Description: NASA and Boeing Phantom Works have been working on the Elastically Shaped Future Vehicle Concept (ESFVC) and have shown that aircraft with elastically shaped wings have great potential to save fuel by minimizing drag. Main feature of the ESFVC is that it uses Variable Camber Continuous Trailing Edge Flap (VCC-TEF) flight control surfaces to bend & twist the wing to a "drooped wing" configuration that was shown capable of achieving drag reduction. However, elastic wings are characterized by reduced stiffness, which may result in lower flutter margins. Hence flutter suppression is an important aspect of the ESFVC. In order to address this technical challenge, SSCI and Boeing Phantom Works propose to design, implement and test an innovative Drag Identification & Reduction Technology (DIRECT) approach to drag reduction and flutter suppression in flexible-wing aircraft. The approach is based on leveraging prior work by SSCI and includes on-line identification of flutter modes using real-time subspace identification techniques, flutter suppression control law development, and the selection of the optimal control allocation that minimizes drag based on the CFD/FEA analysis. The approach will be tested on aircraft dynamics simulation, developed by Boeing, that includes a large number of relevant flexible modes. Boeing Phantom Works (Mr. James Urnes, Sr) will provide technical and commercialization support under the project.

Benefits: High Altitude, Long Endurance (HALE) Unmanned Aerial Vehicles (UAVs) are designed to cruise above 60,000 ft and to fly missions ranging from a few days to a few years. Such a unique flight profile allows the use of these aircraft as platforms for scientific research. The implementation of the concept of flexible wings and the DIRECT technology in HALE UAVs would result in lowering the costs of NASA scientific research by reducing fuel consumption, and in contributing to environmental protection by lowering emissions and noise.

The proposed DIRECT system is applicable to future flexible-wing commercial vehicle concepts where the main objective is to enhance fuel efficiency while reducing noise and emissions. The approach will also be applicable to military versions of HALE UAVs.