title: Modeling internal ballistics of gas combustion guns.
abstract: Potato guns are popular homemade guns which work on the principle of gas combustion. They are usually constructed for recreational rather than criminal purposes. Yet some serious injuries and fatalities due to these guns are reported. As information on the internal ballistics of homemade gas combustion-powered guns is scarce, it is the aim of this work to provide an experimental model of the internal ballistics of these devices and to investigate their basic physical parameters. A gas combustion gun was constructed with a steel tube as the main component. Gas/air mixtures of acetylene, hydrogen, and ethylene were used as propellants for discharging a 46-mm caliber test projectile. Gas pressure in the combustion chamber was captured with a piezoelectric pressure sensor. Projectile velocity was measured with a ballistic speed measurement system. The maximum gas pressure, the maximum rate of pressure rise, the time parameters of the pressure curve, and the velocity and path of the projectile through the barrel as a function of time were determined according to the pressure-time curve. The maximum gas pressure was measured to be between 1.4 bar (ethylene) and 4.5 bar (acetylene). The highest maximum rate of pressure rise was determined for hydrogen at (dp/dt)max = 607 bar/s. The muzzle energy was calculated to be between 67 J (ethylene) and 204 J (acetylene). To conclude, this work provides basic information on the internal ballistics of homemade gas combustion guns. The risk of injury to the operator or bystanders is high, because accidental explosions of the gun due to the high-pressure rise during combustion of the gas/air mixture may occur.
authors.affiliation: Department of Trauma and Orthopedic Surgery, University Medicine Greifswald, Sauerbruchstraße, 17475, Greifswald, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Schorge
authors.affiliation: Department of Trauma and Orthopedic Surgery, University Medicine Greifswald, Sauerbruchstraße, 17475, Greifswald, Germany.
authors.forename: Rico
authors.initials: R
authors.lastname: Grossjohann
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany.
authors.forename: Holger C
authors.initials: HC
authors.lastname: Schönekess
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Herbst
authors.affiliation: Department of Legal Medicine, University Medicine Greifswald, Kuhstraße 30, 17489, Greifswald, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Bockholdt
authors.affiliation: Department of Trauma and Orthopedic Surgery, University Medicine Greifswald, Sauerbruchstraße, 17475, Greifswald, Germany.|Department of Trauma and Orthopedic Surgery, Unfallkrankenhaus Berlin (ukb), Warener Str. 7, 12683, Berlin, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Ekkernkamp
authors.affiliation: Department of Trauma and Orthopedic Surgery, University Medicine Greifswald, Sauerbruchstraße, 17475, Greifswald, Germany. matthias.frank@uni-greifswald.de.|Department of Trauma and Orthopedic Surgery, Unfallkrankenhaus Berlin (ukb), Warener Str. 7, 12683, Berlin, Germany. matthias.frank@uni-greifswald.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Frank
mesh_terms: D000114:Acetylene; D005030:Ethylenes; D044709:Forensic Ballistics; D005740:Gases; D006801:Humans; D006859:Hydrogen; D008961:Models, Structural; D011312:Pressure
chemical_list: D005030:Ethylenes; D005740:Gases; D006859:Hydrogen; C036216:ethylene; D000114:Acetylene
keywords: Blunt ballistic impact; Blunt trauma; Gas combustion gun; Internal ballistics; Potato cannon; Potato gun; Spud gun