Sergei Sikorsky discusses the long and successful heavy-lift helicopter partnership between Sikorsky and Germany, a relationship that lasted more than 50 years. The Sikorsky CH-53K King Stallion is a large, heavy-lift cargo helicopter currently being developed by Sikorsky Aircraft for the United States Marine Corps (USMC). The design features three 7,500 shp (5,590 kW) engines, new composite rotor blades, and a wider aircraft cabin than previous CH-53 variants. It will be the largest and heaviest helicopter in the U.S. military. The USMC plans to receive 200 helicopters at a total cost of $25 billion. Ground Test Vehicle (GTV) testing started in April 2014; flight testing began with the maiden flight on 27 October 2015.