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| S-97 Raider in flight | |
| Role | Reconnaissance and attack compound helicopter |
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| National origin | United States |
| Manufacturer | Sikorsky Aircraft |
| First flight | 22 May 2015 |
| Status | Under development |
| Number built | 3 |
| Developed from | Sikorsky X2 |
| Developed into | Sikorsky Raider X |
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The S-97 design includes variable speed rigid coaxial main rotors and a variable-pitch pusher propeller, making the S-97 a compound helicopter. Like the X2, it has fly-by-wire control and dynamic anti-vibration actuators to cancel out shaking. The main rotors have hingeless hubs and stiff blades, to improve low-speed handling and efficiency of hover. At high speeds, the close spacing of the hubs reduces drag. The stiff blades allow each rotor to have low lift on the retreating side of its rotor disk (reducing drag), whereas each rotor on a conventional coaxial rotor with "floppy" blades needs nearly equal lift distribution. The propeller relieves the rotor of propulsion, further reducing drag.
Maneuverability is improved compared with earlier helicopters because of the ability to tilt the coaxial rotors together or tilt each one differently, and because of the variable pitch propulsor and active elevons At low speed the S-97 yaws by differential torque of the upper and lower rotor, at high speed it uses ruddersCeiling
MAX RANGE
Aircraft Speed
Max Crew
The first flight of the S-97 occurred on 22 May 2015. It flew for 1 hour instead of the planned 30 minutes, completing three takeoffs and landings; forward, rearward and sideward. For this initial flight, the Raider was flown with its triplex fly-by-wire flight control system in backup degraded mode so as to focus on basic airworthiness in the low-speed regime.
On 25 June 2019, the S-97 returned to flight testing and reached a speed of 190 knots (350 km/h)
Based on the technology from the Sikorsky X2 demonstrator, the prototype S-97s will be powered by a General Electric YT706 turboshaft (the same engine used on the MH-60M Black Hawk).
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