Companies Step Up Investment in Future Army Helicopter

A Boeing-Sikorsky team continues to pour money into a prototype helicopter that it hopes the Army will select as its future rotorcraft.

A competition for the Army's "future vertical lift," or FVL, isn’t scheduled to kick off in earnest until the next decade, but the Army has defined some preliminary requirements for the aircraft. It should be able to carry 12 troops equipped with Land Warrior systems, cruise at 230 knots and have a combat radius of 424 kilometers. It will also be able to fly at altitudes of 6,000 feet in 95 degree Fahrenheit weather.

Sikorsky and Boeing are developing a prototype that will fulfill those requirements, and also offer the Army other capabilities for the FVL-medium, said Pat Donnelly, Boeing's program director for the team’s Joint Multirole Rotorcraft entry, called the Defiant.

“There may be certain technologies that we will not be able to fly because of the maturity level in three years, but the Boeing-Sikorsky team will continue to develop those technologies on the side,” he told reporters during a June 17 conference call.

Four teams are working on joint multirole technology demonstrators that will be used to inform requirements for the future vertical lift program, which Army officials intend to be the acquisition vehicle for a next-generation family of rotorcraft to replace its current helicopter fleet. Initial operating capability for a medium-lift FVL variant is scheduled for the mid 2030s.

As part of the JMR program, competitors are required to pay at least 50 percent of the costs of developing and producing a prototype, said Doug Shidler, Sikorsky's Defiant program director. Boeing and Sikorsky are contributing “significantly more” funding than that, although he would not specify how much.  

“We think it’s important to develop the technologies to inform the Army and the customers on what is in the art of the possible for the future, so as they are developing the requirements for future vertical lift medium, they have the knowledge [of what] we're able to provide them based on testing, building and demonstrating capabilities that exist,” he said.

Three other companies — Bell Helicopter, AVX Aircraft and Karem Aircraft — won technology investment agreements in 2013 for JMR. The Army is expected to select two competitors, which will fly prototypes in 2017. Bell and Karem are proposing tiltrotors, while AVX and the Sikorsky-Boeing team are offering a coaxial-rotor design.

Boeing and Sikorsky have submitted the Defiant’s initial design and risk report to the government and are scheduled for a review with the Army next week, Shidler said. A final design and risk review is planned for mid-2015.

Jose M. Gonzalez, Defense Department deputy director of land warfare, munitions and tactical warfare systems, said earlier this month that although the Pentagon is committed to the future vertical lift program, a difficult budget environment could keep a new-start program from coming to fruition. Instead of procuring a brand new aircraft, technology demonstration efforts could help inform upgrades or changes to rotorcraft concept of operations, he said.

As the manufacturers of the UH-60 Black Hawk and AH-64 Apache, Boeing and Sikorsky would be able to transfer technology created for the Defiant back into their existing platforms, Shidler said.

The most unique feature of Defiant’s design is its rotor configuration — a rigid, coaxial rotor system where two blades share the same axis and rotate in opposite directions, said Donnelly. “What that does is it counters the torque generated by that rotor, so there's no need for an anti-torque system, which in a conventional helicopter, could draw up to 15 percent of the power."

By making the rotors rigid instead of flexible, they can be installed closer together, which reduces drag, he said. 

“What's unique about our aircraft is that thrust can be regulated,” Donnelly said. “Not only does it allow us to accelerate at great speeds at level attitude ... we can also use it as a brake, so we can use it to significantly decelerate as we are entering a [landing zone].”

The companies selected an off-the shelf engine for the demonstrator — the Honeywell T55, which is installed on CH-47 Chinook cargo helicopters, he said. Choosing an engine that could modify its speed was necessary so that the Defiant could modulate its rotor speed.  

Risk reduction will be a key driver for the JMR program. Boeing and Sikorsky have targeted several technologies for further maturization during wind tunnel and flight testing, Shidler said. For instance, the company wants to improve the aircraft’s lift-over-drag ratio.

The Navy said it is interested in procuring FVL aircraft, but so far the Army led efforts to define requirements for the program. The Navy will likely merge in its own requirements later on, Shidler said.

Topics: Aviation, Rotary Wing