More than two and a half years since its rollout, the U.K. defense ministry has finally lifted the veil on the test program for the Taranis unmanned combat air vehicle demonstrator.

Little has been heard of the £185 million ($300 million) program since the project went black shortly after its unveiling.

But now, with the first phase of trials completed with flights of up to an hour in duration, industry and defense officials say the aircraft, claimed to be the most advanced ever produced in the U.K., has surpassed all expectations.

First flight of the Taranis was a 15-min. hop that took place on Aug. 10, 2013 at the Woomera Test Range in South Australia, although officials won’t confirm the location. A second flight followed a week later, and since then the aircraft has flown sorties up to an hour in length, at various speeds and altitudes, although the details on the number of sorties remains classified.

Officials described the flight test program as taking a “gated” approach, with funding dependent on the success of the previous phase. The aircraft is now flying a second phase of tests and a decision on a third phase will be “decided in weeks,” said Chris Boardman, managing director of military air and information at BAE Systems, speaking at the Royal Academy of Engineering in London on Feb. 5.

“The aircraft has surpassed all our expectations. It was an outstanding achievement,” said BAE Systems Group Managing Director Nigel Whitehead. “There were significant challenges along the way, but passing any technological boundary comes with risk.”

Whitehead said the achievements of Taranis were comparable to those of the Experimental Aircraft Program (EAP) in the 1980s. That aircraft went on to pave the way for the development of the Eurofighter Typhoon.

The program’s cost has risen, from the envisioned £126 million ($205 million) in 2010 to £185 million today. Asked about the price increase, Whitehead said the company had been given “opportunities to expand the nature of what we were testing.”

The U.K. defense ministry will now use the Taranis program to inform its Future Combat Air System program, which is exploring the platform that will likely replace the Eurofighter Typhoon and work alongside the F-35 Joint Strike Fighter beyond 2030. Taranis experience will also feed into a joint French UCAV feasibility study announced by British Prime Minister David Cameron and French President Francois Hollande during a U.K.-French summit at RAF Brize Norton, Oxfordshire on Jan. 31.

Both nations have agreed to pledge £120 million for the two-year study, which will see BAE Systems, Dassault and other aerospace companies working together. A memorandum of understanding on the study is due to be signed by the 2014 Farnborough air show.

Philip Dunne, minister for defense equipment, support and technology, said: “As we bring in JSF we need to think about the technologies that follow…and projects like Taranis keeps the U.K. in a strong position as we tackle that challenge.”

About the size of a BAE Systems Hawk aircraft and powered by a Rolls-Royce Adour 951 engine from the same aircraft, Taranis has been designed and built by BAE Systems, Rolls-Royce, the systems division of GE Aviation; and Qinetiq, working alongside defense ministry military staff and scientists.