Developing Means of Compliance for eVTOL Vehicles: Phase II Final Report

692M15-18-C-00010Development of new air vehicles types (e.g., personal air vehicles, urban taxis, etc.) have led to a proliferation of Vertical Takeoff and Landing (VTOL) vehicle concepts including electric vehicles, many of which are well funded and are in various stages of prototype development and testing. These vehicles almost exclusively feature fly-by-wire (FBW) flight control systems with advanced flight control system response-types. The processes and requirements needed to certify these disparate vehicles for operation within the National Airspace System are still emerging. To aid in the requirements and certification process, a mission-oriented approach is being applied to define Mission Task Elements (MTEs), often referred to as Flight Test Maneuvers (FTMs), that will serve as a means of compliance with Part 21.17(b) of certification regulations. This report summarizes the Phase II effort of this program wherein an industry representative lift plus cruise electric Vertical Takeoff and Landing (eVTOL) configuration was used to develop and exercise via analysis and fixed-base simulation candidate Handling Qualities Task Elements (HQTEs), a subset of MTEs/FTMs, that address control law transitions, envelope protections, and automation. MTEs/FTMs are repeatable tests based on the vehicle Concept of Operations (CONOPS) and tailored to evaluate aircraft characteristics that assure safe operations within the flight envelope and the ability to perform the intended mission(s) with acceptable pilot workload/compensation

Gust Loads Calculation for a Flying Wing Configuration

This work presents results of dynamic 1-cos gust load simulations for a flying wing configuration. The in-house toolbox Loads Kernel is used for the loads analysis of the free flying aircraft. Flight mechanical characteristics are captured application of a non-linear equation of motion in the time domain. The underlying aerodynamic methods are the Vortex Lattice and the Doublet Lattice Method with a rational function approximation (RFA) for unsteady simulations in the time domain. The structural model was created using DLR's parametric ModGen/Nastran design process. The structure is optimized for minimum structural weight with typical design load cases including maneuver, gust and landing loads. In this paper, the focus lies on gust encounters and the flight characteristics of the MULDICON, which differs from classical configurations. It involves a pitching motion and a pronounced penetration effect when the aircraft enters the gust field. Finally, a flight controller is designed to increase the pitching stability. It is shown that the loads during a gust encounter increase moderately. The influence on the structural weight is small as the layout is very robust and the required material thickness is below the minimum thickness in most areas