The UK Ministry of Defence (MoD) has exercised its option to purchase a third Airbus Defence & Space Zephyr high-altitude pseudo-satellite, which will be acquired under the £13 million ($16.9 million) contract covering the first two examples that was signed in February.

Delivery of all three single-tailed Zephyr S variants is due in 2017.

Zephyr is being purchased under an Operational Concept Demonstrator (OCD) effort, and will result in an MoD assessment of the surveillance system next year. Opting to acquire the extra airframe will allow the UK government to test two Zephyrs simultaneously, the MoD says.

“Zephyr is a cutting-edge, record-breaking piece of kit that will be capable of gathering constant, reliable information over vast geographical areas at a much greater level of detail than ever before,” defence secretary Michael Fallon says.

“They are part of our plan for stronger and better defence, backed by a budget that will rise each year of this decade.”

Artist's impression of Zephyr T and Zephyr S flyin

Airbus Defence and Space

Zephyr can operate for weeks at a time at an altitude of some 65,000ft. It is designed for persistent surveillance and communications relay applications, but the exact envelope covered by the UK trials has not been disclosed.

In May this year, the company revealed that a larger, twin-tailed version of the aircraft – the Zephyr T – was in development, and that a scaled-down model had begun flight trials.

Development of the larger variant, which will have four times the payload capacity in order to be able to carry a radar, is occuring in parallel with the construction of the first three Zephyr S – but production of a full-scale T-model and subsequent first flight are not expected until 2018.