Abstract
Hover performance analyses of coaxial co-rotating rotors (or stacked rotors), which can be used as lifting rotors for electric VTOL (eVTOL) aircraft, are conducted here. In this study, the rotorcraft comprehensive analysis code, CAMRAD II, is used with the general free-wake model. The generic coaxial co-rotating rotor without the blade taper and built-in twist is considered as the baseline rotor model, and the rotor is trimmed to match a prescribed rotor thrust value. The hover performance, including the rotor power and Figure of Merit (FM), is investigated for various index angles, axial spacings, blade taper ratios, and built-in twist angles. A maximum FM value is obtained near an index angle of 0° and 10° when the axial spacing is below and above 5.27%R, respectively. When the index angle is 0° and axial spacing is 1.44% R, the maximum increments in the FM are 3.03% and 6.06%, respectively, for a rotor with a blade taper ratio of 0.8 and a built-in twist angle of −12°. Therefore, this simulation study demonstrates that the hover performance of coaxial co-rotating rotors can be changed by adjusting the index angle or the axial spacing.
Highlights
There are several problems associated with traffic congestion and environmental pollution in modern urban areas owing to high population densities
This simulation study demonstrates that the hover performance of coaxial co-rotating rotors can be changed by adjusting the index angle or the axial spacing
This study aims to analyze the hover performance of a coaxial co-rotating rotor using
Summary
There are several problems associated with traffic congestion and environmental pollution in modern urban areas owing to high population densities. Urban Air Mobility (UAM) is considered a potentially viable transportation solution. Aircraft that are utilized for UAM require a vertical take-off–landing (VTOL) capability and outstanding aerodynamic performance [1]. Structural safety and low acoustic noise are important issues for these aircraft because they are operated at relatively low altitudes in urban areas. Electric VTOL (eVTOL, Figure 1 [2]) aircraft have attracted significant attention for this application because of their advantages over conventional rotorcrafts, such as the simplicity of the drivetrain system, low acoustic noise, and safe operation in modern urban environments [3]. An eVTOL aircraft uses distributed electric propulsion (DEP) with a multi-rotor system
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