Tech Questions 2

  1. o 15ft
    • o q26
    • 27. State the critical engine on a jet during take off?
    • o Nil in head wind
    • o The most upwind engine in crosswind due to increased yaw if engine fails (weather cocking).
    • o In the cruise the outboard engines of a 4 engine aircraft are critical.
    • o Beech 1900d Left engine
    • o q27
    • 28. What effect does a balanced field have on take off performance?
    • o A balanced field means that it is critical that an abort is carried out immediately on engine failure recognition.
    • o Also that the take off on one engine could be marginal if continued as a balance field is a take off right on performance limits for the given aircraft weight - not favourable.
    • o q28
    • 29. Definition of second segment of take off path?
    • o From gear retraction to level acceleration altitude, which is normally a minimum of 400 ft above take off surface. In this segment the gear is retracted, the flaps are in take off position and the aircraft is set in take off power. The speed is equal to V2 (initial climb out speed) and the required minimum gross gradient of climb, in a two engined aircraft, is 2.4%. The net flight path gradient is the gross flight path gradient reduced by 0.8%, i.e 1.6%.
    • o Conditions are
    • o Landing gear is retracted
    • o Flaps are still in take off position
    • o Speed is V2
    • o The minimum gross climb gradient in a twin engined aircraft is 2.4%
    • o The minimum net climb gradient in a twin engined aircraft is 1.6% and
    • o take off power is still set.
    • o q29
    • 30. Definition if ISA
    • o 1013.25 hPa (29.92"hg)
    • o 15 degrees Celcius
    • o Lapse rate is 1.98 degrees celcius per 1000' up to 36,090' then -56.5 degrees celcius
    • o Density is 1.225 kg/m3
    • o q30
    • 31. Temperature at 39,000ft?
    • o -56.5 degrees celcius
    • o q31
    • 32. Aircraft maintains a constant IAS in climb, what happens to TAS & LSS & Mach?
    • o Constant IAS
    • o TAS will increase
    • o LSS will decrease
    • o Mach will increase
    • o q32
    • 33. How does temperature affect the speed of sound?
    • o The speed of sound is directly proportional to the square root of the absolute temperature (the speed of sound will increase with an increase in temperature)
    • o LSS =38.94^K
    • o At sea level ISA LSS=661kts
    • o At 35,000' ISA LSS=575kts
    • o q33
    • 34. Airspeed in a climb at a constant TAS/IAS/Mach No. What do each other do?
    • o Constant IAS = Both TAS & Mach No INCREASE
    • o Constant Mach No = Both IAS & TAS DECREASE
    • o Constant TAS = Mach No INCREASE, IAS DECREASE
    • o q34
    • 35. Cruise Mach No is more limiting when?
    • o In warm temperatures
    • o The higher the aircraft flies
    • o *When Mach number is reduced (high altitudes) and when TAS is reduced (warm temperatures)*
  2. o Mach No = TAS
    o LSS
  3. q35
    • 36. What happens to the speed of sound with altitude / temperature?
    • o LSS reduces with altitude and with cooling temperatures
    • o q36
    • 37. Formula for True Altitude?
    • o TA = Actual temp (K) x Indicated altitude
    • o . ISA temperature (K)
  4. True altitude is your actual altitude above mean sea level, no errors.
  5. Absolute altitude is your height above ground.
  6. q37
    • 38. Formula for Mach No?
    • o M = TAS / LSS
    • o q38
    • 39. Explain airspeed errors?
    • o IAS - Position error - CAS - Compressibility error - EAS - Density error - TAS
    • o q39
    • 40. What errors does a Mach meter NOT suffer from?
    • o Density error and compressibility error
    • o q40
    • 41. The two capsules in a Mach meter are what?
    • o Airspeed
    • o Altitude calibration
    • o q41
    • 42. Mfs is...
    • o Free stream Mach Number - airflow unaffected by the aircraft
    • o q42
    • 43. Ml is...
    • o Local Mach number - is the speed of air relative to the local speed of sound measured at a point on the aircraft.
    • o q43
    • 44. Mcrit is...
    • o The lowest free stream Mach number at which Mach 1 is reached on any part of the aircraft.
    • o MCRIT is the critical Mach number. This is the speed at which the airflow over certain parts of the airframe (most likely the point of maximum camber of the aerofoil) reaches M1.0. MCRIT is increased through slimness and through the use of sweepback.
    • o q44
    • 45. How does weight affect Mcrit?
    • An increase in weight will reduce Mcrit
  7. q45
    • 46. Drag divergence Mach number is...
    • o The increase in drag associated with compressibility effect (110-115% of Mcrit)
    • o q46
    • 47. What happens to the centre of pressure (CP) leading up to super sonic flight?
    • o The CP is well forward (below Mcrit)
    • o The CP moves rearward (in excess of Mcrit)
    • o The CP moves forward Mcrit - Mfs > M1
    • o The CP gradually moves further rearward as speed increases further
    • o q47
    • 48. Wave drag is...
    • o The separation of the airflow behind the shock wave
    • o q48
    • 49. A shock stall is the result of...
    • o The boundary layer behind the shock wave becoming turbulent and separating, spilling rearwards and striking the tailplane, creating buffet and rearwards CP movement. Rear movement of the CP causes nose pitch down.
    • o q49
    • 50. Wing design for high speed flight takes into consideration..
    • o Minimal camber to delay shock waves
    • o Manoeuvrability
    • o Low thichness chord ratio
    • o q50
    • 51. The primary purpose of sweep back is to..
    • o Increase the value of the critical mach number
    • o q51
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Tech Questions 2
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