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Matthias Nott
2026-03-23 2fcb4fb3d911a5eb6ee57d0e9195252c05505248 
 SPL Exam Questions EN/80 - Principles of Flight.md
....@@ -126,6 +126,8 @@
126126 CG = Centre of Gravity
127127 ### Q7: What purpose does the vertical tail fin (rudder assembly) serve? ^t80q7
128128 
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129131 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q7) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q7)
130132 
131133 - A) Providing roll stability
....@@ -378,6 +380,8 @@
378380 The minimum sink rate speed is the speed at the lowest point of the speed polar. Any speed change — faster or slower — from this point increases the sink rate. Accelerating beyond minimum sink speed increases parasite drag faster than induced drag decreases, resulting in a higher total drag and therefore a greater rate of descent. This is the trade-off in cross-country flying: flying faster covers more ground but at the cost of increased sink rate.
379381 
380382 ### Q20: What is the effect of extending airbrakes (spoilers) on a glider? ^t80q20
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382386 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q20) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q20)
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12901294 
12911295 > **Speed Polar:**
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-> ![[figures/t80_q66.png]]
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+> ![](figures/t80_q66.png)
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12951299 > *A = tangent from the origin → best glide speed (best L/D ratio, best glide)*
12961300 > *B = tangent from a point shifted to the right on the V axis → best glide with headwind*
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14751479 
14761480 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q75) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q75)
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14801484 - A) The air mass flows through a larger cross-section at a higher speed
14811485 - B) The air mass flows through a smaller cross-section at a lower speed
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15091513 
15101514 ### Q77: When the frontal area of a disc in an airflow is tripled, drag increases by: ^t80q77
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15121518 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q77) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q77)
15131519 
15141520 - **A)** 9 times
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15181524 
15191525 #### Answer
15201526 
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-B)
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+C)
15221528 
15231529 #### Explanation
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-Stall occurs at a critical angle of attack (stall angle), regardless of airspeed. At this angle, airflow separation on the upper surface causes a sudden drop in lift.
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+The drag equation is D = ½ × rho × V² × Cd × A, where A is the frontal (reference) area. Drag is directly proportional to frontal area: if A triples, drag triples.
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+- **A (9 times)** is wrong — that would apply if drag were proportional to A² (it is not).
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+- **B (1.5 times)** is wrong — there is no ½ factor when scaling area.
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+- **D (6 times)** is wrong — no physical basis for this multiplier.
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+- **C (3 times)** is correct because D is linearly proportional to A.
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+#### Key Terms
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+- **D** — Drag force
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+- **rho** — ρ (rho) — air density
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+- **V** — Velocity / Airspeed
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+- **Cd** — Drag Coefficient — dimensionless shape-dependent factor
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+- **A** — Frontal Area — cross-sectional area perpendicular to the airflow
15261545 
15271546 ### Q78: Aerodynamic wing twist (washout) is a modification of: ^t80q78
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+![](figures/t80_q78.png)
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15291550 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q78) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q78)
15301551 
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15391560 
15401561 #### Explanation
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-Airflow separation occurs at a determined angle of attack (critical angle), specific to each airfoil. It is not related to the nose attitude relative to the horizon.
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+There are two types of wing twist (washout):
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+- **Geometric washout** changes the angle of incidence of the SAME aerofoil from root to tip (the wing is physically twisted so the tip has a lower angle).
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+- **Aerodynamic washout** changes the AEROFOIL PROFILE from root to tip (different cross-sections are used so the tip section has a lower zero-lift angle or stalls at a higher local angle of attack).
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+The question specifically asks about "aerodynamic wing twist," which is the aerofoil profile change (B). Both types aim to make the wing root stall before the tip, preserving aileron effectiveness during stall.
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+- **A** describes geometric washout, not aerodynamic washout.
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+- **C** is wrong — ailerons change angle of attack dynamically, not as a permanent design feature.
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+- **D** is wrong — dihedral is a separate concept (wing angled upward for lateral stability).
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+#### Key Terms
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+- **Washout** — wing twist that reduces lift at the tip to delay tip stall
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+- **Geometric washout** — same profile, twisted to lower incidence at the tip
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+- **Aerodynamic washout** — different profiles from root to tip
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+- **Dihedral** — upward angle of the wing from root to tip for lateral stability
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15431581 
15441582 ### Q79: What is the average value of gravitational acceleration at the Earth's surface? ^t80q79
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15791617 Airspeed indicator reading is based on the difference between static pressure and total pressure (dynamic pressure). The ASI measures this difference via the Pitot tube and static port.
15801618 
15811619 ### Q81: The horizontal and vertical stabilisers serve in particular to: ^t80q81
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15831623 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q81) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q81)
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16911731 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q87) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q87)
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16951735 - **A)** Fowler
16961736 - **B)** Split Flap
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17481788 
17491789 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q90) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q90)
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17531793 - **A)** M
17541794 - **B)** K
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18631903 
18641904 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q95) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q95)
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18681908 - A) H
18691909 - B) B
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20302070 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q102) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q102)
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20342074 - A) Plain Flap
20352075 - B) Split Flap
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23632403 
23642404 ### Q117: The elevator causes the aircraft to rotate around the ^t80q117
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23662408 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q117) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q117)
23672409 
23682410 - **A)** Longitudinal axis
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24072449 
24082450 CG = Centre of Gravity
24092451 ### Q119: What benefit does differential aileron deflection provide? ^t80q119
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24112455 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q119) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q119)
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27212765 - **CL_max** — Maximum Lift Coefficient — highest CL the wing can produce before stalling
27222766 ### Q133: What is the aerodynamic effect of deploying airbrakes? ^t80q133
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27242770 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q133) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q133)
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27262772 - A) Both drag and lift increase
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28772923 
28782924 ### Q140: What happens when the rudder is deflected to the left? ^t80q140
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28802928 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q140) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q140)
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28822930 - **A)** The aircraft pitches to the right
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30113059 - Pilots experience ground effect as a floating sensation during the landing flare.
30123060 
30133061 ### Q146: Rudder deflections rotate the aircraft around the ^t80q146
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30153065 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q146) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q146)
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31703220 
31713221 ### Q153: If the right aileron deflects upward and the left aileron deflects downward, how does the aircraft react? ^t80q153
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31733225 [DE](../SPL%20Exam%20Questions%20DE/80%20-%20Grundlagen%20des%20Fliegens.md#^t80q153) · [FR](../SPL%20Exam%20Questions%20FR/80%20-%20Principes%20du%20vol.md#^t80q153)
31743226 
31753227 - **A)** Rolling to the right with yaw to the left