Small and Lightweight Gas Measurement System for Unmanned Fixed-Wing Research Aircrafts

 

The ability to reduce CO2 and other gas emissions to meet global emission targets and air quality standards also requires measuring gas sources and sinks and gas transport mechanisms with the highest possible spatial and temporal resolution.

For a higher spatially resolution of gas distributions and concentrations in the sub-atmosphere unmanned aerial systems (UAS) can be used for in-situ measurements in conjunction with stationary ground measurements. In particular, the use of fixed-wing UAS due to their inability to flight longer times and ranges with only a minor disturbance to the measured volume compared to widely used multicopter UASs.

This study presents a lightweight, small, cost-effective nondispersive infrared CO2 gas sensor system for universal use on board fixed wing UASs. The gas sensor is integrated into an aerodynamic 3D-printed housing, so-called "EGG-Pod". This housing is designed as a gas measurement system that acts as a passive pump which maintains and measures a constant volumetric flow that feeds a gas measurement chamber during flight. This cost-effective approach can be transferred to other mobile platforms, especially due to its simple structure, and its scalability to fit other gas sensors. 

To characterize this measurement system, the nocturnal CO2 stratification effect was measured. The ground-level build-up effect of CO2 is caused by ground cooling in radiant and anticyclonic weather conditions. The resulting CO2 vertical gradient was used to define the resolution of the system. For this purpose, flight measurements were compared with the CO2 measurements from the ICOS-Tower (Integrated Carbon Observation System) near Lindenberg Meteorological Observatory - Richard Aßmann Observatory (German Weather Service DWD).