Advances in avionics

By Martin Keenan   |   March 24, 2021

The global pandemic of 2020 has upended expectations about growth in the aerospace industry and therefore demand for the avionics equipment that enables it. 

What was, according to a report from consultants Deloitte, already a down year for commercial aircraft deliveries in 2019, has been exacerbated by general uncertainty about travel caused by the 2020 pandemic. It is not clear whether old travel patterns will resume once the crisis is over, or whether our habits and expectations will have been so completely remade that it demands a rethink of the whole aerospace sector.

What does seem likely, though, is that the current uncertainty will accelerate the pace of change and create mid-term opportunities to innovate in support of a renewed aerospace industry. Electronics engineers will be at the heart of such innovation, building the avionics systems that will enable the reconfigured industry to survive and thrive.
 

Mid-term opportunities

Electric vehicles are just reaching the point at which they are regarded as a credible alternative to petrol or diesel cars. While this evolution has been underway, some aerospace propulsion companies, including Rolls-Royce, have been developing electric powertrains for aircraft, to reduce the carbon footprint, noise and cost of air travel. The Rolls-Royce ‘Spirit of Innovation’ demonstrator, pictured below left, has been built to challenge for the title of the world’s fastest electric aircraft. The company claims it could fly from London to Paris on the charge held in its 6000-cell battery pack.

The uptake of electric propulsion in aircraft will create demand for sophisticated new control systems, which use the learning that emerged from the rise of electric vehicles to create advanced control systems and powertrains focused on efficiency.

For example, the avionics of the Rolls-Royce plane include the engine control unit, power distribution unit, and flight sensors. The company says it will collect in-flight information, such as battery voltage, temperature and other performance metrics, at more than 20,000 points a second on the powertrain.

Experience with electric cars may have taught us that, at first, electric propulsion systems will work best for short journeys, given the energy storage challenges of today’s battery technology. However, this apparent limitation could dovetail well with emerging plans for ‘urban air mobility ecosystems’, which might be better thought of as flying taxis for use in cities.

As the Deloitte report argues, it’s going to take a lot of work to create the infrastructure and ecosystem necessary to enable urban air mobility. There will be the challenges of regulating pilotless vehicles, certifying their airworthiness and controlling the way they use airspace. There will be substantial avionics challenges as well. The vehicles will need to be extremely energy efficient, and have multiple sensors and rich data fusion capabilities to enable effective collision avoidance systems. There will also be a lot of work to be done to create the supporting infrastructure, such as upgraded air traffic control management systems that work flawlessly all the time, which will encourage and sustain consumer demand.

Although this may sound like science fiction, in November 2020 the city of Orlando, Florida, and Lilium, a German aviation company, announced plans to build a ‘vertiport’ in the city by 2025. The vertiport will be home to a fleet of vertical-take-off, electrically powered aircraft that will be used as air taxis to help the city’s wealthiest passengers avoid the pain of ground-based gridlock. Lilium’s development aircraft uses 36 electric motors, mounted in the wings, to provide directed thrust. The company argues that this allows its design to do away with many of the control surfaces, and the associated gearboxes and lubrication circuits, of conventional aircraft. This should increase the vehicle’s reliability while reducing its weight and the maintenance overhead.

Lilium's vertiport in Orlando, Florida (Source: Lilium)

Lilium isn’t alone in its ambition to build an electric vertical take-off and landing craft. Japanese company SkyDrive said in August 2020 that it had completed a four-minute test flight in its SD-03 test vehicle, which uses eight propellers, two at each corner of the roughly rectangular vehicle, to provide lift. The company also said it had received Yen3.9bn (€31.5 million) in funding from the Development Bank of Japan and other investors to continue its work.

Other avionics opportunities may emerge from moves to increase the amount of automation used on flight decks, which will demand more computing power. In the cabin, too, rising passenger expectations will prompt the installation of much more complex seatback entertainment and communication systems, creating demand for more computing power, better graphics, seat to seat networking, onboard Wi-Fi and air to ground connectivity. The challenge here is to create such powerful systems, and the wiring infrastructure to power, connect and manage them, while minimising their mass and power consumption.

The avionics of unmanned aerial vehicles, such as inspection drones or unmanned cargo aircraft, will undergo almost continuous updates. You can see this trend at work in the consumer and semi-professional drones offered by companies such as DJI. The control software for its drones is constantly being updated to improve features such as the stability of the platform in flight for photography, or its ability to track a moving subject, such as a skier, in order to film them in motion.

Interestingly, the intense development pressure brought to bear by competing in a consumer market such as drones is likely to prompt innovations that will, in turn, be fed back into the company’s professional ranges. After all, nothing will test a piece of equipment quite as harshly as handing it over to a YouTuber for the weekend. It may also provide the insight necessary to make informed decisions about whether avionics equipment always needs to use the most highly rated componentry, or whether Commercial Off-The-Shelf (COTS) parts will be good enough in many use cases.
 

Technical challenges and responses

As in the space and defence sectors, future avionics systems will be making much greater use of sensor data to increase their situational awareness and ability to make accurate decisions quickly. This will mean that developers will have to think more carefully about how they connect to these sensors, the bandwidth of the interconnect schemes they specify, and the physical ruggedness of their implementation. This could see a shift to the use of two-wire Ethernet implementations, fibre-optic systems, and denser/lighter traditional interconnect strategies.

Avionics developers will also need to think about how to provide the computing power necessary to capture, fuse and interpret this data, which may lead to an exploration of alternate computing architectures such as machine-learning coprocessors, 
to handle pattern recognition tasks efficiently and at low energy cost.

In the powertrain, especially for electric flight vehicles, the emphasis will be on making the absolute most of the energy stored in the battery pack. This will  lead to an emphasis on maximising the efficiency with which power can be converted and distributed to the motors and other systems that use it. Rolls-Royce is exploring these issues with its Magnus eFusion two-seater training aircraft, a testbed for sub100kW electric propulsion systems.  The first iteration of the powertrain had a 45kW electric motor, but after a  series of upgrades it has a continuous power output of 70kW. The motor and its associated inverter have now been registered by Rolls-Royce for certification.

There will also be a strong focus on minimising the mass of everything in the aircraft, to compensate for the relatively low energy/mass ratio of batteries when compared to fossil fuels. Some of this will be achieved by taking learnings from the development of e-vehicle powertrains, which are evolving very rapidly at the moment, and then carrying across the relevant architectural and component choices for use in avionics. 

For example, Molex makes cable assemblies, such as the OTS Multicat, that can provide dense power distribution with high reliability.

And, as in almost all other avionics designs, there will be continuing pressure to minimise factors such as equipment size, energy consumption, and cooling requirements, within the envelope of traditional avionics design concerns such as reliability, operating lifetimes, and robustness. 

Even the specifications of a humble potentiometer have to be carefully considered if it is going to be used as part of a human machine interface for an avionics system, like the PDF241 long-life part from Bourns. It is specified to last for one million rotations and also meets standards that enable it to be used in medical lab equipment and medical diagnostics systems.

Molex's Multicat OTS cable assemblies (left) and Bourns' PDF241 potentiometers (right)

Avionics is at the heart of the aerospace industry and is the key enabler of the innovations that are likely to follow from the current restructuring of the industry. It will be down to electronics engineers to make the complex design trade-offs necessary to create these innovative avionics systems which, in turn, will help provide a route back to a thriving aerospace industry.

Are you working on a related design and in need of advice and support? Get in touch with our technical specialists to discuss your requirements. Alternatively, find out more about our solutions for aerospace and defence, and explore our knowledge library.

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Martin Keenan

As Technical Director, Martin is responsible for technical marketing strategy across IP&E, power and...

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