1 / 36

Flight Mechanics - Preliminaries

Flight Mechanics - Preliminaries. Center for Aerospace Systems Design & Engineering Department of Aerospace Engineering IIT Bombay, Mumbai 400076. Aircraft Come in All Shapes. What makes them fly?. Contents . Principles of Flight Airfoil Wing Wing + Horizontal tail

ricky
Télécharger la présentation

Flight Mechanics - Preliminaries

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Flight Mechanics - Preliminaries Center for Aerospace Systems Design & Engineering Department of Aerospace Engineering IIT Bombay, Mumbai 400076

  2. Aircraft Come in All Shapes What makes them fly? Dept of Aerospace Engineering, IIT-B

  3. Contents • Principles of Flight • Airfoil • Wing • Wing + Horizontal tail • Flight Mechanics? Dept of Aerospace Engineering, IIT-B

  4. Why Airfoil ? V V Drag Drag Airfoil : Shape that offers very low drag Dept of Aerospace Engineering, IIT-B

  5. Airfoil – Lift, Moment Thickness, Camber t h L = Lift  c M = Moment V h > 0  M < 0 Sign convention V Dept of Aerospace Engineering, IIT-B

  6. Lift & Moment L = Lift  M = Moment h=0 h L M h=0 h   Fixed  & V Some MRF dL/d & dM/d are constant over a range of  Dept of Aerospace Engineering, IIT-B

  7. Watch out ! : CP and AC L1 = Lift L = Lift M1 = Moment x1 M = Moment Center of pressure, M1=0 xcp = M/L M & L depend on  Xcp shifts with  Aerodynamic Center, dM1/d=0 xac = (dM/d)/(dL/d) In linear range of  xac does not depend on . Is fixed at 0.25% of C L1 = L M1 = M - L x1 (dM1/d) = (dM/d) – (dL/d) x1 Dept of Aerospace Engineering, IIT-B

  8. Lift & Moment Lift C  Moment V Lift = 0.5  V2 C a  Moment = 0.5  V2 C2 d Moment is about 0.25 C Dept of Aerospace Engineering, IIT-B

  9. Flat Plate Lift  Drag V More than that for airfoil Lift = 0.5  V2 C a Moment = 0.5  V2 C2 d; d = 0 Dept of Aerospace Engineering, IIT-B

  10. Lift & Moment Lift  Drag Moment (Pitching) V Lift = 0.5  V2 C a Moment = 0.5  V2 C2 d; d > 0 Dept of Aerospace Engineering, IIT-B

  11. Lift & Moment Lift  Drag Moment (Pitching) V Lift = 0.5  V2 C a Moment = 0.5  V2 C2 d; d < 0 Dept of Aerospace Engineering, IIT-B

  12. Airfoil / Flat Plate Symmetric M = 0 Cambered h > 0 M < 0 Cambered h < 0 M > 0 Moment is about = 0.25C Moment does not change with  Lift increases with  Dept of Aerospace Engineering, IIT-B

  13. Airfoil Symmetric M = 0 Cambered h > 0 M < 0 Cambered h < 0 M > 0 Moment is about = 0.25C Moment does not change with  Lift increases with  Dept of Aerospace Engineering, IIT-B

  14. Equilibrium & Stability L L M V M V W W W L L L L M M W V V Stable Unstable Dept of Aerospace Engineering, IIT-B

  15. Aerodynamic Center Stable Unstable Point about which Moment does not change with  0.25 C for an Airfoil. CG w.r.t. Aerodynamic Center  Stability Dept of Aerospace Engineering, IIT-B

  16. Flat Plate  Strip of Paper L W L M0 W • How to make a strip of paper fly? • AR is large  Like a flat plate airfoil • h = 0  M0 = 0  X = 0 • X = 0  Neutral • For stability • h < 0  M0 > 0  X < 0 • X < 0  Stable Dept of Aerospace Engineering, IIT-B

  17. Lets Fly a Strip of Paper! CG without ballast Stable Dept of Aerospace Engineering, IIT-B

  18. Lets Fly a Strip of Paper! CG with ballast Stable Dept of Aerospace Engineering, IIT-B

  19. Lets Fly a Strip of Paper! Stable Hinge line of elevator Dept of Aerospace Engineering, IIT-B

  20. Wing Aerodynamic Center Cr Ct Cr - Root chord Ct - Tip chord  = Ct /Cr = Taper ratio Dept of Aerospace Engineering, IIT-B

  21. Wing Stable Aerodynamic Center Unstable Dept of Aerospace Engineering, IIT-B

  22. Wing Stable Aerodynamic Center Unstable Dept of Aerospace Engineering, IIT-B

  23. Lets Fly a Wing! Dept of Aerospace Engineering, IIT-B

  24. Wing + Horizontal Tail (No Fuselage) Sw Stable Unstable ST acw acT lT Dept of Aerospace Engineering, IIT-B

  25. Vertical Tail? ? Dept of Aerospace Engineering, IIT-B

  26. Vertical Tail? Dihedral? ? Dept of Aerospace Engineering, IIT-B

  27. Flight Mechanics? Bifurcation analysis Simulation Stability – Eigenvalues of A Modes - Eigenvectors of A Thank You Dept of Aerospace Engineering, IIT-B

  28. Equations of Motion • Rigid body dynamics • Aerodynamic forces & moments modeled Dept of Aerospace Engineering, IIT-B

  29. Decoupled Equations Dept of Aerospace Engineering, IIT-B

  30. Decoupled Equations BLo ALo ALD BLD Lo = Longitudinal, LD = Lateral-Directional Dept of Aerospace Engineering, IIT-B

  31. http://www.casde.iitb.ac.in sudhakar@aero.iitb.ac.in Thank You Dept of Aerospace Engineering, IIT-B

  32. Airfoil, Flat Plate Or Strip of Paper L L L x x W W W L = W L * X + Mo = 0; X = - Mo/L Dept of Aerospace Engineering, IIT-B

  33. Control Surfaces Elevators Ailerons Rudder Dept of Aerospace Engineering, IIT-B

  34. Elevators - Pitch Dept of Aerospace Engineering, IIT-B

  35. Ailerons - Roll Dept of Aerospace Engineering, IIT-B

  36. Rudder - Yaw Dept of Aerospace Engineering, IIT-B

More Related