In order to enhance performance, a completely new streamlined fuselage was designed and the boom carrying the tail rotor was lengthened and straightened.

It was initially intended to pass 150 R-6s to the Royal Air Force (RAF), but delays caused by the switch of production from Sikorsky's factory at Stratford, Connecticut, to Nash-Kelvinator at Detroit, Michigan, meant that only 27 R-6As were actually delivered to the RAF as the Hoverfly II.

657 Squadron operated their Hoverfly IIs as Air Observation Posts, spotting for Army artillery units.

The Hoverfly IIs remained in operation until April 1951, and one squadron example was displayed at the September 1950 Farnborough Air Show.

Disposals of surplus military S-49s were made in the civil market in the late 1940s but none now remain in operation.