Mechanics of Flight SESA2025 Part A

61 flashcards · Physics · by Zack Phipps

  1. what is pitch altitude equal to pitch altitude = angle of climb + angle of attack

  2. what is angle of climb

    angle of the velocity vector of the aircraft to the horizontal

  3. assuming steady flight and that aoa is small what is thrust equal to T = - D - DT - Wsin(gamma)

  4. force balence equation for steady flight L* = L +LT = wcos(gamma)

    L* = L +LT = w cos(gamma)

  5. moment balance equation for steady flight: 0 = M0 + L*(h-h0)C - LTl

  6. tail volume fraction k = STl/SC

  7. coefficient moment balance equation for steady flight

  8. coefficient force balance equation for steady flight

  9. what is

    setting angle = angle between aircraft body axis and zero lift line of the tailplane

  10. what is the effective angle of the tail-plane

  11. what is the effective angle of the tail-plane with expanded terms

  12. what is the linear model of the tailplane coefficient of lift

  13. what are the a1 a2 a3

  14. fun facts about the elevator (4)

    hinged by the hinge line controlled by the pilot the moment around the hinge line is CMH increasing the velocity increases the CMH

  15. the elevator hinge moment can be modelled using what eqaution?

  16. what is b1

  17. what is b2

    difficulty to change the elevator angle

  18. what is b3

  19. what is the purpose of the horn balance?

    a horn balance can be shielded or unshielded and they reduce floating and the restoring tendency of an aircraft

  20. What is the purpose of the yoke

    controls the elevator directly

  21. what is the purpose of the trim tab

    controls the elevator indirectly

  22. Four important facts about stick fixed flight

    applies force on the yoke to overcome the hinge moment Cmh != 0 beta = 0 high pilot effort

  23. Four important facts about stick free flight

    rotates trim tab to move elevator Cmh = 0 elevator can float uses aerodynamics to change elevator angle

  24. CLt model for stick fixed flight S

  25. CLt model for stick free flight S

  26. CMh model for stick free flight

  27. CMh model for stick fixed flight

  28. what are a1 and a3

  29. as a1_bar < a1 what dpes this mean for lift and why

    as the tail plane produces less lift per unit change of angle of attack this is because the geometry of the wing changes with different angles of attack making less efficient at producing lift. this also leads to lower pitch stiffness and worse stability characteristics needs to use horn balance to reduce the floating tendency

  30. what is fixed tail trim and what are the pros and cons

    the whole elevator moves as one pros light cheap easy to design safe in case of failure negs limited control high drag associated with trim

  31. what is an all moving trim design and what are the pros and cons

    changes the installation angle of the wing - whole wing moves pros higher trimming power wider range of CG movements lower drag as elevator and stabiliser are aligned when aircraft is trimmed cons structural design

  32. what is an adjustable tail trim design and what are the pros

    changes the installation angle for trim and uses an elevator for control around the trim point low rotation rate required higher trimming power wider range of CG movements lower drag as elevator and stabiliser are aligned when aircraft is trimmed

  33. what is moving CG trim design and what are the pros

    moving the fuel back and forth between different departments in order to control the CG point no drag from the tail

  34. the main wings are optimised for high so=peed and efficiency by maximising:

    d is depending on the efficiency and propulsion

  35. for take offf aand landing a high SCL* is required, why? and what does this mean for other flight parameters?

    a high SCL* is needed because of the low speed at landing this means: high angles of attack - reduces the risk of stall changing wing geometry to boost SCL* high velocities at take off at landing to reduce the need for such a high SCL*

  36. what do flaps do

    change the camber line near the trailing edge temporary transformation into a different aerofoil great increase in surface area higher h0 more negative M0 high drag penalty

  37. describe the five different flap designs plain flaps split flaps slotted flaps fowler flap double-slotted fowler flap

  38. what is the downside to flaps?

    lift production is not free, is causes drag to combat this different deployment is used is take off and landing flaps away for cruise flaps out for take off and initial climb max flaps for approach to landing - max lift and high drag

  39. what is the influence of the flaps?

    they increase the effective camber of the wing and increasing the wing area, this changes the zero lift angle alpha0, the more the flaps deploy the more negative alpha0, the stall angle may also drop due to flow separation on the flap

  40. what do slats do?

    mmanipulate flow , flow remains attached for higher aoa so is less likely to stall and therefore increase CL,Max lower drag penalty then other methods small influence on alpha0 and CM0 lower h0

  41. what is a krueger flap

    portion of the lower wing is rotated out in front of the main wing leading edge

  42. what is a leading edge droop

    morphing of the leading edge wing geometry to increase camber

  43. what is the fuselage fineness ratio

    length of the fuselage over the diameter

  44. what impact does the fuselage fitness ratio have over the drag penalty? and what are the limitations

    the higher the fuselage fineness ratio the lower the drag penalty but it cant be too long as the fuselage limits the angle the aircraft can achieve before tail strike occurs - which affects mimimum take off speed(runway length) can be minimised by optimising tail shape

  45. what is zero lift drag?

    D0 Zero-Lift Drag (also Parasitic Drag): The sum of drags not directly associated with the production of lift.

  46. whats is induced drag?

    DL Lift-related Drag (also Induced Drag): The sum of drags associated with the production of lift (typically due to wings & tail-planes)

  47. What is Dint

    Interference Drag: Additional drag resulting from bringing two bodies in proximity to each other wing-fuselage joints prevented by using suitable fairings

  48. whats is Dpro

    Profile Drag: Drag due to the sum of skin friction drag and pressure drag (form drag) A boundary layer over a surface causes skin friction, which creates drag •Laminar flow results in significantly lower skin friction coefficient

  49. what is Dwav

    Wave Drag: Drag resulting from compressibility effects • Caused by shock waves appearing around the airfoil, causing additional drag Reduced with supercritical airfoils • Has zero-lift and lift-related component

  50. what is Di

    Vortex-Induced Drag: Drag resulting from trailing vortices at the tips of a finite wing (3-D effect)

  51. what is Dm

    Trim Drag: Change of drag due to the tail-plane’s contribution at a trim condition

  52. how to reduce induced drag

    Decreasing the lift, L, i.e. weight of the aircraft – Increasing the aspect ratio A – Change e, the spanwise lift distribution

  53. equations for induced drag and induced drag coefficient

  54. what does the transition from laminar to turbulent flow on the aerofoil depend on?

    Reynolds number (i.e. aircraft velocity) Surface finish Free-stream turbulence intensity Geometry

  55. what happens to lift of the main wing and tail lift if the CG moves foreward

    if CG moves forward ac moves so h decreases as CLT depends on h, CLT decreases, as L* remains the same L must increase

  56. trim drag equation?

  57. what is equation

  58. what is CDL* equation

  59. what is the minimum CDm

  60. overall aircraft drag after trim can be expressed s