Flying-V Family Design for Stability and Control

Abstract

The Flying-V is a novel aircraft configuration which promises better fuel efficiency than the current state of the art in commercial passenger transport. The main contributing factor to this accomplishment is its small wetted area relative to the available volume. Three family variants carrying different numbers of passengers are designed simultaneously. The airplane has elevons and rudders serving as control surfaces for trim and maneuvering. The Flying-V has been optimized for aerodynamic efficiency in previous research, but stability and control constraints have not yet been considered in detail. To find the effect of stability and control on the design variables and performance, an aerodynamic solver, mass distribution model, and control authority simulation have been established. The mass distribution model can be used to find the center of gravity and moment of inertia in any loading scenario. A strategy for fuel distribution for minimum CGtravel is proposed. An optimization is performed using SciPy optimization tools. Planformgeometry is used as the design vector. The design constraints include geometric contraints like maximum span and fuel capacity, and stability and control constraints like control authority for pitch, roll, and yaw maneuvers and static stability. The results of the optimization have shown that the stability and control constraints can be satisfied without a large fuel burn penalty (less than one percent) and stability and control constraints are not driving as long as the fins are large enough to accommodate rudders that provide sufficient directional control power. An optimized design that meets all requirements has a shorter outer wing, shorter fuselage, longer fins, and smaller outer wing sweep compared to the initial design. For the three optimized aircraft, the acceptable range of center of gravity is bounded by longitudinal stability and control requirements. The distribution of passenger and cargo weight in combination with the active fuel distribution system should be such that the CG during flight stays within these bounds. This is shown to be the case for the design payload configuration.