Physics of the Atmosphere
Not publishedof exam
Aerodynamics and Airflow
Not publishedof exam
Lift and Drag
Not publishedof exam
Theory of Flight
Not publishedof exam
Four ForcesStallLoad FactorGlide RatioHigh-Lift Devices
Flight Stability and Dynamics
Not publishedof exam
LongitudinalLateralDirectionalDihedralCG Effects
Quick Facts
- Exam
- Module 8
- Credential
- Part-66 AML
- Questions
- 24
- Time
- 30 min
- Pass
- 75%
- Format
- MCQ, 3 options (real exam)
- Level
- A: L1; B1/B2/B3: L2
- Blueprint
- Reg (EU) 2023/989
ISA Sea-Level Numbers
15°C, 1013.25 hPa, lapse 1.98 per 1000ft
15°C temperature1013.25 hPa pressure1.98°C per 1000ft lapse
Density Altitude vs Pressure Altitude
Pressure Altitude
- Altimeter set to 1013 hPa
- No temperature correction
Density Altitude
- Pressure altitude, temp corrected
- Hot day raises it
Raw vs corrected altitude
Atmosphere Value Lookup
- Need the sea-level datum→15°C and 1013.25 hPa
- Need the lapse rate→1.98°C per 1000 ft
- Need the tropopause altitude→36,090 ft
- Need the tropopause temperature→Constant -56.5°C
ISA Datum
- Sea-level temp
- 15°C (288.15 K)
- Sea-level pressure
- 1013.25 hPa
- Lapse rate
- 1.98°C per 1000 ft
- Tropopause altitude
- 36,090 ft
- Tropopause temp
- Constant -56.5°C
- Pressure decay
- Exponential with altitude
Density and Humidity
- Density vs altitude
- Decreases with height
- Humid air density
- Less dense than dry
- Relative humidity
- Actual vs max vapor ratio
- Dew point
- Saturation temp, condensation begins
- Density altitude
- Pressure altitude, temp corrected
- Hot day effect
- Density altitude rises, performance drops
Laminar vs Turbulent Flow
Laminar Flow
- Lower skin friction
- Separates earlier
Turbulent Flow
- Higher skin friction
- Resists separation longer
Smooth vs mixed flow
Boundary Layer
- Boundary layer
- Viscosity-slowed air near surface
- Laminar flow
- Smooth, low skin friction
- Turbulent flow
- Mixed, higher skin friction
- Transition point
- Laminar to turbulent
- Turbulent vs separation
- Resists separation longer
- Separation cause
- Adverse pressure gradient
Washout vs Wash-in
Washout
- Tip incidence lower
- Root stalls first
Wash-in
- Tip incidence higher
- Rarely used, riskier
Lower tip vs higher tip
Aerofoil Geometry
- Chord line
- Leading to trailing edge
- Camber
- Curvature of mean line
- MAC
- Reference for CG/AC position
- Aspect ratio
- Span squared over area
- Fineness ratio
- Chord over max thickness
- Washout
- Tip incidence lower than root
- Wash-in
- Tip incidence higher than root
Airflow Patterns
- Free stream
- Undisturbed air, ahead of aircraft
- Relative airflow
- Opposite to flight path
- Upwash
- Air drawn up ahead of wing
- Downwash
- Air deflected down behind wing
- Stagnation point
- Zero velocity, max pressure
- Tip vortices
- Spanwise flow at wingtip
- Strongest vortices
- Slow, heavy, clean config
Drag Crossover Point
Induced drag falls, parasite drag rises with speed
Induced: high at slow speedParasite: high at fast speed
Induced vs Parasite Drag
Induced Drag
- Lift by-product
- Falls as speed rises
- Caused by tip vortices
Parasite Drag
- Not lift-dependent
- Rises with speed squared
- Form plus skin friction
Speed down vs speed up
Drag Type Identifier
- Drag falls as speed rises→Induced drag
- Drag rises with speed squared→Parasite drag
- Wingtip vortices are present→Induced drag source
- Skin friction plus form drag→Parasite (profile) drag
- Total drag is minimum→Induced equals parasite drag
Bernoulli and Pressure
- Bernoulli principle
- Velocity up, static pressure down
- Total pressure
- Static plus dynamic pressure
- Dynamic pressure (q)
- Half rho V squared
- Venturi throat
- Higher velocity, lower pressure
Angle of Attack vs Incidence
Angle of Attack
- Chord to relative airflow
- Varies during flight
Angle of Incidence
- Chord to aircraft axis
- Fixed rigging angle
Variable vs fixed
Lift Equation
- Lift formula
- CL times half rho V² S
- Lift vs speed
- Varies with V squared
- rho
- Air density
- CLmax
- Just before critical angle
- Angle of attack
- Chord line to relative airflow
- Angle of incidence
- Chord to aircraft axis, fixed
- Aerodynamic centre
- About 25% chord, subsonic
Drag Types
- Induced drag
- Lift by-product, tip vortices
- Induced drag vs speed
- Greatest at low speed
- Parasite drag
- Form, skin friction, interference
- Parasite drag vs speed
- Rises with speed squared
- Profile drag
- Parasite drag of wing section
- Min total drag
- Where induced equals parasite
- Polar curve
- CL vs CD, best L/D
Four Forces Balance
Lift equals weight; thrust equals drag
Lift up, weight downThrust forward, drag back
Stall Behavior Check
- AoA exceeds the critical angle→Wing stalls, lift drops
- Load factor increases in a turn→Stall speed rises
- One wing is more stalled→Aircraft enters a spin
- Buffet felt before the stall→Separated turbulent airflow
- Need a lower stall speed→Extend flaps or slats
- Ice contaminates the wing→Stall speed increases
Four Forces and Equilibrium
- Four forces
- Lift, weight, thrust, drag
- Level flight
- Lift = weight, thrust = drag
- Clean config
- Flaps and gear retracted
- Glide, no thrust
- Weight component drives forward
- Glide ratio 10:1
- 10 ft forward per ft down
Stall and High-Lift Devices
- Stall cause
- Critical AoA exceeded
- Critical AoA
- About 15-16°, fixed per aerofoil
- Stall speed
- Varies with weight, load
- Stall warning
- Buffet from separated airflow
- Spin
- Autorotation, one wing more stalled
- Flaps effect
- More camber, lower stall speed
- Slats/slots
- Re-energize the boundary layer
- Contamination effect
- Raises the stall speed
Load Factor and Envelope
- Load factor
- Lift divided by weight
- Level turn
- Load factor above 1g
- Stall speed vs load
- Rises with square root
- 2g turn
- Stall speed times 1.41
- V-n diagram
- Load factor vs airspeed limits
Three Axes of Stability
Pitch tailplane, roll dihedral, yaw fin
Longitudinal: tailplaneLateral: dihedralDirectional: fin
Static vs Dynamic Stability
Static Stability
- Initial tendency only
- Return toward trim
Dynamic Stability
- Motion over time
- Damped or diverging
First instant vs history
Stability Axis Picker
- Pitch oscillates after a gust→Tailplane provides restoring moment(Longitudinal)
- Wing drops in sideslip→Dihedral rolls it back level(Lateral)
- Nose yaws off heading→Fin weathercocks it back(Directional)
- Wing is swept back→Acts like added dihedral(Lateral boost)
- CG moves aft→Pitch stability weakens(Check limits)
Stability Axes
- Longitudinal stability
- Pitch axis, tailplane provides
- Lateral stability
- Roll axis, dihedral provides
- Directional stability
- Yaw axis, fin provides
- Sweepback
- Adds dihedral-like roll stability
- Aft CG effect
- Reduces longitudinal stability
Static and Dynamic Stability
- Static stability
- Initial return tendency only
- Dynamic stability
- How motion develops over time
- Positive dynamic
- Oscillations decreasing over time
- Neutral dynamic
- Oscillations of constant amplitude
- Negative dynamic
- Oscillations increasing, diverging
- Dutch roll
- Combined yaw-roll oscillation
Common Traps
Angle of Attack vs Incidence
AoA: chord to airflow ≠ Incidence: chord to aircraft, fixed
Static vs Dynamic Stability
Static: initial tendency only ≠ Dynamic: motion over time
Induced vs Parasite Drag
Induced: falls with speed ≠ Parasite: rises with speed
Washout vs Wash-in
Washout: tip incidence lower ≠ Wash-in: tip incidence higher
Density Altitude vs Pressure Altitude
Pressure alt: no temp correction ≠ Density alt: temp corrected
Laminar vs Turbulent Boundary Layer
Laminar: low friction, early separation ≠ Turbulent: high friction, resists separation
Real Exam vs This Practice Bank
Real EASA exam: 3 options ≠ This practice bank: 4 options
Last Minute
- 1.ISA: 15°C, 1013.25 hPa sea-level
- 2.Lapse rate: 1.98°C per 1000ft
- 3.Tropopause: 36,090 ft, -56.5°C
- 4.Lift varies with velocity squared
- 5.Induced drag: high at low speed
- 6.Parasite drag: high at high speed
- 7.Critical AoA fixed near 15-16 degrees
- 8.Stall speed rises with load factor
- 9.Longitudinal stability: tailplane; lateral: dihedral
- 10.Directional stability comes from the fin
- 11.24 questions in 30 minutes
- 12.Real exam uses 3-option MCQs
- 13.Pass mark is 75% per module
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