Tools and Challenges in Evaluating Control Surface Airworthiness for a Blended-Wing-Body UAV

Abstract: For transport aeroplanes the Blended-Wing-Body (BWB) configuration shows promise in improving aerodynamic efficiency. The Green Raven project strives to demonstrate hydrogen fuel-cell-electric propulsion on a 4 m wingspan BWB. Due to the lack of a traditional horizontal tailplane, BWBs commonly have multifunctional control surfaces that void assumptions needed for traditional sizing methods. This work endeavoured to produce a control surface configuration that would permit adequate flying qualities of the Green Raven according to the MIL-F-8785C specification, preferably while minimising cruise power draw. The open-source aerospace modelling and optimisation environment SUAVE was chosen for the task, with the intention of adding any needed functionality.SUAVE was modified to permit the definition of general-purpose control surfaces and stability derivatives to be obtained for the additional degrees of freedom they bring which was demonstrated using a SUAVE representation of the Green Raven. The precise procedure for airworthiness-constrained control surface optimisation could not be determined before cessation of work but an outline of a simplified procedure was proposed.