Armor & Mobility

AUG 2017

Military magazines in the United States and Canada, covering Armor and Mobility, focuses on tactical vehicles, C4ISR, Special Operations Forces, latest soldier equipment, shelters, and key DoD programs

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U.S. Army Yuma Proving Ground (YPG) is well known for testing virtually every piece of equipment in the ground combat arsenal. The fruits of this testing include better and longer lasting equipment, as well as the ability to multiply a ground force more rapidly. Prior to the first Gulf War in the early 1990's, the life-expectancy of the tracks used to propel an M1 Abrams Main Battle Tank along the ground was measured in the hundreds of miles. After extensive testing at U.S. Army Yuma Proving Ground, today's tank treads last for thousands of miles. Mitigating the Turbulence to Chute Threat A more recent example of this high-impact, long-term testing is studies the proving ground's Air Combat Systems Test Directorate have conducted on the C-17 Globemaster to determine the heaviest weight the aircraft can safely carry. A follow-on study has looked at the amount of time and distance necessary between each element of a multi-element insertion of combat parachutists, known tactically as a mass exit insertion of the Global Response Force (GRF). As air behaves like a fluid, the air disturbance left by massive cargo aircraft speeding through the sky is extremely turbulent and fast. The shedding of high and low pressures required for lift rolls up near the aircraft wing tips, result in powerful vortices that can remain over the drop zone for several minutes. "It is very violent," said Keith Allen, team lead in the Aviation Systems and Electronic Test Division. "We're talking 150 to 200 feet per second in tangential velocity. It would definitely collapse a parachute if you got caught up in it." The wings of military cargo planes are equipped with specially shaped finlets to help dissipate this vortex, but the extreme turbulence is still invisible and not able to be completely eliminated. As a result, formations of C-17s carrying jumpers are required to keep a minimum distance from each other: if this distance could be safely shortened, more airborne Soldiers could reach the ground and enter a battle faster. "The current spacing is based on a very conservative approach to ensure, in all conditions, that the vortices are dissipated or have moved off the drop zone in time for the next element of jumpers," said A U.S. Army Yuma Proving Ground study could lead to faster, more precise mass parachute drops. By Mark Schauer, YPG Public Affairs TAMING THE DROP ZONE Airborne Soldiers participating in a mass insertion must contend with a roiling aerial sea caused by the backwash of massive cargo airplanes speeding through the air. Testers at U.S. Army Yuma Proving Ground have conducted an ambitious study of the life cycle of these aerial disturbances in an effort to reduce the amount of distance required between planes participating in a mass jump. (U.S. Army Photo) ENHANCING RE-SUPPLY LOGISTICS AIR DROP PRECISION www.tacticaldefensemedia.com 22 | Armor & Mobility | August 2017

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