HR2S-1 (CH-37C) Mojave, 145864
Sikorsky HR2S-1 (CH-37C after 1962) Mojave, 145864
These unique twin-engine helicopters provided some of the early "heavy lift" capability required by the Marine Corps as it developed "vertical envelopment" tactics in the 1950s and early 1960s.
Film of HR2S-1 helicopters operating from USS Valley Forge in 1957 is here:
National Naval Aviation Museum
Naval Air Station Pensacola