Zephyr and the development of high-altitude military surveillance drones

The Zephyr ‘High Altitude Pseudo Satellite’ drone

The Guardian reported recently that the Pentagon’s Southern Command are testing stratospheric balloons over the US, to combat drug trafficking and support homeland security. The news has caused concern among US civil liberties advocates angry that American citizens will be being monitored in these tests. However, these balloons are just one of a new type of unmanned aerial vehicle / drone called High-Altitude Pseudo-Satellites (HAPS).  This post takes a brief look at this type of drone, which is on the horizon for a number of armed forces, and examines the UK’s development of a HAPS drone called Zephyr.

What are HAPS?

HAPS are a type of drone that, at the moment, are configured in three different models; either an incredibly flimsy structure that is almost all wings, covered in solar panels; a helium-filled air-ship; or smaller ‘hot-air balloons.’ The latter is more likely to be used by commercial companies, whilst the other two by the military. These various shapes are said by their producers to combine the advantages of Medium-Altitude Long Endurance (MALE) drones with the advantages of satellites. For instance, the use of solar energy and light-weight batteries, which power the HAPS in darkness, mean they can stay airborne for much longer than MALE drones, but they are also manoeuvrable and can be brought down easily for maintenance or mission change, unlike a satellite. They can provide long term imaging and monitoring over a particular location for a longer period of time than either a satellite or a MALE drone, whilst (like other drones) provide imaging that is much clearer than satellite images. HAPS are designed to fly in the ‘low stratosphere’ – around 20km up, or 65,000 feet – above weather systems and air traffic.


The UK is developing a HAPS drone called Zephyr. Zephyr was originally designed and built by British defence firm QinetiQ but bought by Airbus in 2013. Airbus have developed two versions, the S and T models, with single and twin tails respectively, both designed for surveillance and communications. Zephyr-T is still under development but the Zephyr-S is undergoing flight tests in Australia and Airbus opened the first HAPS manufacturing plant in Farnborough in August 2018.

With an incredibly thin structure, the Zephyr-S has a wide wingspan of 25m but weighs only 75kg. It can carry what Airbus describes as “see, sense and connect” payloads. “See” refers to its high-resolution imaging payload, “sense” to its ability to know what else is in the stratosphere, and “connect” to communications payload. Airbus expects Zephyr to be used by a variety of customers, both institutional and commercial.

The Zephyr is of course very fragile and there are some concerns about its viability in the tech press. Due to its thin structure it is easily breakable, especially when being launched, as it must be run down an airstrip by a team of people placed along the length of its structure until it reaches take-off speed (see the video above). Lifting it by the wing tip or mid-section would cause parts would break off.  Once it’s in the air, the Zephyr has to reach low atmosphere (above 20km) where wind is much slower, to avoid it being knocked off course, or even breaking. Moreover, the launch must take place in perfect weather conditions and, so far, tests have been carried out in the deserts of Australia and the USA. Launching in the northern hemisphere in winter may raise a whole different set of problems, should that ever happen.

Airbus claim that each airframe will be able to stay aloft for over 100 days, and customers would have a fleet that provides a continuous presence in the air.  So far Zephyr holds the last two records for the longest non-refuelling flight. The first was in 2010 in Arizona. This was for 14 days (336h, 22 minutes and 8 seconds). Then in 2018, it again broke the record, flying continuously for 25 days, 23 hours, and 57 minutes after taking off from Arizona on July 11.

UK involvement

The MOD helped to fund QinetiQ’s development of the Zephyr, and committed to buying Zephyr air frames in their Strategic Defence and Security Review (SDSR) from 2015. This was part of a £6bn package to upgrade the RAF’s capabilities. The MOD have so far purchased three Zephyr-S types in a £13mn contract from Airbus, first ordering two, then a third in August 2016. Defence Secretary Michael Fallon said in a statement, “all three [UAVs] will form part of an Operational Concept Demonstrator (OCD) to assess Zephyr’s capabilities and explore its potential for use by the UK Armed Forces. The additional Zephyr-S will allow 2 airframes to be tested simultaneously and demonstrate operational handover to show that the capability could be sustained indefinitely.”


These models are now under construction at the plant in Farnborough, and the first made its way to Australia for flight testing early in 2019. Staff from the MoD’s Defence Equipment and Support (DES) department are in Australia to monitor trials and learn how Zephyr can best be integrated to support all parts of the British military.  However, the latest news on Zephyr is in fact that a crash occurred in March 2019.  It is thought that the HAPS struggled on the ascent in “severe adverse weather” conditions, was knocked off course and crash landed. However, neither Airbus nor the UK MoD or Australian authorities provided any further comments.

Airbus are also working on a ‘Network for the Sky’ (NFTS), which would allow militarises, and presumably other customers, to have a fully integrated, and therefore secure, high-speed, communications system. The tests done so far linked, radio, video, satellite and other communications in a real-time scenario that was secure from end-to-end.


Keenly aware of the public perception of drones, Airbus advertise the Zephyr for internet connectivity, monitoring disasters, changing landscapes and border security.  An MoD minister even went so far as to cite Zephyr as an example of how it is working clean energy (feeding in to the false narrative that there are viable military solutions to the climate crisis.) The reality, however is that,  as noted by the MoD in the  SDSR 2015 Zephyr gives increased surveillance capabilities. As Earl Howe said at the time, these UAVs would “allow us to observe our adversaries for weeks, providing critical intelligence for our forces.”   Former Defence Secretary Michale Fallon also stated in 2016, without elaboration, that “other government departments” (often code for the security services) would potentially make use of the technology while the Daily Mail suggested that they would be used by Special Forces.

Daily Mail’s view of the Zephyr drone

The attractiveness of HAPS drones for ongoing surveillance – cheaper and more manoeuvrable than a satellite coupled with the clarity of imaging that lower-flying drones give – means they are expected to grow in popularity. Whilst it is unknown what exactly the UK will use Zephyr for, it is clear that military uses in the UK and elsewhere will allow for increased surveillance through extended coverage of the earth’s surface as well as increased temporal coverage. The benign purposes outlined by companies like Airbus obscure the fact that HAPS drones like Zephyr are there to give a military advantage that serve to increase the use of force from the air when surveillance and data gathering increasingly define which targets to attack.

Who is else is developing HAPS drones?

Lockheed Martin: Lockheed Martin were a pioneer of this technology and their High Altitude Airship (HAA) demonstrator, HALE-D was one of the first HAAs to fly. However, this had to be brought down during tests in November 2011. Lockheed Martin’s website still promotes the HAA as a product but it is not clear at what stage the development is at.

Boeing: A subsidiary of Boeing, Aurora, has been working on a HAPS model called Odysseus that was scheduled to begin test flights in the second half of 2019. However, they have since delayed flight testing “indefinitely” stating that they want to give more time to exploring customer uses before finalising design and manufacture. The Odysseus is similar to the Zephyr in shape but has 3 tails.

BAE Systems: BAE Systems is also working on the development of a similar HAPS called the PHASA-35 HALE UAV, jointly with Prismatic, and it was due to begin test flights this year. BAE claim it will have the potential to stay airborne for up to a year.

Thales Alenia Space: a joint venture between Thales (67%) and Leonardo (33%), this has focused on developing airship models. The ‘Stratobus’ is under development and completed a design review in November 2018.

AVIC (China): Successfully tested their Morning Star UAV at a height of 20,000m. “With the development and first flight, in addition to a great number of ground, wind tunnel and scale model tests … a solid foundation has been laid for follow-up development,” AVIC said. “We will move quickly towards large-scale, heavy load and long endurance solar-powered UAVs.”

Tao Group: And in Germany the Tao Group are developing the Sky Dragon, which they call a High Altitude Platform, a “segmented airship” which can carry telecoms equipment. The website notes its long durability in comparison with competitors but doesn’t specify how long it can stay in the air.

Rosa Aero Systems: Russian company, Rosa Aero Systems, have an HAA under development, the Berkut, which they say can be taken anywhere with a portable and inflatable hangar.

Leave a Reply