Requirements from National Regulations for Microlight Aircraft and Statistical Parameters for Preliminary Sizing

The purpose of this project is to examine and describe the regulations of microlight aircraft. The national rules of mostly European countries are described in more detail and are compared to the German rules. Most important among the regulations is the maximum take-off mass. In some countries, the limit of 472.5 kg has been raised recently to 600 kg. The report leads from microlight regulations to preliminary sizing of microlight aircraft. Preliminary sizing is based on statistical parameters, which are evaluated for typical microlight aircraft. The parameter k_APP relates landing field length to approach speed. From microlight statistics it was determined an average value k_APP = 2.149 m^0.5/s. The parameter k_TO helps to determine the ratio of power-to-mass and wing loading. An average value k_TO = 1.915 m³/kg was determined. The glide ratio can be estimated from "wetted aspect ratio" with an average k_E = 12.12. The average operating empty mass ratio was determined to 0.578. This means that a microlight aircraft with a maximum take-off mass of 600 kg might have an operating empty mass of about 347 kg. This work does not provide a spreadsheet tool for microlight sizing. But at least the project provides the input parameters for preliminary sizing from microlight regulations together with necessary statistical parameters. As such, a preliminary microlight aircraft sizing by a hand calcuation becomes possible. The report also helps pilots and microlight owners to understand why certain values appear in the operating manual and on which regulations they are based.