Boeing and NASA are conducting a joint study program to design a wing flap system that will provide mission-adaptive lift and drag performance for future transport aircraft having light-weight, flexible wings. This Variable Camber Continuous Trailing Edge Flap (VCCTEF) system offers a lighter-weight lift control system having two performance objectives: (1) an efficient high lift capability for take-off and landing, and (2) reduction in cruise drag through control of the twist shape of the flexible wing. This control system during cruise will command varying flap settings along the span of the wing in order to establish an optimum wing twist for the current gross weight and cruise flight condition, and continue to change the wing twist as the aircraft changes gross weight and cruise conditions for each mission segment. Design weight of the flap control system is being minimized through use of light-weight shape memory alloy (SMA) actuation augmented with electric actuators. The VCCTEF program is developing better lift and drag performance of flexible wing transports with the further benefits of lighter-weight actuation and less drag using the variable camber shape of the flap.

Tbis paper presents the findings of a study conducted tn 2010 by the NASA Innovation Fund Award project entitled "Elastically Shaped Future Air Vehicle Concept" . The study presents three themes in support of meeting national and global aviation challenges of reducing fuel burn for present and future aviation sys tems. The first theme addresses tlle drag reduction goal tbrougb innovative vebicle configurations via non-planar wing optimization. Two wing candidate concepts bave been identified from tbe wing optimization: a drooped wing s bape and an inflected win g shape. The drooped wing shape is a truly biologically inspired wing concept that mimics a seagull wing and co uld acbieve about 5% to 6% drag reductio n, wbicb is aerodynamically significa nt. From a practical perspective, this concept would require new radical changes to the current aircraft development capabilities for new vehicles witb futuristiC-looking wings sucb as tbis concept. T be inflected wing concepts conld acbieve between 3% to 4% drag reduction . While the drag reductio n benefit may be les , tbe inflected-wing concept could bave a near-term impact si nce thi s concept could be developed within the current aircraft development capabilities. The second theme addresses the drag reducti on goa l through a new concept of elastic wing shaping control. By aeroelasticaUy tailoring tbe wing sbape with active control to mailltatn optimal aerodynamics, a sig nificant drag reduction benefit could be realized . A significant reduction in fuel burn for lo ng-range cruise from elastic wing sbaping control could be realized. To reali ze the potential of the elastic wi ng shaping control concept, the third theme emerges that addresses the drag reduction goal througb a new aerodynamic co ntrol effector called a variable camber continuou trailing edge flap. Conventional aerodynami c control surfaces are di screte independent surfaces that cause geometriC di sco ntinuities at the trailing edge region. These discontinuities promote vorticities which result in drag rises as well as noise sources. Tbe variable camber trailing edge flap concept could provide a substantial drag reduction benefi t over a co nventional discrete flap system. AerodynamiC simulations sbow a drag reduction of over 50% could be acbieved witb tbe flap concept over a conventional discrete flap sys tem.

Ultralight materials present an opportunity to dramatically increase the efficiency of load-bearing aerostructures. To date, however, these ultralight materials have generally been confined to the laboratory bench-top, due to dimensional constraints of the manufacturing processes. We show a programmable material system applied as a large-scale, ultralight, and conformable aeroelastic structure. The use of a modular, lattice-based, ultralight material results in stiffness typical of an elastomer (2.6 MPa) at a mass density typical of an aerogel 5.6 mg cm 3 (). This, combined with a building block based manufacturing and configuration strategy, enables the rapid realization of new adaptive structures and mechanisms. The heterogeneous design with programmable anisotropy allows for enhanced elastic and global shape deformation in response to external loading, making it useful for tuned fluid-structure interaction. We demonstrate an example application experiment using two building block types for the primary structure of a 4.27 m wingspan aircraft, where we spatially program elastic shape morphing to increase aerodynamic efficiency and improve roll control authority, demonstrated with full-scale wind tunnel testing.

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