The notion of electric flight has much appeal, and as a general aviation publication we have enthusiastically reported on the progress of both engines and batteries.
The capability of electric flight has advanced rapidly, from underpowered motor gliders, where all the engine was required to do was move the wing sedately through the sky, to an Extra aerobatic aircraft with a 300-hp electric motor. And let’s not forget that the all-electric Solar Impulse aircraft has flown around the world – using solar power.
However, general aviation’s fond hopes of practical, and above all safe, electric flight had a major setback after a fatal accident at the end of May in Hungary. One of the leaders in the drive towards a practical electric plane, the eFusion, crashed near Budapest, killing the pilot and passenger. The eFusion is powered by a Siemens motor and battery set, and Siemens’ electric flight efforts garnered public attention after their first version of the electric plane achieved a top speed of 340 km/h.
Initial indications are that the cause of the crash appears to be that old demon of electric cars – and Boeing 787s – namely fire. Witnesses on the ground reported seeing the aircraft catch fire and then crash in a near vertical dive. Siemens was testing its latest high-power electric motors and high-energy density batteries in the aircraft. This size electric motor has immense appeal for general aviation as it has a power output of 260 kW (340 hp) and a weight of just 50 kg (110 lbs). To compensate for the light weight of the motor, it was mounted directly in front of a large ‘fuel tank’ of li-ion batteries.
The challenges of electric planes lie in harnessing the massive current flows, both into and out of the battery banks. They need sophisticated rectifiers, voltage and current regulators and back-ups, plus very tight temperature control, if we are not to see a terrifying series of inflight battery fires which will make cell phone battery fires look tame.
It’s early days in the investigation, but if the plane indeed caught fire in the air, the batteries will certainly be a major suspect as it was anticipated that this would be the reason that electric planes would face an uphill battle in being accepted. The sporadic crashes of Tesla cars also shows how vulnerable they are to fire, since a number burned fiercely after their battery packs were damaged in a collision. However, it’s worth noting that this was an aerobatic aircraft where fatal crashes are a higher risk.
Meanwhile, Airbus is continuing development of its own electric prototype, called the E-Fan, which after a controversially close race became the first electric aircraft to fly across the English Channel in 2015.
There will be electric planes in our future – just not as soon as we might have hoped.