The four-seat XH-39 was powered by one Continental CAE XT51-T-3 400 shp (298 kW) turboshaft engine, a license-built development of the Turbomeca Artouste. It was developed from a previous Sikorsky model, the H-18 (company model S-52), and had the same layout. It differed in using retractable landing gear, modified tail rotor, and four-blade main rotor. In the end, the U.S. Army selected the Bell XH-40, prototype of the UH-1 Huey. Two YH-18As were modified into XH-39s; one for flight testing and the other for static test.
On 26 August 1954, the XH-39 set a world helicopter speed record of 156.005 mph (251 km/h) over a three kilometer closed course at Bradley Field (now Bradley International Airport) in Windsor Locks, CT.  The same year, on October 17, 1954, it set an unofficial world helicopter altitude record of 24,500 ft (7,474 m) at Bridgeport, CT.
In addition to the two XH-39's, one S-59, serial number 52004, registration number N74150, was produced for use for company demonstration flights.  It has been restored and is now on display at the New England Air Museum, Windsor Locks, CT