Subsonic Aerodynamics Part 2 Flashcards
The region of this shearing action between the surface and the full velocity is knows as the -
boundary layer
Relevant to the boundary layer: there is a gradual increase in velocity as the distance from the surface -
increases
Aspect ratio is -
the ratio between the span of a wing and its chord
In the case of swept wings or wings of unusual shape, the aspect ratio formula is -
span² / area
the unit for density is -
g/m3 or kg/m3
Dynamic pressure in the lift formula is -
1/2 𝜌 V²
Air density is -
1/2 𝜌
Metres to feet is?
3.28
Vs =
√weight / Cl(max) 1/2 p s
Assuming no flow separation and no compressibility effects, the location of the centre of pressure of a symmetrical aerofoil section:
Is at approximately 20% chord irrespective of angle of attack
Which flap: The type of flap that slides rearwards and then downwards?
fowler flap
Which flap: There is a gap or slot between the wing and the flap. This allows higher pressure air from below the wing to flow over the upper surface of the flap which effectively delays the normal airflow separation and the stall.
Slotted flap
The type of wing that will produce a “nose-up” pitch during stall is?
The sweepback wing
The lift coefficient (CL) of an aeroplane in steady horizontal flight is 0.4. Increase of angle of attack of 1 degree will increase CL by 0.09. A vertical up gust instantly changes the angle of attack by 5 degrees. Describe in detail how to calculate:
Load factor is L / W Thus, in level flight( when lift is equal and opposite weight) LF = 1 In this question, our original lift value in level flight equals 0.4. Thus, load factor = 0.4 / 0.4 which is 1. LF = 1 Our lift increase by 0.85 ( 0.4 + 0.45) Thus, 0.85 / 0.4 = LF 2.13.
Which of the following wing planforms produces the lowest induced drag? (all other relevant factors constant)
Elliptical.
