Hybrid cannon - Revision history

DYI at 17:05, 14 May 2012

2012-05-14T17:05:18Z

← Older revision		Revision as of 12:05, 14 May 2012
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	[[Image:hybrid.jpg\|right\|thumb\|300px\| A very well built hybrid, although it is not safe for handheld operation due to its use of a PVC chamber]]		[[Image:hybrid.jpg\|right\|thumb\|300px\| A very well built hybrid, although it is not safe for handheld operation due to its use of a PVC chamber]]
	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 than a normal combustion or pneumatic gun could.		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 than a normal combustion or pneumatic gun could.
	The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have ~~broken the sound barrier~~. This is possible because of the higher [[pressure]] ~~and temperature~~ gases generated by a hybrid [[combustion process\|combustion]].		The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have reached almost 1000 m/s. This is possible because of the higher [[pressure]] gases generated by a hybrid [[combustion process\|combustion]].

	A hybrid launcher consists of seven basic elements:		A hybrid launcher consists of seven basic elements:
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	*[[Barrel]]		*[[Barrel]]
	*Fuel system (usually [[fuel meter\|metered propane]])		*Fuel system (usually [[fuel meter\|metered propane]])
	*~~Air injection valve~~ (usually [[schrader valve\|schrader]] or [[quick disconnect\|quick connect]])		*Inlet port for propellant mix with a connection for attaching fueling line(s)(usually [[schrader valve\|schrader]] or [[quick disconnect\|quick connect]])
	*High-voltage [[Ignition source]]		*High-voltage [[Ignition source]]
	*One or more [[pressure gauge]]s		*One or more [[pressure gauge]]s

DYI: /* Safety */

2012-04-17T20:32:41Z

Safety

← Older revision		Revision as of 15:32, 17 April 2012
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	===Safety===		===Safety===
	A hybrid is one of the more dangerous types of launchers to build, apart from high pressure pneumatics. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]), generally SCH 40 steel or better. SCH 80 PVC has been used, but is not safe due to recurring fatiguing problems that have been observed in PVC hybrids and multiple failures even at low mixes. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must if PVC is used as a construction material, and is strongly advised for the initial testing of any hybrid. Although it was originally thought that mixes higher than 4x posed an unacceptable risk of [[DDT]] (deflagration to detonation transition), further calculations have revealed that the increased temperature of higher mixes barely counters the decreased burn rate ~~cause~~ by higher pre-ignition pressures, and that even a 20x mix will only burn a few m/s faster than a 1x mix. If DDT did occur, it would produce an extremely violent shock and pressure spike, which would cause any PVC chamber to ~~shrapnel~~, and damage ~~most~~ steel or ~~iron chambers beyond repair~~. The standard for hybrid construction is currently SCH 40 [[Steel Pipe\|steel pipe]] and fittings, which have been tested in 2" sizes at mixes of up to ~~11x~~, repeatedly without failure. Theoretical burst pressure of SCH 40 2" steel pipe is >~~2kpsi~~, and no ~~catastrophic failure has ever been achieved, accidentally or by design,~~ in a hybrid ~~made from safe materials~~.		A hybrid is one of the more dangerous types of launchers to build, apart from high pressure pneumatics. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]), generally SCH 40 steel or better. SCH 80 PVC has been used, but is not safe due to recurring fatiguing problems that have been observed in PVC hybrids and multiple failures even at low mixes. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must if PVC is used as a construction material, and is strongly advised for the initial testing of any hybrid. Although it was originally thought that mixes higher than 4x posed an unacceptable risk of [[DDT]] (deflagration to detonation transition), further calculations have revealed that the increased temperature of higher mixes barely counters the decreased burn rate caused by higher pre-ignition pressures, and that even a 20x mix will only burn a few m/s faster than a 1x mix. If DDT of all or most of the fuel load did occur, it would produce an extremely violent shock and pressure spike, which would cause any PVC chamber to rupture, and damage steel or copper components which were not highly overbuilt. The standard for hybrid construction is currently SCH 40 [[Steel Pipe\|steel pipe]] and fittings, which have been tested in 2" sizes at mixes of up to 20x, repeatedly without failure. Theoretical burst pressure of SCH 40 2" steel pipe is >4kpsi (ignoring threaded sections and end effects), and there is no recorded incidence of ruptures occurring in SCH 40 steel hybrid chambers. Copper tube barrels have burst and/or bulged due to what is thought to be localized DDT.

Fnord: bbq's are a legitimate option...

2009-03-31T23:27:51Z

bbq's are a legitimate option...

← Older revision		Revision as of 18:27, 31 March 2009
Line 18:		Line 18:
	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 gauges and fuel [[fuel meter\|meters]] are used for this.		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 gauges and fuel [[fuel meter\|meters]] are used for this.

	The ignition of a hybrid gun is more difficult than a normal combustion, 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]], [[flyback circuit]], or other high-voltage source; [[BBQ ignitor\|grill igniters]] ~~frequently won't jump~~ a [[spark gap]] in pressurized fuel/air environments.		The ignition of a hybrid gun is more difficult than a normal combustion, 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]], [[flyback circuit]], or other high-voltage source; [[BBQ ignitor\|grill igniters]] may be unreliable and require a very small [[spark gap]](typically 1mm or less) to work correctly in pressurized fuel/air environments.

	The gases resulting from the combustion of the fuel/air mixture 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. The valve is required to contain the pressure of the mixture pre-ignition, in other words, to prevent the pressurized fuel/air mixture from exiting out the barrel before ignition. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.		The gases resulting from the combustion of the fuel/air mixture 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. The valve is required to contain the pressure of the mixture pre-ignition, in other words, to prevent the pressurized fuel/air mixture from exiting out the barrel before ignition. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.

Benstern: added links

2008-06-01T11:38:55Z

added links

DYI at 19:08, 11 March 2008

2008-03-11T19:08:23Z

← Older revision		Revision as of 14:08, 11 March 2008
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	[[Image:hybrid.jpg\|right\|thumb\|300px\| A very ~~badly constructed~~ hybrid ~~cannon(~~it is ~~made~~ of ~~pvc never use pvc unless you want shrapnel flying everywhere~~]]		[[Image:hybrid.jpg\|right\|thumb\|300px\| A very well built hybrid, although it is not safe for handheld operation due to its use of a PVC chamber]]
	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 than a normal combustion or pneumatic gun could.		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 than a normal combustion or pneumatic gun could.
	The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.		The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.

Bigbob12345 at 16:26, 9 March 2008

2008-03-09T16:26:47Z

← Older revision		Revision as of 11:26, 9 March 2008
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	[[Image:hybrid.jpg\|right\|thumb\|300px\| A very ~~well~~ constructed hybrid cannon]]		[[Image:hybrid.jpg\|right\|thumb\|300px\| A very badly constructed hybrid cannon(it is made of pvc never use pvc unless you want shrapnel flying everywhere]]
	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 than a normal combustion or pneumatic gun could.		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 than a normal combustion or pneumatic gun could.
	The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.		The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.
Line 23:		Line 23:

	===Safety===		===Safety===
	A hybrid is one of the more dangerous types of launchers to build, apart from high pressure pneumatics. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]), generally SCH 40 steel or better. SCH 80 PVC has been used, but is not ~~advised~~ due to recurring fatiguing problems that have been observed in PVC hybrids. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must if PVC is used as a construction material, and is strongly advised for the initial testing of any hybrid. Although it was originally thought that mixes higher than 4x posed an unacceptable risk of DDT (deflagration to detonation transition), further calculations have revealed that the increased temperature of higher mixes barely counters the decreased burn rate cause by higher pre-ignition pressures, and that even a 20x mix will only burn a few m/s faster than a 1x mix. If DDT did occur, it would produce an extremely violent shock and pressure spike, which would cause any PVC chamber to shrapnel, and damage most steel or iron chambers beyond repair. The standard for hybrid construction is currently SCH 40 steel pipe and fittings, which have been tested in 2" sizes at mixes of up to 11x, repeatedly without failure. Theoretical burst pressure of SCH 40 2" steel pipe is >2kpsi, and no catastrophic failure has ever been achieved, accidentally or by design, in a hybrid made from safe materials.		A hybrid is one of the more dangerous types of launchers to build, apart from high pressure pneumatics. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]), generally SCH 40 steel or better. SCH 80 PVC has been used, but is not safe due to recurring fatiguing problems that have been observed in PVC hybrids and multiple failures even at low mixes. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must if PVC is used as a construction material, and is strongly advised for the initial testing of any hybrid. Although it was originally thought that mixes higher than 4x posed an unacceptable risk of DDT (deflagration to detonation transition), further calculations have revealed that the increased temperature of higher mixes barely counters the decreased burn rate cause by higher pre-ignition pressures, and that even a 20x mix will only burn a few m/s faster than a 1x mix. If DDT did occur, it would produce an extremely violent shock and pressure spike, which would cause any PVC chamber to shrapnel, and damage most steel or iron chambers beyond repair. The standard for hybrid construction is currently SCH 40 steel pipe and fittings, which have been tested in 2" sizes at mixes of up to 11x, repeatedly without failure. Theoretical burst pressure of SCH 40 2" steel pipe is >2kpsi, and no catastrophic failure has ever been achieved, accidentally or by design, in a hybrid made from safe materials.

DYI: /* Safety */

2008-02-01T03:38:59Z

Safety

← Older revision		Revision as of 22:38, 31 January 2008
Line 23:		Line 23:

	===Safety===		===Safety===
	A hybrid is the ~~most~~ dangerous ~~type~~ of ~~launcher that can be built~~. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]) ~~such as Sch~~. 80 PVC, ~~or even better, metal pipe and fittings~~. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must, and the ~~limit~~ of ~~a 4x propane/ 4 atmosphere mix should never be breached when using~~ any ~~type of plastic pipe~~. ~~If a~~ higher ~~mix is attempted, [[~~DDT]] (deflagration to detonation transition, ~~where~~ the ~~flame front exceeds~~ the ~~sound barrier in the combustion gases) theoretically can~~ occur, ~~causing~~ an ~~extreme pressure spike. No plastic pipe can handle this~~ pressure spike, and ~~will probably shatter, launching plastic shards everywhere~~. ~~A chamber made of~~ steel, ~~iron, or aluminum can survive higher mixes than 4x propane/ 4 atmospheres, and~~ have been ~~used~~ at up to ~~8x propane/ 8 atmosphere mixtures~~. ~~However~~, ~~utmost care must be taken with these launchers~~, in ~~construction and~~ materials ~~used~~.		A hybrid is one of the more dangerous types of launchers to build, apart from high pressure pneumatics. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]), generally SCH 40 steel or better. SCH 80 PVC has been used, but is not advised due to recurring fatiguing problems that have been observed in PVC hybrids. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must if PVC is used as a construction material, and is strongly advised for the initial testing of any hybrid. Although it was originally thought that mixes higher than 4x posed an unacceptable risk of DDT (deflagration to detonation transition), further calculations have revealed that the increased temperature of higher mixes barely counters the decreased burn rate cause by higher pre-ignition pressures, and that even a 20x mix will only burn a few m/s faster than a 1x mix. If DDT did occur, it would produce an extremely violent shock and pressure spike, which would cause any PVC chamber to shrapnel, and damage most steel or iron chambers beyond repair. The standard for hybrid construction is currently SCH 40 steel pipe and fittings, which have been tested in 2" sizes at mixes of up to 11x, repeatedly without failure. Theoretical burst pressure of SCH 40 2" steel pipe is >2kpsi, and no catastrophic failure has ever been achieved, accidentally or by design, in a hybrid made from safe materials.

Pete Zaria at 08:16, 23 October 2007

2007-10-23T08:16:38Z

← Older revision		Revision as of 03:16, 23 October 2007
Line 23:		Line 23:

	===Safety===		===Safety===
	A hybrid is the most dangerous type of launcher that can be built. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]) such as Sch. 80 PVC, or even better, metal pipe and fittings. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must, and the limit of a 4x propane/ 4 atmosphere mix should never be breached when using any type of plastic pipe. If a higher mix is attempted, DDT (deflagration to detonation transition, where the flame front exceeds the sound barrier in the combustion gases) can occur, causing an extreme pressure spike. No plastic pipe can handle this pressure spike, and will probably shatter, launching plastic shards everywhere. A chamber made of steel, iron, or aluminum can survive higher mixes than 4x propane/ 4 atmospheres, and have been used at up to 8x propane/ 8 atmosphere mixtures. However, utmost care must be taken with these launchers, in construction and materials used.		A hybrid is the most dangerous type of launcher that can be built. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]) such as Sch. 80 PVC, or even better, metal pipe and fittings. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must, and the limit of a 4x propane/ 4 atmosphere mix should never be breached when using any type of plastic pipe. If a higher mix is attempted, [[DDT]] (deflagration to detonation transition, where the flame front exceeds the sound barrier in the combustion gases) theoretically can occur, causing an extreme pressure spike. No plastic pipe can handle this pressure spike, and will probably shatter, launching plastic shards everywhere. A chamber made of steel, iron, or aluminum can survive higher mixes than 4x propane/ 4 atmospheres, and have been used at up to 8x propane/ 8 atmosphere mixtures. However, utmost care must be taken with these launchers, in construction and materials used.

Pete Zaria at 07:56, 23 October 2007

2007-10-23T07:56:12Z

← Older revision		Revision as of 02:56, 23 October 2007
Line 1:		Line 1:
	[[Image:hybrid.jpg\|right\|thumb\|300px\| A very well constructed hybrid cannon]]		[[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.		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 than a normal combustion or pneumatic gun could.
	The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.		The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.

Pete Zaria: Corrected gramatical errors and added formatting

2007-10-23T07:55:36Z

Corrected gramatical errors and added formatting

← Older revision		Revision as of 02:55, 23 October 2007
Line 1:		Line 1:
	[[Image:hybrid.jpg\|right\|thumb\|300px\| A very well constructed hybrid cannon]]		[[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.		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 gases.		The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.

	A hybrid launcher consists of seven basic elements:		A hybrid launcher consists of seven basic elements:

	*High pressure combustion chamber		*High pressure combustion chamber
	*Pressure-triggered main valve (usually a [[burst disk]])		*Pressure-triggered main valve (usually a [[burst disk]], see below)
	*[[Barrel]]		*[[Barrel]]
	*Fuel system (usually [[fuel meter\|metered propane]])		*Fuel system (usually [[fuel meter\|metered propane]])
	*Air ~~filling~~ valve		*Air injection valve (usually schrader or quick connect)
	*~~powerful~~ [[Ignition source]]		*High-voltage [[Ignition source]]
	*One or more [[pressure gauge]]s		*One or more [[pressure gauge]]s

	==Operation theory==		==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 is first injected with a measured amount of fuel - much more than would be used in a regular combustion. However, without adequate oxygen, the mixture would be far too rich to ignite, so the chamber is 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~~]].		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 resulting ~~gases~~ 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.		The ignition of a hybrid gun is more difficult than a normal combustion, 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]], flyback, or other high-voltage source; grill igniters frequently won't jump a spark gap in pressurized fuel/air environments.

			The gases resulting from the combustion of the fuel/air mixture 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. The valve is required to contain the pressure of the mixture pre-ignition, in other words, to prevent the pressurized fuel/air mixture from exiting out the barrel before ignition. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.

	===Safety===		===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. [[Remotely_activated_valve \|Remote ignition]] is a must, and the limit of a 4x propane/ 4 atmosphere mix should never be breached when using any type of plastic pipe. If a higher mix is attempted, DDT (deflagration to detonation transition) can occur, causing an extreme pressure spike. ~~Most~~ plastic pipe ~~cannot~~ handle ~~the~~ spike, and will shatter, launching plastic shards everywhere. A steel, iron, aluminum ~~hybrid~~ can survive higher mixes than 4x propane/ 4 atmospheres, and have been used at up to 8x propane/ 8 atmosphere mixtures. However, utmost care must be taken with these launchers, in construction and materials used.		A hybrid is the most dangerous type of launcher that can be built. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]) such as Sch. 80 PVC, or even better, metal pipe and fittings. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must, and the limit of a 4x propane/ 4 atmosphere mix should never be breached when using any type of plastic pipe. If a higher mix is attempted, DDT (deflagration to detonation transition, where the flame front exceeds the sound barrier in the combustion gases) can occur, causing an extreme pressure spike. No plastic pipe can handle this pressure spike, and will probably shatter, launching plastic shards everywhere. A chamber made of steel, iron, or aluminum can survive higher mixes than 4x propane/ 4 atmospheres, and have been used at up to 8x propane/ 8 atmosphere mixtures. However, utmost care must be taken with these launchers, in construction and materials used.

← Older revision		Revision as of 18:27, 31 March 2009
Line 18:		Line 18:
	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 gauges and fuel [[fuel meter\|meters]] are used for this.		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 gauges and fuel [[fuel meter\|meters]] are used for this.

	The ignition of a hybrid gun is more difficult than a normal combustion, 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]], [[flyback circuit]], or other high-voltage source; [[BBQ ignitor\|grill igniters]] ~~frequently won't jump~~ a [[spark gap]] in pressurized fuel/air environments.		The ignition of a hybrid gun is more difficult than a normal combustion, 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]], [[flyback circuit]], or other high-voltage source; [[BBQ ignitor\|grill igniters]] may be unreliable and require a very small [[spark gap]](typically 1mm or less) to work correctly in pressurized fuel/air environments.

	The gases resulting from the combustion of the fuel/air mixture 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. The valve is required to contain the pressure of the mixture pre-ignition, in other words, to prevent the pressurized fuel/air mixture from exiting out the barrel before ignition. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.		The gases resulting from the combustion of the fuel/air mixture 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. The valve is required to contain the pressure of the mixture pre-ignition, in other words, to prevent the pressurized fuel/air mixture from exiting out the barrel before ignition. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.

← Older revision		Revision as of 06:38, 1 June 2008
Line 1:		Line 1:
	[[Image:hybrid.jpg\|right\|thumb\|300px\| A very well built hybrid, although it is not safe for handheld operation due to its use of a PVC chamber]]		[[Image:hybrid.jpg\|right\|thumb\|300px\| A very well built hybrid, although it is not safe for handheld operation due to its use of a PVC chamber]]
	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 than a normal combustion or pneumatic gun could.		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 than a normal combustion or pneumatic gun could.
	The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher pressure and temperature gases generated by a hybrid combustion.		The hybrid is capable of higher velocities than a combustion or pneumatic spudgun; projectiles fired by a hybrid have broken the sound barrier. This is possible because of the higher [[pressure]] and temperature gases generated by a hybrid [[combustion process\|combustion]].

	A hybrid launcher consists of seven basic elements:		A hybrid launcher consists of seven basic elements:

	*High pressure combustion chamber		*High pressure combustion [[chamber]]
	*Pressure-triggered main valve (usually a [[burst disk]], see below)		*Pressure-triggered main [[valve]] (usually a [[burst disk]], see below)
	*[[Barrel]]		*[[Barrel]]
	*Fuel system (usually [[fuel meter\|metered propane]])		*Fuel system (usually [[fuel meter\|metered propane]])
	*Air injection valve (usually schrader or quick connect)		*Air injection valve (usually [[schrader valve\|schrader]] or [[quick disconnect\|quick connect]])
	*High-voltage [[Ignition source]]		*High-voltage [[Ignition source]]
	*One or more [[pressure gauge]]s		*One or more [[pressure gauge]]s
Line 16:		Line 16:
	A hybrid is first injected with a measured amount of fuel - much more than would be used in a regular combustion. However, without adequate oxygen, the mixture would be far too rich to ignite, so the chamber is 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 is first injected with a measured amount of fuel - much more than would be used in a regular combustion. However, without adequate oxygen, the mixture would be far too rich to ignite, so the chamber is 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.		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 gauges and fuel [[fuel meter\|meters]] are used for this.

	The ignition of a hybrid gun is more difficult than a normal combustion, 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]], flyback, or other high-voltage source; grill igniters frequently won't jump a spark gap in pressurized fuel/air environments.		The ignition of a hybrid gun is more difficult than a normal combustion, 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]], [[flyback circuit]], or other high-voltage source; [[BBQ ignitor\|grill igniters]] frequently won't jump a [[spark gap]] in pressurized fuel/air environments.

	The gases resulting from the combustion of the fuel/air mixture 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. The valve is required to contain the pressure of the mixture pre-ignition, in other words, to prevent the pressurized fuel/air mixture from exiting out the barrel before ignition. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.		The gases resulting from the combustion of the fuel/air mixture 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. The valve is required to contain the pressure of the mixture pre-ignition, in other words, to prevent the pressurized fuel/air mixture from exiting out the barrel before ignition. Upon ignition of the fuel-air mix, the pressure rises and the valve opens.

	===Safety===		===Safety===
	A hybrid is one of the more dangerous types of launchers to build, apart from high pressure pneumatics. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]), generally SCH 40 steel or better. SCH 80 PVC has been used, but is not safe due to recurring fatiguing problems that have been observed in PVC hybrids and multiple failures even at low mixes. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must if PVC is used as a construction material, and is strongly advised for the initial testing of any hybrid. Although it was originally thought that mixes higher than 4x posed an unacceptable risk of DDT (deflagration to detonation transition), further calculations have revealed that the increased temperature of higher mixes barely counters the decreased burn rate cause by higher pre-ignition pressures, and that even a 20x mix will only burn a few m/s faster than a 1x mix. If DDT did occur, it would produce an extremely violent shock and pressure spike, which would cause any PVC chamber to shrapnel, and damage most steel or iron chambers beyond repair. The standard for hybrid construction is currently SCH 40 steel pipe and fittings, which have been tested in 2" sizes at mixes of up to 11x, repeatedly without failure. Theoretical burst pressure of SCH 40 2" steel pipe is >2kpsi, and no catastrophic failure has ever been achieved, accidentally or by design, in a hybrid made from safe materials.		A hybrid is one of the more dangerous types of launchers to build, apart from high pressure pneumatics. It is advised to only attempt to build one with pipe that can handle the high pressure environment (300+ [[Pressure gauge\|PSI]]), generally SCH 40 steel or better. SCH 80 PVC has been used, but is not safe due to recurring fatiguing problems that have been observed in PVC hybrids and multiple failures even at low mixes. As with any launcher, the entire chamber is only rated to the spec of the lowest-rated part, so care must be taken when constructing the chamber of a hybrid. [[Remotely_activated_valve \|Remote ignition]] is a must if PVC is used as a construction material, and is strongly advised for the initial testing of any hybrid. Although it was originally thought that mixes higher than 4x posed an unacceptable risk of [[DDT]] (deflagration to detonation transition), further calculations have revealed that the increased temperature of higher mixes barely counters the decreased burn rate cause by higher pre-ignition pressures, and that even a 20x mix will only burn a few m/s faster than a 1x mix. If DDT did occur, it would produce an extremely violent shock and pressure spike, which would cause any PVC chamber to shrapnel, and damage most steel or iron chambers beyond repair. The standard for hybrid construction is currently SCH 40 [[Steel Pipe\|steel pipe]] and fittings, which have been tested in 2" sizes at mixes of up to 11x, repeatedly without failure. Theoretical burst pressure of SCH 40 2" steel pipe is >2kpsi, and no catastrophic failure has ever been achieved, accidentally or by design, in a hybrid made from safe materials.