Flying blind at Mach 1: how China is bringing world’s first supersonic rail to life
Peer-reviewed paper sheds light on Chinese research team’s sonic breakthrough, achieved by ‘listening’ to system’s power supply
A rail system that accelerates heavy objects faster than the speed of sound using pure electromagnetic force has been operating in the eastern Chinese city of Jinan for more than two years.
But one of the biggest mysteries remains: how does it stay in control?
The sonic boom the system generates at ground level could blind or wreck traditional sensors, while the slightest miscalculation due to missing data could mean disaster at supersonic speeds.
The system, known as the electromagnetic sledge, made headlines in 2023 when it became the first large-scale electromagnetic launcher to break the sound barrier, accelerating one-tonne test vehicles beyond Mach 1.
In a peer-reviewed paper published this month, Xu Fei and his colleagues at the Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology said the experience was like driving a car blindfolded at more than 1,200km/h (746mph).
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“When linear induction motors operate at supersonic speeds – around 340 metres (1,120 feet) per second – at altitudes below 100 metres and temperatures below 30 degrees Celsius (86 Fahrenheit), unsteady aerodynamic forces caused by shock waves can create severe disturbances to the mover,” they wrote.