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  1. 1. How Gliders Work CUO Tonya Brown Apr 11
  2. 2. Not talking about this glider...  <ul><li> </li></ul>
  3. 3. Aim <ul><li>Learn the basics of how gliders work </li></ul><ul><li>Create a model glider (Squadron Competition) </li></ul>
  4. 4. Introduction <ul><li>Glider is an unpowered aircraft </li></ul><ul><li>Aerodynamic and piloting factors that apply to powered airplanes also apply to gliders </li></ul><ul><li>Lack of motor changes a lot about how gliders work </li></ul><ul><li>Closest humans get to soaring like a bird </li></ul>
  5. 5. Parts of a Glider <ul><li>A glider has many of the same parts as an airplane: </li></ul><ul><ul><li>Fuselage </li></ul></ul><ul><ul><li>Wings </li></ul></ul><ul><ul><li>Control Surfaces </li></ul></ul><ul><ul><li>Landing Gear </li></ul></ul><ul><li>But there are significant differences </li></ul>
  6. 6. Fuselage <ul><li>As small and light as possible </li></ul><ul><li>Basically sized around the cargo they carry (1 or 2 people) </li></ul><ul><li>Cockpit of a single-seat glider is small, but large enough for most </li></ul><ul><li>Pilots recline with their legs stretched out in front of them </li></ul><ul><li>Frontal exposure of pilot is reduced and cross-sectional area of cockpit can be substantially smaller </li></ul>
  7. 7. <ul><li>Designed to have skins that are as smooth as possible to allow plane to slip more easily </li></ul><ul><li>Modern gliders – composite construction using materials such as fibreglass and carbon fibre </li></ul><ul><li>Materials allow aircraft designers to create seamless and rivet-less structures, producing less drag </li></ul>
  8. 8. Wings <ul><li>Longer and narrower than conventional a/c </li></ul><ul><li>Slenderness of wing expressed as aspect ratio (calculated by dividing the square of the span of the wing by the area of the wing) </li></ul><ul><li>High aspect ratio (long wing compared width) </li></ul><ul><li>Drag created during the production of lift (induced drag) can account for significant portion of drag on glider </li></ul>
  9. 9. <ul><li> </li></ul>
  10. 10. Control Surfaces <ul><li>Gliders use same control surfaces that are found on conventional aircraft </li></ul><ul><li>Ailerons and elevator controlled using single stick between pilots legs </li></ul><ul><li>Rudder – controlled using foot pedals </li></ul>
  11. 11. Ailerons <ul><li>Moveable sections cut on trailing edge of wing </li></ul><ul><li>Used as primary directional control and they control roll of plane </li></ul><ul><li>Operate in opposite directions of each side of the plane </li></ul><ul><li>Roll to the right - move control stick to right </li></ul><ul><ul><li>Left aileron deflect down (more lift) </li></ul></ul><ul><ul><li>Right aileron deflect up (less lift) </li></ul></ul><ul><ul><li>Difference in lift causes rotation along axis </li></ul></ul>
  12. 12. Elevator <ul><li>Horizontal Stabiliser </li></ul><ul><li>Movable wing like structure on the tail </li></ul><ul><li>Used to control pitch of plane </li></ul><ul><li>Allowing to point nose up/down </li></ul>
  13. 13. Rudder <ul><li>Vertical Stabiliser </li></ul><ul><li>Wing structure on tail </li></ul><ul><li>Control the yaw </li></ul><ul><li>Allowing pilot to point nose left/right </li></ul>
  14. 14. Landing Gear <ul><li>Reduce size of aircraft by reducing landing gear </li></ul><ul><li>Glider typically consists of a single wheel mounted just below cock pit </li></ul>
  15. 15. Getting off the ground <ul><li>3 basic forces act on a glider (they do not have thrust like airplanes) </li></ul><ul><li>Lift – created by wings, counteracting weight </li></ul><ul><ul><li>Lift enhanced </li></ul></ul><ul><li>Drag – tends to slow plane down </li></ul><ul><ul><li>In motorised thrust overcomes drag, in glider try to reduce with the design of glider </li></ul></ul><ul><li>Weight – can be made to work for or against </li></ul><ul><ul><li>Lighter keeps in air, heavier increases speed </li></ul></ul><ul><ul><li>Tanks of water can be used for weight and dumped off during flight </li></ul></ul>
  16. 16. <ul><li>Without an engine needs to get up in air by aero-tow </li></ul><ul><li>Conventional powered plane tows glider up in sky using long rope </li></ul><ul><li>Glider takes of before tow plane </li></ul><ul><li>When at the desired altitude – release rope </li></ul>
  17. 17. Staying in the air <ul><li>Thermals </li></ul><ul><ul><li>Columns of air rising by heating of earth surface </li></ul></ul><ul><ul><li>Absorbing more sun (asphalt parking lots, dark ploughed fields, rocky terrain) </li></ul></ul><ul><ul><li>Circle within column (gaining height) </li></ul></ul><ul><li>Ridge Lift </li></ul><ul><ul><li>Winds blow against mountains/hills/ridges </li></ul></ul><ul><li>Wave Lift </li></ul><ul><ul><li>Winds meet mountain – leeward side </li></ul></ul><ul><ul><li>Can lift up to thousands of feet high (more than 35000ft) </li></ul></ul>
  18. 18.
  19. 19. Landing <ul><li>Much like conventional except only single small wheel located directly under the pilot </li></ul><ul><li>Wings are strong and reinforced to prevent damage (usually manage to keep off anyway until slowed sufficiently) </li></ul><ul><li>Spoilers are on each wing - disrupting airflow drastically reducing lift </li></ul>
  20. 20. Glider World Records <ul><li>Absolute Altitude: 49, 009ft </li></ul><ul><li>Speed over 100km triangular course: 217.4km/h </li></ul><ul><li>Free distance: 1460.8 km </li></ul><ul><li>Distance around triangular course: 1399.4 km </li></ul>
  21. 21. Make a Model Straw Glider <ul><li>Refer to Activity Sheet </li></ul>