# Lift and Drag

## Body - like an airfoil - in fluid flow

### Lifting Force

The lifting force acting on a body in a fluid flow can be calculated

FL = 1/2 cL ρ v2 A                                        (1)

where

FL = lifting force (N)

cL = lifting coefficient

ρ = density of fluid (kg/m3)

v = flow velocity (m/s)

A = body area (m2)

### Drag Force

The drag force acting on a body in fluid flow can be calculated

FD = cD 1/2 ρ v2 A                                     (2)

where

FD = drag force (N)

cD = drag coefficient

ρ = density of fluid (kg/m3)

v = flow velocity (m/s)

A = body area (m2)

### Required Thrust Power to overcome Drag Force

The thrust power required to overcome the drag force can be calculated

P = FD v                                       (3)

where

P = power (W)

### Example - Aeroplane and Airfoil Lift - Drag and required Thrust Power

For an aeroplane with velocity 100 m/s, wing area 20 m2, a drag coefficient 0.06 and a lift coefficient 0.7 - the lifting force acting on the airfoil can be calculated

FL = 0.7 1/2 (1.2 kg/m3) (100 m/s)2 (20 m2)

= 84000 (N)

= 84 (kN)

The drag force can be calculated

FD = 0.06  1/2 (1.2 kg/m3) (100 m/s)2 (20 m2)

= 7200 (N)

= 7.2 (kN)

Required thrust power to overcome the drag force:

P = (7200 N) (100 m/s)

= 720000 (W)

= 720 (kW)

## Related Topics

• Fluid Mechanics - The study of fluids - liquids and gases. Involves velocity, pressure, density and temperature as functions of space and time

## Tag Search

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• es: el flujo de fluido telesquí peso empuje cuerpo ala potencia
• de: Aufzug Drag Flüssigkeitsströmung gestoßen Gewichtskraft Wing Body

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