L1 Instructor Self Test Part 2 Basic Theory.txt

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L1 Instructor Self Test Part 2 Basic Theory.txt
2012-09-06 08:23:25
Gliding Instructor Theory

L1 Instructor Basic Theory
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  1. What happens to lift and induced drag when the angle of attack of the wing is increased?
    They both increase (BGK)
  2. In what proportion do profile and induced drag increase with an increase in speed?
    Profile drag increases as the square of the airspeed, induced drag increases as the inverse square of the airspeed (BGK)
  3. What is the name of the speed at which total drag is at a minimum?
    The speed for minimum drag (BGK)
  4. What is the primary turning control?
    The ailerons (BGK)
  5. Why is it necessary to apply a certain amount of back stick in a turn?
    Theory: to increase lift Practice: to prevent the nose falling (BGK)
  6. What is the difference between rough air speed and manoeuvre speed?
    Rough air speed (Vra) is the speed above which strong gusts may damage the glider. Manoeuvre speed (Va) is the speed above which only one-third deflection of the aileron and rudder controls are permitted and the elevator must be used to keep applied "G" forces within permitted limits (BGK)
  7. What is VNE?
    The maximum permitted speed in smooth air (BGK)
  8. Why must VNE be reduced with an increase in height?
    At constant TAS, IAS decreases with height because air density decreases.
  9. In the absence of placarded information, by how much would you reduce VNE with height?
    If no placard, reduce VNE by 1.5% per 1,000 feet from placarded VNE (BGK)
  10. What happens to the stall speed with a forward movement in centre of gravity?
    It increases. Heavier tailplane download detracts from the tailplane's contribution to total lift, resulting in a marginal increase in stalling speed
  11. What happens to the stalling speed on a winch/auto launch?
    It increases, because of a combination of cable weight and cable download
  12. What is the minimum speed to allow a glider to enter the climb on a winch/auto launch?
    1.3Vs (BGK, IH)
  13. What is the standard recovery action from a fully-developed spin?
    Full opposite rudder, central ailerons stick progressively forward until spinning stops, centralise rudder and recover from dive (BGK, IH)
  14. What is lateral damping?
    Resistance to rolling, because of increased angle of attack (increased lift) of the downgoing wing. Loss of lateral damping is the primary cause of the onset of autorotation (BGK)
  15. What is the difference between the observed secondary effect of rudder at 1.5 Vs and 1.2Vs?
    At 1.5Vs there is a marked yaw, followed after a short delay (2-3 seconds) by a developing roll, with noticeable deflection of the yaw string. At 1.2Vs, there is roll as soon as the rudder is applied, with no discernible yaw and little or no deflection of the yaw string (Refer NGS "blue pages" and note that some training gliders do this demonstration better than others)
  16. What effect does extension of the airbrakes have on the stalling speed?
    An increase in stalling speed of 2-5 knots. Retraction of airbrakes in a mishandled landing restores much-needed energy to the wings (BGK)
  17. What effect does downward extension of flaps have on the stalling speed?
    A reduction in stalling speed (BGK)
  18. What effect does downward extension of flaps have on the glide angle?
    It makes the glide angle worse, because of the increase in both kinds of drag
  19. Define "safe speed near the ground".
    1.5Vs (everybody knows that!)
  20. What is "autorotation"?
    Loss of lateral damping leads to one wing stalling and the glider rotates in the direction of the falling wing. Due to the large increase in AoA as this "inner" wing drops, with no lateral damping to stop it, the AoA increases even further, the drag increase is very large and a continuous rotation is encouraged. The "outer" wing remains virtually unstalled (BGK)
  21. what is the purpose of an "anti-balance tab" and where would you be likely to find one?
    Anti balance tab moves in the same direction as a control surface, making it more difficult to move the control surface and giving the pilot an improved "feel" (usually in pitching plane), especially at high speeds. In gliders, usually combined with the trim tab e.g. ASK13
  22. Does the dihedral angle of a wing have any effect in turning flight if sideslip is not present?
    None noticeable
  23. What effect does water-ballast have on the maximum L/D ratio of a glider?
    Does not change the L/D ratio, but causes it to occur at a higher airspeed
  24. If a variometer system is "over-compensated", what indication will the pilot get when pulling up into a thermal from a fast glide?
    A "down" indication
  25. What kind of stability is desirable in the rolling plane?
    Neutral stability, provided no slip is present (BGK)
  26. What is the difference between the static and dynamic pitch stabilities of a glider?
    Static stability is what the glider tends to do immediately after it has been displaced in pitch and the elevator control released. All gliders must be statically stable. Dynamic stability is what the glider tends to do over a period of time after the static stability has been checked. It is acceptable for a glider to be dynamically neutral or even unstable and most modern gliders are exactly in this category
  27. What is the effect of rain on a laminar-flow wing and what does the pilot do about it?
    Rain degrades the laminar flow, increases the stalling speed and causes a marked loss of performance. The pilot should add at least 5 knots to the speed and anticipate an increase in the sink rate and degradation in the glide angle of about 20%
  28. What is the difference between a spoiler and an airbrake?
    Spoiler: limited ability to control descent rate and is not speed-limiting. Airbrake: better ability to control descent rate and is speed-limiting in a 30 degree dive. Some older airbrake designs may be speed-limiting in a vertical dive (BGK)
  29. What is a "drag bucket"?
    This refers to the shape of the area where the profile and induced drag curves cross over. Rather than being an actual point at which they cross, there is a larger area, encompassing a reasonably wide speed range, at which total drag is at a minimum. This area is fondly imagined to be bucket-shaped, hence the name.
  30. What is a "netto" or "air mass" variometer?
    The netto system is a total-energy vario, from which the sink-rate of the glider at any given speed is subtracted, by means of a calibrated pitot leak. The "net" result is that the pilot is shown only the sink rate of the air through which the glider is flying
  31. What is a "high speed stall"?
    A stall during which the glider is in accelerated flight, that is, it is pulling "G" forces. Under such circumstances, the glider can be flown to its stalling angle of attack at an indicated speed much higher than the normal unaccelerated stall speed.
  32. Describe the cause and effect of aileron drag
    The downgoing aileron produces an increased AoA, the upgoing aileron produces a decreased AoA. Increased AoA means increased lift and also increased induced drag, which causes a yaw in the "adverse" direction
  33. What are "differential ailerons"?
    Ailerons in which the upward movement is greater than the downward movement (mostly 2 to 1, but may be 3 to 1). This reduces the induced drag of the downgoing aileron and makes more use of the upgoing aileron.
  34. What is the difference between a spin and a spiral dive?
    In a spin, the airspeed is low and constant (although ASI may be unreliable), the rotation rate is high (loss of lateral damping), the sound level is constant and minimal G forces. In a spiral dive, airspeed is high and increasing rapidly, the rotation rate is low (no loss of lateral damping), the sound level and G forces are increasing rapidly
  35. What is wind gradient?
    Wind gradient is the reduction in windspeed near the ground, due to ground friction
  36. What is the effect of wind gradient on a glider taking off?
    Rapidly increasing airspeed as the glider gains height. Due to inertia the glider cannot change speed quickly enough to match the rapidly changing speed of the airmass into which it is moving
  37. What is the effect of wind gradient on a glider approaching to land?
    Reduction in airspeed as the glider descends into the region of reducing windspeed. Due to inertia the glider cannot change speed quickly enough to match the rapidly changing speed of the airmass into which it is moving