A challenging issue associated with fixed-wing Unmanned Aerial Vehicles (UAVs) is that these vehicles are often not appropriate for operating effectively in limited airspace. This problem emerges especially in urban environment where the usage of a runway is not possible, and UAVs usually have to fly at a relatively low speed and altitude. The development of a vertical take-off and landing (VTOL) fixed-wing plane is a promising trend which hopefully will solve this issue. This paper presents the design process of an unmanned vertical take-off and landing aircraft including prototyping of the airframe construction and mathematical modeling as well as computational fluid dynamics (CFD) simulations. The designed system is to be a hybrid platform, for which different operating modes correspond to the vertical flight, transition, and spatial flight in the airframe system. The paper discusses an iterative design process of the platform with emphasis on CAD design and aerodynamic analysis for particular flight modes. The operating prototype is presented and future plans for platform improvement are discussed.

The application of polymers as a tool in the crystallization process is gaining more and more interest among the scientific community. According to Web of Science statistics the number of papers dealing with “Polymer induced crystallization” increased from 2 in 1990 to 436 in 2020, and for “Polymer controlled crystallization”—from 4 in 1990 to 344 in 2020. This is clear evidence that both topics are vivid, attractive and intensively investigated nowadays. Efficient control of crystallization and crystal properties still represents a bottleneck in the manufacturing of crystalline materials ranging from pigments, antiscalants, nanoporous materials and pharmaceuticals to semiconductor particles. However, a rapid development in precise and reliable measuring methods and techniques would enable one to better describe phenomena involved, to formulate theoretical models, and probably most importantly, to develop practical indications for how to appropriately lead many important processes in the industry. It is clearly visible at the first glance through a number of representative papers in the area, that many of them are preoccupied with the testing and production of pharmaceuticals, while the rest are addressed to new crystalline materials, renewable energy, water and wastewater technology and other branches of industry where the crystallization process takes place. In this work, authors gathered and briefly discuss over 100 papers, published in leading scientific periodicals, devoted to the influence of polymers on crystallizing solutions.