In researching this helicopter on the inter-web I discovered many sites give conflicting information as to when this helicopter first flew, some say 1943, another says 1946, the Sikorsky S-51 Archives gives no dates.  This U.S. Navy photo is dated 05DEC1945, Sikorsky S-51 lands on the deck of United States Ship (USS) Princeton.

Sikorsky Aviation Corporation’s S-51 was developed from the S-48.   The U.S. Army Air Force (USAAF) called it R-5, later becoming the H-5/SH-5 by the new U.S. Air Force (USAF).  U.S. Navy(USN)/Marine Corps(USMC)/Coast Guard(USCG) called it HO3S.  The British called their versions WS-51 (silly-vilian) and Dragonfly HR (Royal Navy)/HC (Royal Air Force).

U.S. Marine Corps HMX-1 was established in December 1947, on Quantico in Virginia, to help test and evaluate the HO3S-1.

Silent USMC film of HO3S med-evac (medical evacuation) operation during Korean conflict, 27MAY1951:

Silent USA (U.S. Army) film, during naval wargames General Dwight D.  Eisenhower meets Admiral Robert B. Carney and Vice Admiral Matthias B. Gardner, on heavy cruiser USS Des Moines (CA-134) and aircraft carrier USS Roosevelt (CVB-42/CVA-42/CV-42) via an HO3S, 16-17OCT1951.  Notice staff cars parked on deck of CA-134:

Silent USA film, by Rex Peterson, of H-5 delivering USA and USN officers to first peace talks during Korean conflict (referred to as ‘police action’ by United Nations), 27NOV1951, Panmunjom:

Date and location (assumed to be Korea) not given, USAF maintainers work on the rotor-hub of the H-5G.

Somewhere in Korea, USAF H-5G undergoing what could be called phased maintenance.

In this photo you can better see the wooden blades of the tail-rotor.

Aerial photo of USN HO3S on Korean farm field.

USAF H-5 with wounded person litter.

You can see the air cooled rotary engine.

Litter/stretcher used on H-5.

First Lieutenant caught laying down on the job!

Silent USN film dated 30JUN1953, by last name Benton, showing Royal Navy Dragonfly HR onboard USS Antietam (CV/CVA/CVS-36):

Silent USN film dated 09JAN1954 (the film slates are dated 09JAN1954 [1-9-54], but news media articles date the event as 10JAN1954), by last names Peterson and Happius (interesting, on one of the slates with Peterson’s name it appears somebody ‘flips the bird’ at the camera), HO3S shuttling officials from Nationalist China (Republic of China/Taiwan) onboard USS Wasp (LHD-1) for some sort of official visit (it included Chiang Kai-Shek who came onboard on a different type of helicopter, but I edited to focus on the HO3S):

 

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