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US Government knocks back Sikorsky-Boeing protest over Blackhawk replacement decision

The US Government Accountability Office (GAO) has knocked back the Sikorsky-Boeing challenge to the US Army’s selection of the Bell Textron V-280 Valor for its Future Long Range Assault Aircraft (FLRAA) program – essentially, the Blackhawk helicopter replacement. The eventual value of the replacement program for the US Army’s UH-60 Blackhawk fleet could be worth as much as US$70 billion.

Despite the V-280 tilt-rotor design being assessed as more expensive than Sikorsky-Boeing’s more conventional Defiant X, the FLRAA source selection board chose the V-280 because Sikorsky-Boeing did not provide sufficient detail on its Engineering Design and Development and Systems Architecture proposals for the Defiant X.

The design goals for the FLRAA are a minimum cruise airspeed of 250kt (275kt for the US Marines; a desired airspeed of 280kt (295 to 330 for the US Marines), an unrefuelled combat radius of at least 300nm (450nm for the US Marines) and a passenger or cargo capacity of 12pax/1500kg/m2 (8pax/2,400kg max for the US Marines).

These goals are well above the 216kt maximum level speed record for a pure rotary wing aircraft (currently held by the Leonardo Lynx and set in 1986). To meet them needed a new technical approach. Bell chose to leverage its investment in tilt-rotor technology, notably the US Military’s V-22 Osprey which is built by a Bell-Boeing consortium and has a maximum speed of 305kt; Bell came up with simplified tilt rotor design using three-bladed propellers.

The Sikorsky-Boeing Defiant X uses twin contra-rotating four-bladed propellers and a thrust propeller to give it maximum forward speed. The concept was proven by the Sikorsky X2 research aircraft which used the same configuration and achieved a maximum speed in 2019 of 260kt.

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