|Empty Weight:||2,105 lbs.|
|Gross Weight:||3,361 lbs.|
|Maximum Speed:||156 mph|
|Powerplant:||Wright R-1820-84 Cyclone|
In 1953, the U.S. Army awarded Sikorsky a contract for the experimental conversion of the H-18 (S-52) helicopter from piston to turbine power. This would be the Army's and Sikorsky's first use of a gas turbine engine in a helicopter. Along with the addition of the turbine, the H-18/S-52 was extensively modified and included retractable landing gear (another first for Sikorsky), strengthened fuselage and updated electronics. The new craft, designated XH-39 by the Army and S-59 by Sikorsky, first flew on June 1, 1954.
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Source: Sikorsky Historical Archives