Overview of RCAS Capabilities and Validations for Rotorcraft and eVTOL Applications

This paper presents an overview of the Rotorcraft Comprehensive Analysis System (RCAS) capabilities, recent enhancements, validations, and application to practical rotorcraft and electric vertical take-off and landing (eVTOL) problems. Nine years have passed since a similar paper was presented in Ref. 1; and 20 years since the first RCAS overview paper was published in Ref. 2. RCAS has been continually enhanced over the last nine years and there have been several significant developments. This paper summarizes these developments, which include improvement of existing structural modeling, better support for multi-rotor variable RPM modeling, enhanced vortex wake and airloads modeling options, expansion of coupling with CFD modules, and improvements to the graphical user interface. This paper also surveys the body of recent RCAS validations, which has greatly expanded since the last paper. RCAS validations now include detailed work on tiltrotor hover and cruise performance, loads, and whirl flutter stability, and coaxial rotor and compound helicopter performance and loads, in addition to conventional rotorcraft configurations. Validation studies are being conducted for eVTOL configurations. This paper provides the rotorcraft technical community with an up-to-date and consolidated resource on RCAS by summarizing capabilities, recent developments, and validations, while also demonstrating selected applications.