Development of Chemical Reaction Airbag Safety System for Multi-Rotor UAV to Mitigate Free-Fall Collision Impact

Significant advances in UAV subsystems, including flight control, communication, propulsion, and onboard energy storage, have accelerated interest in commercial UAV operations within civilian airspace. However, widespread deployment remains limited by unresolved safety concerns, particularly the risk posed by uncontrolled descent following in-flight failures. In such events, free-fall impact can result in severe damage to personnel and property underneath. This paper proposes a novel UAV safety system based on an autonomous chemically-inflated airbag designed to deploy during a rapid descent and attenuate impact forces. While prior UAV airbag systems have relied on compressed-gas canisters, the proposed chemically-actuated approach enables faster deployment and reduces volumetric integration requirements. Experimental testing demonstrates a reduction in impact force from 4638.8 N to 1562.76 N (approximately 66%), with airbag inflation occurring within a fraction of a second. Additionally, the added mass of the safety system remains within the payload capacity of the selected UAV platform. These results indicate that chemically-inflated airbag systems offer a promising solution for improving UAV safety and facilitating scalable civilian deployment.