Correct: B)
Explanation: The centre of gravity (CG) is determined by the distribution of mass within the aircraft, so only physically moving mass — such as shifting ballast, passengers, or baggage — changes it. Option A is wrong because changing angle of attack alters aerodynamic forces, not mass distribution. Option C is incorrect because the angle of incidence is a fixed structural dimension. Option D is wrong because the aerodynamic centre is a property of the wing shape, not of the aircraft's mass distribution.
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- A) Plain Flap
- B) Split Flap
- C) Slotted Flap
- D) Fowler
Correct: D)
Explanation: A Fowler flap moves rearward and downward, simultaneously increasing both wing area and camber, making it the most effective type of trailing-edge flap. The diagram shows this characteristic rearward extension. A plain flap (A) simply hinges downward without moving aft. A split flap (B) deflects only the lower surface panel. A slotted flap (C) opens a gap but does not significantly increase wing area like the Fowler design.
Correct: C)
Explanation: The aerodynamic centre is the point on the aerofoil through which the resultant of all aerodynamic pressure forces (lift and drag combined) is considered to act, and about which the pitching moment coefficient remains approximately constant with changes in angle of attack, located near the quarter-chord point. Option A is wrong because the centre of gravity is where weight acts, not aerodynamic forces. Option B is incorrect because the stagnation point is where airflow velocity is zero at the leading edge. Option D is not a standard aerodynamic term.
Correct: D)
Explanation: In the ICAO standard atmosphere, air density decreases approximately exponentially with altitude and reaches half its sea-level value at roughly 6,600 m (about 21,600 ft). Option A (2,000 ft) is far too low — density barely changes at that altitude. Option B (20,000 m) is in the stratosphere, where density is far below half. Option C (2,000 m) is also too low — density there is still about 80% of the sea-level value.
Correct: B)
Explanation: The ASI measures dynamic pressure, which is the difference between total (pitot) pressure and static pressure: q = ptotal - pstatic = 0.5 × rho × V². This differential measurement directly indicates airspeed. Option A is nonsensical — a weathervane measures wind direction, not pressure. Option C is wrong because measuring only total pressure without subtracting static pressure gives no speed information. Option D is also incorrect because static pressure alone tells you only about altitude, not airspeed.
Correct: D)
Explanation: Roll (lateral) stability — the tendency to return to wings-level after a disturbance — is primarily provided by wing dihedral and wing sweep, both of which create restoring roll moments when the aircraft sideslips after a bank disturbance. Option A is wrong because leading-edge slats are high-lift devices that delay stall, not stability features. Option B describes pitch motion, not roll stability. Option C is incorrect because the horizontal stabiliser provides pitch (longitudinal) stability, not roll stability.
Correct: C)
Explanation: The permitted speed range for flap operation varies between aircraft types and is always specified in the Aircraft Flight Manual (AFM), typically also indicated on the ASI as a white arc. Option A is dangerously wrong — flaps have structural speed limits. Option B is incorrect because the upper flap speed (VFE) is typically different from the manoeuvring speed (VA). Option D is wrong because the red radial line is VNE (never-exceed speed), which has nothing to do with the lower flap speed limit.
Correct: C)
Explanation: Geometric twist (washout) is a physical twist built into the wing so that the angle of incidence progressively decreases from root to tip. This ensures the root stalls first, preserving aileron effectiveness near the tips. Option A (aspect ratio) is the span-to-chord ratio. Option B (aerodynamic twist) achieves a similar stall progression by using different aerofoil profiles along the span rather than physical twist. Option D (interference compensation) is not a standard aerodynamic term for wing twist.
Correct: D)
Explanation: Atmospheric pressure follows an approximately exponential decay with altitude, as described by the barometric formula. Each equal altitude increment reduces pressure by the same percentage, not the same absolute amount. Option A is wrong because the relationship is exponential, not linear. Option B is obviously false — pressure clearly drops with altitude. Option C is incorrect because pressure continues to decrease in the stratosphere; it is temperature, not pressure, that stabilises or increases in the stratosphere.
Correct: B)
Explanation: The continuity equation for incompressible flow states A1 × V1 = A2 × V2 (area times velocity is constant). If the cross-section increases, velocity must decrease proportionally to maintain the same mass flow rate. Option A is wrong because velocity does change with cross-section. Option C reverses the relationship — velocity decreases, not increases, with a larger cross-section. Option D also reverses it — velocity increases through a smaller section, not decreases.
Correct: B)
Explanation: Point 4 on the boundary layer diagram (PFA-009) marks the separation point, where the boundary layer detaches from the upper wing surface due to an adverse pressure gradient, forming a turbulent wake behind it. Option A is wrong because the stagnation point is at the leading edge (point 1). Option C is incorrect because the centre of pressure is a theoretical force application point, not a boundary layer feature. Option D is wrong because the transition point (laminar to turbulent) occurs further forward on the surface.
Correct: C)
Explanation: Point 1 on the boundary layer diagram (PFA-009) is the stagnation point at the leading edge, where the incoming airflow divides into upper and lower streams, velocity is zero, and static pressure reaches its maximum. Option A is wrong because the transition point occurs further aft where laminar flow becomes turbulent. Option B is incorrect because the centre of pressure is a resultant force point, not a physical flow location on the leading edge.
Correct: C)
Explanation: The figure shows wing dihedral — the upward V-angle of the wings relative to the horizontal plane — which provides lateral (roll) stability. When one wing drops in a sideslip, the lower wing experiences a higher effective angle of attack, generating more lift and producing a restoring roll moment. Option A is wrong because directional stability comes from the vertical tail, not dihedral. Option B incorrectly identifies the axis — dihedral affects roll (lateral), not pitch (longitudinal) stability. Option D describes an aileron design feature unrelated to the figure.
Correct: C)
Explanation: Despite its potentially confusing name, longitudinal stability refers to pitch stability, which is rotation around the lateral axis (the axis running from wingtip to wingtip). It describes the aircraft's tendency to return to a trimmed pitch attitude. Option A is wrong because the vertical axis governs yaw (directional stability). Option B is incorrect because the longitudinal axis governs roll (lateral stability). Option D is not a recognised stability axis in standard aeronautical terminology.
Correct: B)
Explanation: Yawing is the rotation of the aircraft around the vertical (normal) axis, causing the nose to swing left or right. It is controlled primarily by the rudder. Option A (pitching) is rotation around the lateral axis. Option C (rolling) is rotation around the longitudinal axis. Option D (slipping) describes a flight condition with a sideways airflow component, not a specific rotational axis.
Correct: D)
Explanation: Pitching is the rotation of the aircraft around the lateral axis (wingtip to wingtip), resulting in nose-up or nose-down movement, controlled by the elevator. Option A (stalling) is an aerodynamic phenomenon of flow separation, not a rotational term. Option B (rolling) is rotation around the longitudinal axis. Option C (yawing) is rotation around the vertical axis.
Correct: B)
Explanation: The elevator controls pitch, which is rotation around the lateral axis (running from wingtip to wingtip). By deflecting the elevator, the pilot changes the aerodynamic force on the tail, creating a pitching moment that raises or lowers the nose. Option A is wrong because the longitudinal axis governs roll, controlled by ailerons. Option C is not a standard aeronautical axis. Option D is wrong because the vertical axis governs yaw, controlled by the rudder.
Correct: C)
Explanation: The centre of gravity position is determined solely by how mass is distributed within the aircraft — only correct loading of occupants, baggage, and ballast within approved limits ensures a safe CG. Option A is wrong because CG must be verified on the ground before flight using weight and balance calculations. Option B is incorrect because aileron trim tabs adjust roll forces, not mass distribution. Option D is also wrong because trim tabs change aerodynamic balance forces, they cannot physically move the CG.
Correct: D)
Explanation: Differential aileron deflection means the down-going aileron deflects less than the up-going aileron, which reduces the extra induced drag on the descending wing and thus minimises adverse yaw — the unwanted yawing opposite to the intended roll direction. Option A is wrong because the purpose is drag reduction, not increasing the drag-to-lift ratio. Option B is incorrect because total lift does change somewhat during aileron deflection. Option C states the opposite of the actual effect — differential ailerons decrease adverse yaw, not increase it.
Correct: B)
Explanation: An aerodynamic rudder balance (such as a horn balance or set-back hinge) positions part of the control surface ahead of the hinge line, so that aerodynamic pressure partially assists the pilot's input, reducing the force needed to deflect the control. Option A is incorrect because the purpose is force reduction, not improved effectiveness. Option C is wrong because stall delay is achieved by devices like slats or vortex generators, not control surface balancing. Option D makes no sense — aerodynamic balance does not reduce the size of control surfaces.
Correct: C)
Explanation: Static (mass) balancing places counterweights ahead of the hinge line to move the control surface's centre of mass to or forward of the hinge. This prevents flutter — a dangerous self-exciting aeroelastic oscillation that can destroy the control surface and airframe at speed. Option A is wrong because limiting stick forces is the role of aerodynamic balance, not mass balance. Option B is the opposite of any balancing goal. Option D is incorrect because force-free trimming is achieved by trim tabs, not mass balance.
Correct: C)
Explanation: An upward-deflected trim tab generates a downward aerodynamic force on the trailing edge of the elevator, which pushes the elevator's leading edge upward, creating a nose-down pitching moment. The trim indicator therefore shows a nose-down position. Option A is irrelevant — lateral trim concerns roll, not pitch. Option B would require the tab to be neutral. Option D is the opposite — a nose-up indication would require the trim tab to deflect downward.
Correct: D)
Explanation: Point 1 on the polar diagram (PFA-008) lies in the region of negative lift coefficient, representing inverted flight where the aircraft flies upside down and the wing produces downward lift relative to its normal orientation. Options A, B, and C all correspond to positive (upright) portions of the polar curve — slow flight is near maximum CL, stall is at CL_max, and best gliding angle is at the tangent point from the origin.
Correct: B)
Explanation: In a coordinated banked turn, the lift vector must support both the weight and provide centripetal force, so the load factor n = 1/cos(bank angle) is always greater than 1. The stall speed increases by the factor sqrt(n), because more lift is needed and thus a higher speed is required to avoid the stall. Options A and C are wrong because n is always above 1 in a level turn. Option D incorrectly states that Vs decreases — higher load factor always raises stall speed.
Correct: D)
Explanation: The pressure difference between the lower (high pressure) and upper (low pressure) wing surfaces causes air to flow around the wingtips, forming trailing vortices. These vortices create downwash that tilts the lift vector rearward, producing induced drag. Option A is wrong because wingtip vortices cause induced drag, not profile drag. Option B is incorrect because vortices create turbulent, not laminar, flow. Option C is false because vortices actually reduce effective lift by reducing the local angle of attack.
Correct: D)
Explanation: In a steady glide at the same mass, lift must equal weight regardless of the aerofoil thickness, so lift remains the same. However, a thicker aerofoil generates greater form (pressure) drag due to its larger cross-section and more severe adverse pressure gradients. Options A and C are wrong because a thicker profile produces more, not less, drag. Option B is incorrect because lift does not decrease — it is fixed by the weight requirement in steady flight.
Correct: D)
Explanation: A profile polar (Lilienthal polar) plots the lift coefficient (cA or CL) against the drag coefficient (cD or CD) at various angles of attack, showing how aerodynamic efficiency changes across the operating range. Option A describes only a CL-vs-alpha curve, not a polar. Option B relates to the speed polar of a glider, not a profile polar. Option C is imprecise — the polar shows the CL-CD relationship directly, not a simple ratio.
Correct: C)
Explanation: Any body in a moving airflow always experiences drag due to viscous friction and pressure forces opposing the motion — this is unavoidable in a real fluid. Lift, however, requires specific aerodynamic shaping or orientation. Option A is wrong because drag varies with the square of velocity, not constant. Option B is physically impossible — drag-free lift does not exist. Option D is incorrect because an arbitrarily shaped body is not guaranteed to produce lift; only specifically shaped or oriented bodies generate lift.
Correct: C)
Explanation: In the aerofoil diagram PFA-010, number 3 represents the camber line (mean camber line), which is the curved line equidistant between the upper and lower surfaces of the aerofoil. Options A and B both refer to the straight reference line from leading to trailing edge, which is a different feature. Option D (thickness) is the perpendicular distance between the upper and lower surfaces, not a line on the diagram.
Correct: C)
Explanation: Differential aileron deflection reduces adverse yaw by deflecting the down-going aileron less than the up-going aileron, thereby reducing the extra induced drag on the descending wing that causes the nose to yaw opposite to the intended turn. Option A is wrong because wing dihedral provides roll stability, not yaw compensation. Option B would actually worsen adverse yaw because full deflection maximises the drag asymmetry. Option D is not a valid answer — it merely repeats the question.
Correct: D)
Explanation: Wing loading is defined as total aircraft weight divided by wing reference area, expressed in units such as N/m² or kg/m². It determines stall speed, gust sensitivity, and overall handling characteristics. Option A (drag per weight) describes a drag-to-weight ratio. Option B is the inverse of wing loading. Option C (drag per wing area) is not a standard aeronautical parameter.
Correct: D)
Explanation: Point 5 on the polar diagram (PFA-008) corresponds to slow flight — a high angle of attack, low speed condition on the positive portion of the polar before reaching the stall point. Option A (best gliding angle) corresponds to the tangent from the origin touching the polar. Option B (inverted flight) would appear on the negative CL side. Option C (stall) is at the CL_max point, which is the very top of the polar, beyond slow flight.
Correct: C)
Explanation: Airbrakes (spoilers/dive brakes) serve to steepen the glide path by significantly increasing drag while simultaneously disrupting upper-surface airflow, which reduces lift. Option A is wrong because lift decreases with airbrakes deployed. Option B is incorrect because drag increases, not decreases. Option D reverses both effects — airbrakes increase drag and decrease lift.
Correct: D)
Explanation: Glide ratio (L/D) is maximised by minimising total drag while flying at the optimal speed. Cleaning surfaces reduces skin friction, taping gaps prevents leakage drag, retractable gear eliminates a major source of parasite drag, and maintaining best-glide speed keeps the aircraft at peak L/D. Option A is suboptimal because a forward CG increases trim drag. Option B is wrong because higher mass does not improve the L/D ratio itself. Option C omits important drag-reduction measures like taping gaps and surface cleaning.
Correct: B)
Explanation: In a spin, the inner (lower) wing is deeply stalled while the outer wing may still be producing some lift, creating autorotation at a near-constant, relatively low airspeed. In a spiral dive, neither wing is stalled, and the aircraft descends in a tightening bank with rapidly increasing airspeed. Option A incorrectly identifies the outer wing as stalled. Options C and D incorrectly assign speed characteristics — in a spin, speed is roughly constant; in a spiral dive, speed increases rapidly.
Correct: C)
Explanation: The longitudinal (fore-aft) position of the CG directly determines pitch stability, which is stability around the lateral axis. The CG must be forward of the neutral point for positive pitch stability; the further forward, the more statically stable but the heavier the elevator forces. Option A is wrong because the longitudinal axis governs roll stability, influenced by dihedral. Option B is not a standard axis. Option D is wrong because the vertical axis governs directional stability, influenced by the vertical tail.
Correct: C)
Explanation: The vertical tail fin acts as a weathervane, producing a restoring yawing moment whenever the aircraft sideslips, thereby providing directional (yaw) stability around the vertical axis. A larger fin provides greater stability. Option A (wing dihedral) provides lateral (roll) stability. Option B (elevator) contributes to pitch stability. Option D (differential aileron deflection) reduces adverse yaw but is not a stability feature.
Correct: D)
Explanation: In a climb at the same engine power, the aircraft flies slower because more energy goes into gaining altitude, requiring a higher angle of attack to maintain sufficient lift. Therefore, the level-flight angle of attack is smaller than in a climb. Option A reverses the relationship. Option B compares to take-off, which is not directly related to the question. Option C is incorrect because in a descent the aircraft accelerates, typically reducing AoA below the level-flight value.
Correct: A)
Explanation: The horizontal tail (stabiliser and elevator) provides longitudinal (pitch) stability, which is stability around the lateral axis. It generates restoring moments when the aircraft's pitch attitude is disturbed. Option B is wrong because turns around the vertical axis are initiated by the rudder. Option C is incorrect because vertical axis stability comes from the vertical tail. Option D is wrong because longitudinal axis (roll) stability is provided by wing dihedral and sweep.
Correct: D)
Explanation: When the rudder is deflected to the left, it produces a sideways aerodynamic force on the tail that pushes the tail to the right, yawing the nose to the left around the vertical axis. Options A and C are wrong because pitching is a nose-up/nose-down motion controlled by the elevator, not the rudder. Option B reverses the yaw direction — left rudder produces left yaw.
Correct: C)
Explanation: Differential aileron deflection gives the down-going aileron less deflection than the up-going aileron, reducing the drag asymmetry between the two wings during a roll input and thereby minimising adverse yaw. Option A is wrong because descent rate is controlled by airbrakes or speed, not aileron geometry. Option B is incorrect because stall prevention at low AoA is not an issue. Option D is wrong because wake turbulence is caused by wingtip vortices, not aileron design.
Correct: C)
Explanation: In a banked turn at constant altitude, the tilted lift vector must be large enough that its vertical component still equals weight while its horizontal component provides the centripetal force for the curved path. This means total lift must exceed the straight-and-level value, with the load factor n = 1/cos(bank angle). Option A is wrong because more, not less, lift is needed. Option B is imprecise — from the aircraft's reference frame it appears as centrifugal force, but the actual physics involves centripetal force. Option D does not fully describe the force balance requirement.
Correct: C)
Explanation: A retractable engine and propeller can be fully stowed inside the fuselage when not in use, completely eliminating the parasite drag from the powerplant and propeller during soaring flight. Options A, B, and D all involve fixed (non-retractable) installations that continuously produce drag even when the engine is shut down, because the propeller and engine cowling remain exposed to the airstream.
Correct: C)
Explanation: Adverse yaw occurs because the down-deflected aileron increases both lift and induced drag on its wing. This extra drag on the rising wing yaws the nose toward it — away from the intended direction of turn. Option A describes the opposite effect. Option B describes a secondary effect of rudder, not the primary adverse yaw phenomenon. Option D incorrectly attributes the extra drag to the up-deflected aileron, when in fact it is the down-deflected aileron that produces more drag.
Correct: A)
Explanation: When flying within approximately one wingspan of the ground, the ground surface restricts the full development of wingtip vortices, reducing downwash. This effectively increases the local angle of attack (more lift) and reduces induced drag simultaneously. Option B reverses both effects. Option C incorrectly states lift decreases. Option D incorrectly states induced drag increases. Pilots experience ground effect as a floating sensation during the landing flare.
Correct: D)
Explanation: The rudder controls yaw, which is rotation around the vertical axis, causing the nose to swing left or right. Option A is wrong because the longitudinal axis governs roll, controlled by ailerons. Option B is not a standard aeronautical axis designation. Option C is wrong because the lateral axis governs pitch, controlled by the elevator.
Correct: C)
Explanation: An upward gust suddenly increases the wing's angle of attack, temporarily generating lift in excess of the aircraft's weight. This additional lift translates into a load factor greater than 1, stressing the structure. Option A (forward CG) affects pitch stability and trim drag but does not directly cause load factor spikes. Option B (higher weight) means higher sustained loads but does not itself cause an increase in load factor n. Option D (lower density) reduces lift for a given speed, which would lower, not raise, the instantaneous load factor.
Correct: C)
Explanation: The McCready ring is always set to the expected climb rate in the next thermal (2 m/s in this case), and the recommended inter-thermal cruise speed is then read at the variometer needle position showing the current sink rate (3 m/s). Option A incorrectly sets the ring to the sink rate instead of the thermal strength. Option B sets the ring to zero, which would give a minimum-sink rather than optimal cruise speed. Option D erroneously adds the sink rate and climb rate together, which is not how McCready theory works.
Correct: C)
Explanation: During approach and landing, switching the camber flap from positive (increased camber, higher lift) to negative (reduced or reflexed camber) would cause a sudden and dramatic drop in lift close to the ground, potentially leading to a dangerous sink or ground contact. Option A is not universally correct — winch launch flap settings vary by type. Option B reverses the restriction. Option D is wrong because negative camber is a cruise setting, not appropriate for the high-lift-demand winch launch phase.
Correct: D)
Explanation: Point 3 on the boundary layer diagram (PFA-009) is the transition point, where the boundary layer changes from smooth laminar flow to turbulent flow. The position of this transition depends on Reynolds number, surface roughness, and pressure gradient. Option A (separation point) occurs further aft, where flow detaches entirely. Option B (centre of pressure) is not a boundary layer feature but a force application point. Option C (stagnation point) is at the leading edge, where flow velocity is zero.
