SSC-Natick Press Release
U.S. Army Soldier Systems Center-Natick
Public Affairs Office
Natick, MA 01760-5012
Contact: Chief, Public Affairs Office
Date: May 26, 2005
Improved pendant assists helicopter sling load delivery
NATICK, Mass. -- Whipping sand was wearing down pendants, grinding its fibers and causing a potential breakage problem for helicopters flown by the 101st Airborne Division in sling load operations.
Within months, the Natick Soldier Center’s Aerial Delivery and Engineering Support Team at the U.S. Army Soldier Systems Center here, along with manufacturers developed a quick improvement for the sand-filled experience of Iraq.
“When we originally developed the pendant, we knew sand could be a problem, especially in a rapid development situation,” said Scott Ullery, project officer for the revised pendant. “Sand can get into the fibers while lying on the ground or as it stretches in the air. The sand particles can be very sharp and cut core fibers in ways you can’t see.”
He said testing of the 40-foot pendants used in the desert revealed up to a 40 percent loss in strength due to sand degradation.
“The idea of a pendant is not new per se. Units in Alaska have done it before, but there are drawbacks to the systems used,” Ullery said. “With potential regular use in a desert environment, it warranted taking a look to bring in new technology for a formal system.”
Two years ago, the 101st Airborne Division (Air Assault) funded the pendant program to relieve them of the problems associated with sling load operations, according to Ullery. Pendants attach to existing slings and enable helicopters hovering over cargo during sling load hookup to land, easing the task for pilots and ground troops.
“Even in the best of conditions, it’s difficult to hover and stay steady,” said Ullery. “When it’s windy, it’s even worse. In the desert, you get brownout or whiteout in the snow, and it’s harder for pilots to remain in position without a visual reference. If it’s really bad, it can be difficult to see the load as they fly in.”
Meanwhile, a Soldier risks getting struck as he connects the sling standing on top of or beside the cargo, and without another Soldier to connect a metal discharge line, could get zapped by static electricity. Furthermore, once the load is ready to go, it’s difficult or impossible for those troops to board the helicopter, necessitating other arrangements.
With the ability to land next to the cargo because of what amounts to extra sling length, the pendant reduces the static electricity and collision hazards, and allows ground troops to fly on the same helicopter that is carrying their equipment.
Time on the pickup zone is reduced because the process is more predictable, Ullery said, and a group of helicopters is less likely to be slowed down by one delayed sling load. For extra distance away from the load, two pendants can be joined. A swivel prevents twisting of the pendant on single-point loads.
Sling loading of military equipment and cargo is accomplished with either Chinook or Blackhawk helicopters in light infantry units.
Ullery said it allows troops to move quickly in and out of a dangerous area and to carry items too big to fit inside the helicopter. Depending on weather and altitude, Blackhawks can lift up to 9,000 pounds of vehicles, weapons or pallets of supplies, while the larger Chinooks can transport more than 20,000 pounds.
Four 12-foot double-braided nylon slings from the cargo are linked to the helicopter on either a single center hook or twin hooks fore and aft, found on Chinooks, for extra stability and easier flying.
Besides extra training, the tradeoff with a pendant is increased height of hover when pilots want to fly as close to the ground as possible. Ullery said considerations for the improved pendant design included compact size, low weight and low stretch, but the most important features of the new design are strength and durability.
Responsible for sling load certification for all military helicopters, the Aerial Delivery and Engineering Support Team investigated different possibilities for an improved pendant, first looking at the original double-braided polyester 40-foot pendant with a 12,500-pound capacity used by the 101st during their last deployment.
The revised version is a more rugged 50-foot length with a 15,000-pound capacity, increased resistance to sand wear and tear, and required 75,000 pound minimum breaking strength.
A blowing sand test in March was performed in the McKinley Climatic Laboratory at Eglin Air Force Base, Fla., on two candidate pendants and an unused 40-foot pendant.
Ullery said good results of the sand and strength testing have permitted the project to move ahead into production. Once testing is complete, the final design will be selected. As many as 1,200 pendants will be purchased for immediate fielding.
For more information about the U.S. Army Soldier Systems Center, please visit our website at: http://www.natick.army.mil.