Taking a punt on a quite literally blue-skies technology is not for the faint-hearted. There are more unknowns than knowns, and opportunities to fail more readily present themselves than the promise of success. Such a venture means taking risks.
This is what Qinetiq did when it developed the Zephyr unmanned aerial vehicle, a solar-powered flight of fantasy that has broken records and won awards for the boldness of its engineering.
Chris Kelleher is chief designer of high-altitude endurance unmanned aerial vehicles at the defence firm. He believes that engineers don’t take enough risks and that promising technologies are sometimes left by the wayside as a result.
“What really worries me,” he says, “is how much technology fails to be developed because no one sees the value of it. There’s a huge aversion to risk. With the Zephyr, there was very significant risk until we built-up confidence in the design.
“But it’s been a hugely productive experience to employ new technology and make it work. We run the risk of becoming Luddites if we stick with the same aeroplanes and the same technology every time.”
The origins of the Zephyr, which smashed the world record for flight endurance in 2010, lie back in Qinetiq’s pre-privatisation history when it was the government’s Defence Evaluation and Research Agency. Kelleher says: “We were doing experimental work with satellites and sub-systems in about 2000. We were obviously familiar with the many military communications satellites that provide services all over the world. We asked ourselves whether there was a better way of doing that job.
“One of the concepts we were looking at was whether an aircraft could exist permanently in the stratosphere. But the technology simply wasn’t available, in terms of the power needed, for example.”
That concept began to be developed further, however. The powers that be planned to float Qinetiq on the stock market as part of its privatisation and wanted the fledgling defence company to make a big splash. As part of the celebrations, the idea was for Qinetiq to sponsor a manned altitude world-record attempt in a balloon. The aim was to soar to 132,000ft. But a problem arose. How would the record attempt be photographed for posterity at altitude?
Various solutions were mulled over, including launching a daughter balloon with equipment to capture the record attempt or using an inflatable arm. But the best option was thought to be a small, high-altitude aircraft that could carry cameras and video equipment. So work started on developing the Zephyr, alongside a rival concept that would have seen a rocket deployed to take pictures.
Kelleher says: “The aeroplane had to be very light and also able to function in extreme cold. It had to be very reliable. So this came back to the background of many members of the team. They’d worked on small experimental satellites. They were in touch with much of the best technology in the world – and they knew how to develop things we hadn’t got.”
The concept plane produced by the team of engineers at Qinetiq would have been tethered to the balloon, circling it in the manner of a toy aircraft pinned to the ceiling of a model shop. “It carried a broadcast video camera and a digital stills camera,” says Kelleher. “The intention was to feed pictures directly to the BBC from the aircraft, looking at the balloon throughout the high-altitude record attempt.”
That attempt, unfortunately, was abandoned. But something had been developed that the engineers thought warranted further attention. They had tested a half-scale version of the Zephyr in a vacuum chamber to simulate high altitudes, subjecting motors and actuators to extremes of heat and cold. Kelleher recalls: “The more we did, there seemed to be no show-stoppers. We began to realise that this could be very useful. The potential was to develop a persistent geo-stationary stratospheric platform for services such as communications for the future: this was a wonderful opportunity to demonstrate that we could do it.”
The next step was to build a prototype aircraft with a 40ft wingspan, weighing in at just over 14kg, and carrying cameras. Although the balloon attempt was scuppered when its envelope tore during inflation, the development of the aircraft had piqued the interest of the Ministry of Defence, which put some funding into it, leading to the design and build of a series of Zephyr craft.
Zephyr 7, which broke the absolute flight endurance record with a time of 14 days, 22 minutes and eight seconds in 2010, weighed in at 50kg. It has a 22m wingspan and soared in excess of 70,000ft during the record flight. That took place over Arizona, and included one of a number of highly capable lightweight payloads developed specifically for Zephyr.
The Zephyr 7 has a series of solar arrays that feed electricity to two highly-efficient brushless motors which drive the propellers. The craft has lithium-sulphur batteries. Kelleher says: “That was an example of where we’ve taken the best in the world in terms of power storage, which is lithium-sulphur. We are the first application in the world to employ that technology, and it’s in an aeroplane.” The record-breaking flight was also a chance to prove the Zephyr’s structure, and to successfully test an MoD payload.
“One of the big breakthroughs we’ve had is to get extremely low drag through the aircraft and a very light structural weight,” he says. The fuselage is made of carbon fibre.
Kelleher points out: “We used a very thin structure, very light, but the aircraft is capable of withstanding 5G. So it’s not actually fragile. It is to handle on the ground, but once it’s in flight it’s absolutely in its element.”
The MoD continues to be interested in the potential of the Zephyr, and the US Department of Defense also recognises its possibilities. Further payload tests are planned, as is the development of larger craft that can stay at altitude for even longer – the next target is three months.
Kelleher says: “It flies higher, longer and more stably than any operational aircraft. So that provides an excellent platform for earth observation or surveillance.” At 65,000ft, the Zephyr could “see” 500km in any direction, covering, for example, a country like the UK for either communications or surveillance. The craft also boasts considerable green credentials – its batteries, for instance, are likely to be more charged at the end of the flight than at the beginning.
“It doesn’t completely replace satellites or stratospheric systems but in many things it could be more cost-effective and better than the alternatives,” says Kelleher. The most recent plaudit to come Zephyr’s way has been recognition of its design in an award by the Institution of Engineering and Technology.
“I’m clearly delighted for our team that we’re getting recognition for a system that I think will be of great value in the future, to society in general and also to the UK economy.
“For Qinetiq engineers it’s well worth developing these new technologies to do things better for the future. It’s one of the ways we do things: developing what others would consider high-risk technologies.” Balloon attempt notwithstanding, it looks like the Zephyr is a risk that has paid off.