Study: Drone collisions pose significant threat to helicopters

A British study has found that drones and helicopters colliding with each other can cause significant damage. The windscreens of the cockpit of helicopters are often not or not well resistant to a collision with a drone.

The aim of the study was to determine the consequences of an air collision between a drone and a helicopter or aircraft. Specifically, we looked at the minimum speed of various types of aircraft at which a collision would lead to critical damage to components. Critical damage was defined in the investigation as major structural damage to an aircraft component or the shattering of a cockpit windscreen.

The study found that helicopter windscreens that are not certified to withstand impacts with birds have only very limited resistance to a collision with a drone even at very low cruising speeds. This finding also applies to other types of aircraft with windscreens that are not certified.

Cockpit windows that are certified to withstand a bird impact are more resistant to impact, but these windows also prove fragile and could sustain critical damage in a collision at normal cruising speeds. The rotor blades of a helicopter’s tail rotor also prove to be a concern: they are very vulnerable during a collision. In general, drone components can cause significantly more damage than birds of comparable mass; this damage from drones can already occur at speeds that would not yet cause problems in the event of a collision with a bird.

The windows on regular passenger aircraft turn out to be much stronger. According to the investigation, there is no risk of critical damage to the windscreens during a collision with a drone weighing approximately 1.2 kg, even if the collision occurs during a high-speed flight phase. However, there appears to be a risk of critical damage to the windows if a drone of about 4 kg is collided with a drone of about 4 kg during the same high speed.

The weight of drones therefore plays a role, but the construction of the drone in question and the materials used are just as important. The research claims that components from drones in a weight class of about 400 grams, including metal motors, can already lead to a broken windshield of a helicopter during a collision at a lower speed. This was not the case, for example, with components from 1.2 kg drones, where the motors were covered with a plastic cover.

The research was conducted by Qinetic, a privatized British defense equipment manufacturer, and Natural Impacts, a research firm that specializes in testing the impact of projectiles or vehicles on materials. The two companies carried out the study on behalf of the UK Department of Transport, the UK Military Aviation Authority and the UK Pilots Association. The findings stem from computer modeling and staged gas cannon collisions conducted in the lab.

The findings of the study have been criticized by drone manufacturers. They point out, among other things, the limitation in the method used. For example, no real drone was used during the tests, because it did not fit in the gas cannon that was used to simulate collisions with a simulated cockpit. Instead, projectiles made up of drone parts were used. Based on the results of these tests, computer models have been made for further experiments.