Equipment of the Vietnam War, National Museum of Military Vehicles, Dubois Wyoming.
UH-1 "Huey", a helicopter synonymous with the Vietnam War.
Hueys came into use in a major way during the war, and remained in use for many years thereafter. They were still the predominant helicopter when I was a National Guardsmen in the 1980s, and even now I'll occasionally see an Air Force example in Cheyenne in operation.