SpudFiles Wiki - User contributions [en]

Gas Gun Design Tool

2010-06-18T12:30:35Z

GalFisk: /* Common problems for first time users */

Hall Consulting's '''Gas Gun Design Tool''' is a simulation program to aid the design of [[pneumatic cannon]]s. It is available [http://www.thehalls-in-bfe.com/GGDT here].

==Common problems for first time users==
Read, and follow, the [http://thehalls-in-bfe.com/GGDT/installation.html installation instructions] for GGDT before installing.

In the "Resevoir Data" section (parameters describing the pressure chamber) the default value for "Inner Diam" is 1.95 inch. This value is for a coaxial design where the barrels is within the chamber. For other designs, for example ball valves or diaphragm valves, this value should be set to zero.

==Suitable parameters for various valves==
''(This section needs a lot more info)''

A rough rule of thumb for calculating the Flow Coefficient (Cv) for various valve types;

Cv = K * D2

Where D is the seat diameter in centimetres, and K is

= 1 for a sprinkler or ball valve
= 2 for a piston of QEV
= 3 for a burst disc.

This formula is not 100% accurate, but it's easy to use, remember, and reasonably accurate.
Using this formula we get a Cv of 3.4 for a 1/2" [[QEV]].

==Physics model==
As of version 4.2, in modeled the following 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 orifice.
# 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 orifice 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://www.thehalls-in-bfe.com/GGDT page] on use

{{stub}}
[[category:Concepts]]

Camera flash

2009-09-23T10:08:02Z

GalFisk: /* Short circuit gap */ typo

[[image:Camera flash.jpg|right|thumb|300px|Camera flash circuit]]
A '''camera flash''' can be used for spudgun [[ignition]] in several ways, either by itself or by feeding the high voltage from the flash capacitor through a step-up transformer (commonly an [[ignition coil]], [[flyback circuit|flyback transformer]] or a mains transformer in reverse).

The main advantage of camera flash-based ignitions is that it can be built using cheap, readily available components. The spark is more powerful than that of a piezoelectric ignitor. A camera flash is usually powered by one or two AAA or AA cells. Disadvantages include several seconds of recharge time before the ignition can be triggered again, and significant shock hazard from the storage capacitor if built improperly. Special care should be taken when used in metal launchers, as both sides of the storage capacitor can have significant voltages between them and other parts of the circuit, such as the battery poles and the trigger switch.

For an excellent description on how these disposable camera photo circuits work see [http://www.talkingelectronics.com/projects/XenonFlasher/XenonFlasher.html].

The camera flash is most easily obtained from a disposable camera, many places that develop films from these will give the discarded camera shell away for free if asked. The flash capacitor can store charge for a long time, and should be discharged before handling the circuit.

=Circuits=

There are several ways to connect a camera flash to a spark gap, which all have their own advantages and drawbacks. These are the most common circuits.

==[[Ignition coil]]==

An ignition coil (or other step-up transformer, such as a flyback or a mains transformer connected in reverse) will provide a high voltage spark when the flash capacitor is discharged through it. Most Ignition coils has a 100:1 winding ratio, meaning that for every 1 volt that is put into the coil, 100 volts come back out.

In order to modify a camera flash circuit for use with an ignition coil, follow these 6 steps:

 [[Step 1 - Removing the Flash Bulb]]

 [[Step 2 - Drilling the Holes for the Ignition Coil Wires]]

 [[Step 3 - Before Adding the Relay]]

 [[Step 4 - Adding the Relay]]

 [[Step 5 - Adding the Ignition Coil and Spark Strip/Spark Gap]]

 [[Step 6 - Providing Power to the Relay]]

 The flimsy battery holder can also be replaced with a plastic one, which is easily attained at any electronics store. Also, you can add a "kill switch" in [[series]] after the battery holder to cut off the power when the circuit is not in use. Be aware that the circuit is not "powered down" when the kill switch is in the off position. The circuit will not be able to charge, but the capacitor will still hold the electricity for a long time. The cannon will need to be "dry fired" after the kill switch is turned off. Be sure to point the cannon away from everyone when doing this.

 [[Step 7 - Removing the Battery Contacts]]

 [[Step 8 - Adding a Battery Holder and Kill Switch]]

 On a final note, the flash charging button on the front of the camera circuit board can also be replaced with an external one to add a finishing touch and an extra degree of safety. This step may be the hardest of all, as the margin for error when drilling the holes may be small. However, in the larger disposable flash cameras such as the [[Kodak Funsaver]] or [[Kodak Max]] cameras, the circuit board is larger and this is not an issue.

 [[Step 9 - Replacing the Charging Button]]

 The relay used in the diagrams is a standard [http://www.rowand.net/Shop/Tech/AllAboutRelays.htm 5-pin automotive relay], which can be purchased at any auto parts or electronics store. It is advisable that you also use a [[relay socket]]; it will make the relay easily removable in case of a wiring problem or to be used in another project.

If a mains transformer connected in reverse is used, the spark gap will be electrically insulated from the rest of the curcuit, an advantage when used in metal cannons.

The output transformer from a stun gun can also be used, which can be useful if the charging circuit in the stun gun has died. These circuits are in fact quite similar to that of a stun gun.

{{stub}}

===Tube Switched Coil===

The ignition that requires the least modification of the camera consists of cutting one of the main leads to the flash tube, and connecting the ignition coil in between. Triggering the flash will produce a spark from the output of the transformer. The advantage to using the flash tube itself to switch the main discharge, is that almost any small switch can be used to trigger the circuit. If the trigger switch is replaced by a thyristor (SCR), the ignition can be triggered by an electronic circuit. The flash circuit itself is mostly intact and not driven out of spec, which means this circuit is quite reliable.

===Manually Switched Coil===

The flash tube can also be replaced by a heavy duty switch for triggering, though if the switch is too weak it may become welded shut. This switch will also be carrying the full voltage of the capacitor, and must be properly insulated to prevent electric shock. If the trigger switch is held down for a long time the charging circuit in the flash may break since its output is shorted for the duration.

==Triggered spark gap==

Another ignition method that does not require an external step-up transformer, consists of removing the flash tube, and taking out the trigger lead as well as the two main leads. These are then connected to three electrodes, which are placed together to form a spark gap of a millimeter or less. Triggering the flash will ionize the air in the gap and discharge the main capacitor. This produces a more intense spark than the first method, but it requires a more complex spark gap. The electrodes can also erode over time, requiring readjustment.

==Trigger transformer spark==

The trigger transformer for the flash tube produces a few kV on its own, and can be connected to a spark gap. The advantage to this method is that the main capacitor is not dumped, so recharge time is eliminated and it uses less battery power. The spark is very weak however, and this method is generally not recommended.

==Short circuit gap==

A camera flash can be used with a short circuit gap, which has movable points that can be brought in contact from outside the chamber. The flash capacitor is connected directly to the gap and creates a spark when it's shorted. This spark gap is more difficult to make, and may have isues with welding and erosion, but is easy to hook up and requires little electronics knowledge.

==Others==

A camera flash can also be used to trigger [[sprinkler valve]] solenoids built for mains voltage, however the opening time will be brief since the flash capacitor is drained quickly.
[[Category:Ignition sources]]

Common Fuels for Combustion Spudguns

2009-08-13T21:29:07Z

GalFisk: H20 -> H2O

So, you've glued together some hunks of PVC, installed an [[Ignition source|ignition
system]] and bought a bag of [[potato|russets]]. What should you use for [[fuel]] to get
the most oomph into
that hunk of starch? There are many ways to judge the best fuel for a
[[Combustion cannon|combustion spud gun]]. How
easy is it to use? How expensive is it? And, perhaps most important to
the average spudder, which fuel
will launch the spud at the highest speed?

=You Must Use The Correct Amount Of Fuel=
Before discussing the various fuel options we'll start with the most important aspect of fueling a combustion spudgun.

'''You Must Use The Correct Amount Of Fuel'''.

An inexperienced spud gunner might think that adding more fuel to the [[chamber]] will increase the power of their gun. This is almost always incorrect. For all common fuels too much fuel won't ignite. All fuels have a property called the "combustion limits". The combustion limits is the range of fuel concentration (usually expressed as the volume percent of fuel in the chamber) that will actually ignite. For most hydrocarbon fuels ([[propane]], [[butane]], flammable [[aerosol]]s etc.) the combustion limits is about 3% to 9% by volume. If you inject less than ~3%, or more than ~9% of the chamber volume in fuel then the gun will not ignite.

'''If you've built a combustion spudgun and you can't get it to fire the most likely problem is that you are using too much fuel.'''

So, your first challenge is to get your fuel in the 3~9% range so that the gun will fire. Your second challenge is to try to get the fuel as close as possible to the '''stoichiometric''' fuel ratio. The [[Stoichiometry|stoichiometric]] fuel ratio is the ratio of fuel to oxygen that allows all the fuel to burn and leaves no oxygen left over at the end of [[Combustion process|combustion]]. The stoichiometric fuel ratio will get you very close to the maximum power the fuel is capable of.

The stoichiometry is determined by the fuel you are using. For example, the balanced chemical equation for the complete combustion of propane (C3H8) in air (~21% oxygen, O2) is;
C3H8 + 5O2 = 3CO2 + 4H2O

For every molecule of propane we need 5 molecules of oxygen. Combustion produces 3 molecules of carbon dioxide (CO2) and 4 molecules of water. Gases have the handy property that the number of molecules is proportional to the volume at a constant [[pressure]] so the volume ratio of fuel to air will be the same as the ratio of molecules. Since air is only ~21% oxygen we can calculate that for every unit of volume of the chamber we need (1C3H8/5O2)*(0.21) = 0.042 volumes of fuel. 0.042 volumes of fuel is the same as 4.2% of fuel. (There are some subtleties about calculating the actual volume percent that'll be discussed below.)

=Common Fuels for Combustion Spud Guns=
<h2>Heats of Combustion</h2>
The "heat of combustion" of a fuel
is a measure of the amount of energy
released when the fuel is
burned. This is an important, but not the only, factor affecting the
performance of a fuel. The table
below lists the heats of combustion along with other parameters for a
variety of pure fuels. 
 
Heats of combustion can be measured in several different ways and this
makes it difficult to find a consistent set of values for various
fuels. Web based sources list both "high heat" values (which are
obtained assuming the water produced condenses to liquid) and "low
heat" values (which assume the water is present as steam) as well as
thermodynamic heats of combustion. For this reason, the table below
lists multiple values for most of the fuels. To obtain a consistent set
of values for comparison purposes, I have used the red ones which were calculated
using the method at [http://home.fuse.net/clymer/rq]. 
 
The "Displasive Volume Percent" column gives the stoichiometric volume
of fuel required if the fuel displaces some of the air in
the chamber when it is injected, for example when fueling with the
"squirt and screw" method or using a syringe. The "Additive Volume
Percent" gives the amount of fuel
required when the fuel does not
displace air from the chamber, for example when using a [[Fuel meter|pressurized
meter system]]. 
 
The key value for comparing two fuels based on their heats of
combustion is not the actual heats of combustion. Instead, the "Heat
per mole Oxygen" should be used since the amount of energy in the
combustion chamber is
limited by the amount of oxygen present in the chamber. Fuel is added
to match that amount
of oxygen. As you can see from the table, there is relatively little
difference between the various fuels based on their "Heat per mole
Oxygen" values. The only two fuels with significantly higher values are
hydrogen and [[acetylene]], both of
which give 10~15% more energy
than the other fuels.
<table border="1" cellpadding="1" cellspacing="0">
<tr>
<td align="center" valign="middle"> Fuel</td>
<td align="center" valign="middle">Heat of Combust.
(Kcal/mole)</td>
<td align="center" valign="middle">Combustion Limits in
Air (Vol%)</td>
<td align="center" valign="middle">Boiling Point,C (F)</td>
<td align="center" valign="middle">Mole O2
per mole Fuel</td>
<td align="center" valign="middle">Heat per mole Oxygen
(Kcal)</td>
<td align="center" valign="middle">Displasive Volume
Percent(1)</td>
<td align="center" valign="middle">Additive Volume
Percent(1)</td>
<td align="center" valign="middle">Molecular Weight
(g/mol)</td>
<td align="center" valign="middle">Combustion Equation</td>
</tr>
<tr>
<td align="center" valign="middle"> Hydrogen</td>
<td align="center" valign="middle">68.3 
62.5 
59.7</td>
<td align="center" valign="middle">4.0 - 74.2</td>
<td align="center" valign="middle">-253 
(-423)</td>
<td align="center" valign="middle">0.5</td>
<td align="center" valign="middle"> 
119</td>
<td align="center" valign="middle">29.5</td>
<td align="center" valign="middle">41.9</td>
<td align="center" valign="middle">2</td>
<td align="left" nowrap="nowrap" valign="middle"> 2H2 +
O2 = 2H2O</td>
</tr>
<tr>
<td align="center" valign="middle"> Methane</td>
<td align="center" valign="middle">192 
191 
212 
215</td>
<td align="center" valign="middle">5 - 15</td>
<td align="center" valign="middle">-162 
(-259)</td>
<td align="center" valign="middle">2</td>
<td align="center" valign="middle">108</td>
<td align="center" valign="middle">9.48</td>
<td align="center" valign="middle">10.5</td>
<td align="center" valign="middle">15</td>
<td align="left" nowrap="nowrap" valign="middle"> CH4 +
2O2 = CO2 + 2H2O</td>
</tr>
<tr>
<td align="center" valign="middle">Ethane</td>
<td align="center" valign="middle">373 
340 
371</td>
<td align="center" valign="middle">3 - 12.5</td>
<td align="center" valign="middle">-89 
(-184)</td>
<td align="center" valign="middle">3.5</td>
<td align="center" valign="middle">106</td>
<td align="center" valign="middle">5.65</td>
<td align="center" valign="middle">5.99</td>
<td align="center" valign="middle">30</td>
<td align="left" nowrap="nowrap" valign="middle"> 2C2H6
+ 7O2 = 4CO2 + 6H2O</td>
</tr>
<tr>
<td align="center" valign="middle">Ethylene 
(Ethene)</td>
<td align="center" valign="middle">315 
337 
337</td>
<td align="center" valign="middle">2.8 - 28.6</td>
<td align="center" valign="middle">-103.7 
(-155)</td>
<td align="center" valign="middle">3</td>
<td align="center" valign="middle">112</td>
<td align="center" valign="middle">6.53</td>
<td align="center" valign="middle">6.98</td>
<td align="center" valign="middle">28</td>
<td align="left" nowrap="nowrap" valign="middle"> C2H4
+ 3O2 = 2CO2 + 2H2O</td>
</tr>
<tr>
<td align="center" valign="middle">Acetylene</td>
<td align="center" valign="middle">322 
301</td>
<td align="center" valign="middle">2.5 - 80 </td>
<td align="center" valign="middle">-81 
(-119)</td>
<td align="center" valign="middle">2.5</td>
<td align="center" valign="middle">120</td>
<td align="center" valign="middle">7.73</td>
<td align="center" valign="middle">8.38</td>
<td align="center" valign="middle">26</td>
<td align="left" nowrap="nowrap" valign="middle"> 2C2H2
+ 5O2 = 4CO2 + 2H2O</td>
</tr>
<tr>
<td align="center" valign="middle"> Propane</td>
<td align="center" valign="middle">525 
487 
530 
527</td>
<td align="center" valign="middle">2.37 - 9.5</td>
<td align="center" valign="middle">-42.1 
(-44)</td>
<td align="center" valign="middle">5</td>
<td align="center" valign="middle">105</td>
<td align="center" valign="middle">4.02</td>
<td align="center" valign="middle">4.19</td>
<td align="center" valign="middle">44</td>
<td align="left" nowrap="nowrap" valign="middle"> C3H8
+ 5O2 = 3CO2 + 4H2O</td>
</tr>
<tr>
<td align="center" valign="middle"> Butane</td>
<td align="center" valign="middle">684 
633 
687 
683</td>
<td align="center" valign="middle">1.86 - 8.41</td>
<td align="center" valign="middle">-0.5 
(31)</td>
<td align="center" valign="middle">6.5</td>
<td align="center" valign="middle">105</td>
<td align="center" valign="middle">3.67</td>
<td align="center" valign="middle">3.81</td>
<td align="center" valign="middle">58</td>
<td align="left" nowrap="nowrap" valign="middle"> 2C4H10
+ 13O2 = 8CO2 + 10H2O</td>
</tr>
<tr>
<td align="center" valign="middle">iso- Butane</td>
<td align="center" valign="middle">683</td>
<td align="center" valign="middle">1.86 - 8.41</td>
<td align="center" valign="middle">-11.7 
(11)</td>
<td align="center" valign="middle">6.5</td>
<td align="center" valign="middle">105</td>
<td align="center" valign="middle">3.67</td>
<td align="center" valign="middle">3.81</td>
<td align="center" valign="middle">58</td>
<td align="left" nowrap="nowrap" valign="middle"> 2C4H10
+ 13O2 = 8CO2 + 10H2O</td>
</tr>
<tr>
<td align="left" bgcolor="#dddddd" valign="middle"> [[MAPP]](2)</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
<td bgcolor="#dddddd"> 
</td>
</tr>
<tr>
<td align="center" bgcolor="#dddddd" valign="middle">Methyl Acetylene</td>
<td align="center" bgcolor="#dddddd" valign="middle"> 
</td>
<td align="center" bgcolor="#dddddd" valign="middle"> 
</td>
<td align="center" bgcolor="#dddddd" valign="middle">-23.2 
(-9.0)</td>
<td align="center" bgcolor="#dddddd" valign="middle">4 </td>
<td align="center" bgcolor="#dddddd" valign="middle"> 
</td>
<td align="center" bgcolor="#dddddd" valign="middle">4.98</td>
<td align="center" bgcolor="#dddddd" valign="middle">5.24</td>
<td align="center" bgcolor="#dddddd" valign="middle">40</td>
<td align="left" bgcolor="#dddddd" nowrap="nowrap" valign="middle"> C3H4
+ 4O2 = 3CO2 + 2H2O</td>
</tr>
<tr>
<td align="center" bgcolor="#dddddd" valign="middle">Propadiene</td>
<td align="center" bgcolor="#dddddd" valign="middle">457</td>
<td align="center" bgcolor="#dddddd" valign="middle"> 
</td>
<td align="center" bgcolor="#dddddd" valign="middle">-34.5 
(-30)</td>
<td align="center" bgcolor="#dddddd" valign="middle">4</td>
<td align="center" bgcolor="#dddddd" valign="middle">114</td>
<td align="center" bgcolor="#dddddd" valign="middle">4.98</td>
<td align="center" bgcolor="#dddddd" valign="middle">5.24</td>
<td align="center" bgcolor="#dddddd" valign="middle">40</td>
<td align="left" bgcolor="#dddddd" nowrap="nowrap" valign="middle"> C3H4
+ 4O2 = 3CO2 + 2H2O</td>
</tr>

<tr>
<td align="center" valign="middle">Propylene(3) (propene, MAP/Pro)</td>
<td align="center" valign="middle">491</td>
<td align="center" valign="middle">?</td>
<td align="center" valign="middle">-47.6 
(-54)</td>
<td align="center" valign="middle">4.5</td>
<td align="center" valign="middle">109</td>
<td align="center" valign="middle">4.7</td>
<td align="center" valign="middle">4.9</td>
<td align="center" valign="middle">42</td>
<td align="left" nowrap="nowrap" valign="middle">
2C3H6 + 9O2 = 6CO2 + 6H2O</td>
</tr>

<tr>
<td align="center" valign="middle">Diethyl Ether</td>
<td align="center" valign="middle">647</td>
<td align="center" valign="middle">1.85 - 36.5</td>
<td align="center" valign="middle">34.5 
(94)</td>
<td align="center" valign="middle">6</td>
<td align="center" valign="middle">108</td>
<td align="center" valign="middle">3.37</td>
<td align="center" valign="middle">3.49</td>
<td align="center" valign="middle">74</td>
<td align="left" nowrap="nowrap" valign="middle"> C4H10O
+ 6O2 = 4CO2 + 5H2O</td>
</tr>
<tr>
<td align="center" valign="middle">Dimethyl Ether</td>
<td align="center" valign="middle">329</td>
<td align="center" valign="middle">3.0 - 18.6</td>
<td align="center" valign="middle">-25 
(-13)</td>
<td align="center" valign="middle">3</td>
<td align="center" valign="middle">110</td>
<td align="center" valign="middle">6.53</td>
<td align="center" valign="middle">6.98</td>
<td align="center" valign="middle">46</td>
<td align="center" valign="middle">C2H6O
+ 3O2 = 2CO2 + 3H2O</td>
</tr>
</table>
'''Table Notes:'''
<ol>
<li>Additive and displasive volumes based on air containing 20.95%
(volume) oxygen.</li>
<li>MAPP gas is a proprietary mixture of various hydrocarbons,
principally methyl acetylene, propadiene and propane.</li>
<li>MAP/Pro gas is a proprietary mixture of propylene and 0.5% propane.</li>
</li></ol>
References: 
http://members.nuvox.net/F~on.jwclymer/Frq/Fhoctable.html 
http://home.fuse.net/clymer/rq combustion calculator 
http://www.nrc.gov/freading-rm/fdoc-collections/fnuregs/fstaff/fsr1805/ffinal-report/f15_explosion_calculations.xls

<h2>"Traditional" Fuels</h2>
<h3>RightGuard</h3>
RightGuard, one of the traditional spudgun fuels, has undergone various
changes in composition over the years. Some types of RightGuard are
still usable as a spudgun fuel.
If the label has a warning about flammability and/or the ingredient
lists includes things like butane,
isobutane, or propane then it is
useable as a fuel. From the
Heats of Combustion table above you can see that there is relatively
little difference between these three ingredients. Even the optimum
volume percents are fairly close to each other. Since RightGuard is
generally used in the "squirt and screw" fueling mode, the actual
percent of fuel is difficult to
control. It seems likely that the other ingredients in the can make up
a fairly low percentage and probably have a relatively minor affect on
the energy of the fuel.
<h3>Aquanet</h3>
Aquanet, and similar hair sprays, have many of the same characteristics
as RightGuard. If the label warns that it is flammable, and if the
ingredient includes things like butane,
isobutane, or propane then it is
probably usable. As with RightGuard, the other ingredients in the can,
which may or may not be flammable, probably constitute a fairly low
percentage of the gas. There is the possibility that the other
ingredients may gum up the [[spark gap]], [[Chamber fan|fan]] or cleanout plug threads
after several uses.
<h3>Starter Fluid</h3>
By definition, automotive [[Starting fluid|starter fluid]] is combustible. There are no
doubt a couple of different formulations. One common formulation
includes 10~30% (weight) dimethyl ether and a propane propellant. Most
formulations should behave about the same as pure propane. 
<h3>Other Fuels</h3>
Pretty much any combustible compound that evaporates significantly
at ~70F can be used as fuel in a
combustion spudgun. Methanol, ethanol, isopropanol (rubbing alcohol),
gasoline, acetone (nail polish remover), paint thinner etc. can all be
used as fuel. The challenge with
these liquid fuels is getting them to evaporate in the gun in a
reproducible fashion. The actual energy
content of this type of fuel is
fairly irrelevant since the shot to shot reproducibility is so poor. It
really doesn't matter, with this type of fuel, whether the predicted
[[muzzle velocity]] is 10% great with one fuel
versus another since the shot to shot variability is probably more like
50%. (Even with precisely metered propane,
the shot to shot variability in muzzle velocity for shooting [[potato|spuds]] is
typically in the 10 to 20% range.)
One thing that you should keep in mind with liquid fuels is the
potential for weakening the PVC. Take a look at the ingredients list on
your cans of PVC [[primer]] and [[PVC Glue|glue]]. Anything listed on those cans should
probably be avoided as fuels. Acetone and tetrahydrofuran (THF) in
particular are probably not the best idea for fuel since they soften
PVC.

<h2>Other Factors</h2>
The heat of combustion is not the only factor affecting the power of a
particular fuel. The rate at
which the fuel burns and the
maximum temperature and pressure obtained from the fuel also affects
the performance
of the gun.
<h3>Flame Speed and Power Law</h3>
Gaseous fuels burn at widely varying rates. For a combustion spudgun,
the faster the fuel burns the
better the gun will perform. Unfortunately, there is not a lot of
information available on the burn rates of various fuels. The table
below lists a few fuels of interests (values from
http://www.ub.uib.no/elpub/2004/h/404003/Hovedoppgave.pdf).
The flame front speed is how fast the flame moves through the mixture
at ambient conditions. In an actual combustion spudgun the flame front
accelerates as the temperature in the chamber rises. The flame front
speed as a function of temperature and pressure can be estimated using;
<blockquote>Flame speedi = (Flame speed0)*(Ti/T0)alpha*(Pi/P0)beta</blockquote>
Where Flame speed0, alpha and beta are the values shown in
the table below and Flame speedi is the speed at temperature
Ti and pressure Pi.
<table border="1" cellpadding="4" cellspacing="1">
<tr>
<td align="center" valign="middle"> Fuel</td>
<td align="center" valign="middle">Flame Front Speed,
meters/sec (FPS)</td>
<td align="center" valign="middle">Maximum Explosion Pressure
(ATM)</td>
<td align="center" valign="middle">Adiabatic Flame
Temperature, C (F)</td>
<td align="center" valign="middle">alpha</td>
<td align="center" valign="middle">beta</td>
</tr>
<tr>
<td align="center" valign="middle"> Methane</td>
<td align="center" valign="middle">0.45</td>
<td align="center" valign="middle">8.6</td>
<td align="center" valign="middle">2591 (4696)</td>
<td align="center" valign="middle">2.0</td>
<td align="center" valign="middle">-1.5</td>
</tr>
<tr>
<td align="center" valign="middle"> Propane</td>
<td align="center" valign="middle">0.43</td>
<td align="center" valign="middle">9.2</td>
<td align="center" valign="middle">2633 (4771)</td>
<td align="center" valign="middle">2.13</td>
<td align="center" valign="middle">-0.17</td>
</tr>
<tr>
<td align="center" valign="middle"> Hydrogen</td>
<td align="center" valign="middle">3.25</td>
<td align="center" valign="middle">7.9</td>
<td align="center" valign="middle">2755 (4991)</td>
<td align="center" valign="middle">1.26</td>
<td align="center" valign="middle">0.26</td>
</tr>
<tr>
<td align="center" valign="middle">Acetylene</td>
<td align="center" valign="middle">1.55</td>
<td align="center" valign="middle">9.6</td>
<td align="center" valign="middle">2918 (5284)</td>
<td align="center" valign="middle">2.0</td>
<td align="center" valign="middle">-0.06</td>
</tr>
</table>
As the table above shows, simple hydrocarbons such as methane and
propane, behave similarly, with
relatively slow flame front speeds and similar peak pressures and
temperatures. Hydrogen and
acetylene are substantially different. These two fuels burn much
faster, 3 to 8 times faster at standard conditions, than does propane.
 Hydrogen and acetylene have
another characteristic that differentiates them from fuels such as
propane of butane. Under certain conditions, hydrogen and acetylene
will
detonate (explode) instead of deflagrate (burn). When a fuel detonates
it releases all of
its energy essentially
instantaneously. The flame front speed in a detonation event is at
hyper-mach speeds (mach 6 to 7), roughly 4,000 times faster than the
laminar flame front speed (Mach ~0.001). Because of the very high burn
rate in a detonation, the gun is subjected to a tremendous shock force.
Most spudders believe that this level of stress is unsafe and that
hydrogen and acetylene are unsafe
fuels for a gun constructed from PVC.
<h2>Latke's Propane vs. MAPP
Study</h2>
Burnt Latke did a detailed study (
[http://www.burntlatke.com/lpmapprussets.html]) comparing the
muzzle velocities of propane and
MAPP</a>. Using a 1.5"D riffled barrel shooting spuds, Latke found that
MAPP out performed propane with
muzzle velocities of 444 (+/-34) FPS for MAPP and 398 (+/-34) FPS for
propane. So MAPP gave muzzle
velocities that were about 12% faster than propane. This increase in
performance is greater than what you would expect based solely on the
"Heat per mole Oxygen" values for the two fuels. If the muzzle velocity
scales as the square root of the ratio of the "Heat per mole Oxygen"
values, then MAPP would be expected to give muzzle velocities about ~4%
higher than propane. It is
possible that the 12% increase Latke observed is not statistically
different from the expected ~4% increase. Alternatively, MAPP may burn
slightly faster than propane.
Two of the components of MAPP, methyl acetylene and propadiene, would
be expected to have burn speeds that are more similar to acetylene than
propane.
<h2>So, What's the Best Fuel?</h2>
There really isn't a "best fuel"
for a combustion spud gun. If you want to get the maximum muzzle
velocity from a gun the difference between the various fuels is
relatively small. A typical combustion spud gun has so much shot to
shot variation in velocity that the relatively small difference between
fuels is not particularly relevant. Latke ([http://www.burntlatke.com/]), as good of a spudder as
there is, has done several studies using an accurate [[chronometer]] to
measure muzzle velocities. In all of his studies with spuds as
projectiles, using precisely metered fuels, the shot to shot
variability in muzzle velocity is typically in the 10 to 20% range. In
studies where Latke used the same round for several shots the
shot to shot variability is still in the 5% range. So it really doesn't
matter very much if one fuel has
5% more energy than another fuel.
 
 
The "best fuel" is the one that
the gunner is most comfortable with, that is easiest to obtain and use,
and is cheap. Beyond that there is really no significant difference
between fuels. 
 
There are other ways to get the best performance out of a combustion
spudgun. Here is my list, from most important to least important;
<ul>
<li>Mix the fuel well using a
chamber fan (like shown at [http://www.burntlatke.com/fan.html]).</li>
<li>Accurately measure the fuel
([http://home.earthlink.net/%7Ejimsluka/Sluka_Spud-zooka.html] describes a cheap
way, another at [http://home.earthlink.net/%7Ejimsluka/Fuel%20Meter%20From%20A%20Disposable%20Butane%20Lighter.html]
way, a way with much more "bling" is at [http://www.burntlatke.com/lp.html]).</li>
<li>Properly size the barrel to the chamber (or vice versa)</li>
<li>Increase the number of sparks</li>
</ul>
Any of these four will give much greater increases in performance than
will changing from, for example, propane
to MAPP. 
 
Originally posted at SpudTech.com on Fri
Feb 09, 2007
--[[User:Jimmy101|Jimmy101]] 13:53, 15 May 2007 (EDT)

Camera flash

2007-05-08T11:05:33Z

GalFisk: +short circuit gap

[[image:Camera flash.jpg|right|thumb|300px|Camera flash circuit]]
A '''camera flash''' can be used for spudgun [[ignition]] in several ways, either by itself or by feeding the high voltage from the flash capacitor through a step-up transformer (commonly an [[ignition coil]], [[flyback circuit|flyback transformer]] or a mains transformer in reverse).

The main advantage of camera flash-based ignitions is that it can be built using cheap, readily available components. The spark is more powerful than that of a piezoelectric ignitor. A camera flash is usually powered by one or two AAA or AA cells. Disadvantages include several seconds of recharge time before the ignition can be triggered again, and significant shock hazard from the storage capacitor if built improperly. Special care should be taken when used in metal launchers, as both sides of the storage capacitor can have significant voltages between them and other parts of the circuit, such as the battery poles and the trigger switch.

The camera flash is most easily obtained from a disposable camera, many places that develop films from these will give the discarded camera shell away for free if asked. The flash capacitor can store charge for a long time, and should be discharged before handling the circuit.

=Circuits=

There are several ways to connect a camera flash to a spark gap, which all have their own advantages and drawbacks. These are the most common circuits.

==[[Ignition coil]]==

An ignition coil (or other step-up transformer, such as a flyback or a mains transformer connected in reverse) will provide a high voltage spark when the flash capacitor is discharged through it. Most Ignition coils has a 100:1 winding ratio, meaning that for every 1 volt that is put into the coil, 100 volts come back out.

In order to modify a camera flash circuit for use with an ignition coil, follow these 6 steps:

 [[Step 1 - Removing the Flash Bulb]]

 [[Step 2 - Drilling the Holes for the Ignition Coil Wires]]

 [[Step 3 - Before Adding the Relay]]

 [[Step 4 - Adding the Relay]]

 [[Step 5 - Adding the Ignition Coil and Spark Strip/Spark Gap]]

 [[Step 6 - Providing Power to the Relay]]

 The flimsy battery holder can also be replaced with a plastic one, which is easily attained at any electronics store. Also, you can add a "kill switch" in [[series]] after the battery holder to cut off the power when the circuit is not in use. Be aware that the circuit is not "powered down" when the kill switch is in the off position. The circuit will not be able to charge, but the capacitor will still hold the electricity for a long time. The cannon will need to be "dry fired" after the kill switch is turned off. Be sure to point the cannon away from everyone when doing this.

 [[Step 7 - Removing the Battery Contacts]]

 [[Step 8 - Adding a Battery Holder and Kill Switch]]

 On a final note, the flash charging button on the front of the camera circuit board can also be replaced with an external one to add a finishing touch and an extra degree of safety. This step may be the hardest of all, as the margin for error when drilling the holes may be small. However, in the larger disposable flash cameras such as the [[Kodak Funsaver]] or [[Kodak Max]] cameras, the circuit board is larger and this is not an issue.

 [[Step 9 - Replacing the Charging Button]]

 The relay used in the diagrams is a standard [http://www.rowand.net/Shop/Tech/AllAboutRelays.htm 5-pin automotive relay], which can be purchased at any auto parts or electronics store. It is advisable that you also use a [[relay socket]], since it make the relay easily removable.

If a mains transformer connected in reverse is used, the spark gap will be electrically insulated from the rest of the curcuit, an advantage when used in metal cannons.

The output transformer from a stun gun can also be used, which can be useful if the charging circuit in the stun gun has died. These circuits are in fact quite similar to that of a stun gun.

{{stub}}

===Tube Switched Coil===

The ignition that requires the least modification of the camera consists of cutting one of the main leads to the flash tube, and connecting the ignition coil in between. Triggering the flash will produce a spark from the output of the transformer. The advantage to using the flash tube itself to switch the main discharge, is that almost any small switch can be used to trigger the circuit. If the trigger switch is replaced by a thyristor (SCR), the ignition can be triggered by an electronic circuit. The flash circuit itself is mostly intact and not driven out of spec, which means this circuit is quite reliable.

===Manually Switched Coil===

The flash tube can also be replaced by a heavy duty switch for triggering, though if the switch is too weak it may become welded shut. This switch will also be carrying the full voltage of the capacitor, and must be properly insulated to prevent electric shock. If the trigger switch is held down for a long time the charging circuit in the flash may break since its output is shorted for the duration.

==Triggered spark gap==

Another ignition method that does not require an external step-up transformer, consists of removing the flash tube, and taking out the trigger lead as well as the two main leads. These are then connected to three electrodes, which are placed together to form a spark gap of a millimeter or less. Triggering the flash will ionize the air in the gap and discharge the main capacitor. This produces a more intense spark than the first method, but it requires a more complex park gap. The electrodes can also erode over time, requiring readjustment.

==Trigger transformer spark==

The trigger transformer for the flash tube produces a few kV on its own, and can be connected to a spark gap. The advantage to this method is that the main capacitor is not dumped, so recharge time is eliminated and it uses less battery power. The spark is very weak however, and this method is generally not recommended.

==Short circuit gap==

A camera flash can be used with a short circuit gap, which has movable points that can be brought in contact from outside the chamber. The flash capacitor is connected directly to the gap and creates a spark when it's shorted. This spark gap is more difficult to make, and may have isues with weldong and erosion, but is easy to hook up and requires little electronics knowledge.

==Others==

A camera flash can also be used to trigger [[sprinkler valve]] solenoids built for mains voltage, however the opening time will be brief since the flash capacitor is drained quickly.
[[Category:Ignition sources]]

Stoichiometry

2007-03-18T14:35:24Z

GalFisk: /* Calculations */ legibility

[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 
2H2 + 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 this number. 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

Marble

2007-01-20T01:49:39Z

GalFisk: /* use and target performance */ typos

'''Marbles''' are good solid projectiles, that can penetrate hard targets like wood and sheet metal. They are cheap easy to find and come in a range of sizes, the most common being 1/2", 5/8", 7/8" and 1 inch, or 12, 16, 22 and 25 mm. Larger marbles exist but are often too costly to be used in day to day shooting.

==use and target performance==
The manufacturing tolerances of marbles are often quite wide, so not all 16mm marbles will fit in a 16mm [[barrel]] for instance. If you go to the store to buy marbles, it is suggested to bring a piece of your [[barrel]] to test fit your ammo.

A marble hitting a hard target (such as a rock) is often crushed to harmless sand, but there are chances of getting sharp splinters and ricochets, and appropriate care should be taken. Because of their relatively consistent shape and size marbles are good projectiles to use in cannons with automatic loading mechanisms.

==specifications==
Diameter: 1/2, 5/8, 7/8, or 1" (12, 16, 22, or 25mm)
Density: glass is ~2.4-2.8 g/ml

[[Category:Projectiles]]

Opening time

2007-01-06T10:00:51Z

GalFisk: typo

"Opening time" is the time it takes a valve to open, and as expected, is most important when the barrel dwell time is low. The approximate opening time of some valves:
* [[Burst disk]]s Practicaly instant... most likely under a millisecond.
* Pilot operated valves ([[diaphragm valve]]s, [[piston valve]]s): 3-5ms.
* [[Ball valve]]s: about 100 ms hand-actuated, maybe 20-30 spring-actuated.

The [[GGDT]] will give you a graph of your valve opening. (valve position vs. time or projectile position)

This author is confused as to what the number is when the valve [[honking|honks]], as this involves opening and closing rapidly - should one measure it from beginning of opening to end of honking, or from beginning to the most open part of the first vibration?

[[category:valves]]

Talk:555 timer

2007-01-06T09:43:53Z

GalFisk:

== why? ==

why did u delete this? it is perfectly fine to copy from wikipedia, the GNU lets us.

----
It looks like the website throws an error when the page is viewed.

Anyone happen to know why? It's something to do with how the page was formatted... some of you guys know more about Wiki editing than I do.
--[[User:PCGUY|PCGUY]] 00:56, 6 January 2007 (EST)

:The spud wiki didn't like the foreign letters in one of the links at the bottom, so I removed it (they were not useful here anyways). I'll see if I can give this article a major rewrite, to cover only the parts that are of interest to us. --[[User:GalFisk|GalFisk]] 04:43, 6 January 2007 (EST)

555 timer

2007-01-06T09:41:23Z

GalFisk:

[[Image:Signetics NE555N.JPG|thumb|right|NE555 from [[Signetics]] in [[Dual in-line package|dual-in-line package]]]]
[[Image:555-schem.png|frame|right|Schematic symbol of the 555 timer]]
The '''555''' is an [[integrated circuit]] (chip) implementing a variety of [[timer]] and [[multivibrator]] applications. The IC was designed and invented by [[Hans R. Camenzind]]. It was designed in [[1970]] and introduced in [[1971]] by [[Signetics]] (later acquired by [[Philips]]). The original name was the SE555/'''NE555''' and was called "The IC Time Machine". It is still in wide use, thanks to its ease of use, low price and good stability. Even today, [[Samsung]] in [[Korea]] manufactures over 1 [[billion]] units per year ([[As of 2003|2003]]).

The 555 timer is one of the most popular and versatile integrated circuits ever produced. It includes 23 [[transistor]]s, 2 [[diode]]s and 16 [[resistor]]s on a silicon chip installed in an 8-pin mini dual-in-line package ([[Dual in-line package|DIP]]). The 556 is a 14-pin DIP that combines two 555s on a single chip. The 558 is a 16-pin DIP that combines four, slightly modified, 555s on a single chip (DIS & THR are connected internally, TR is falling edge sensitive instead of level sensitive). Also available are ultra-low power versions of the 555 such as the 7555. The 7555 requires slightly different wiring using fewer external components and less power.

The 555 has three operating modes:
*[[Monostable]] mode: in this mode, the 555 functions as a "one-shot". Applications include timers, missing pulse detection, bouncefree switches, touch switches, etc.
*[[Astable]] mode: the 555 can operate as an [[oscillator]]. Uses include [[LED]] and lamp flashers, pulse generation, logic clocks, tone generation, security alarms, etc.
*[[Bistable]] mode: the 555 can operate as a [[Flip-flop (electronics)|flip-flop]], if the DIS pin is not connected and no capacitor is used. Uses include bouncefree latched switches, etc.

==Usage==
The connection of the pins is as follows:
{| border=1
! Nr. !! Name !! Purpose
|-
| 1 || GND || '''G'''rou'''nd''', low level
|-
| 2 || TR || A short pulse high->low on the '''tr'''igger starts the timer
|-
| 3 || Q || During a timing interval, the '''o'''utput stays at [[Vcc|+VCC]]
|-
| 4 || R || A timing interval can be interrupted by applying a '''r'''eset pulse to low (0V)
|-
| 5 || CV || '''C'''ontrol '''v'''oltage allows access to the internal voltage divider (2/3 VCC)
|-
| 6 || THR || The '''thr'''eshold at which the interval ends (it ends if U.thr > 2/3 VCC)
|-
| 7 || DIS || Connected to a capacitor whose '''dis'''charge time will influence the timing interval
|-
| 8 || V+, VCC || The positive supply '''v'''oltage which must be between 5 and 15 V, high level
|}

Using simply a [[capacitor]] and a [[resistor]], the timing interval, i.e. the time during which the output stays low, can be adjusted to the need of the specific application. An example configuration is shown below:

<center>[[Image:555-schem-2.png|Example 555 schematic]] Example 555 schematic </center>

The interval time ''t'' is given by

:<math>t = RC</math>

which is the time it takes to charge C to 63% of the applied voltage (exact figure: ''(1-1/e)V''). See [[RC circuit]] for an explanation of this effect.

In the astable mode, the high time from each pulse is given by

:<math>high = 0.69 \cdot (R1 + R2) \cdot C</math>

and the low time from each pulse is given by

:<math>low = 0.69 \cdot R2 \cdot C</math>

where R1 and R2 are the values of the resistor in [[ohm]]s and C is the value of the capacitor in [[farad]]s.

==Specifications==
These specifications apply to the NE555. Other 555 timers can have better specifications depending on the grade (military, medical, etc).

{| border=1 cellpadding=2
|Supply voltage (VCC)
|4.5 to 15 V
|-
|Supply current (VCC = +5 V)
|3 to 6 mA
|-
|Supply current (VCC = +15 V)
|10 to 15 mA
|-
|Output current (maximum)
|200 mA
|-
|Power dissipation
|600 mW
|-
|Operating temperature
|0 to 70° C
|}

==Derivatives==

Many pin-compatible variants, including [[CMOS]] versions, have been built by various companies. The 555 is also known under the following type numbers:

{| border="1" cellpadding="2"
!Manufacturer
!Model
!Remark
|-
|ECG Philips
|ECG955M
|-
|Exar
|XR-555
|-
|Fairchild
|NE555/KA555
|-
|Harris
|HA555
|-
|Intersil
|SE555/NE555/ICM7555
|-
|Lithic Systems
|LC555
|-
|Maxim
|ICM7555
|-
|Motorola
|MC1455/MC1555
|-
|National
|LM1455/LM555C
|-
|NTE Sylvania
|NTE955M
|-
|Raytheon
|RM555/RC555
|-
|RCA
|CA555/CA555C
|-
|Sanyo
|LC7555
|-
|Texas Instruments
|SN52555/SN72555; TLC555
|-
|USSR
|K1006ВИ1
|-
|Zetex
|ZSCT1555
|down to 0.9V
|}

==External links==
*[http://www.uoguelph.ca/~antoon/gadgets/555/555.html 555 Timer Tutorial]
*[http://www.fairchildsemi.com/ds/NE/NE555.pdf Data Sheet (Fairchild) (PDF)]
*[http://www.falstad.com/circuit/ex-555.html Java simulation] of 555 oscillator circuit
*[http://www.datasheetarchive.com/search.php?q=NE555&sType=part&ExactDS=Starts 1972 Signetics NE555 datasheet (PDF)]

Fuel meter

2006-11-13T20:35:29Z

GalFisk: added calculations (somewhat rudimentary)

A '''fuel meter''', also known as a '''propane meter''' is used to inject a predetermined amout of fuel gas (usually [[propane]]) into the chamber of a [[Combustion cannon|combustion]] or [[hybrid cannon|hybrid]]. It typically consists of an adjustable [[pressure regulator]] and [[pressure gauge]], connected to two [[ball valve]]s with a length of pipe in between. The volume of this pipe and the pressure of the gas determines the amount of gas injected. The second ball valve is connected to the chamber of the gun.
A fuel meter is operated as follows:
*The regulator is set to a predetermined pressure for the particular meter and chamber size
*The ball valve closest to the regulator is opened, filling the pipe up until the second ball valve with gas at the regulated pressure
*The first ball valve is closed again, closing off the section of pipe between the two valves
*The second ball valve is opened, the pressurized gas inside the meter expands and enters the main chamber
*The second ball valve is closed, and the cannon is ready to fire

The regulator usually only needs to be set the first time, and further fueling can be done simply by opening and closing the two ball valves. A fuel meter provides fast and very consistent fueling, and is the easiest way to use bottled gas for fuel.

===Calculations===

Constructing a fuel meter and determining the correct pressure to use requires a few calculations. First you need to calculate the fuel:air ratio, and from that the amount of fuel needed. These calculations are covered under [[stoichiometry]].

Formulas for fuel meters:

P=pressure in bar, Vf=fuel volume, Vm=meter volume. Any unit of measurement can be used for the volume, as long as the same unit is used throughout. Pressure needs to be converted to bar, if you have the pressure in psi divide it by 14.7.
*P = Vf/Vm
*Vm = Vf/P
*Vf = P*Vm

===Concrete example===

In the example from the stoichiometry article, we found that the fuel volume needed for a 3000 cc chamber is 126 cc. At 1 atmosphere (14.7 psi) of overpressure, we'd need a meter volume of 126 cc. At twice the pressure, we'd need half the volume and so on.

For the example, we decide that meter pressure will be 3 bar. The meter volume required is then 126/3 = 42 cc.

The Fuel Tool (found on Burnt Latke's [http://www.burntlatke.com/calc.html performance calculators page]) automates the fuel meter calculations.

[[Category:Accessories]]

Piston valve

2006-10-26T10:53:37Z

GalFisk: Rearranged article, added some info.

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 diaphragm with a rigid cylinder. There are 2 varieties; barrel sealing and chamber sealing.

== Barrel sealing valve ==

In a barrel sealing valve, the piston seals against the breech of the barrel. this is the most common piston valve design.

=== construction ===

The piston is often a well fitting cup-shaped object, such as a end cap. 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 co-axially 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 ===
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]
Operation:
#Air is added by filling behind the piston (C).
#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.)
#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.
#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.
#The air flows around from the chamber, and into the barrel, propelling the projectile.

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]]

===Explanation and plans===

[http://www.magooffl.com/images/diagram.jpg Image]

The air is put into the gun from behind the piston. the piston is pushed into the rubber coupler, and it seals so no air can go out the barrel.

but air goes between the piston and pipe, and goes through the bottom of the tee, into the chambers. Okay, this is where the sprinkler valve comes in. Since there is air pressing on the front and back of the piston, but there is less surface on the front, the pressure on the back keeps it seated.

to fire, activate the solenoid, which vents the back of the piston, so there is much more more pressure pushing it on the front. This causes it to slam backwards, unseating the valve, and dumping huge amounts of air out the barrel at once.

this all actually happens instantaneously(instantly) at the near instant you hit the button.

NOTE:the 3 inch sch 40 end cap piston was sanded around the back, where you will find small ridges of extra PVC from when it was injection molded. buy the smoothest end cap and rubber coupler you can find, and it will seal

Talk:Propane

2006-08-07T11:20:45Z

GalFisk:

Needs more relevant information (containers, fittings, where to buy etc) --[[User:GalFisk|GalFisk]] 07:20, 7 August 2006 (EDT)

Gas Gun Design Tool

2006-04-24T11:31:35Z

GalFisk: /* Physics model */ typo

Hall Consulting's '''Gas Gun Design Tool''' is a simulation program to aid the design of [[pneumatic cannon]]s. It is available [http://www.thehalls-in-bfe.com/GGDT here].

==Physics model==
As of version 4.2, in modeled the following 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://www.thehalls-in-bfe.com/GGDT page] on use
{{stub}}

Gas Gun Design Tool

2006-04-24T11:31:20Z

GalFisk: updated URL

Hall Consulting's '''Gas Gun Design Tool''' is a simulation program to aid the design of [[pneumatic cannon]]s. It is available [http://www.thehalls-in-bfe.com/GGDT 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://www.thehalls-in-bfe.com/GGDT page] on use
{{stub}}

Gas Gun Design Tool

2006-04-24T11:30:48Z

GalFisk: /* Use */

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://www.thehalls-in-bfe.com/GGDT page] on use
{{stub}}

Ignition coil

2006-03-25T13:50:18Z

GalFisk: /* Manual switch */ +file

An '''ignition coil''' is the ignition source used in most gas engines, and can be adapted for use as a spudgun ignition. Almost any coil will work as long as it's in good condition. Ingition coils will give powerful sparks, which means most circuits will also require a lot of power (the camera flash circuit is an exception).

===Driving circuits===

An ignition coil needs a pulsed current through its primary winding to generate the high voltage, so it cannot simply be connected to a car battery. These are the most common ways to drive an ignition coil:

====Buzzer relay====

A relay is connected so that when it activates, it will cut its own current. This will cause it to oscillate, and the resulting pulsed current can be fed to the ignition coil.

There are several ways to set up this circuit depending on the configuration of the relay. The most reliable and powerful design uses a relay with two normally closed contacts, where one is connected in series with the relay solenoid to make it oscillate, and the other contact is connected in series with the ignition coil. The contact that closes first upon return should be connected to the ignition coil, so the contacts should be swapped during testing to see which configuration gives the most consistent spark.

====Electronic oscillator circuit====

An oscillator circuit, typically made up of a [[555 timer]] circuit and switching transistor, is used to interrupt the current through the coil with a frequency of 5-20 kHz.

====Camera flash====

The voltage from the storage capacitor of a camera flash is dumped through the ignition coil. See the [[camera flash]] article for circuit details.

====Manual switch====

If the current through the ignition coil is switched on and off manually, the coil will produce a spark every time the current is shut off. A crude way to create many sparks in rapid succession consists of using the surface of a file, when one wire is connected to the file and the other raked over its surface, the current will be interrupted many times in rapid succession.

====Mains dimmer====

An ignition coil can be driven by mains power, by connecting it in series with a light dimmer and a motor start capacitor. The dimmer should be set at about 50% for maximum voltage. The dimmer will chop the mains power and discharge the capacitor through the coil. This circuit is dangerous since it carries mains voltage on all parts, and should NOT be used for spudgun ignition.
[[Category:Ignition sources]]

Talk:Acetylene

2006-03-23T17:35:43Z

GalFisk:

I think it's better to have proper information on dangerous subjects such as this on the wiki, rather than treating them as taboo and leaving people to get bad info from somewhere else. --[[User:GalFisk|GalFisk]] 12:35, 23 March 2006 (EST)

Acetylene

2006-03-23T17:32:40Z

GalFisk: typo

'''Acetylene''' (chemical formula C2H2) is a flammable gas used for welding and cutting. It is far too powerful for a spudgun, and its use can result in injury or death. There are also dangers that are unique to acetylene, because the molecule contains an unstable and energetic triple bond that is easily broken.

Acetylene is a very reactive gas, with a flammability limit of 2.5 to 100% in air. It can decompose spontaneously with no air present, if there is an ignition source, or simly if the pressure of the gas exceeds 15 psi. Because of this it is more prone to [[detonation]] than any other gas. Acetylene is also very sensitive to static electricity, and it comes out of the tank dry which means that plastic materials containing the cas get charged easily.

In addition to these dangers, the gas doesn't even contain as much energy per volume as [[propane]], it's gross calorific value is 56000 kJ/m2 as opposed to propane's 101000 kJ/m2. The destructive power comes from the extremely rapid release of energy, which creates very high pressure spikes.

Acetylene

2006-03-23T17:32:17Z

GalFisk: created page (hazards of acetylene)

'''Acetylene''' (chemical formula C2H2) is a flammable gas used for welding and cutting. It is far too powerful for a spudgun, and its use can result in injury or death. There are also dangers that are unique to acetylene, because the molecule contains an unstable and energetic triple bond that is easily broken.

Acetylene is a very reactive gas, with a flammability limit of 2.5 to 100% in air. It can decompose spontaneously with no air present, if there is an ignition source, or simly if the pressure of the gas exceeds 15 psi. Because of this it is more prone to [[detonation]] than any other gas. Acetylene is also very sensitive to static electricity, and it comes out of the tank dry which means that plastic materials containing the cas get charged easily.

In addition to these dangers, the gas doesn't even contain as much energy per volume as [[propane]], it's gross calorific value is 56000 kJ/m2 as opposed to propne's 101000 kJ/m2. The destructive power comes from the extremely rapid release of energy, which creates very high pressure spikes.

Chamber

2006-03-23T16:58:48Z

GalFisk: +cat

The '''chamber''' or '''reservoir''' is the power source of a spudgun. It is, along with the [[barrel]], the only component found in all launchers. In [[combustion cannon]]s, the chamber contains the flammable fuel/air mixture, and in [[pneumatic cannon]]s it contains the compressed gas. The chamber is connected to the barrel either directly or through a valve, to propel the projectile when the energy is released. The chamber is often the part of the launcher that is subjected to the highest stress, and it's important that it is well [[Cannon construction|constructed]]. It is also the part where the most accessories are connected, especially combustion launchers; they can have a multiple holes to accommodate [[spark gap]]s, [[chamber fan]]s, [[fuel meter]]s and for [[venting]].

{{stub}}
[[Category:Components]]

Flyback circuit

2006-03-23T16:53:43Z

GalFisk:

[[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.

[http://www.angelfire.com/80s/sixmhz/flyback.html A page about building the basic flyback circuit]

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

Flyback circuit

2006-03-23T16:53:22Z

GalFisk: +external link

[[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.

[[http://www.angelfire.com/80s/sixmhz/flyback.html A page about building the basic flyback circuit]]

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

Category:Ignition sources

2006-03-23T16:50:52Z

GalFisk:

Ignition source

2006-03-23T16:50:24Z

GalFisk:

The '''ignition source''' is used to ignite the flammable gasses in the chamber of [[combustion cannon|combustion]] and [[hybrid cannon]]s. The most common ignition sources include:
*[[Lantern sparker]]s
*Piezoelectric [[BBQ ignitor]]s
*[[Stun gun]]s
*[[Camera flash]]-based ignitions
*[[Flyback circuit|Flyback ignition]]s
*Automotive [[ignition coil]]s

For a full overview, see [[:Category:Ignition sources]]

All of these except the lantern sparker produce an electric spark, and need to be connected to some form of [[spark gap]] or [[spark strip]].

[[Category:Components]]

Lantern sparker

2006-03-23T16:47:54Z

GalFisk: fixed category

[[Image:sparker.jpg|frame|Replacement lantern sparker]]'''Lantern sparkers''' are a method of ignition and are usually cheaper than [[BBQ ignitor]]s or [[stun gun]]s. They work by spinning a knurled wheel connected to a rod of steel. A piece of flint pressed against a rifled section of the steel by a spring. When the wheel is spun rapidly, pieces of the flint material are shaved off and ignite spontaneously, causing a shower of sparks. The main disadvantage with lantern sparkers is that they have the tendency to not spark when wet with ANYTHING! Axe, hairspray, and [[starting fluid]] will all stop a lantern sparker from working if they should get on the flint/steel sparking assembly. They are very cheap however, and the flints are replaceable. If you can afford it, a good [[BBQ ignitor]] or [[stun gun]] is superior.
the lantern sparker is mounted through a single hole in the chamber. It protrudes into the chamber, and may therefore be impractical or impossible to use in [[coaxial]] launchers.
[[Category:Ignition sources]]

Camera flash

2006-03-23T16:47:35Z

GalFisk: fixed category

BBQ ignitor

2006-03-23T16:47:16Z

GalFisk: fixed category

[[Image:BBQ_Ignitor.jpg|right|thumb|250px|A simple piezo ignitor for a grill]]A '''BBQ ignitor''' or grill ignitor is arguably the simplest spudgun [[ignition source]]. It consists of a pushbutton, that activates a hammer mechanism that strikes a piezoelectric crystal. The crystal generates a high voltage pulse that can be made to jump a small spark gap. One of the main advantages to a BBQ ignitor is that it doesn't use batteries, and is cheap and relatively small. Quality differs quite a bit though, some ignitors last for many years while other break after some time of use. The spark is also the weakest of the common ignition sources, and achieving ignition may take several attempts in some circumstances (cold weather, sub-optimal fuel mixes, etc).
Piezoelectric ignitors can also be obtained from a few other devices, notably long-nosed lighters, and some gas ignitors and cigarette lighters.

There are also electric BBQ ignitors that run on a 1.5V or 9V battery. They are weak compared to other electronic [[ignition source]]s, but a good choice for remote ignition.
[[Category:Ignition sources]]

Ignition coil

2006-03-23T16:45:50Z

GalFisk: +cat

An '''ignition coil''' is the ignition source used in most gas engines, and can be adapted for use as a spudgun ignition. Almost any coil will work as long as it's in good condition. Ingition coils will give powerful sparks, which means most circuits will also require a lot of power (the camera flash circuit is an exception).

===Driving circuits===

An ignition coil needs a pulsed current through its primary winding to generate the high voltage, so it cannot simply be connected to a car battery. These are the most common ways to drive an ignition coil:

====Buzzer relay====

A relay is connected so that when it activates, it will cut its own current. This will cause it to oscillate, and the resulting pulsed current can be fed to the ignition coil.

There are several ways to set up this circuit depending on the configuration of the relay. The most reliable and powerful design uses a relay with two normally closed contacts, where one is connected in series with the relay solenoid to make it oscillate, and the other contact is connected in series with the ignition coil. The contact that closes first upon return should be connected to the ignition coil, so the contacts should be swapped during testing to see which configuration gives the most consistent spark.

====Electronic oscillator circuit====

An oscillator circuit, typically made up of a [[555 timer]] circuit and switching transistor, is used to interrupt the current through the coil with a frequency of 5-20 kHz.

====Camera flash====

The voltage from the storage capacitor of a camera flash is dumped through the ignition coil. See the [[camera flash]] article for circuit details.

====Manual switch====

If the current through the ignition coil is switched on and off manually, the coil will produce a spark every time the current is shut off.

====Mains dimmer====

An ignition coil can be driven by mains power, by connecting it in series with a light dimmer and a motor start capacitor. The dimmer should be set at about 50% for maximum voltage. The dimmer will chop the mains power and discharge the capacitor through the coil. This circuit is dangerous since it carries mains voltage on all parts, and should NOT be used for spudgun ignition.
[[Category:Ignition sources]]

Ignition coil

2006-03-23T16:44:38Z

GalFisk: /* Camera flash */ fixed link

An '''ignition coil''' is the ignition source used in most gas engines, and can be adapted for use as a spudgun ignition. Almost any coil will work as long as it's in good condition. Ingition coils will give powerful sparks, which means most circuits will also require a lot of power (the camera flash circuit is an exception).

===Driving circuits===

An ignition coil needs a pulsed current through its primary winding to generate the high voltage, so it cannot simply be connected to a car battery. These are the most common ways to drive an ignition coil:

====Buzzer relay====

A relay is connected so that when it activates, it will cut its own current. This will cause it to oscillate, and the resulting pulsed current can be fed to the ignition coil.

There are several ways to set up this circuit depending on the configuration of the relay. The most reliable and powerful design uses a relay with two normally closed contacts, where one is connected in series with the relay solenoid to make it oscillate, and the other contact is connected in series with the ignition coil. The contact that closes first upon return should be connected to the ignition coil, so the contacts should be swapped during testing to see which configuration gives the most consistent spark.

====Electronic oscillator circuit====

An oscillator circuit, typically made up of a [[555 timer]] circuit and switching transistor, is used to interrupt the current through the coil with a frequency of 5-20 kHz.

====Camera flash====

The voltage from the storage capacitor of a camera flash is dumped through the ignition coil. See the [[camera flash]] article for circuit details.

====Manual switch====

If the current through the ignition coil is switched on and off manually, the coil will produce a spark every time the current is shut off.

====Mains dimmer====

An ignition coil can be driven by mains power, by connecting it in series with a light dimmer and a motor start capacitor. The dimmer should be set at about 50% for maximum voltage. The dimmer will chop the mains power and discharge the capacitor through the coil. This circuit is dangerous since it carries mains voltage on all parts, and should NOT be used for spudgun ignition.

Ignition coil

2006-03-23T16:44:17Z

GalFisk: +dimmer, editing, etc

An '''ignition coil''' is the ignition source used in most gas engines, and can be adapted for use as a spudgun ignition. Almost any coil will work as long as it's in good condition. Ingition coils will give powerful sparks, which means most circuits will also require a lot of power (the camera flash circuit is an exception).

===Driving circuits===

An ignition coil needs a pulsed current through its primary winding to generate the high voltage, so it cannot simply be connected to a car battery. These are the most common ways to drive an ignition coil:

====Buzzer relay====

A relay is connected so that when it activates, it will cut its own current. This will cause it to oscillate, and the resulting pulsed current can be fed to the ignition coil.

There are several ways to set up this circuit depending on the configuration of the relay. The most reliable and powerful design uses a relay with two normally closed contacts, where one is connected in series with the relay solenoid to make it oscillate, and the other contact is connected in series with the ignition coil. The contact that closes first upon return should be connected to the ignition coil, so the contacts should be swapped during testing to see which configuration gives the most consistent spark.

====Electronic oscillator circuit====

An oscillator circuit, typically made up of a [[555 timer]] circuit and switching transistor, is used to interrupt the current through the coil with a frequency of 5-20 kHz.

====Camera flash====

The voltage from the storage capacitor of a camera flash is dumped through the ignition coil. See the [[[camera flash]] article for circuit details.

====Manual switch====

If the current through the ignition coil is switched on and off manually, the coil will produce a spark every time the current is shut off.

====Mains dimmer====

An ignition coil can be driven by mains power, by connecting it in series with a light dimmer and a motor start capacitor. The dimmer should be set at about 50% for maximum voltage. The dimmer will chop the mains power and discharge the capacitor through the coil. This circuit is dangerous since it carries mains voltage on all parts, and should NOT be used for spudgun ignition.

Ignition coil

2006-03-23T16:34:07Z

GalFisk: +more info, -stub (though it can still use more work ,and a nice pic)

An '''ignition coil''' is the ignition source used in most gas engines, and can be adapted for use as a spudgun ignition. To generate a high voltage pulse, the current in the primary coil needs to be pulsed.

===Driving circuits:===
====Buzzer relay====

A relay is connected so that when it activates, it will cut its own current. This will cause it to oscillate, and the resulting pulsed current can be fed to the ignition coil.

There are several ways to set up this circuit depending on the configuration of the relay. The most reliable and powerful design uses a relay with two normally closed contacts, where one is connected in series with the relay solenoid to make it oscillate, and the other contact is connected in series with the ignition coil. The contact that closes first upon return should be connected to the ignition coil, so the contacts should be swapped during testing to see which configuration gives the most consistent spark.

====Electronic oscillator circuit====

An oscillator circuit, typically made up of a [[555 timer]] circuit and switching transistor, is used to interrupt the current through the coil with a frequency of 5-20 kHz.

====Camera flash====

The voltage from the storage capacitor of a camera flash is dumped through the ignition coil. See the [[[camera flash]] article for circuit details.

====Manual switch====

If the current through the ignition coil is switched on and off manually, the coil will produce a spark every time the current is shut off.

Camera flash

2006-03-23T16:12:01Z

GalFisk: organized, +trigger trafo, etc

Spud

2006-03-23T15:39:34Z

GalFisk: added redirect

#redirect[[Potato]]

Marble

2006-03-23T15:37:52Z

GalFisk: created page

'''Marbles''' are good solid projectiles, that can penetrate hard targets like wood and sheet metal. They are cheap easy to find and come in a range of sizes. The most common dimensions are 1/2, 5/8, 7/8 and 1 inch, or 12, 16, 22 and 25 mm. Larger marbles exist but are often too costly to be used in day to day shooting.

The manufacturing tolerances of marbles are often quite wide, so not all 16mm marbles will fit in a 16mm [[barrel]] for instance.

A marble hitting a hard target (such as a rock) is often crushed to harmless sand, but there are chances of getting sharp splinters and ricochets, and appropriate care should be taken. Because if their relatively consistent shape and size marbles are good projectiles to use in cannons with automatic loading mechanisms.

[[Category:Projectiles]]

Talk:Piston valve

2006-03-23T15:16:10Z

GalFisk:

Info on chamber-sealing piston is needed. --[[User:GalFisk|GalFisk]] 31 October 2005 06:51 (CST)

put up the 3 flash animations...
and find mine on spudfiles.
:Wiki doesn't support flash (as far as I can see), is there a site we can link to, which has the same info as the sticky on spudtech? --[[User:GalFisk|GalFisk]] 10:16, 23 March 2006 (EST)

Tee

2006-03-23T15:08:22Z

GalFisk: typo

A '''tee''' has 3 [[socket-weld]] (or [[female threads|threaded]] in the case of steel) openings. 
These are arranged in a planar arrangement, each skewed 90* from the last. This looks a bit like the letter "T", which is where the fitting derives it's name.

Tees are useful for connecting 2 pipes into one, such as connecting two chambers to one valve or connecting many valves to a common trigger.

A more advanced use of tee fittings is as the basis for both barrel- and chamber-sealing [[piston valve]]s. The valve itself is constructed inside the tee, and the outlets are connected to the [[chamber]], [[barrel]] and [[pilot valve]].

[[category:fittings]]

Tee

2006-03-23T15:07:56Z

GalFisk: formatting

A '''tee''' has 3 [[socket-weld]] (or [[female threads|threaded]] in the case of steel) openings. 
These are arranged in a planar arrangement, each skewed 90* from the last. This looks a bit like the letter "T", which is where the fitting derives it's name.

Tees are useful for connecting 2 pipes into one, such as connecting two chambers to one valve or connecting many valves to a common trigger.

A more advanced use of tee fittings is as the basis for both barrel- and chamber-sealing [[piston valve]]s. The valve itself is constructed inside the tee, and the outlets are conencted to [[chamber]], [[barrel]] and [[pilot valve]].

[[category:fittings]]

Tee

2006-03-23T15:07:20Z

GalFisk: +uses

A '''tee''' has 3 [[socket-weld]] (or [[female threads|threaded]] in the case of steel) openings. 
These are arranged in a planar arrangement, each skewed 90* from the last. This looks a bit like the letter "T", which is where the fitting derives it's name.

Tees are useful for connecting 2 pipes into one, such as connecting two chambers to one valve or connecting many valves to a common trigger.
A more advanced use of tee fittings is as the basis for both barrel- and chamber-sealing [[piston valve]]s. The valve itself is constructed inside the tee, and the outlets are conencted to [[chamber]], [[barrel]] and [[pilot valve]].

[[category:fittings]]

Piston valve

2006-03-23T14:59:56Z

GalFisk: changed to wikicode

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:
#Air is added by filling behind the piston (C).
#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.)
#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.
#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.
#The air flows around from the chamber, and into the barrel, propelling the projectile.

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]]

Chamber fan

2006-03-15T16:48:11Z

GalFisk: +brushless info, formatting

A '''chamber fan''' is a device used in [[combustion launcher|combustion]] or [[hybrid cannon|hybrid]] cannons for creating an even mixture of fuel and air within the chamber, and/or venting the chamber between shots. The commonly used fan is a CPU or case fan from a computer, these use brushless motors which do not create sparks that can ignite the fuel/air mix. A chamber fan setup also has a switch to operate the fan, and a power source such as batteries to power it. It can also be controlled automatically using a [http://www.burntlatke.com/fan-controller.html timer circuit] which turns the fan off when it's not needed.

The benefits of using a chamber fan include, but are not limited to:

*Mixing the fuel within the chamber to provide an even distribution.
*Venting the chamber of exhaust gases after a shot.
*inducing turbulence into the flow contaning the flame front.

The effects on cannon performance include [http://www.burntlatke.com/jpg600/fan-data.gif increased] [[muzzle velocity]], and the ability to quickly vent the chamber of exhaust gases.

[[Category:Accessories]]

Coaxial

2006-03-15T16:38:26Z

GalFisk: formatting, fixed half sentence

In a coaxial configuration, the [[barrel]] is placed in the center of the [[chamber]], and the breech end is near the chamber endcap. The design makes a very compact and rather nice looking launcher, since part of the barrel is enclosed in the chamber. Also, this is useful for [[diaphragm valve]]s or [[piston valve]]s. However, this also means that the volume of the enclosed barrel is subtracted from the total chamber volume, so a longer chamber is needed than in equivalent [[over/under]] or [[linear]] designs. Mounting the barrel like this is usually done by means of a [[bushing modification|modified bushing]].

In [[combustion cannon]]s, another advantage of the coaxial design is that the cannon can be easily breech-loaded when removing the endcap for venting. However, it can be a pain to vent and mix the combustion products/fuel since there usually isn't much space for [[chamber fan]]s or traditional [[spark gap]]s. A [[spark strip]] is well suted for use in a coaxial chamber.

Coaxial [[pneumatic cannon]]s almost exclusively use a custom built barrel-sealing piston or diaphragm valve design, since they are perfectly suited for this configuration.

In long chambers, internal barrel supports may be needed to keep the breech end of the chamber centered. The part of the barrel inside a pneumatic coaxial launcher is subjected to outside pressure, it should be noted that the tolerance for this can be lower than the pressure rating of the pipe. There has been at least one [http://forums.spudtech.com/topic.asp?ARCHIVE=true&TOPIC_ID=1909 incident] where a thinwall barrel has collapsed from the outside pressure.

Aerosol

2006-03-15T16:30:42Z

GalFisk: +right guard update, etc

'''Aerosol''' propellants come in cans, you can buy them at wal*mart, and they do not need any auxillary hardware (like a [[fuel meter]]) to use. As such, they are quite popular.

It is recommended that you avoid using hairspray, as it will gum up your chamber. Deoderant is much better - "Right Guard" in the brown can was the generaly recommended one until recently, when the formula was changed to use a non-combustible propellant. Any spray with flammable propellants will work, look for things like [[propane]], [[butane]], isobutane and/or [[starter fluid|ether]]).

Because the amount of fuel cannot be measured accurately (the usual procedure is timing the spray duration by feel), it does not yield the performance that [[fuel meter|metered propane]] does - the pressure generated during a [[closed chamber]] firing is estimated to about 30-40 [[psi]], as compared to 40-50.
If your cannon is not firing, or is firing weakly and you have a flammable fuel (verified by spraying over a flame): check the [[ignition source]]. If you are getting a spark, you are most likely spraying too much fuel in; play around with how much you spray in until you get a good bang. And always remember to [[venting|vent]] your chamber between shots.

[[category:fuels]]

Solvent welding

2006-03-15T16:26:08Z

GalFisk: bold

[[Image:primer_cement.jpg|right|thumb|250px|Cans of PVC primer and cement]]'''Solvent welding''' is a method of joining plastic pipe, usually used on PVC or ABS to achieve a high strength joint. In the process, the plastic in the joined surfaces is chemically melted, and joins together to a solid piece when the solvent evaporates. A properly made solvent weld will have a pressure rating equal to that of the individual parts. The joints will take some time to achieve full strength, cannons should be left to dry at least 24 hours before use.

Solvent vapors are flammable and hazardous to your health, work should be done in a well ventilated area and away form ignition sources. The chamber of combustion and hybrid cannons should be vented before testing the ignition, accidents have happened when solvent vapors have ignited in newly constructed guns.

; External Links
* [http://www.burntlatke.com/weld.html Solvent Welding Guide]

{{stub}}
[[Category:Construction methods]]

Potato

2006-03-15T15:59:31Z

GalFisk: fixed link, bold, etc

[[Image:Potato.jpg|frame|Some standard potatos.]]

The '''potato''' (aka '''spud''') is the original and most common ammo for a spud cannon. Typically large and juicy ones are perferred, this is because the size is needed for larger barrels and the juice acts as a lubricant in the barrel when muzzle loaded. Also when muzzle loaded, the spud is typically forced into the barrel that has a [[muzzle knife]] on the end. When this is done, the spud is shaved to a perfect fit for the barrel which makes an air tight seal.

Potatos are also typically fairly cheap and can be found anywhere, thus why it started as the original ammo.

Quick-exhaust valve

2006-03-13T08:50:39Z

GalFisk: formatting

'''Quick-exhaust valves''' ('''QEVs''' for short) are ready-made piston or diaphragm valves, designed to quickly exhaust pneumatic cylinders. They work somewhat similarly to [[sprinkler valve modification|pneumatically modified]] [[sprinkler valve]]s, they are more expensive and harder to find, but also perform better.

QEVs need a separate [[pilot valve]] for triggering. They can be very sensitive, triggering at a pressure drop of a few psi, so care should be taken when filling with a [[schrader valve]] or other valves that will let out air when disconnected.

Most QEVs are designed to be filled from the pilot side, and will typically work well using a 3-way valve as the fill/pilot valve. Some QEVs will also work when filled from the chamber side.

Small QEVs are sometimes used as pilots for larger valves, often to allow the use of a [[blowgun]] as the trigger.

http://www.pbreview.com/pics/1057167629.jpg

Talk:Quick-exhaust valve

2006-03-13T08:46:14Z

GalFisk:

We need a better image here, one that is high resolution and not hotlinked. Preferrably of a QEV big enough to be used as the main valve. --[[User:GalFisk|GalFisk]] 03:46, 13 March 2006 (EST)

Hybrid cannon

2006-03-13T08:36:44Z

GalFisk: thumbnailed image

[[Image:hybrid.jpg|right|thumb|300px| A very well constructed hybrid cannon]]
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.

Main Page

2006-03-11T17:26:40Z

GalFisk: /* External links */ removed dead link

[[Image:Cannon.jpg|frame|An Advanced Combustion Cannon]]

=== The Spudding Handbook ===
Provided By The Users of [http://www.spudfiles.com SpudFiles]
----

[[What is a spudgun?]]

[[Combustion cannon]]s

[[Pneumatic cannon]]s

[[Hybrid cannon]]s

[[BB machine gun]]s

[[Cannon construction]]

[[Launcher configuration]]

[[Computer Applications|Computer simulators]]

[[Safety]]

[[Legal issues]]

[[History]]

This website is here to teach you about potato guns, also called spudguns, spudzookas, and spud chuckers. So far there are pneumatic, combustion, hybrid, and BB type cannons/launchers. Here you will learn all about spud safety, how to make things like breech loaders and what types of fuel to use in your spud gun (like propane, butane, hairspray, rightguard, etc.). You will learn the good and bad types of ammo to use as well as learn the best types of ignition (like stunguns, flint ignitors, BBQ ignitors, etc.) and how legal your cannon is. You just may learn how to get something totally free. You will learn about ABS and PVC pipe and how to correctly mount a pressure gauge into your cannon. You will learn all about the different kinds of valves and how to use them. (sprinkler valves, diaphragm valves, pistons, etc.) You will learn how to make a hybrid and a pneumatic/combustion cannon. You can even learn about strafers and submachine BB guns! Above all you will be able to find instructions on how to build things that you will love for years to come. All of this is totally free so be happy and get on to registering and posting!

-PCGUY, maker of SpudFiles

==External links==

*[http://www.bcvids.com BCVids (aka Utopia), video tutorials (in part by PCGUY)]
*[http://www.bavetta.com/aircannon.html Air Cannon Barrel Length Numerical Analysis]
*[http://www1.iwvisp.com/thehalls/ggdt Gas Gun Design Tool, simulation program for pneumatic guns]
*[http://www.spudfiles.com/Other/are_they_legal.php ATF Correspondence concerning spud guns]
*[http://www.spudfiles.com Spud Files (aka The Spud Cannon Database)]
*[http://www.spudtech.com Great source of spudgun information]

Talk:Main Page

2006-03-11T08:06:14Z

GalFisk: /* Spam */

I moved (renamed) the entries on the different types of cannons to singular form ([[Combustion cannon]], [[Hybrid cannon]] etc), it's standard in wikis and makes linking much easier. Edit: removed capitalization in the titles as well, should not be used unless neccessary (such as in person names) since wiki is picky about capitals. I put redirects in place. --[[User:GalFisk|GalFisk]] 18 October 2005 04:22 (CDT)

== Formatting ==

Question: should the preferred formatting of lists be like that on the cannon pages
*item 1
*item 2
*etc
or the default one, like this

*item 1
*item 2
*etc

The second one is more common, but the first one has precedence on this page. I prefer the second one since it's more integrated with the rest of the text (same font/size) and think the other should be reserved for ascii drawings and the like that needs a monospace font. It would be nice to have a rule either way though, have the pages edited to correspond to that rule, and so set a consistant basis for future articles.
-- [[User:GalFisk|GalFisk]] 18 October 2005 09:04 (CDT)

== Whatever you please ==

If you think the second way is better then go with it. I'm still trying to get used to using a Wiki and it seems that you've been on more than be so you've had more experience.

Have fun :)

Thanks a lot.
:Ok, I'll change the formatting in the affected articles to the way I like it then. I've edited a bit on Wikipedia and I enjoyed it, I'll be adding/fixing stuff here whenever I feel like it.
:I see that the box formatting can creep in by simply custting and pasting from Wikipedia, it's created by adding a space in front of a line and that can creep in during that operation for some reason.
:You can sign your posts by putting three tildes (<nowiki>~~~</nowiki>) at the end, or sign it with date using four tildes. Remember to be logged in then of course. Preview is a good tool when trying out stuff.
:Result: [[User:GalFisk|GalFisk]] 18 October 2005 11:47 (CDT)

== duplicate articals ==

There are multiple articals that are exactly the same, but with slightly different names.
What's up with this?
:Some items redirect to other articles, if you search for [[ignition]] you're redirected to [[ignition source]] for instance. some articles were also renamed, when that is done a redirect is automatically placed on the old name. If you have been redirected, it will say so at the top of the page.
:The reason for having redirects is to make searching and linking easier, as well as not losing all previous links to a page if it gets renamed for some reason.
:If you find genuine duplicate identical articles, delete one and place a redirect from that to the other one. A redirect consists of the following text:

:<nowiki>#redirect [[article name]]</nowiki>

:--[[User:GalFisk|GalFisk]] 18 October 2005 17:35 (CDT)

== Some info on how Wiki handles capital letters: ==

The first letter in an article name will always be a capital letter. If you try to create an article on "psi" (which is the correct capitalization), it will be named "Psi".

When linking, the first letter is treated the same whether it is capital or not. Both <nowiki>[[psi]] and [[Psi]]</nowiki> will get you to the "Psi" article.

This is not the case with capital letters elsewhere in the article name though, a link to <nowiki>[[PSI]]</nowiki> will point to an article with the entire title in capitals.

To create more confusion, the search function is less picky, a search for both "PSI" and "psi" will send you to the same article.

Because of this, it's important not to use capital letters except where warranted. Valid cases are abbreviations ([[BBQ ignitor]], [[PVC]]), proper names, ([[The Spudgun Technology Center]], [[Gas Gun Design Tool]]), and other things that are normally written capitalized. If it's done both ways (many don't bother capitalizing either of these two), make a redirect from one version to the other.

As a rule of thumb, only capitalize when it looks wrong if you don't.

If you are unsure just go ahead and do it either way, if it's wrong someone will come along and fix it.

i think linking to a particular post on spudtech is a bad idea, people may have to sign up.

== Stubs, categories ==

A '''stub''' is a short article where a lot of information could be added. To mark an article as a stub, add <nowiki>{{stub}}</nowiki> at the bottom. A notice will be added that the article needs to be expanded. When you expand on a stub, you can remove the notice. All current stubs can be found in [[:Category:Stubs]]. [[The Spudgun Technology Center]] article is a good example, it's very short and a lot more can be written about it.

'''Categories''' are a way to automatically organize articles. When a new article is made, it can be added to a category by adding <nowiki>[[Category:Category name]]</nowiki> at the bottom. An article should not be member of too many categories, only those to which is has a direct connection. For instance [[Pneumatic cannon]] could be a member of the category "cannons", but should not be in the category "valves" or "construction materials". And a valve fits perfectly in the category "valves", but is unneccessary in "construction materials".

To take an example, I just made the [[:Category:Valves]]. We could instead have had an article on [[valves]] which linked to all the valve articles, but that would mean this article would need to be updated each time a new "valve" article is added to stay current. By just adding the new article to the appropriate category, an up to date list is always maintained.

An article on valves (Edit: called, for instance, [[valve]]) could be useful too of course, it should then link to the category for the listing of valves. I will be adding more categories and sort the current articles. If you find or write an article that fits in a current category, link it, and if you find that a particular useful category doesn't exist, you can create it, or put up a suggestion that it be created.

Edit: Categories are by their nature in plural form, articles should be in singular where possible.

A few useful templates also need to be added, such as one for footnotes. Unless someone else does it, I will as soon as I have found out how they work :)

--[[User:GalFisk|GalFisk]] 24 October 2005 10:20 (CDT)

== Spam ==

There has been a person repeatedly adding hidden links to various pakes including the main page. I've reverted this vandalism several times now, it's a pretty quick job but it's getting annoying. The originating IP is different every time so I don't think an IP ban will be effective.

One suggestion is to disable editing by people who are not logged in, would this be acceptable, or is there a better way? We've also had many good edits from anonymous visitors, and it's easier for them to fix stuff on the spot if they're not required to log in. --[[User:GalFisk|GalFisk]] 8 March 2006 12:22 (CST)
:I blocked 209.123.8.145 for one week today after the third spamming from this IP. The spammer is evidently using a script, the same pages are changed in the same way every time and on some of them the script seems to fail, and only cuts the last few characters without adding anything. --[[User:GalFisk|GalFisk]] 03:06, 11 March 2006 (EST)

User:Boilingleadbath

2006-03-11T08:00:29Z

GalFisk: Reverted edit of 209.123.8.145, changed back to last version by GalFisk

A mod on both Spudfiles and The Spudding Handbook, he can be contacted at either boilingleadbath (AIM) or dylanBLAB.foltz@GABgmail.com (without the spammer-thwarting "BLAB & GAB").