50 Years Ago Today – Mullinnix Experiences a “Hang Fire” in MT 51
Excerpt from “The Last Gun Ship - History of USS Mullinnix DD-944” - A Historical Novel By Frank A. Wood
While conducting drone firing exercises on 7 April, the ship experienced a hang fire (a round stuck in the barrel) in MT 51. Hang-fire occurs when there is a delay beyond the normal ignition time after the initiating action is taken (eg. the gun fires 15 seconds after the firing key is closed). The mount had been firing for only 2 minutes, therefore it was considered a “cold gun" condition, where the gun barrel and chamber wall temperature have not been raised by prolonged firing to a point where “cook-off” can occur.
Extensive testing of the 5"/54 under continuous sustained firing conditions had shown cook off temperature is achieved in approximately 3 minutes.
Cook-off occurs when components of the gun reach a temperature high enough (e.g. “hot gun”) to cause some form of explosive reaction in the projectile. As long as the breech is closed, cook-off will cause the round to be fired in a near normal manner. However, with the breechblock open, cook-off usually results in personnel injuries/fatalities and major equipment damage.
Regulations require that the gun mount remain idle for two hours in a safe firing bearing to preclude danger to other craft and friendly forces in the event of a cook-off. With fully charged fire hoses at the ready, MT 51 was fired to starboard at 1253, with the casualty restored.
To be continued...
Cheers,
Woody
While conducting drone firing exercises on 7 April, the ship experienced a hang fire (a round stuck in the barrel) in MT 51. Hang-fire occurs when there is a delay beyond the normal ignition time after the initiating action is taken (eg. the gun fires 15 seconds after the firing key is closed). The mount had been firing for only 2 minutes, therefore it was considered a “cold gun" condition, where the gun barrel and chamber wall temperature have not been raised by prolonged firing to a point where “cook-off” can occur.
Extensive testing of the 5"/54 under continuous sustained firing conditions had shown cook off temperature is achieved in approximately 3 minutes.
Cook-off occurs when components of the gun reach a temperature high enough (e.g. “hot gun”) to cause some form of explosive reaction in the projectile. As long as the breech is closed, cook-off will cause the round to be fired in a near normal manner. However, with the breechblock open, cook-off usually results in personnel injuries/fatalities and major equipment damage.
Regulations require that the gun mount remain idle for two hours in a safe firing bearing to preclude danger to other craft and friendly forces in the event of a cook-off. With fully charged fire hoses at the ready, MT 51 was fired to starboard at 1253, with the casualty restored.
To be continued...
Cheers,
Woody
posted by Frank A. Wood at 07:38
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