This paper presents experimental results of a flexible wing wind tunnel model with a variable camber continuous trailing edge flap (VCCTEF) design for drag minimization, tested at the University of Washington Aeronautical Laboratory (UWAL). The wind tunnel test was designed to explore the relative merit of the VCCTEF concept for improved cruise efficiency through the use of low-cost aeroelastic model test techniques. The flexible wing model is a 10%-scaled model of a typical transport wing and is constructed of woven fabric composites and foam core. The wing structural stiffness in bending is tailored to be half of the stiffness of a Boeing 757-era transport wing, while the torsional stiffness is about the same. This stiffness reduction results in a wing tip deflection of about 10% of the wing semi-span. The VCCTEF is a multi-segment flap design having three chordwise camber segments and five spanwise flap sections for a total of 15 individual flap elements. The three chordwise camber segments can be positioned appropriately to create a desired trailing edge camber. Elastomeric material is used to cover the gaps in between the spanwise flap sections, thereby creating a continuous trailing edge. Wind tunnel data indicate a high degree of data correlation and repeatability. The VCCTEF can achieve a drag reduction of up to 6.31% and an improvement in the lift-to-drag ratio (L/D) of up to 4.85%. The paper also presents two methods for estimating the lift coefficient of a rigid wing using a dynamic pressure correction and an aeroelastic deflection correction. Both methods provide good estimates of the rigid-wing lift coefficient.

This paper presents wind tunnel experimental results of a flexible wing high-lift configuration with a variable camber continuous trailing edge flap (VCCTEF) design for drag minimization, tested at the University of Washington Aeronautical Laboratory (UWAL) in July of 2014. The objective of the high-lift test in UWAL is to assess the high-lift performance of the VCCTEF. The wing bending stiffness is tailored to achieve a wing tip deflection of about 10% of the wing semi-span at 1-g flight conditions. The VCCTEF is a multi-segment flap design having three chordwise camber segments and five spanwise flap sections for a total of 15 individual flap elements. The high-lift design includes a Variable Camber Krueger (VCK) leading edge device and an inboard high-lift trailing edge flap with a Fowler motion. Two inboard high-lift flap configurations are tested: a single-element plain flap and a three-segment cambered flap. The outboard VCCTEF is rigged at varying flap deflections of up to 30 • formed by a circular arc camber and has no Fowler motion. A premature flow separation associated with the initial configuration of the VCK leading edge device, as indicated by an abrupt stall, was encountered during the initial runs. A final VCK configuration was found experimentally with a varying rigging angle from 65 • at the inboard to 50 • at the outboard. Wind tunnel test results indicate a C L max = 2.13 is achieved for a wing-body configuration with the single-element plain flap versus C L max = 2.09 with the cambered flap. This C L max is close to the desired C L max for a typical Boeing 757 landing configuration. The cambered flap achieves a L/D improvement by 6% over the single-element plain flap due to the reduced profile drag with the cambered flap. Sensitivities due to VCCTEF spanwise deflection shapes, combined Reynolds number / aeroelastic effect, and Fowler slot width were studied. Reynolds / aeroelastic and Mach number corrections

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