Unmanned aerial systems (UAS) fill a gap in high-resolution observations of meteorological parameters on small scales in the atmospheric boundary layer (ABL). Especially in the remote polar areas, there is a strong need for such detailed observations with different research foci. In this study, three systems are presented which have been adapted to the particular needs for operating in harsh polar environments: The fixed-wing aircraft M ${}^2$ AV with a mass of 6 kg, the quadrocopter ALICE with a mass of 19 kg, and the fixed-wing aircraft ALADINA with a mass of almost 25 kg. For all three systems, their particular modifications for polar operations are documented, in particular the insulation and heating requirements for low temperatures. Each system has completed meteorological observations under challenging conditions, including take-off and landing on the ice surface, low temperatures (down to −28 ${}^{\circ }$ C), icing, and, for the quadrocopter, under the impact of the rotor downwash. The influence on the measured parameters is addressed here in the form of numerical simulations and spectral data analysis. Furthermore, results from several case studies are discussed: With the M ${}^2$ AV, low-level flights above leads in Antarctic sea ice were performed to study the impact of areas of open water within ice surfaces on the ABL, and a comparison with simulations was performed. ALICE was used to study the small-scale structure and short-term variability of the ABL during a cruise of RV Polarstern to the 79 ${}^{\circ }$ N glacier in Greenland. With ALADINA, aerosol measurements of different size classes were performed in Ny-Ålesund, Svalbard, in highly complex terrain. In particular, very small, freshly formed particles are difficult to monitor and require the active control of temperature inside the instruments. The main aim of the article is to demonstrate the potential of UAS for ABL studies in polar environments, and to provide practical advice for future research activities with similar systems.

Laminar flow offers significant potential for increasing the energy-efficiency of future transport aircraft. The German Cluster of Excellence SE²A is developing a new approach for hybrid laminar flow control. The concept aims to maintain laminar flow up to 80% of the chord length by integrating suction panels at the rear part of the wing, which consist of a thin suction skin and a supporting core structure. This study examines effects of various suction panel configurations on wing mass and load transfer for an all-electric short-range aircraft. Suction panel material, as well as thickness and relative density of the suction panel core are modified in meaningful boundaries. Suction panels made from Ti6Al4V offer the most robust design resulting in a significant increase in wing mass. For the studied configurations, they represent up to 33.8% of the mass of the wingbox. In contrast, panels made from Nylon11CF or PU1000 do not significantly increase the wing mass. However, the use of these materials raises questions about their robustness under operational conditions. The results demonstrate that the choice of material strongly influences the load path within the wing structure. Ti6Al4V suction panels provide sufficient mechanical properties to significantly contribute to load transfer and buckling stiffness. Locally, the share of load transfer attributed to the suction panel exceeds 50%. In contrast, compliant materials such as Nylon11CF or PU1000 are inherently decoupled from load transfer. Unlike the thickness of the suction skin, the relative density of the core structure strongly affects the wrinkling stiffness. However, wrinkling failure did not appear critical for the examined suction panel configurations. In the present study, the mechanical properties of Ti6Al4V cannot fully be exploited. Therefore, compliant suction panels made from Nylon11CF are preferred in order to achieve a lightweight solution, provided that they meet operational requirements.

Previous research shows that thin-ply composite materials offer superior static and fatigue characteristics to standard laminates used in aviation. Therefore, they are expected to be capable of significantly contributing to a mass reduction needed to improve the energy-efficiency of future aircraft. However, so far, thin-ply composites have only been employed in special applications. Quantitative full-scale assessments of the benefits on the level of global aircraft structures are missing. This study employs a parametric, finite element-based tool chain with a fully-stressed design methodology to investigate potential benefits from the use of thin plies, which may result from increased strength, an extended design freedom and stability considerations, in a generic wing structure of a conceptual medium-range aircraft in order to reduce this research gap. The methodology is validated using an academic test case. Naturally, mass reductions from strength enhancements are limited by buckling constraints in thin-walled structures. However, for the wing examined in this study, an increase in strength of 10% still yields up to a 7.9% reduction in global wing mass, while an increase of 20% results in mass savings of up to 13.4%. The use of thin-ply composites may allow for reducing minimum wall thickness constraints. Associated mass savings of up to 3.1% found in this study on global wing level when alleviating the requirement from 2.4 $\mathrm{m}$$\mathrm{m}$ to 1.2 $\mathrm{m}$$\mathrm{m}$ are, however, restricted to rib mass and may better be achieved by different means such as topology optimisation. In contrast, mass penalties from the application of a simplified manufacturing constraint are reduced significantly from beyond 10% on global wing level for plies with a thickness of 0.175 $\mathrm{m}$$\mathrm{m}$ to approximately 1.5% with a ply thickness of 0.05 $\mathrm{m}$$\mathrm{m}$.