Boeing’s FARA Contender Finally Emerges

 - March 4, 2020, 11:25 AM
In Boeing’s design, the armament is carried internally, the fold-up doors also acting as launchers. (Image: Boeing)

Boeing has revealed details of its entry for the U.S. Army’s Future Attack Reconnaissance Aircraft (FARA) program—the last of the five rival bidders to do so. FARA aims to provide the Army with an advanced light attack and reconnaissance capability, replacing the now-retired Bell OH-58D Kiowa Warrior scout helicopter. It will also eventually replace those AH-64 Apaches that are now used in the armed reconnaissance role—accounting for nearly half of the fleet.

Five teams were awarded FARA design contracts in April 2019. Three teams will be dropped later this month when the remaining two teams will be funded to build competitive prototypes. They will fly by 2022 before a head-to-head fly-off at the end of Fiscal Year 2023. The final design is due to be fielded by 2028.

The design Boeing revealed is a purpose-built, clean-sheet design employing a broadly conventional configuration. The aircraft is a thrust-compounded helicopter with a propulsor on the tail, a configuration that Boeing says will allow the helicopter “to maintain airspeed during maneuvers that would cause other helicopters to lose airspeed.”

The chosen configuration is reminiscent of Lockheed’s AH-56 Cheyenne, especially around the tail rotor and pusher prop, with the tailwheel similarly integrated in a ventral tailfin. The aircraft also bears some resemblance to the stealthy Boeing/Sikorsky RAH-66A Comanche, especially in its fuselage cross-section and internal weapons bays.

The same model-based engineering that formed the basis for the T-7 Red Hawk jet trainer and the MQ-25 Stingray unmanned carrier-launched tanker aircraft has been used in the FARA design. This promises a smooth transition to production if the design is down-selected.

The company is following a “One Boeing” approach and has not partnered with any other vendors at this stage, although other suppliers and partners could join the program later. Instead, the company’s FARA bid is being led by the Boeing Phantom Works, operating with the company’s AvioniX and Aurora Flight Sciences divisions.

Boeing claims that it has blended “innovation, ingenuity, and proven rotorcraft experience with extensive testing and advanced analysis” to produce the FARA design, though Shane Openshaw, FARA program manager, stressed that the company is “not inventing new technologies,” but is instead “improving upon and integrating mature technologies” to meet the requirement within schedule and cost.

The new design incorporates a single six-blade hingeless “high-solidity” main rotor, a canted four-blade tail rotor, and a four-blade pusher propeller. The hingeless main rotor provides agility and maneuverability without the disadvantages of a fully articulated “flapping” rotor. It is based on Boeing’s experience with the hingeless rotor developed for the company’s YUH-61 entrant in the utility-helicopter competition that resulted in the Sikorsky UH-60 Black Hawk, and on work Boeing undertook with MBB on the Bo 105 light helicopter. The tail rotor provides maneuverability at low speeds, while the pusher propeller provides high-speed capability. The pusher is driven via a clutch in the drive train, mounted behind the intermediate gearbox that drives the tail rotor.

Boeing FARA
Boeing’s FARA design has a sleek, low-drag fuselage to maximize its speed. (Image: Boeing)

To meet the U.S. Army’s requirement for a maximum speed of at least 180 knots, Boeing assessed single- and twin-engine configurations, as well as the use of a single engine with a supplemental power unit. Based on digital modeling and extensive wind tunnel testing, Boeing is confident it can achieve 180 knots at 4,000 feet on a 95-degree F day in cruise conditions with a single 3,000-shp General Electric T901 engine. The T901 was the winner of the U.S. Army’s Improved Turbine Engine Program (ITEP) and will be used to re-engine AH-64 Apaches and UH-60 Black Hawks.

In the FARA design, Boeing focused a great deal of effort on reducing drag, and this drove the selection of a narrow fuselage cross-section with a tandem cockpit configuration. The need to minimize drag also drove the adoption of internal weapons bays on each side of the lower fuselage, with the doors opening to act as pylons. Even the three-barrel 20mm cannon is mounted in a low-drag turret. The cockpits are state-of-the-art, modular, and feature reconfigurable large-area displays and optionally-manned capability. The aircraft incorporates a fly-by-wire control system developed from those used in the RAH-66 Comanche and the Sikorsky/Boeing SB-1 Defiant demonstrator.

Comments

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