Submitted at the same time as the Sikorsky S-69 ABC (Advanced Blade Concept) was the Bell Model 560 prototype. It was built using the third, unused XV-15 fuselage and fitted with two co-axial rotors, which was quite unusual for Bell. Just as unusual was the unique triple fin in a Y-shaped configuration.
The Bell 560's rotors used two advanced rotors that previously belonged to the unfortunate YAH-63 attack prototypes, but Sikorsky's technology was much more advanced and won it a contract as the YH-59A. Undeterred, Bell offered the model for export, and 50 were ordered by the Japanese Navy, with deliveries commencing in 1983.
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© Stéphane Beaumort / AviaDesign 2011