:41Z

SpudMonster:

The '''barrel''' is the pipe used to launch the projectile, and is, along with the [[chamber]], the only component found in all launchers. The diameter determines what projectiles will fit in the launcher, and the length affects how much energy is transferred to the projectile.

Modifications and improvements to the basic barrel include [[sleeving]], [[rifled barrel|rifling]], [[hop-up]]s and flatline barrels.

There are many diameters of barrels popular in spudding, below are some that fit certain ammo:

* 4.5mm brakeline - fits bbs, good for [[BBMGs]]
* 6mm brakeline - fits [[airsoft bb]]s, a commonly used ammo in BBMGs.
* 3/4" CPVC, 3/4" sch 80 PVC (looser fit), or 3/4" sch 120 PVC - fits .68" [[paintball]]s
* 1/2" sch 40 PVC (.602" id) - fits "AA" batteries, marbles.
* 3/4" sch 40 PVC (.804" id) - fits 12g [[CO2 cartridge]]s, C batteries.
* 1" sch 40 PVC (1.029" id) - size [[C cell|"C" batteries]], smaller sized [[bouncy balls]].
* 1.25" sch 40 PVC (1.360" id) - Fits size [[D cell|"D" batteries]], [[film canister]]s
* 1.5" sch 40 PVC (1.590" id) - a common size, good trade-off between power and [[potato]] usage. [http://www.spudtech.com/components.asp Available rifled from the [[SGTC]]]
* 1.5" sdr 21 PVC (1.700" id) - fits [[golf ball]]s. Traditionally [[sleeving|sleeved]] within SCH-80 PVC.
* 1.5" sdr 26 PVC (1.734" id)- fits golfballs, but it is thinner than sdr 21, so the golfballs fit a little looser. Traditionally sleeved within 2" SCH-80 PVC.
* 2" sch 40 PVC (2.047" id) - fits caulk tubes and (large) potatoes.
* 2" sch 80 PVC (1.913" id) - fits 1.5" nominal pipe well, making it ideal for [[sleeving]] Also used as a golf ball barrel by itself, with the golf ball held in place by a rag patch, or other wadding. Also fits normal light bulbs! [http://advancedspuds.com/concreteballs.htm (Details)].
* 2.5" sch 40 PVC (2.445" id) - fits [[tennis ball]]s well.
* 3" sch 80 PVC (2.864" id) - fits many drink bottles well.
* 3" sch 40 PVC (3.042" id) - fits normal [[steel can|cans]], empty propane torch tanks, certian wine bottles, and gatorade bottles.
* 4" sch 40 PVC (3.998" id) - fits 29 oz. cans

Inside diameter (id) data from www.harvel.com
[[Category:Components]]

PVC pipe

2006-04-29T20:21:53Z

SpudMonster:

'''PVC pipe''' and fittings are the most common material for spudgun construction. PVC is cheap, lightweight and available in a wide range of dimensions and ratings. PVC is usually joined by [[solvent welding]], which is easy to do and requires no special tools. Threaded fittings are also used, but then solvent welded to the pipe. PVC is easy to machine, and parts are sometimes [[bushing modification|customized]] to fit a certain purpose.

PVC is usually colored white or shades of gray, but transparent PVC pipe is also available. It's more expensive than normal PVC, but is somewhat popular in combustion launchers, where clear parts will let you see that happens inside during the combustion process.

One of the main disadvantages of PVC is that it becomes brittle in cold weather, which may lead to chamber failure, especially in pneumatic launchers. When PVC fails under pressure it breaks into sharp shards, which are propelled at high velocity. Because of this danger PVC pipe is not rated for use with pressurized gasses, and the use in spudguns is to be regarded as outside of specifications. When proper precautions are taken, it is still very safe to use.

===Naming Conventions===

====Schedule====
Schedule is a method of denoting pipe dimensions with a standardized set of nominal sizes. Note that this is a ''size'' convention, and does not neccessarily denote a pressure rating. [http://harvel.com/pipepvc-sch40-80-dim.asp Harvel] has tables of dimensions for SCH40 and SCH80 pipe sizes.

====SDR====
SDR (Standard Dimension Ratio) pipe has the same O.D. as Schedule pipe, but with different pipe I.D. All SDR pipe in a series has the same ratio of O.D to wall thickness throughout the sizes, and thus has the same pressure rating. All SDR pipe is rated for pressure, but becuase it often has relatively thin walls (in smaller diameters), it should be [[sleeving|sleeved]] or otherwise reinforced before use (in some cases). [http://harvel.com/pipepvc-sdr-dim.asp Harvel]
has charts of dimensions and pressure ratings for SDR pipe.
(Larger diameters of some SDR pipe actually have thicker walls than Schedule pipe. For example, SDR21 pipe 5" and up in diameter is thicker than Schedule 40 and is used
in well casings. SDR21 2.5" (Tennis Ball Barrels) are thick enough to not require sleeving in barrel use). SDR21 1.5" Golf Ball barrels are not rugged and sleeving is reccomended.

{{Stub}}
[[Category:Construction materials]]

PVC pipe

2006-04-29T20:21:32Z

SpudMonster:

'''PVC pipe''' and fittings are the most common material for spudgun construction. PVC is cheap, lightweight and available in a wide range of dimensions and ratings. PVC is usually joined by [[solvent welding]], which is easy to do and requires no special tools. Threaded fittings are also used, but then solvent welded to the pipe. PVC is easy to machine, and parts are sometimes [[bushing modification|customized]] to fit a certain purpose.

PVC is usually colored white or shades of gray, but transparent PVC pipe is also available. It's more expensive than normal PVC, but is somewhat popular in combustion launchers, where clear parts will let you see that happens inside during the combustion process.

One of the main disadvantages of PVC is that it becomes brittle in cold weather, which may lead to chamber failure, especially in pneumatic launchers. When PVC fails under pressure it breaks into sharp shards, which are propelled at high velocity. Because of this danger PVC pipe is not rated for use with pressurized gasses, and the use in spudguns is to be regarded as outside of specifications. When proper precautions are taken, it is still very safe to use.

===Naming Conventions===

====Schedule====
Schedule is a method of denoting pipe dimentions with a standardized set of nominal sizes. Note that this is a ''size'' convention, and does not neccessarily denote a pressure rating. [http://harvel.com/pipepvc-sch40-80-dim.asp Harvel] has tables of dimensions for SCH40 and SCH80 pipe sizes.

====SDR====
SDR (Standard Dimension Ratio) pipe has the same O.D. as Schedule pipe, but with different pipe I.D. All SDR pipe in a series has the same ratio of O.D to wall thickness throughout the sizes, and thus has the same pressure rating. All SDR pipe is rated for pressure, but becuase it often has relatively thin walls (in smaller diameters), it should be [[sleeving|sleeved]] or otherwise reinforced before use (in some cases). [http://harvel.com/pipepvc-sdr-dim.asp Harvel]
has charts of dimensions and pressure ratings for SDR pipe.
(Larger diameters of some SDR pipe actually have thicker walls than Schedule pipe. For example, SDR21 pipe 5" and up in diameter is thicker than Schedule 40 and is used
in well casings. SDR21 2.5" (Tennis Ball Barrels) are thick enough to not require sleeving in barrel use). SDR21 1.5" Golf Ball barrels are not rugged and sleeving is reccomended.

{{Stub}}
[[Category:Construction materials]]

Muzzle loading

2006-04-03T22:04:01Z

SpudMonster:

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 (straight) 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.

User:Spudmonster

2006-04-03T22:02:45Z

SpudMonster:

I'm hungry...

Computer Applications

2006-03-19T05:02:03Z

SpudMonster:

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

==the [[GGDT|Gas Gun Design Tool]]==
Written by David Hall (D_hall 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 <b>Compressed Air Launcher Model</b> 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==

Hybrid cannon

2006-03-13T04:55:26Z

SpudMonster:

A '''hybrid''' is a type of spudgun that combines principles of the [[combustion cannon|combustion]] and [[pneumatic cannon|pneumatic]] spudgun. It uses a pressurized mixture of fuel and air to get more power out of a given chamber volume.
The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier (Source). This is possible because of the higher pressure and temperature gasses.

A hybrid launcher consists of seven basic elements:

*High pressure combustion chamber
*Pressure-triggered main valve (usually a [[burst disk]])
*[[Barrel]]
*Fuel system (usually [[fuel meter|metered propane]])
*Air filling valve
*powerful [[Ignition source]]
*One or more [[pressure gauge]]s

==Operation theory==
A hybrid is first injected with fuel, then with pressurized air. The amount of air depends on how much fuel was added, and is calculated to achieve a [[stoichiometric]] fuel/air ratio in the chamber.
A hybrid using twice as much fuel and air as a comparable combustion gun is said to be using a 2X mix, higher mixtures can be used and will produce even higher pressures. The fuel and air needs to be measured and matched carefully to ensure reliable operation, [[pressure gauge]]s and fuel [[fuel meter|meters]] are used for this.

The ignition of a hybrid gun is more difficult, as the length of a spark is roughly inversely proportional to the density of the gas. This necessitates the use of high-powered [[ignition source]] such as a [[stungun]].

The resulting gasses are released to the barrel via a self-operating valve of some sort, most commonly a [[burst disk]] because of it's simplicity and reliability, although self-venting [[piston valve|piston]]/[[diaphragm valve|diaphragm]] valves have been used. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.

===Safety===
A hybrid is the most dangerous launcher that can be built. It is advised to build with pipe that can handle the high pressure environment (200+ [[Pressure gauge|PSI]]) such as Sch. 80 PVC or metal. Remote ignition is a must, and the limit of a 4x propane/ 4 atmosphere mix should never be breached. If a higher mix is attempted, DDT (deflagration to detonation transition) can occur, causing an extreme pressure spike. Most pipe cannot handle the spike, and will shatter, launching plastic shards everywhere. Therefore utmost care must be taken with these launchers.

[[Image:hybrid.jpg]]

Hybrid cannon

2006-03-13T04:55:10Z

SpudMonster:

Hybrid cannon

2006-03-13T04:54:51Z

SpudMonster:

File:Hybrid.jpg

2006-03-13T04:54:05Z

SpudMonster: A very well constructed hybrid cannon.

A very well constructed hybrid cannon.

Hybrid cannon

2006-03-13T04:51:07Z

SpudMonster: