# Difference between revisions of "Rifled barrel"

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− | In order to more accurately send a vegetable projectile towards the desired target, barrels for produce accelerators can be "rifled" which produces spiral grooves on the inside surface of the barrel. | + | In order to more accurately send a vegetable projectile towards the desired target, barrels for produce accelerators can be "rifled" which produces spiral grooves on the inside surface of the barrel. |

− | + | These grooves impart rotation to the projectile as it accelerates down the barrel, gyroscopically stabilizing it and preventing the projectile from tumbling end-over-end. This spinning motion has been demonstrated to have positive effects accuracy of potatoes, as seen in [http://www.burntlatke.com/rifle.html this] test done by the [[burnt latke]] group. | |

− | + | The rate of twist required can be approximated through a version of the Greenhill equation that has been modified to take into account the density of the projectile, though one must remember that the Greenhill equation was developed to deal with supersonic, pointed, and very dense projectiles: | |

+ | Twist = (C*D<sup>2</sup>)/L * sqrt(SG/10.9) | ||

+ | |||

+ | where: | ||

+ | *Twist = number of inches per rotation | ||

+ | *C = 150 (use 180 for muzzle velocities higher than 2,800 f/s) | ||

+ | *D = bullet's diameter in inches | ||

+ | *L = bullet's length in inches | ||

+ | *SG = bullet's specific gravity | ||

+ | |||

+ | Rates of twist higher than this should not hurt accuracy much, unless they break off the bits of potato that are engaging the rifling and thusly transmit no rotation at all. | ||

+ | |||

+ | Rifled barrels are available from the [[SGTC]]. | ||

+ | |||

+ | See also [[spudgun accuracy]] | ||

[[Category:Components]] | [[Category:Components]] |

## Revision as of 18:29, 26 July 2007

In order to more accurately send a vegetable projectile towards the desired target, barrels for produce accelerators can be "rifled" which produces spiral grooves on the inside surface of the barrel.

These grooves impart rotation to the projectile as it accelerates down the barrel, gyroscopically stabilizing it and preventing the projectile from tumbling end-over-end. This spinning motion has been demonstrated to have positive effects accuracy of potatoes, as seen in this test done by the burnt latke group.

The rate of twist required can be approximated through a version of the Greenhill equation that has been modified to take into account the density of the projectile, though one must remember that the Greenhill equation was developed to deal with supersonic, pointed, and very dense projectiles:
Twist = (C*D^{2})/L * sqrt(SG/10.9)

where:

- Twist = number of inches per rotation
- C = 150 (use 180 for muzzle velocities higher than 2,800 f/s)
- D = bullet's diameter in inches
- L = bullet's length in inches
- SG = bullet's specific gravity

Rates of twist higher than this should not hurt accuracy much, unless they break off the bits of potato that are engaging the rifling and thusly transmit no rotation at all.

Rifled barrels are available from the SGTC.

See also spudgun accuracy