During the 1990s, two highly-modified S-76s were used to develop technologies embodied later in the RAH-66 "Comanche". The Shadow (Sikorsky Helicopter Advanced Demonstrator and Operator Workload) S-76 in the foreground evaluated the built-on nose-mounted single-seat cockpit, with features such as fly-by-wire sidestick control, a voice interactive system and state- of-the-art combat avionics. The rear aircraft flew extensively to determine the optimum size and shape of the type of shrouded tail rotor once fitted temporarily to the S-67 "Blackhawk".

John W.R. Taylor "Images of America - Sikorsky", 1998