Which of these statements about the gust load factor on an aeroplane are correct or incorrect?
I. When the wing area increases, the gust load factor decreases.
II. When the EAS increases, the gust load factor increases.
Refer to figure.
A gust is a localized sudden and rapid change to the speed of the air in the atmosphere that can be either horizontal or vertical. The horizontal gust is of little importance because it causes a change to an airplane’s dynamic pressure that results in an insignificant change to the load factor. The vertical gusts are far more important because they change the effective angle of attack, total lift, and the load factor.
The gust load is the extra load imparted to the airplane by vertical gusts or turbulence. Its magnitude is unaffected by increased altitude but is increased with increased aspect ratio and/or decreased mass.
The load factor for any given angle of attack can be derived from the basic load factor for the normal cruise angle of attack because it is increased by the same percentage as the increase of angle of attack.
High wing loading reduces the ‘g’ increment in a gust. This is because the lift increment produced is a smaller proportion of the original lift force for the more heavily loaded aircraft.
For a given TAS and gust speed, the increase of lift will be proportional to the wing area. Therefore, the increase in load factor is inversely proportional to the wing loading.
Wing Loading = Weight/(Wing Area)
Therefore, statement 1 is incorrect.
The load factor deriving from a gust is determined by the magnitude of the vertical velocity of the gust and the forward speed of the airplane. An increase in speed results in an increased gust load factor. Therefore, statement 2 is correct.
Your Notes (not visible to others)
This question has appeared on the real examination, you can find the related countries below.
-
Greece