WASHINGTON – The Army has been planning for two vertical lift aircraft to begin flight demonstrations in the fall of 2017 critical to the process of informing and shaping the design of a Future Vertical Lift helicopter fleet expected to come online in the 2030s.
But one of the demonstrators – the Sikorsky-Boeing-made SB-1 Defiant coaxial helicopter – is now slated to start flying some time in the first half of 2018, behind the original schedule.
Bell Helicopter has been very vocal about its own demonstrator – the V-280 Valor tiltrotor – and recently said the aircraft is roughly 95 percent complete. The company said it will be ready to fly on schedule in the fall of 2017, but also believes the Army, given the technology on display now, could start building a new aircraft by 2020.
While Defiant may start its flight test phase later, the Boeing and Sikorsky team believes it’s following "a very disciplined approach," according to Pat Donnelly, Defiant program manager at Boeing.
The delay seems to be a relatively new development. In December, the Boeing-Sikorsky team told Defense News in an interview that it was anticipating flying on time.
"Honestly, there’s nothing significant that happened that caused a delay," Donnelly told reporters during an April 18 teleconference. "There were no problems that we’ve encountered; it’s just a process as we’ve been following it. Things aren’t happening as quickly as we would like, but again there has been no negative elements going on, we are marching down the path, as we said."
Donnelly added the Army and Marine Corps "fully understand where we are and fully support" the process "because, again, it is the belief that when we do fly we will have validated all of our components and, as such, we will be entering a much more risk-reduced flight test program."
When pressed further on what was slowing the process, Donnelly said the focus of the team in developing Defiant has been on work in its systems integration lab and propulsion system test bed. He said the third leg of the development work is flying the aircraft. The process requires coordination across the three legs, as hardware is refined, for instance.
The team thinks it is possible to make up for lost time as it begins to fly the aircraft due to its thorough risk reduction process now, but Donnelly added, "we do recognize that our flight test program has probably a year duration. Certainly as we start to fly the aircraft, while we still have to expand an envelope and still have to prove all of the flight characteristics of this vehicle, we will be doing it with more confidence I think than we would be if we didn’t do all of this risk reduction beforehand."
The Boeing-Sikorsky team also said the delay in flight schedule should not have a negative impact on the Army launching its FVL program within its planned timeline. The program is expected to become a full-fledged program-of-record in 2019.
Meanwhile, the Lockheed Martin-owned Sikorsky has made progress in its S-97 Raider helicopter program, which uses the same X2 coaxial technology as Defiant but on a smaller scale. Raider is a scaled-up version of its X2 demonstrator that broke unofficial helicopter cruise speed records in 2010.
The aircraft flew in March this year in a series of tests and Lockheed posted a video Tuesday of it in action. The Army considered Raider as an option when it was looking to procure an armed reconnaissance helicopter around 2012, but ultimately it opted not to procure a new helicopter for the mission.
Sikorksy has moved at lightning speed with Raider’s development. At the time the service was mulling a new armed scout, Raider was an aircraft just on paper.
The service originally intended to include the attack mission in its first variant of FVL that it calls "Capability Set 3," but the Army is taking a step back to debate what it truly needs in an attack helicopter and where it fits in the family of future rotorcraft. The analysis of alternatives the service has begun for its first variant of FVL does not include examining the attack mission.
The Army will likely follow the development of capability set 3 with capability set 1 development – which is expected to address light attack – due to a current gap in the service’s light attack and reconnaissance helicopter fleet with the retirement of the OH-58D Kiowa Warrior helicopter.
In scaling up in size, moving from the X2 to Raider to Defiant, Sikorsky is increasing the weight of the platform from 6,000 lbs to 11,000 lbs to 30,000 lbs, Donnelly said.
When asked what the challenges might be in scaling the aircraft up in size and weight, Donnelly said, while loads on the rotor system increase with size, the task "doesn’t appear to be a challenge at this time."
Dan Spoor, Sikorsky vice president told reporters in the small teleconference that using a currently fielded engine – the T-55 – puts some limitation on the aircraft and a future engine that would come along with FVL would match up well with what the team has designed and would bring it to its full potential.
Jen Judson is an award-winning journalist covering land warfare for Defense News. She has also worked for Politico and Inside Defense. She holds a Master of Science degree in journalism from Boston University and a Bachelor of Arts degree from Kenyon College.