Airbus Defence & Space has begun flight testing a scaled model of a larger twin-tailed variant of its Zephyr high-altitude pseudo satellite (HAPS).

The Zephyr T has four times the payload capacity of the current Zephyr 8 at 20kg (44lb), which has been developed as a result of customer requirements for the HAPS to be able to carry a radar.

Three flight tests of the quarter-sized Zephyr T have been carried out to date, the first of which was in January. More flight testing is now expected, Airbus says, ahead of a full-scale build and first flight of the type in 2018. It is then expected to be operational in 2019.

Paul Brooks, Zephyr lead at Airbus, told Flightglobal at the AUVSI Xponential conference in New Orleans on 2 May that the larger design was always in the developmental roadmap, and having proven the design of the Zephyr 8, the company is developing the T version in parallel.

However, Brooks adds that the current priority of the Airbus is to fulfil its contract with the UK Ministry of Defence for the two Zephyr 8 aircraft that it ordered under a £13 million deal in February. The Zephyr T will be built when the MoD has received its ordered aircraft.

Artist's impression of Zephyr T and Zephyr S flyin

An artist's impression of the Zephyr T and Zephyr S (previously called Zephyr 8) flying in formation

Airbus Defence & Space

He adds that the UK contract also contains options for one more aircraft, and this could be provided from two extra aircraft that the company is building for itself in parallel to the two for the MoD.

Airbus is referring to the Zephyr 8 as the Zephyr S, for single-tail, and Brooks says that by having the S and T offerings, it will cover all potential customer requirements.

Three months of testing from an undisclosed location is being planned by the MoD to take place in 2017, which will allow it to assess the benefits of operating the HAPS for battlefield surveillance.