Concerns have been raised that the capabilities of the US Navy's proposed Unmanned Carrier Launched Surveillance and Strike (UCLASS) aircraft have been so watered down from the original concept that the programme is now vulnerable to cancellation by a cash-strapped Pentagon.
"The less-survivable, less-endurance approach, although cheaper, is, to me, not transformational," says retired chief of naval operations Adm Gary Roughead. "With the UCAS [Unmanned Combat Air System] you really do have a transformational weapon system."
The original UCAS concept - championed by Roughead and former under-secretary of the navy Robert Work - called for a very stealthy, carrier-based, long-range bomber with a hefty payload that could be refuelled in-flight.
"The idea [of] a long-dwell, long-range, refuellable, survivable UAV coming off a carrier was extremely important," Roughead says.
By contrast, the current vision is for a modestly stealthy UCLASS that emphasises intelligence, surveillance and reconnaissance (ISR) missions over lightly contested airspace, with a light secondary strike mission.
Roughead says that in a difficult budgetary climate, it is better to "ride a winner" that has a greater chance of surviving a cash crunch than to build a platform that adds little to the fleet's capabilities.
"The UCLASS system will support missions in permissive and low-end contested environments and provide enabling capabilities for high-end denied operations," says the office of the Chief of Naval Operations (OPNAV). "The requirements were written to fill a long-standing gap in persistent, sea-based ISR and a review of the overall UAS portfolio."
Roughead is not alone in his criticism, however. "The current UCLASS makes little sense to me," says airpower analyst Rebecca Grant, president of IRIS Independent Research. "A UCLASS as described by [Adm] Roughead would make sense. So would an armed UCAS vehicle if embarked in numbers adequate to provide [enough orbits to be] usable to a joint force commander."
She says that the aircraft's lack of stealth capability and the small number the navy proposes to acquire have eroded its worth.
Sources say that the specifications for the UCLASS were diluted by the vice-chairman of the Joint Chiefs of Staff, Adm James "Sandy" Winnefeld, who heads the Pentagon's Joint Requirements Oversight Council (JROC).
Why Winnefeld would insist on a set of reduced capabilities for the UCLASS is not clear, and his office was unable to respond to requests for comment by press time, but some sources suggested it was at the behest of the White House.
The lower requirements mean many are questioning the necessity of the programme at all. As a result, there are some within the navy who believe UCLASS could be offered as a sacrifice as the Pentagon copes with a reduced budget.
Roughead says that the current approach will not yield an aircraft that will be able to operate in the contested airspace the service will encounter in the future.
Originally, he says, the USN's concept was to evolve the Northrop Grumman X-47B UCAS-demonstrator aircraft into an operational machine. "The whole intent was to take that form, pursue refuellability - you get long endurance - and then use that and move forward on that," Roughead says. "Do it as an evolutionary process."
Among the key requirements that were deleted by the JROC is aerial refuelling. "By not having it refuellable I think it really changes what I would consider a transformational dimension of naval aviation," Roughead says.
Aerial refuelling would have allowed the navy to move unmanned assets from shore bases to a carrier at sea from across the globe, Roughead says. That would allow a carrier strike group commander to either reconfigure the air wing as needed or replenish combat losses. "It gives you a tremendous amount of flexibility," Roughead says.
However, Naval Air Systems Command (NAVAIR) says aerial refuelling capability might be added as a future goal, but it will not be required on the UCLASS initially. "OPNAV is looking to prioritise air refuelling as a future requirement pending early operational capability performance and fleet feedback," NAVAIR says.
But in addition to endurance and range, another key tenet of the USN's original vision was the low observability needed to penetrate into dense anti-access/area-denial environments, Roughead says. However, the stealth requirements have been sharply reduced.
Defence industry officials say the low-observable requirements allow for very wide margins, running from marginal stealth to Lockheed F-35-level signatures; however, the primary driver is low cost. Because stealth costs money, the requirement therefore defaults to a greatly reduced specification.
Likewise, the payload originally envisioned for a naval UCAS was much greater. Northrop officials in 2009 were expecting to develop a UCLASS that resembled a longer X-47B with weapons bays that could hold as many as 24 small diameter bombs, each weighing 113kg (250lb).
The present UCLASS requirements call for a total payload of 1,360kg, of which only 454kg would consist of air-to-ground weapons. "I would like to see us evolve into something that has greater capability," Roughead says.