SHEDDING pounds isn’t just a preoccupation of dieters, it is a prime concern for aircraft builders too. In a bid to cut weight to the minimum they are considering the controversial move of getting rid of the huge quantity of copper wiring used in modern planes and replacing it with a series of wireless networks.
Users of Wi-Fi may be forgiven for wondering if this is wise. Reliability is not one of the defining characteristics of existing wireless networks, so employing them to operate a plane’s flight systems might seem a little risky. But if they can be made robust, such “fly-by-wireless” networks have the potential to improve reliability and possibly even make flying a little less environmentally damaging.
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Though fly-by-wireless is the ultimate aim, the first step along the way is likely to be the introduction of wireless sensors. Aircraft are already fitted with numerous sensors that provide information about the plane’s performance, such as how efficiently engines are operating. Data from the sensors can also be recorded and used to alert maintenance crews on the ground to any abnormal events.
The principal motivation for getting rid of the copper cabling that is now used to collect data from these monitors comes down to weight, “which on aircraft comes at a premium”, says Mark Begbie, director of the Institute for System Level Integration, a collaboration of engineers at UK universities in Edinburgh, Glasgow and Lancaster.
As the complexity of aircraft and their engines has grown, so too has the amount of wiring needed to monitor, maintain and control them. The trend is towards increasing the number of sensors in aircraft in order to improve the ways they are maintained, Begbie says (see “Economical by design”).
This presents a challenge: how to prevent this ever increasing complexity from making aircraft heavier. Modern airliners already have several kilometres of wiring, says Myles Taylor at GE Aviation Systems, a maker of aircraft infrastructure in Bishop’s Cleeve, Gloucestershire, in the UK. If you can replace this with a wireless system, you not only considerably reduce the weight of the aircraft and the amount of fuel it uses, but also make it easier to build and maintain.
The ability to mount sensors on many more parts of the airframe and engines could lead to design improvements in future aircraft that will cut their weight by as much as 15 per cent, says Roger Hazelden of British engineering consultants TRW Conekt. That could equate to a 12 per cent reduction in fuel consumption. Operating the plane wirelessly should cut the weight even further.
“Data from wireless sensors will lead to designs that are up to 15 per cent lighter than existing planes”
Any wireless network built into aircraft will have to be resistant to interference, not least from passengers’ Wi-Fi devices and cellphones, and environmental effects such as lightning strikes. It will also have to contend with the possibility of a deliberate attack by hackers.
This should not pose insuperable problems, according to , director of the Centre for Software Reliability, at Newcastle University in the UK. He says similar concerns were raised when plane-makers started to replace mechanical flight controls with digital “fly-by-wire” control systems, but proved unfounded.
Peter Mellor, formerly a researcher at the Centre for Software Reliability at City University in London, points to an as yet unsolved problem that could affect even the most interference and hacking-resistant wireless network. A strong radio signal could be used to jam the network by swamping its wireless communications, Mellor says. “You would effectively have a denial of service attack, which would be a very unfortunate thing to have on an aircraft.”
We should not let the poor design of existing wireless networks put us off, Anderson says. Wireless doesn’t have to be any less secure than wired networks, and is immune to some of the problems that can befall cabling, such as broken connections or short circuits.
Before any wireless system is implemented it will have to meet rigorous criteria set by bodies like the International Civil Aviation Organization. A working group of the International Telecommunications Union is currently examining the prospects for wireless avionics systems.
Economical by design
Aircraft are currently maintained according to a strict schedule based on how long their various components are expected to operate. That could change if planes can be fitted with sensors that continuously monitor the components’ health, allowing planes to keep flying until they actually need attention.
“If the airframe has had an easy life it may not need to come in for maintenance,” says Mark Begbie, director of the Institute for System Level Integration (ISLI), a UK-based consortium of universities. “If it’s had a particularly hard landing you may want it to come in sooner.” The hope is that this sort of “prognostic” approach will make it possible to anticipate failures well before they occur.
Data from wireless strain gauges embedded in the airframe and other components can also be used to improve the design of future aircraft, says Roger Hazelden of British engineering consultants TRW Conekt in Solihull, West Midlands. To this end TRW Conekt is joining forces with ISLI, and aerospace companies GE Aviation Systems, Rolls-Royce and BAE Systems in a ÂŁ3.4 million three-year project to develop a wireless monitoring system called Wireless Technologies for Novel Enhancement of Systems and Structures Serviceability, or Witness.
The Witness project’s initial aim is to develop wireless systems that can monitor engines while they are under development, and to provide in-flight structural monitoring and eventually a system for monitoring the rotors on helicopters. The project is part-funded by the UK government-funded Technology Strategy Board.
