Boeing formally released on 3 March the first high-resolution images of its offering for the US Army's Future Attack Reconnaissance Aircraft-Competitive Prototype (FARA-CP) competition.
The thrust compounded single-main rotor helicopter features a six-blade rotor system, a single engine, tandem seating, a modern cockpit with a reconfigurable large area display, and autonomous capabilities, according to a company statement. Boeing's FARA-CP offering also has a downward-pointing vertical fin and a tail rotor for anti-torque.
Boeing spokesperson Deborah VanNierop said on 3 March that Boeing's FARA-CP platform has three rotors to enable high agility and manoeuvrability. The main rotor, she said, is a high-performance and hingeless rotor system while the tail rotor provides low-speed manoeuvrability. The four-bladed pusher propeller provides the thrust necessary for high-speed flight and additional low-speed manoeuvrability.
Mike Hirschberg, Vertical Flight Society (VFS) executive director, told Jane's on 3 March that the aircraft's six rotor blades can reduce its noise signature. The more of an aircraft's weight that is distributed, the quieter it can be, he said. But the trade-off is cost, weight, and the complexity of more rotor blades.
Hirschberg said that the downward-pointing vertical fin provides directional stability as does a fixed-wing aircraft's tail - it helps the aircraft fly straight at high speeds due to the aerodynamic forces. The structure of the fin, he said, also supports the tail rotor, which provides the counter-torque to the forces of the main rotor. Having the tail rotor higher as Boeing does on its FARA-CP offering puts it about level with the main rotor to better counteract its torque.
Hirschberg also noted that the pusher propeller appears to leverage the extensive simulation and wind tunnel testing of their compound Apache configuration over the past several years. Indeed, Jane's reported in October 2018 that Boeing was testing possible modifications to the AH-64E that featured a large fixed-wing, rearward-pointing exhaust, a downward-pointing vertical fin, and a pusher propeller in the rear.
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