INSUBCONTINENT EXCLUSIVE:
demonstrating the effectiveness of drone lightning resistance technology and lightning induction technology using electric field
fluctuations with actual lightning.In the future, this result is expected to contribute to research into the generation of lightning, which
has yet to be fully understood, and to the reduction of lightning damage to cities and people.
1
Background
Lightning is one of the natural phenomena that causes great damage to human society
facilities, lightning damage has not been eliminated even today, and the damage is estimated to be 100 to 200 billion yen per year in Japan
NTT aims to significantly develop the technology it has cultivated to protect communications facilities from lightning and to realize
technology that will eliminate lightning strikes on critical infrastructure and cities altogether.Conventional lightning countermeasures
have widely used methods that use lightning rods, but the range that lightning strikes is limited, and there are also cases where it is
difficult to install lightning rods, such as wind turbines for wind power generation and outdoor event venues
move drones according to the position of thunderclouds, actively induce lightning, and then guide them to a safe place.On this occasion, to
conducted a drone lightning induction experiment under an actual thundercloud.
2
Experimental Overview and Results
A lightning-triggering experiment using a drone was conducted at an altitude of 900m in the mountainous
area of ??Hamada City, Shimane Prefecture, from December 2024 to January 2025
In this experiment, a device called a field mill (*3) was used to observe the electric field on the ground, and when the electric field
strength in the vicinity increased due to the approach of thunderclouds, a drone equipped with a unique lightning-resistant cage was flown
to attempt to induce lightning (Figure 1).Figure 1 Lightning-resistant droneWhen the electric field strength observed by the field mill rose
when the thundercloud approached on December 13, 2024, the drone with the wire was flown to an altitude of 300 m, and a switch installed on
the ground was used to connect the drone to the ground (Figure 2)
As a result, it was confirmed that a large current flowed through the wire, and at the same time, the surrounding electric field strength
changed significantly (Figure 3)
Furthermore, it was confirmed that a voltage of more than 2000 V was generated between the wire and the ground just before the lightning was
induced, and lightning was induced in the drone by suddenly changing the electric field strength around the drone
This is the first successful lightning induction using a drone in the world.In addition, at the same time as the lightning was induced, a
On the other hand, it was confirmed that the drone equipped with the lightning-resistant cage continued to fly stably even after the
lightning was induced.Figure 2
Drone-triggered lightning experiment systemFigure 3
Waveforms observed when lightning was inducedFigure 4
Winch illumination when lightning strike3
Key Points of the Technology
In order to trigger lightning by drones, the drone must continue flying even when lightning strikes
Furthermore, since it is difficult to strike lightning by simply flying a drone under a thundercloud, it is necessary to actively induce
To achieve this, we proposed and demonstrated the following two technologies (1) and (2).(1) Lightning resistance technology for dronesWe
have devised a design method for a lightning-resistant cage that will not malfunction or break even if the drone is hit directly by
lightning, and that can be installed on drones in the city
The lightning-resistant cage is a metal shield that prevents the lightning current from flowing through the drone body by diverting the
large current that flows when the drone is hit directly by lightning
In addition, by making the lightning current flow radially, the strong magnetic fields generated by the large current cancel each other out,
reducing the magnetic field effect on the drone (Figure 5).Furthermore, we conducted an artificial lightning application test on a drone
equipped with a lightning-resistant cage
As a result, we confirmed that the cage covers more than 98% of natural lightning strikes, and that the drone will not malfunction or
malfunction even when artificial lightning of 150kA, which is five times the average value of natural lightning strikes, is applied.Figure 5
Lightning-resistant design for large currents and strong magnetic fields(2) Lightning triggering technology using electric field
fluctuationsTo induce lightning, we devised a method to connect a flying drone to the ground with a conductive wire, attach a high-voltage
switch to the ground side, and change the electric field strength around the drone by operating the switch
The switch connects the drone to the ground at the optimal timing, suddenly increasing the electric field strength around the drone, which
can help induce lightning (Figure 6).Figure 6 Principle of lightning induction technology using electric field fluctuations4
Future Developments
NTT aims to protect cities and people from lightning damage by flying drones that will not break down even if struck
directly by lightning to highly accurately predicted lightning locations, inducing lightning and guiding the drones to safe locations
In the future, we will continue to promote research and development into highly accurate lightning location predictions and the mechanisms
behind lightning generation in order to increase the success rate of drone-induced lightning as demonstrated in this study.Furthermore, we
will also work on research and development into methods for storing lightning energy, with the aim of storing and utilizing the energy of
induced lightning (see top image)[Terminology]*1 Institute of Electrical Engineers of Japan Technical Report No
