Sikorsky reduces rotor part count in coaxial S-97 Raider

Sikorsky believes the lower rotor part count in its coaxial rotor S-97 Raider light tactical prototype helicopter compared to legacy UH-60 Black Hawk utility aircraft will result in lower acquisition and lifecycle costs.

Tim Malia, Sikorsky Future Attack Reconnaissance Aircraft (FARA) director, told reporters on 19 February at the company’s facility here that the S-97 being developed for the US Army’s FARA-Conventional Prototype (CP) effort has about 225 parts. The Black Hawk’s main rotor, he said, has roughly 460 parts—roughly twice as many.

Sikorsky's S-97 Raider demonstrator on display at the company's West Palm Beach, Florida, flight facility on 20 February. (Janes/Pat Host)

Not only does the S-97 have roughly half as many rotor parts, Malia said Sikorsky designed out many of the maintenance drivers found in conventional single main rotorheads such as dampers and droop stops. Malia told Jane’s on 20 February that the main rotor blade in a conventional rotor system moves in multiple directions. It has pitch, but also goes forward and has aft due to changing loads as the rotor turns in its circle.

Dampers, he said, soften the edges of that movement envelope to prevent metal-on-metal contact. Droop stops constrain that movement in all three axis.

These fewer rotor parts, he said, result in a reduced logistics or sustainment footprint.

“Initially people see ‘Well there are two main rotors, so therefore it must be a lot more expensive,’” Malia said. “Half the parts, easier to maintain…more importantly, you have designed out parts that are causing some of those operational and sustainment costs down stream.”