The engineers behind the UK’s experimental new combat drone, Taranis, have given a glimpse of how it can become ‘virtually invisible to radar’.
Project leader BAE Systems yesterday described how a second phase of flight-testing earlier this year showed the aircraft could maintain communications and gather a full set of flight data without giving away its position to potential enemies.
At a briefing at the Farnborough Airshow yesterday, July 15 BAE also confirmed the knowledge gained from the Taranis project would feed into a new £120m UK-France feasibility study into unmanned combat aircraft.
The £185m Taranis, said to be about the size of the 10m-wingspan BAE Hawk training aircraft, has already demonstrated its ability to autonomously plan and execute flight paths for the duration of a mission, although the decision of which routes and actions to take still resides with a human operator on the ground.
In what was described as a ‘major technological breakthrough’, BAE and its partners were able to redesign Taranis’s antennas and external sensors to make the craft less detectable by radar. Its exhaust and engine were also designed to minimise any infrared heat signature.
‘If you’re making an LO [low-observability] aircraft you’ve got to think about the number of features that radar returns,’ said BAE’s Chris Garside, engineering director for future combat air systems. ‘You don’t want any sharp corners or shapes that radar reflections can be returned from.’
The Taranis team developed a ‘conformal air data system’ of sensors that can gather critical flight information such as the craft’s altitude, attitude and angle of attack without the need for an external boom or probe on its nose (although BAE was unable to reveal how it had done this).
The craft’s antennas were also replaced with less visible ‘signature control variants’ to further reduce its radar profile, and a suite a software upgrades were introduced to operate these new sensor and communication systems.
Conrad Banks, chief engineer for research and technology at Rolls-Royce, explained how the craft’s Adour 951 turbofan engines – variants of which are used in training aircraft such as the BAE Hawk – also had to be prevented from producing a trackable radar or heat signature.
‘The challenge for us is not about the engine; it’s about the integration and it’s about the LO exhaust system,’ he said. ‘We have to fully embed and hide the gas turbine within the heart of the aircraft. That is essential to minimise the radar cross-section.’
This had to be done in a way that managed the resulting unusual airflow and aerodynamics through the propulsion system to prevent any engine surge and preserve its performance.
The engine also had to be highly thermally insulated and include a large number of internal sensors to monitor its performance because of the difficulty of removing it for inspection and maintenance.
The majority of Rolls-Royce’s time, however, was spent on reducing the IR and radar signature of the exhaust. Banks revealed that measures for this included a thin rectangular-shaped port that would disperse exhaust gas very rapidly and at an angle that matched the trailing edges of the aircraft, as well as advanced internal geometry and cooling systems.
Although Banks couldn’t discuss manufacturing for the craft in detail, he said a lot of work was done on titanium processing.
The second-phase flight trials, which took place at an undisclosed location (although some unconfirmed press reports have pointed to Woomera in the Australian desert), were deemed a complete success.
The craft is now undergoing maintenance and the Taranis consortium is negotiating with the Ministry of Defence for funding for further trials, said Garside.
Yesterday, the UK and France announced a two-year study of how the technology behind Taranis and the French equivalent programme Neuron could be put to use in future autonomous combat systems – effectively enabling the countries to compete with the US and other combat drone producers.
The study will see BAE team up with fellow fighter plane builder Dassault, Rolls-Royce and Safran engine subsidiary Snecma, and electronics firms Selex and Thales.