The US Navy solidified parameters for its unmanned MQ-25 Stingray, setting up a spartan platform that will satisfy not much more than carrier suitability and air refueling requirements.

Following years of fluctuating requirements and various UAV incarnations, the navy appears to have nailed down its vision for MQ-25 in its final requirements documents. The service is focusing on the MQ-25’s basic ability to operate from a carrier and adjusted the mission focus for air refueling, according to a Government Accountability Office report released this week. The Joint Requirements Oversight Council (JROC) validated two requirements this July and the service is capping MQ-25’s development costs at $2.5 billion, with funding projected to jump from $89 million in 2017 to $554.6 million in 2022.

Although the navy has identified an intelligence, surveillance and reconnaissance capability as part of MQ-25’s portfolio, the Pentagon directed the navy last year to shift its focus away from ISR and toward an unmanned carrier based air refueling aircraft. That move reflected a crackdown on MQ-25’s development, which has seen several iterations since the programme’s inception early in the last decade.

The navy originally set out to acquire an unmanned tanker but by 2013, the programme had evolved into the Unmanned Carrier Launch Airborne Surveillance and Strike (UCLASS) platform. Three years later, the service restructured the stealthy UCLASS into the Carrier Based Aerial Refueling System, which the navy designated MQ-25.

Four companies are bidding for the contracts to develop and produce the MQ-25 fleet: Boeing, General Atomics-Aeronautical Systems Inc, Lockheed Martin and Northrop Grumman.

As the navy reins in its capabilities for MQ-25, the service is also constraining the programme’s development schedule to a maximum of eight years after the start of development, which is scheduled for summer of 2018. The navy plans to limit technology risk during development by mandating the aircraft carry proven subsystems.

“If a technology is identified that does not meet this criteria, the navy plans to push that technology into the future and include it only when it reaches the specified level of maturity,” the GAO report states. “As we reported in March 2017, failure to fully mature technologies prior to developing the system design can lead to redesign and cost and schedule growth if later discoveries during development lead to revisions.”