Free PPL principles of flight 080 questions: 9 with answers
9 principles of flight questions from the PPL bank of ForAllPilots, with no account and no sign-up. Answer in your head, then open the answer: the right letter and its explanation are under each question. The full bank has 419 questions for this subject.
The 9 questions
Question 1 · 1 Subsonic aerodynamics
All other things being equal, when altitude increases:
- Alift increases and drag decreases.
- Blift decreases and drag increases.
- Clift and drag both decrease.
- Dlift and drag both increase.
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Answer: C. lift and drag both decrease.
Lift and drag formulas: L = ½ ρ S V² CL and D = ½ ρ S V² CD, where ρ = air density, S = wing area, V² = square of the speed, CL = lift coefficient, CD = drag coefficient. When altitude increases, air density decreases, so lift and drag both decrease.
Question 2 · 1 Subsonic aerodynamics
Wingtip vortices originate from:
- Athe propeller wake.
- Bthe pressure difference between the upper and lower surfaces.
- Cthe transition zone between the fuselage and the wing.
- Dthe shape of the fuselage.
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Answer: B. the pressure difference between the upper and lower surfaces.
Pressure is higher on the lower surface than on the upper surface: at the wingtips, air flows around the tip from the lower surface to the upper surface, which creates the wingtip vortices responsible for induced drag.
Question 3 · 2 Stall and high-lift devices
In level flight, starting from a stabilized speed, extending the flaps results in:
- Aan increase in indicated airspeed due to increased lift.
- Ba decrease in indicated airspeed due to increased wing drag.
- Can increase in both lift and drag, with the two effects offsetting each other so indicated airspeed does not change.
- Dan increase in lift due to the increased wing surface area, with indicated airspeed remaining constant.
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Answer: B. a decrease in indicated airspeed due to increased wing drag.
Extending the flaps causes an increase in both lift and drag. If power is not adjusted, this will result in a loss of speed.
Question 4 · 2 Stall and high-lift devices
An aircraft has a wings-level (1g) stall speed of 48 kt. What is its approximate stall speed in a level turn at 60° bank?
- A61 kt
- B48 kt
- C68 kt
- D75 kt
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Answer: C. 68 kt
Load factor n = 1/cos(60°) ≈ 2.0. Vs(turn) = Vs(1g) x √n = 48 x √2.0 ≈ 68 kt.
Question 5 · 3 Stability
Directional stability (about the yaw axis) is the aircraft's natural tendency to maintain:
- Aattitude.
- Bwings level.
- Csymmetry of flight.
- Daltitude.
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Answer: C. symmetry of flight.
Directional stability is the aircraft's tendency to return by itself to symmetrical flight (without sideslip) after a disturbance about the yaw axis. It is provided mainly by the fin.
Question 6 · 4 Control
The role of the ailerons is to control the aircraft in:
- Apitch.
- Broll.
- Cyaw.
- Daltitude directly.
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Answer: B. roll.
The ailerons, located on the trailing edge of the wings and deflected in opposite directions, control the aircraft's roll movement about its longitudinal axis.
Question 7 · 5 Limitations and propellers
The propeller's helical slipstream tends to cause:
- Ayaw due to the asymmetric impact of the swirling flow on the vertical tail.
- Ba systematic increase in stall speed.
- Cno effect on yaw behavior.
- Dan effect only in inverted flight.
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Answer: A. yaw due to the asymmetric impact of the swirling flow on the vertical tail.
The helical airflow generated by the propeller strikes the fin and fuselage asymmetrically, contributing to a yaw effect, generally compensated for in cruise by tail/trim adjustment.
Question 8 · 6 Flight mechanics
On a strut-braced wing, the load borne by the struts in a turn is double the load in straight flight for a bank angle of:
- A90°.
- B45°.
- C60°.
- D30°.
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Answer: C. 60°.
At 60° of bank, the load factor equals 2, which also means that the wing develops twice as much lift (force). The loads are therefore multiplied by 2.
Question 9 · 6 Flight mechanics
In calm air, with no wind, the glide ratio corresponds to the ratio of:
- Aheight lost / distance covered.
- Bheight lost / airspeed.
- Cdistance covered / vertical speed.
- Ddistance covered / height lost.
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Answer: D. distance covered / height lost.
There are several ways to define the glide ratio: - the Lift/Drag ratio. - the ratio of distance covered / height lost while gliding. - the ratio of horizontal speed / vertical speed.
Each answer was checked again before publication; like every explanation on the site, these may contain errors. Some explanations were rewritten for this page, sometimes with the help of an AI. Spotted a mistake? Write to us at contact@forallpilots.com.
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