Accession Number : AD0014543


Title :   DETERMINATION OF OBTURATION EFFECTIVENESS OF ROTATING BANDS BY PHOTOGRAPHIC MEANS


Descriptive Note : Final rept.


Corporate Author : NAVAL PROVING GROUND DAHLGREN VA


Personal Author(s) : Hedden, S E


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/014543.pdf


Report Date : 01 Apr 1953


Pagination or Media Count : 13


Abstract : High-speed movies were taken of the muzzle region at the time of emergence of the projectile to determine whether, and to what extent, propellant gases emerge before ejection of the projectile. Firings were conducted in two 3- in./70-cal type G Mod 7 guns, one new and one old. Photographs obtained on the first firing indicated the differences in obturation effectiveness existed between rounds fired in a gun when cold and when warm, between guns at different stages of wear. The second firing was conducted to differentiate the effects of these conditions on obturation. The use of sealing cups on the projectile resulted in a reduction in the density of gases emerging ahead of the projectile over similar round without sealing cups. Obturation on rounds with sealing cups was more effective in the new gun than in the old, but better obturation was obtained in the old gun with sealing than in the new gun without cups. It was concluded that high-speed moving pictures of the muzzle region at the time of emergence of projectile provided an excellent qualitative comparison of the relative obturation effectiveness obtained under varying conditions of gun wear and band design.


Descriptors :   *OBTURATION(BALLISTICS) , *ROTATING BANDS , *PHOTOGRAPHIC ANALYSIS , WEAR , EJECTION , SEALING COMPOUNDS , GUN MUZZLES , HIGH SPEED PHOTOGRAPHY , MOTION PICTURES , PROPELLANTS , COMPARISON , PROJECTILES , GUNS


Subject Categories : Ballistics


Distribution Statement : APPROVED FOR PUBLIC RELEASE