Gun Turret #2 Explosion Investigation
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Gun Turret #2 Explosion Investigation |
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EXPLOSION IN TURRET TWO
8. In general, low-order in-bore bursts in guns of modern construction have done relatively little damage. This has ranged from internal marring of the bore, sometimes not realized or discovered until later, up to externally-visible bulging or swelling of the barrel. On the other hand, high-order in-bore detonations burst the barrel catastrophically, and blow out high-energy fragments capable of penetrating decks and structures, and causing various further damage and personnel casualties. 9. Explosive D has been in Navy use as a projectile filler since 1907. It is the least sensitive to shock or friction, and has the lowest explosive energy, of any explosive filler in use today. It has successfully withstood the impact of test firings against armor plate in all calibers of projectiles thus tested. Nonetheless, it has figured in a number of premature projectile explosions. Reference (c) includes D-loaded high-order in-bore prematures which occurred as soon after propellant ignition as “at the origin of rifling”, and others in proving ground firings in which the projectile included no fuzes, or inert fuzes. Over-all, causes to which D-loaded projectile in-bore prematures have been attributed (sometimes on the basis of little more than on-the-spot opinion) include “lose detonator firing on setback”; premature fuze action; cracked projectiles; and propellant flame entry via faulty gas check seal in the projectile base. In-bore explosions of projectiles loaded with the more sensitive Composition A-3 have shared similar attributions, and in addition, two other causes which have been reproduced experimentally: faulty ADF threads allowing the ADF to slam to the rear in an oversize fuze cavity under firing set-back, and gaps or porosity in the explosive, discussed in paragraph 10. 10. A series of proving ground firings were done in 1969-70 to investigate premature explosions in A3-loaded 5”/38 and 5”/34 projectiles, over a range of loading densities, when gaps of various dimensions existed between filler and projectile base. The gaps investigated ranged from zero up to 1”. More than 800 rounds were fired, producing 30 high-order and 2 low-order in-bore prematures. Correlation of premature probability was direct with size of gap and inverse with loading density. No comparable tests appear to have been done for Explosive D in any caliber. 11. Several series of proving
ground test firings for exploration of projectile prematures have produced a mix of
apparently normal projectile flights, out-of-bore prematures at various muzzle distances,
and in-bore
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