Sikorsky unveils CH-53K "King Stallion" helicopter

Sikorsky unveiled EDM-2, one of four CH-53K flight test aircraft that will participate in the flight test program beginning late 2014.

Sikorsky Aircraft Corp. (Stratford, Conn., USA), a subsidiary of United Technologies Corp. (Hartford, Conn., USA), has officially unveiled the CH-53K heavy lift helicopter, the next generation in the CH-53 type series that the U.S. Marine Corps expects to begin operational service in 2019. During the rollout ceremony, attended by members of Congress, the Department of Defense, major suppliers to the program, international guests and company employees, the Commandant of the Marine Corps General James F. Amos introduced the name for the new aircraft: the “King Stallion.”

According to Sikorsky President Mick Maurer, “The CH-53K aircraft will effectively triple the external load carrying capacity of the CH-53E aircraft — to more than 27,000 pounds over a mission radius of 110 nautical miles. With its 88,000-pound maximum gross weight, powerful new engines, lightweight composite structure, new rotor blades and fly-by-wire flight controls, the CH-53K will have the means to move troops and equipment from ship to shore, and to higher altitude terrain, more quickly and effectively than ever before.”

For increased lift, Sikorsky developed the largest and most technologically advanced main rotor blade the company has ever produced. At a span length of 35 ft (10.7m), and chord width of almost 3 ft (0.9m), the all-composite blade has 12 percent more surface area than the CH-53E blade. According to Frank Colucci's article "Constructing the Kilo" in Vertiflite magazine (Vol. 59, Issue 2), the rotor blades feature fiberglass skins, honeycomb core and 30-ft (9m) long carbon fiber spars.

Colucci says Sikorsky engineers calculate that the CH-53K airframe is more than 75 percent fiber-reinforced composite, compared to the previous CH-53E which uses composites in less than 10 percent of its wetted area, limited to mostly secondary structure. The CH-53K cabin is composed of five 30-ft long contoured skins which carry the fusleage bending loads. Made mostly from IM7 carbon fiber and 8552 toughened epoxy resin, the CH-53K airframe construction also includes a new, patented aramid-reinforced honeycomb with a fiberglass layer in the laminate to impart high impact resistance and improved durability. The large composite skins were designed to reduce parts count, eliminating hundreds of mechanically fastened stiffeners, doublers and clips,.

Spirit Aerosystems (Wichita, Kan., USA) builds and joins the CH-53K cockpit and cabin. GKN Aerospace (St. Louis, Mo., USA) produces the aft fuselage transition. Exelis (Salt Lake City, Utah, USA) makes the 25-ft long tail pylon, including stabilizer and tail cone. And Aurora Flight Sciences (Bridgeport, W.V., USA) supplies the engine nacelles and main rotor pylon.

Colucci noted that thermoplastic composites offer greater strength, durability and a 200 to 300 lb weight savings vs. aluminum in the cargo floor, but the materials and process remain in development for now. Until that technology is perfected for production, the CH-53K models be delivered with aluminum floors.

The CH-53K is one of the first all-digitally designed helicopters. This approach enabled Sikorsky to assemble the aircraft inside a 3D virtual reality lab before prototype production began. “Our ‘build before you build’ approach allowed our engineers to work ‘inside’ the helicopter,” said Maurer, “to verify assembly designs and correct issues long before discovery and expensive rework on the assembly line.”

In April, Sikorsky began powered ground tests of the CH-53K aircraft systems, such as rotors, drive, electrical, hydraulic, avionics and flight controls. Hundreds of hours of powered ground tests will prepare the CH-53K team for first flight at the end of 2014. Thus will begin a three-year flight test program using four Engineering and Manufacturing Development (EMD) models. Pentagon post-EMD phase acquisition review is scheduled for 3Q 2015. Approval should launch low-rate initial production in 2016.

Currently, the Marine Corps order is for 200 CH-53K production aircraft to be delivered from the West Palm Beach assembly line by 2028. These will be used to field up to eight operational squadrons and one training squadron.