The aircraft, named after the Celtic god of thunder, made a perfect take-off, rotation, climb-out and landing on its 15-minute first flight.
A number of flights took place last year, of up to one hour each and at a variety of altitudes and speeds.
Costing £185 million and funded jointly by government and industry, the Taranis demonstrator aircraft was formally unveiled in July 2010.
Only a limited number of scientists and engineers have been given full access to the top secret aircraft.
The unmanned air system, under the control of a human operator, can undertake sustained surveillance, mark targets, gather intelligence, deter adversaries and carry out strikes in hostile territory.
NOW WATCH: Briefing videos
Business Insider Emails & Alerts
Site highlights each day to your inbox.