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GLIDER DESIGN PROJECT

GLIDER DESIGN PROJECT. The Task. To design, build and test a scale-model glider Designs will be judged on four criteria: Distance travelled, D Time of flight, T The product D × T The quantity D × T ÷ M where M is the glider mass. 60 cm. 50 cm.

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GLIDER DESIGN PROJECT

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  1. GLIDER DESIGN PROJECT

  2. The Task • To design, build and test a scale-model glider • Designs will be judged on four criteria: • Distance travelled, D • Time of flight, T • The product D×T • The quantity D×T÷M where M is the glider mass

  3. 60 cm 50 cm Design Requirements The glider must: • Have a wing span of no more than 60 cm • Be no more than 50 cm long

  4. Materials • Thick foam board – 2 sheets ~33×8 cm • Thin foam board – 2 sheets ~31×19.5 cm • A4 paper – 4 sheets • Drinking straws – 8 • Tissue paper – 1 sheet • Masking tape • Adhesive

  5. Equipment • Scissors • Stanley knife • Steel ruler • Sand paper • Radius aids • Bluetack (for centre of gravity adjustment)

  6. Objectives To give a taste of what Engineering is all about: • Problem solving • Being creative – an Engineer is by definition an ingenious person • Team work • Rewarding • Fun

  7. Project Timetable Introduction to Design Task 10 minutes Introduction to Glider Design 20 minutes Design Session 15 minutes Construction/Test Session 60 minutes Final Test Session 15 minutes

  8. An Introduction to Glider Design Geoff Parks

  9. Stabiliser Main wing Vertical tail Fuselage Glider Parts

  10. Elevator Ailerons Rudder Glider Control Surfaces

  11. Lift Drag Weight Forces on a Glider

  12. Weight • The weight of a glider is simply its mass multiplied by g, the acceleration due to gravity W = Mg

  13. Lift I • The Coanda Effect: a fluid has a natural tendency to follow the shape of a body as it flows past it • If the body is correctly shaped (airfoil shaped), this can be used to generate lift

  14. Lift II Fluid is deflected downwards by airfoil  Force acts downwards on fluid  Force acts upwards on airfoil (by Newton’s 3rd Law)

  15. Lift III The amount of lift depends on: • Wing size – larger area  more lift • Speed – higher speed  more lift • Airfoil shape – more flow turning  more lift • Airfoil angle of attack – larger angle of attack  more lift

  16. Stall • If the airfoil angle of attack (a) becomes too large and/or the flow speed becomes too large… • The Coanda effect can break down, leading to flow separation • This separation, known as stall, reduces lift Attached Separated

  17. Drag I There are two forms of drag: • Form Drag • Induced Drag Form Drag depends on: • The size of the object – larger projected area  more drag • Speed – higher speed  more drag

  18. Drag II Induced Drag, ID, depends on: • The amount of lift, L • Wing aspect ratio, AR ID  L2÷AR

  19. Typical Glider Profile

  20. Lift Weight Lines of Action • To maximise flight distance, the lines of action of the lift and weight must coincide

  21. Design Tips I • Tape pieces of thin board onto the glider to act as ailerons, elevator and rudder; you can then slightly bend these to help trim your glider and direct it in flight. • Add dihedral to the wing tips by making the outer portions of the wing angle upwards.

  22. Design Tips II • Make the wings moveable – so you can slide them fore and aft along the fuselage to find their optimal position. • Round the leading edges of all surfaces and “point” the trailing edges.

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