Feature: Avionics


flights is not likely. A more realistic solution is to reduce each airplane’s fuel consumption, which will also reduce the amount of greenhouse gases released. Airlines are already taking action to reduce


their fleets’ fuel consumption, cutting weight wherever possible through various measures – by using advanced materials, thinner seats, providing pilots with tablets instead of large and heavy paper manuals, and even giving passengers fewer ice cubes for their drinks. Motors also play an important role in


reducing aircraſt weight – there are many of them on board, so reducing their weight will also reduce fuel consumption.


Electronic fuel injection It’s not just commercial airlines that contribute to the emissions problem in the aviation industry. Currently, 15% of aviation emissions come from non-passenger aircraſt. While these aeroplanes don’t have motors in luxury features, motors may still play a role in reducing their fuel consumption. Unmanned aerial vehicles (UAVs) are


smaller aircraſt used as vital transport methods for the military, emergency services and, increasingly, industry and agriculture for reconnaissance and measurement. To achieve extended flight time using minimal fuel quantities, these aircraſt require reliable propulsion systems. Previously, a carburettor was the only way


of delivering fuel to a UAV engine, providing the right combustible mix of fuel and air. However, the carburettor is unable to provide an optimum mix of fuel for all the various phases of flight – the ideal mix at sea level is too rich at altitude, yet the optimum mix at altitude is too weak on the ground. Tis compromise leads to reduced performance and increased fuel consumption. Smaller aircraſt manufacturers are


UAVs contain many DC motors on board


On-board luxury requires many motorised features


increasingly turning to electronic fuel injection (EFI), which works by injecting fuel, under pressure in the system, into the intake manifold using special injectors, with the fuel-to-air ratio controlled by an ECU (electronic control unit). Sensors in the engine’s intake and exhaust system supply data to the ECU, where it is assessed and the ideal amount of fuel required at a particular moment is calculated. For fuel to burn properly, the right mix


of fuel and air is essential, so the sensors also help the system fine-tune the mixture for the load and conditions at each precise moment of the flight. Te high pressure of EFI means the amount injected is continuously electronically calculated, even at high altitudes, based on data such as temperature, air pressure and required performance. Because the pressure creates an extremely fine vaporisation of fuel, it ensures a consistent mix of fuel and air. As a result, using an injection system can reduce fuel consumption by up to 30%. When designing an injection system


for a small aircraſt, everything needs to be minimised. Te compact system consists of many components, including the injector, a fuel pump, ignition module and a fuel pressure accumulator. Tese mechanical components need to weigh as little as possible to keep the aircraſt light.


Reliable motors A small, high-performance, low-weight DC motor can fit compactly into an EFI system to help deliver consistent fuel pressure. Te motor helps create the auxiliary energy required to build up the necessary pressure, which powers the fuel pump to deliver fuel and air into the system. In EFI, motors must be able to work


tirelessly, with low rotor inertia for fast and reliable acceleration and braking. EMS is the sole UK supplier of Faulhaber motors, which are characterised by their high power and low weight. Tey can be incorporated as part of this fuel system without contributing to unnecessary weight gain. Comfort and safety features can also


benefit from reliable motors. It is important that nothing fails or breaks during a flight, particularly where passenger and crew safety is concerned. Maintenance intervals should also be as long as possible. Faulhaber motors are made in a finely-controlled manufacturing process that ensures consistent high quality. As we take to the skies again, the aviation


industry must work to keep its emissions under control. Reducing weight and improving the efficiency of fuel consumption is essential.


www.electronicsworld.co.uk June 2022 17


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