Design of a Composite Wing with Leading Edge Discontinuity Daniel Hult AerE 423 Project December 12, 2009 Overview • • • • • • • • Background Project Goals Design Computational Analysis Fabrication Testing Results & Conclusions Future Work Background • Purpose – Discontinuity causes vortex to form, keeping flow attached to outer wing and ailerons – Improved stability and performance at high α – Spin prevention Cirrus Aircraft Company Project Goals • Determine the structural feasibility of a composite, single-piece wing with a discontinuous leading edge. • Design, build and structurally test a singlepiece composite wing. Design • Phases: – Aerodynamic Analysis – Structural Design • Purpose of project is structural • Aerodynamics only to get accurate loads Aerodynamics • XFLR5 Analysis – Open source aerodynamics for R/C gliders – Uses Vortex Lattice Method – Allows low Reynolds Number analysis of any wing Structural Design • Laminate Study – Analysis of laminate geometry with comp_core – Varied combinations of 0/90 plies and ±45 plies – Loading • Tension and Bending • Compression and Bending – Laminates with more ±45 plies performed better in bending Structural Design • Final Laminate – 6 plies of 0.002 in. thick bi-weave fiberglass – 4 plies at 0 and 90 degrees – 2 plies at +45 and -45 degrees Computational Analysis • ANSYS used for Finite Element Analysis • Three cases tested – Isotropic material (aluminum) – Graphite-Epoxy composite – Fiberglass-Epoxy composite • 300 N distributed load at tip – Loading from XFLR5 – Depicted test to be performed Computational Analysis • Fiberglass – Max Stress= 587 Mpa – Max disp = 1.25 cm Fabrication • Mold – Airfoil sections cut out of particle board – Used as stencils to hotwire blue foam – 2 sections joined and handle added to root Fabrication Fabrication • Lay-up – Hand lay-up around mold – Wrapped and cured with vacuum assistance. Testing • A Successful test would clearly accomplish project goals • Wing anchored at root with load applied at tip • Load added to tip until failure Testing Screw Method Clamp Method Testing • Wood mount failed along screws (20 lb) • Fiberglass failed along clamped shims (40 lb) Results & Conclusions • Wing failed at clamped root at small load • ANSYS predicted stress concentrations and therefore failure at discontinuity • The results were inconclusive, necessitating further testing Future Work • Better fabrication techniques and materials – Two-piece wing – Carbon Fiber – VARTM or Pre-Preg • Better testing and mounting methods – Metal or composite mounting plate and insert – Metal or composite tip insert for loading References • Abbott, Ira H. and Albert E. von Doenhoff. Theory of Wing Sections: Including a Summary of Airfoil Data. New York: Dover Publications, Inc. c1959. • “CAPS™ and Stall/Spin.” Cirrus Aircraft Company. Accessed 12 October 2009. <http://www.whycirrus.com/engineering/stall-spin.aspx>. • Deperrois, André. “About XFLR5 calculations and experimental measurements” August 2008. <http://xflr5.sourceforge.net/xflr5.htm#_Help>. • Deperrois, André. “Guidelines for XFLR5 V4.16.” April 2009. <http://xflr5.sourceforge.net>. • Goyer, Robert. “Airplane on a Mission: Created for use in the humanitarian field, the Quest Kodiak delivers raw utility at a great price.” Flying Magazine. February 2009 <http://www.flyingmag.com/turbine/1344/quest-kodiak-airplane-on-a-mission.htmlQuest Kodiak>. • “Kodiak Features.” Quest Aircraft Company. Accessed 29 September 2009. http://www.questaircraft.com/index.php?filename=features.php • Meschia, Francesco. “Model analysis with XFLR5.” RC Soaring Digest. February 2008: p27-51. • NASA Langley Research Center. “Spin Resistance” Updated 17 October 2003. <http://oea.larc.nasa.gov/PAIS/Concept2Reality/spin_resistance.html>. Acknowledgments • Dr. Vinay Dayal, Professor • Chunbai Wang & Peter Hodgell, TA’s • AerE 462 group, especially Robert Grandin for ideas and support • Iowa State University, Department of Aerospace Engineering Questions? Background Airliners.net • Uses – Messerschmitt Bf-109 Airliners.net – Large commercial jets – NASA Spin Prevention Tests – Cirrus SR20 – Quest Kodiak Cirrus Airliners.net NASA Spin Prevention Figures from NASA Langley report Aerodynamics • Airfoil Design – NACA 2412 chosen for basis – Common, well-known low-speed airfoil – Discontinuity created by extending NACA 2412 Aerodynamics • Wing Design – Basic wing designed to be fabricated and tested structurally – NACA 2412 inner section (0.3 m) – Modified airfoil outer section (0.2 m) – b/2=0.5 m – cr=0.25 m Table A1: Test Laminates Laminate Study Test T1 T2 T3 T4 A1 A2 A3 A4 Test T1 T2 T3 T4 A1 A2 A3 A4 Ex (Gpa) 95.99 88.51 79.84 69.68 73.83 68.34 62.02 54.69 Material T300/5208 Graphite-Epoxy T300/5208 Graphite-Epoxy T300/5208 Graphite-Epoxy T300/5208 Graphite-Epoxy AS/3501 Graphite-Epoxy AS/3501 Graphite-Epoxy AS/3501 Graphite-Epoxy AS/3501 Graphite-Epoxy Planar Ey (Gpa) Gxy (Gpa) 95.99 7.17 88.51 13.74 79.84 20.31 69.68 26.88 73.83 6.9 68.34 11.68 62.02 16.47 54.69 21.25 Poisson 0.0302 0.1058 0.1934 0.296 0.0367 0.1085 0.1909 0.2865 Laminate {[0,90];6}s {[0.90];2,[45,-45];1,[0.90];3}s {[0,45,90,0,-45,90];2}s {[0,90,45,-45];3}s {[0,90];6}s {[0.90];2,[45,-45];1,[0.90];3}s {[0,45,90,0,-45,90];2}s {[0,90,45,-45];3}s Ex (Gpa) 106.7 96.74 88.69 83.25 81.95 74.58 71.95 64.69 Bending Ey (Gpa) Gxy (Gpa) 85.28 7.17 79.68 13.9 70.31 19.97 71.33 21.85 65.73 6.9 61.67 11.8 51.05 15.89 55.66 17.59 Poisson 0.0339 0.1187 0.2103 0.2333 0.0413 0.1214 0.2116 0.2286 Laminate Study Test T1 T2 T3 T4 A1 A2 A3 A4 Tensile X (Mpa) Y (Mpa) -7.59 39.9 -57.9 39.4 -95.1 38.7 -132 38.5 -9.75 48.1 -59.7 47 -95.2 45.6 -130 45.3 Z (MPa) 1.22E-08 -1.89 -6.33 -2.3 1.25E-08 -2.22 -7.68 -2.82 Compressive X (Mpa) Y (Mpa) Z (Mpa) -8.23 39.9 1.22E-08 -58.6 39.4 -1.89 -95.7 38.7 -6.33 -132 38.5 -2.3 -10.4 48.1 1.25E-08 -60.4 47 -2.21 -95.8 45.6 -7.67 -131 45.2 -2.82 Computational Analysis • Isotropic – Max Stress= 654 Mpa – Max disp = 1.34 cm Computational Analysis • Carbon Fiber – Max Stress= 600 Mpa – Max disp = 1.25 cm Mold Finished Laminate Testing