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US Army outlines CH-47F upgrades for 100-year lifespan

The US Army is laying plans to revamp the CH-47F Chinook with a series of major upgrades over the next 15-20 years as the current multi-year production deal expires in Fiscal 2019.

Already the army’s oldest helicopter still in production, the service wants to continue operating the Boeing tandem-rotor helicopter beyond 2060, or 99 years after Frank Piasecki’s heavy-lifter achieved first flight.

The latest Chinook model – the CH-47F – entered production a decade ago adding a more powerful version of the Honeywell T55 engine, a single-piece airframe, a glass cockpit and digital flight controls.

Over time, the CH-47F could become more powerful and even longer, but in the near-term the army wants to extract more lifting capability and range from the existing powerplant and airframe.

A development contract for a Block 2 version of the CH-47F could be awarded in Fiscal 2017, with remanufactured airframes starting to roll off Boeing’s assembly line near Philadelphia beginning in 2020, Col Rob Barrie, CH-47 project manager, says in an interview.

The Block 2 upgrade should raise the maximum take-off weight of the CH-47F by 8% to 24,500kg (54,000lb). At the same time, the army will reduce weight by about 90kg by consolidating a main fuel tank and two auxiliary fuel tanks into two tanks, one on each side of the aircraft.

As the weight of the aircraft increases, the outdated airfoils of the rotor blades could be replaced by composite blades featuring modern design techniques, including swept leading edges, anhedral tips and better aerodynamic shaping, Barrie says.

The existing T55-714A engine is likely to remain the standard through Block 2, but the army could boost the power capacity of the transmission and drive train to eventually accept a new engine, he says.

The army is funding early development of the 6,000shp-class future affordable turbine engine (FATE). That engine – or perhaps FATE technologies inserted into the T55 – could form the basis for a Block 3 upgrade programme to launch after 2025, Barrie says.

More ambitious concepts under review for Block 3 include increasing the length of the CH-47F fuselage by inserting plugs in the airframe, Barrie says.

The army’s Future Vertical Lift (FVL) programme proposes to replace the sub-175kt, army helicopter fleet with a new generation of 220kt-or-faster rotorcraft with enough range to self-deploy anywhere in the world. That concept is initially aimed at replacing the army’s medium-lift helicopters, leaving the Chinook fleet to operate for several decades.

Although Boeing has toyed with concepts for high-speed Chinook designs for decades, the army for the moment is content with the 175kt maximum speed of the CH-47F, Barrie says.

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