Sikorsky R-4

Target entity: Sikorsky R-4
Context triple: [R-4, alsoKnownAs, Sikorsky R-4]

• A. Sikorsky S‑40
  The Sikorsky S‑40 was an early 1930s American amphibious flying boat airliner used primarily by Pan American Airways for long-range overwater routes.
• B. Sikorsky H-5 helicopter
  The Sikorsky H-5 is an early post–World War II American utility and rescue helicopter that played a key role in pioneering rotary-wing military and search-and-rescue operations.
• C. Bell 47 helicopter
  The Bell 47 helicopter is a pioneering light utility helicopter, famous as the first helicopter certified for civilian use and widely recognized for its distinctive bubble canopy and extensive service in both military and civilian roles.
• D. Bell H-13 Sioux
  The Bell H-13 Sioux is a light, single-rotor helicopter best known for its extensive use by the U.S. Army during the Korean War, particularly in medical evacuation and observation roles.
• E. O-47 observation aircraft
  The O-47 observation aircraft was a pre–World War II American military reconnaissance plane used by the U.S. Army Air Corps for aerial observation and liaison duties.
• F. None of above. chosen
• G. Unsure - the case is ambiguous/there is not enough information to decide.

Target entity: Sikorsky R-4
Target entity description: The Sikorsky R-4 was the world’s first mass-produced helicopter and the first helicopter to be used operationally by the U.S. military during World War II.

• A. Sikorsky S‑40
  The Sikorsky S‑40 was an early 1930s American amphibious flying boat airliner used primarily by Pan American Airways for long-range overwater routes.
• B. Sikorsky H-5 helicopter
  The Sikorsky H-5 is an early post–World War II American utility and rescue helicopter that played a key role in pioneering rotary-wing military and search-and-rescue operations.
• C. Bell 47 helicopter
  The Bell 47 helicopter is a pioneering light utility helicopter, famous as the first helicopter certified for civilian use and widely recognized for its distinctive bubble canopy and extensive service in both military and civilian roles.
• D. Bell H-13 Sioux
  The Bell H-13 Sioux is a light, single-rotor helicopter best known for its extensive use by the U.S. Army during the Korean War, particularly in medical evacuation and observation roles.
• E. O-47 observation aircraft
  The O-47 observation aircraft was a pre–World War II American military reconnaissance plane used by the U.S. Army Air Corps for aerial observation and liaison duties.
• F. None of above. chosen