Sikorsky, Boeing submit ‘early’ US Army FLRAA proposal with Defiant X

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Sikorsky, Boeing submit ‘early’ US Army FLRAA proposal with Defiant X
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The partnership between Boeing and Lockheed Martin‘s Sikorsky subsidiary has submitted a proposal for the US Army’s development program that seeks to replace the UH-60 Black Hawk utility helicopter with a new assault aircraft, the joint team announced on 7 September.

The bid comes as flight testing continues on the team’s SB-1 Defiant demonstrator, a compound co-axial helicopter upon which the proposed Defiant X is based, the companies said on 7 September. The proposal includes flight data from the SB>1 Defiant demonstrator co-axial compound helicopter currently being tested and virtual modelling of the Defiant X bid.

To replace the US Army’s fleet o fUH-60 Black Hawk helicopters, the proposed Sikorsky-Boeing Defiant X competes against Bell’s V-280. The US Army plans to field a family of its FVL platforms as replacements for the Sikorsky UH-60 Black Hawk transport (FVL – Medium) helicopter and Boeing AH-64 Apache attack helicopter (FVL – Attack) in about 2030 and 2040, respectively (these two requirements now make up the FLRAA effort).

A joint statement from Paul Lemmo, president of Sikorsky; and Mark Cherry, vice president and general manager for vertical lift at Boeing’s defence, space and security business, noted that the team’s pursuit of the FLRAA program builds on a 75-year partnership with the Army to sustain Black Hawk, Chinook and Apache helicopters; “Today, Team Defiant completed and submitted the proposal for the US Army’s FLRAA competition, offering low-risk, transformational capability that delivers on an army critical modernisation priority and advances the future of army aviation”.

Sikorsky, Boeing submit ‘early’ US Army FLRAA proposal with Defiant X

The Sikorsky-Boeing team did not say why it chose to submit the FLRAA proposal “early”. The SB-1 did not fly until 2019 due to problems with its composite rotor blade manufacturing process and transmission gears.

FLRAA is intended to be a utility rotorcraft replacement for the Black Hawk. The service wants the next-generation rotorcraft to have a maximum cruise speed of 280kt (519km/h). It also wants the aircraft to have an unrefuelled combat radius of 300nm (556km) and a one-way unrefuelled range of at least 2,440nm. While the V-280 has a higher maximum cruise speed, the Sikorsky-Boeing team emphasises Defiant X’s performance during landing and take-off.

The proposed helicopter’s exhaust outlets are covered with a shroud to reduce its infrared signature, a precaution against infrared-homing missiles.

The Defiant X closely resembles the SB-1 demonstrator. However, the Sikorsky-Boeing team unveiled in January a few subtle changes to its shape. While the SB-1 has two mid-section wheels and a tailwheel, the Defiant X has a nose wheel, two mid-section wheels and a small wheel under the tail. The trailing edge of the vertical stabilisers on the SB-1 was straight but has been changed to a V-shape on the Defiant X.

The US Army is expected to issue a production contract for FLRAA in 2022. It wants to field its first example of the utility rotorcraft no later than 2030.

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