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Principles of flight
This occurs when a certain angle for the given wing profile is exceeded.
This angle is called the critical angle of attack.
5.3.6.5 Relationship between lift and the angle of attack
The diagram below shows the relationship between the angle of attack and lift.
When the angle of attack reaches a certain size (the shown profile is about 19),
turbulent airflow begins to form on the upper surface of the wing.
Further increases in the angle of attack will lead to a stall, where lift decreases
(for the profile
shown here, this
happens at around
20).
The critical angle of
attack varies from
profile to profile but
remains constant
for a given profile.
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5.3.7 Drag
There are different types of drag acting on the aircraft:
- Profile drag
o Form drag
o Friction drag / surface drag / skin friction drag
- Induced drag
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 457
