Assertion: airfoil's angle | /r/HasProperty | 20°
Facets:
value: usually
type: DEGREE
Source sentences:
text: As said earlier, the stalling angle is usually 20°.
text: An excessive angle of attack, referred to as the critical angle of attack (usually about 20°) will produce a stalled condition—laminar airflow above the wing is displaced by turbulent airflow, and differential pressure collapses.