By Ashley Crick, ATECJuly 18, 2014
Insensitive munitions? Now that is a strange term. Are we talking about munitions that are thoughtless or inconsiderate? Not quite. Have you ever watched an action movie where someone fired a bullet, triggered an explosive device or set fire to stacks of ammunition and it detonated or burned uncontrollably? If you have, then you have seen what could happen when conventional weapons and explosive devices that are "sensitive" react when exposed to an unplanned heat, shock or impact event. So how can this be avoided? That's where Redstone Test Center comes into play.
"Simply put, insensitive munitions are explosive weapons or devices that are intentionally designed to be less sensitive to unplanned heat, shock or impact events in order to reduce the risk of damage to equipment, facilities and people," Buddy Wilkinson, Missile Flight Test Division directorate chief, said. "The trick is how to minimize the reaction to an unplanned event or stimulus without sacrificing the performance of the weapon."
So to create a world dedicated to doing just that, Redstone Test Center has been developing Test Area 4 since the late 1980s in order to provide the ability to subject test articles to the ever changing standards required by Department of Defense. Test Area 4 specializes in state-of-the-art instrumentation, data acquisition and test control equipment and has the capability to conduct IM tests that fully meet the DoD and North Atlantic Treaty Organization requirements. Some of these tests include bullet impact, fragment impact, slow cook off, fast cook off, 12-meter (40-foot) drop, sympathetic reaction, shaped charge jet impact, and small impact tests.
The Fragment Impact Test Stand is used primarily for Fragment Impact and Bullet Impact tests. The fragment impact cannon is a 40mm smooth bore gun that uses smokeless powder to fire an 18 gram steel fragment at a velocity of 8,300 feet per second into the test article. The bullet impact cannon is an array of .50-caliber rifled guns that accept the .50-caliber armor piercing cartridge, which is fired into the test article in a three-round burst to simulate a machine gun.
Two Fast Cook-off stands provide facilities to subject test articles to a fuel fire. The small Fast Cook-off pan is 24-by-32 feet and can contain up to 7,000 gallons of JP-8 (widely used military fuel). The large Fast Cook-off pan is 50-by-70 and can contain up to 70,000 gallons of JP-8 fuel. Typically, the amount of fuel required is less than half those amounts which will provide a 30-45 minute fire.
The Sympathetic Reaction Area is where intentional detonations involved with Sympathetic Reaction, Shaped Charge Jet Impact and Spall Impact tests are conducted. Sympathetic Reaction tests involve the detonation/ignition of a "donor" test article that is stacked alongside other "acceptor" test articles to assess the reaction of the acceptors to the donor detonation or ignition. The Shaped Charge Jet Impact test involves the detonation of a standard shaped charge warhead positioned to impact the test article with the molten jet of the shaped charge. The Spall Impact test is similar to the Shaped Charge Jet test except that the jet is fired through a steel plate so that only the fragments from the steel plate impact the test article.
The Slow Cook-off Test stand provides a position to subject test articles to a relatively slow increase in temperature in an expendable oven until the test article reacts. Typical temperature rise rates are from 6 degrees Fahrenheit per hour to 50 degrees per hour until the test article has a reaction.
The 40-foot Drop Test stand is a caged area with a thick steel base where test articles are dropped from a height of 40 feet to assess their reaction to the impact.
"Inadvertent initiation and detonation of our own conventional munitions in the last 50 years has caused catastrophic damage," Wilkinson said. "Some of these were caused by unplanned reactions but with RTC's state-of-the art testing capabilities we are committed to providing the best weapons and explosive devices fielded for our military."
RTC, a subordinate command of the Test and Evaluation Command, provides technical expertise, state-of-the-art facilities, and capabilities to plan, conduct, analyze, and report the results of tests on missile and aviation systems, sensors, subsystems and components.