Graduate Theses, Dissertations, and Problem Reports 2012 Planform Characterization of a High Lift, Low Speed, Ground Effect Glider Meagan L. Hubbell West Virginia University Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Hubbell, Meagan L., "Planform Characterization of a High Lift, Low Speed, Ground Effect Glider" (2012). Graduate Theses, Dissertations, and Problem Reports. 4869. https://researchrepository.wvu.edu/etd/4869 This Dissertation is protected by copyright and/or related rights. It has been brought to you by the The Research Repository @ WVU with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you must obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Dissertation has been accepted for inclusion in WVU Graduate Theses, Dissertations, and Problem Reports collection by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. Planform Characterization of a High Lift, Low Speed, Ground Effect Glider Meagan L. Hubbell Dissertation submitted to the College of Engineering and Mineral Resources at West Virginia University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Aerospace Engineering Dr. James Smith, PhD., Committee Chair Dr. Gerald Angle, PhD. Dr. MaryAnn Clarke, PhD. Dr. Eric Johnson, PhD. Dr. John Kuhlman, PhD. Department of Mechanical and Aerospace Engineering Morgantown, West Virginia 2012 Keywords: Ground Effect, Low Speed, Spanwise Wing Curvature Copyright 2012 Meagan L. Hubbell Abstract Planform Characterization of a High Lift, Low Speed, Ground Effect Glider Meagan L. Hubbell The main objective of this research was to design and develop a planform shape for a single passenger, unpowered, subsonic glider that relies on gravitational forces for momentum. The wing structure and aerodynamic shape optimized the benefits of near-ground flight (i.e. the increased lift and decreased induced drag), and as a result reduced the overall aircraft weight and wingspan, and enhanced the maneuverability of the craft. The design faced many challenges as a result of flight in the ground effect regime. There were natural instabilities, primarily in the longitudinal direction that caused the glider to pitch up. In addition, the wing size needed to be minimized in order to contain flight to the ground effect regime while maintaining enough lift to generate flight for a given rider. An initial straight wing design was developed to determine if a ground effect vehicle without specialty aerodynamic features (such as wingtips, dihedral, twist, etc) could be created. As a result, a basic glider was designed that had a 10.6 ft root chord length with a wing span of 18 ft; this design accommodated the physical requirements of a pilot while maintaining acceptable but limited maneuverability. In an effort to enhance aerodynamic performance, above that achieved by a straight wing design, variations in the planform shape were examined computationally in ground effect. These changes were inspired by the wing structures of birds that utilize ground effect for a large portion of their flight regime such as seagulls and pelicans. The modifications include twisting and curving the wings in an effort to vary the frontal areas and arc the wings towards the ground plane. The optimal design configurations were then tested experimentally in the subsonic wind tunnel, at reduced Reynolds number, to verify the performance characteristic trends and compared with the predicted CFD and analytical results. Results indicated that 10% twisted wings produced the greatest improvement in the lift profile as compared to the baseline straight wing design of the glider while in ground effect. This allowed for a reduction in the overall size of the glider by 4.5% which allows for an overall reduction in weight and a decrease in the wing span allowing for an increasing in the banking angle and thus an increase in the maneuverability. Table of Contents Abstract ........................................................................................................................................... ii Table of Contents ........................................................................................................................... iv List of Tables ............................................................................................................................... viii List of Figures ..................................................................................................................................x List of Symbols ............................................................................................................................ xiii List of Nomenclature ................................................................................................................... xiv Chapter 1.0 Introduction ............................................................................................................1 1.1 Background/Genesis ........................................................................................................ 1 1.2 Program Objectives .......................................................................................................... 2 1.3 Research Objectives ......................................................................................................... 3 1.4 Benefits of Contribution .................................................................................................. 3 Chapter 2.0 Literature Review ...................................................................................................5 2.1 Review of General Aerodynamics ................................................................................... 5 2.1.1 Early Developments ........................................................................................... 5 2.1.2 Sweep ................................................................................................................. 6 2.1.3 Twist ................................................................................................................... 8 2.1.4 Wing Tips Add-Ons ........................................................................................... 9 2.1.5 Dihedral ............................................................................................................ 11 2.1.6 Wing Curvature ................................................................................................ 11 2.1.7 Pitch Stability ................................................................................................... 13 2.2 Aerodynamic Ground Effect Research .......................................................................... 13 2.2.1 Introduction ...................................................................................................... 14 2.2.2 Historical Overview ......................................................................................... 14 2.2.3 Sweep ............................................................................................................... 18 2.2.4 Wing Tips ......................................................................................................... 19 2.2.5 Pitch Stability Research .................................................................................... 21 2.2.6 Numerical Wing-in-Ground Effect Research ................................................... 21 2.2.7 Computational Wing-in-Ground Effect Research ............................................ 22 2.2.8 Experimental Wing-in-Ground Effect Research .............................................. 23 2.2.9 Ekranoplan Design Problems ........................................................................... 26 2.2.10 Ground Effect Testing Methods ....................................................................... 27 iv 2.3 Non-Aircraft Ground Effect Research ........................................................................... 29 2.3.1 Hydrofoils ......................................................................................................... 29 2.3.2 Venturi Effect ................................................................................................... 30 2.4 Biomimicry .................................................................................................................... 31 2.4.1 Historical Overview ......................................................................................... 31 2.4.2 Morphing Wing Research ................................................................................ 32 2.4.3 Physiology of Birds in Flight ........................................................................... 33 2.5 Previous AirRay Research ............................................................................................. 35 Chapter 3.0 Preliminary Research ...........................................................................................39 3.1 Preliminary Weight Estimate ......................................................................................... 39 3.2 Design Parameters ......................................................................................................... 41 3.3 Lift Estimation