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Special Operations: Falling In Thin Air
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January 31, 2011: The U.S. Air Force is, after more than half a century, introducing a new parachute for use by its special operations rescue personnel. The GAAPS (Guardian Angel Advance Parachute System) is primarily designed to meet the needs of pararescue troops, who are dropped to assist in the rescue of downed aircrew, often in enemy territory. GAAPS has dozens of improvements over the existing parachute, but the big one is that it allows users to land safely at higher altitudes. The existing parachute assumes the user will be landing at or near sea-level. But in Afghanistan, pararescue operators are landing at 3,000-5,000 meters (or more) up. The air is thinner at those altitudes (nearly 15,000 feet), and that means parachutes come down faster, and this causes more injuries. GAAPS will also be able to handle heavier loads and, well, bigger and heavier troops, as well as allowing users to more safely maneuver the chute to a specific landing spot. Once testing is complete, the air force will offer GAAPS to the other services, as well as replacing all the older parachutes used on their aircraft. The ejection seats use a special parachute designed for each model of seat.

The army had similar problems and recently begun using the new T-11 parachute, for its paratroopers. The T-11 ATPS (Advanced Tactical Parachute System) is replacing the half century old T-10 parachute. The new and improved model is urgently needed because, in the last half century, paratroopers, and their equipment, have gotten heavier. The current T-10 was designed to handle a maximum weight of 136 kg (300 pounds, a paratrooper and his equipment.) In practice, the average weight is now a third more. This meant that the troops were hitting the ground faster and harder using the T-10, resulting in more injuries. Since World War II, the average injury rate for mass parachute drops has been 1.5 percent, but all that extra muscle and gear has pushed it to over two percent.

The basic problem was that the venerable T-10 was not able to handle larger and heavier (it's all muscle, folks) paratroopers and the more numerous bits of equipment they jump with. The 23.2 kg/51 pound T-11 (main chute and backup) can bring over 182 kg (400 pounds) of paratrooper and equipment to the ground at 5.2 meters (16 feet) per second. The 20 kg (44 pound) T-10 could bring 136 kg down at 7.4 meters (23 feet) per second. When the T-10 was dealing with more weight, it came down faster, causing more injuries. The T-11, when deployed has a diameter 14 percent greater than that of the T-10, with 28 percent more surface area. The T-11 harness is more reliable and comfortable. Operational testing of the T-11 was four years long, and the new chute will have completely replaced the T-10 in three more years.


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esmoore5       1/31/2011 12:55:13 PM
Yay! Now parachuting will be perfectly safe: Or maybe not...... :)
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VelocityVector       1/31/2011 3:07:10 PM

GAAPS is a ram air design that stalls at landing with forgiving behavior.  Most ram air landing injuries are not caused by vertical descent rate as suggested by the article.  The injuries result from horizontal travel near the ground as a canopy seeks its stall point.  Horizontal speeds increase agl due to the thinner air as stated by the article.  What GAAPS does with asymmetrical cells and line loading is transfer a "square" ram air canopy into a round button canopy configuration during landing which negates horizontal travel and stalling behavior.  This simply makes GAAPS easier to land for low-time jumpers like military operators as compared with what traditional ram air designs offer.  In essence, the military will be combining the best characteristics of the two parachute types into a single design, which is slick.  As round canopies, the T-11 and ejection types are not comparable to GAAPS since the former do not provide anywhere near the degree of horizontal speed, wind penetration and maneuver capabilities that a relatively highly trained (but still low relative to civilian or military demo team jumpers) pararescue jumper can exploit to perform the mission.  There really was no point in discussing the two types in this article, which ought to have focused on GAAPS exclusively and in detail.  0.02


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