Subsonic

Parasite, Induced

-Two types of drag

Parasite Drag

-It is all drag that is not associated with the production of lift

Form, Skin,

Interference

-Type of Parasite Drag

Induced Drag

-Is that portion of total drag associated with the production of lift.

Airfoil

-is a streamline body which when set at a suitable angle of attack produces more lift than drag.

-Any surface such as an airplane wing, aileron, elevator.

Mean Camber Line

-is the line joining the midpoints between the upper and lower surfaces of an airfoil and measured normal to the mean camber line.

-Determines the camber (curvature) of the airfoil.

Chord Line

-Is the line joining the end points of the mean camber line.

Maximum Thickness

-the largest distance between the upper and lower surfaces of the airfoil, measured perpendicular to the chord line.

Thickness Ratio

-Is the maximum thickness to the chord ratio, 𝑡/𝑐

-Determines the aerodynamic efficiency of the airfoil (balance between lift and drag)

Maximum Chamber

-Is the maximum distance of the mean camber line from the chordline

Leading Edge Radius

-Is the radius of a circle tangent to the upper and lower surfaces, with its center located on a tangent to the mean camber line drawn through the leading edge of this line.

Velocity of air, V

Air density, ρ

Characteristic area or size, S

Coefficient of dynamic

viscosity, 𝜇

Speed of sound

(compressibility effect), 𝑉a

- Factors affecting the aerodynamic forces

Pressure Coefficient

-The pressure coefficient is a dimensionless number which describes the relative pressures throughout a flow field in fluid dynamics. The pressure distribution is normally expressed in terms of the

pressure coefficient 𝐶?

Critical Pressure

-It is the vapor pressure of a fluid at the critical temperature above which distinct liquid and gas phases do not exist.

-It refers to the pressure at a point on the airfoil’s surface when the airflow over the surface reaches the speed of sound for the first time.

-This phenomenon is significant in transonic flight.

Critical Pressure Coefficient

-The pressure coefficient of the point of minimum pressure on an airfoil section

Critical velocity

-The velocity with which the liquid flows changes from streamlined to turbulent.

Geometric Wingspan, b

-is the distance between tip to tip of the wing, measured perpendicular to the airplane wing centerline, regardless of the

geometric shape of the wing.

Wing Area, S

-is the projection of the planform on a plane of reference which is usually the chord plane.

Aspect Ratio

-is a measure of how long and slender a wing is from tip to tip of a wing is defined to be the square of the span divided by the wing area

-The higher the AR, the higher the span, the

heavier

High Maneuverability

Compact Design

Better for High-Speed Flight

Structural Strength

-Low Aspect Ratio Advantages

Low Lift to Drag Ratio

Increased Fuel

Consumption

Poor Glide Performance

Less Stability at Low

Speeds

-Low Aspect Ratio Disadvantages

High Lift to Drag Ratio

Efficient for Cruise and Glide

Improved Stability

Good for Soaring

-High Aspect Ratio Advantages

Structural Challenges

Reduced Maneuverability

Limited Low-Speed

Applications

Operational Limitations

-High Aspect Ratio Disadvantages

Taper Ratio 𝝀

-is the ratio of the tip chord 𝒄𝒕 to the root chord 𝒄𝒓

Mean Aerodynamics Chord

-is the average chord length of a tapered, swept wing.

Total Drag Coefficient CD

-sum of all the individual drag components acting on an aircraft or object. It represents the overall aerodynamic resistance and is given by

Oswald Efficiency

-Factor It reduces the estimated induced drag for real-world wings. Helps in aerodynamic design by improving fuel efficiency and reducing drag especially during cruise speeds. Used in performance calculations for aircraft range and endurance. If a wing is an elliptical, it is 1, this means the induced drag is minimized. But most aircrafts have non-elliptical wing leading to higher induced drag, so usually it is less than 1.