OpenVSP with AVL. Erik D. Olson NASA-Langley Research Center OpenVSP Workshop v3 Aug. 22, Aeronautical Sciences Project 1

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1 OpenVSP with AVL Erik D. Olson NASA-Langley Research Center OpenVSP Workshop v3 Aug. 22,

2 Outline NASA EET AR12 Model Flap Modeling OpenVSP to AVL Conversion Validation Results Degenerate Geometry 2

3 NASA EET AR12 Model Morgan, H.L. and Paulson, J.W.: NASA TP-1580 (1979) L

4 NASA EET AR12 Model Langley 14x22 Wind Tunnel ca foot span supercritical wing Full-span slats Part-span double-slotted flaps with cutout Moveable horizontal tail Flow-through nacelles, landing gear Morgan, H. L.: NASA TM (1979) and Morgan, H.L. and Paulson, J.W.: NASA TP-1580 (1979) 4

5 EET AR12 OpenVSP Model Planform shape from configuration description Wing airfoils from tabulated coordinates Fuselage sections digitized from plotted cross sections No nacelles, gear or gear pod Wing twist added to Hermite export file using external utility 5

6 Flap and Control Surface Layout 15.5% chord slat 15.5% chord slat h = 96 Constant-chord double-slotted flap (30% chord at e=0.383) h = h = 0.45 h = 0.97 h = 0.71 h = % chord double-slotted flap 6

7 Modeling of Flap Effects In practice, the theoretical lift increment from linear theory cannot be realized inadequacy of linear theory at large flap angles viscous effects flow separation at large flap angles Apply a flap effectiveness factor, η δ Account for slotted flap chord extension 7

8 Slotted Flap Effectiveness Single-slotted Double- and triple-slotted 8

9 Empirical Chord Extension Ratios single-slotted double-slotted w/ fixed vane double-slotted (variable geom) Fowler, single-slotted, doubleslotted w/ fixed vane Fowler, double- and triple-slotted Dc / c f Flap deflection, deg 9

10 Athena Vortex Lattice (AVL) Open-source (GPL) code developed at MIT (Drela & Youngren) Forces and moments, trim, steady rotation Stability derivatives w.r.t. angles, rotation, control surfaces Rigib-body, quasi-steady eigenmode analysis Incidence, camber, and control-surface or flap deflections modeled as normal-vector tilt only 10

11 OpenVSP to AVL Conversion Uses OpenVSP Hermite (Xsec) file export with external HRM2AVL utility AVL lifting surface sections (leading-edge coordinate, chord, incidence) calculated from Hermite cross sections Lifting-surface sections converted to normalized airfoils camberline determined by AVL Cruciform fuselage interpolated from Hermite cross sections Flap chord extension built into model 11

12 EET AR12 AVL Model Cruise Wing Segmented panels with local cosine spacing Cruciform fuselage Uncambered wing carry-through Takeoff Flaps Flap chord extension 12

13 Cruise Wing Validation Results Mach 0.168, Re c = 1.37x10 6 C L AVL + XFoil XFoil C L,max = angle of attack, deg C L AVL + Xfoil C D C m AVL + XFoil angle of attack, deg Actual C L,max = 1.34 Predicted C L,max (XFoil) = 1.79 (+33%) 13

14 Takeoff Wing Validation Results Mach 0.168, Re c = 1.37x10 6 C L Cruise Wing XFoil C L,max = angle of attack, deg C L C D C m angle of attack, deg Actual C L,max = 2.51 Predicted C L,max (Xfoil + empirical Dc l,max ) = 2.41 (-4.0%) 14

15 Landing Wing Validation Results Mach 0.168, Re c = 1.37x10 6 C L Cruise Wing XFoil C L,max = angle of attack, deg C L C D C m angle of attack, deg Actual C L,max = 2.82 Predicted C L,max (Xfoil + empirical Dc l,max ) = 2.77 (-1.8%) 15

16 OpenVSP v3.0 Degenerate Geometry OpenVSP Model Plate Export 16

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