Sikorsky S-61F / NH-3
Officially listed as an HSS-2, the U.S. Navy's BuNo. 148033 was actually a Sikorsky S-61F compound research helicopter sponsored by the Army and Navy. Sikorsky tested the S-61F compound helicopter, an SH-3A with a new, streamlined fuselage, fully retractable undercarriage, swivelling tail rotor and 9.75m span wings supporting two 1350kg Pratt & Whitney J60-P-2 turbojets engines to complement the two 1,200 shp General Electric T58-GE-8B turboshafts. The five-bladed rotor shown here was later replaced by a six-bladed rotor.
First flight as a compound helicopter was on 21 May 1965. This aircraft has reached a level speed of 390km/h.
Sam Grober, 22.01.2010