06 Drag

Definition of the drag force

Drag components (4 fundamentals + 4 further)

Drag-components —> Differentiation by type of inflow

Typical drag differentiation for an commercial aircraft (by type and components)

Drag polar curve

Approximation of drag polar curve using drag coefficient

Definition boundary layer

Influencing variables of the boundary layer

Shear stress equation and reynolds number

Laminar and turbulent flow

Whats the critical reynolds number (height) and what other factors influence the characteristics of flow

Estimates for the friction coefficient

approximations of the friction coefficient of a flat plate

Further influencing parameters on flow

Determination of the friction coefficient

Estimation of the friction drag

Karman-Schoenherr equation

graphical solution

Definition of form drag

Name the reasons for a strong drop in form-drag for blunt bodies

The Raymer approximation for the form factor for form-drag of slim bodies

Describe the Vortex system of a wing with finite span

Explain lift-induced drag

Lift-induced drag

• Applicable formulas

Prandtl ́s lifting-line theory

• What can be determined/Calculated?

• Assumptions and Limitations

Lift-induced drag with elliptical lift distribution

• How is Wave-Drag generated?

• What is the critical Mach number?

• When does Wave-drag occur?

Name the two types of shock

What is the difference between those?

Pressure coefficient on airfoil

• Standard formula

• Isentropic flow

• M=1

Prandtl-Gaulert transformation for the pressure coefficient

• Which factor can be determined by iterative solution

The minimum pressure coefficient depends on which 3 Factors?

What increases the transonic drag?

What is the drag divergence Mach number?

Name the two components wave drag can be divided into

What increases these?

What is high-speed buffeting?

Name a possibility to reduce wave drag

What can be achieved by this method?

The area rule applies to?

The application of the area rule leads to?

Higher Mach numbers?

What is interference drag?

What causes pressure and friction drag due to interference?

Name two measures to reduce interference drag

What is the rule of thumb in this case?

Which areas are particularly vulnerable to increased interference drag?

What are suitable counter-measures?

Explain parasitic drag

Explain Trim-drag

Approximation equation for the trim drag

Explain Cooling drag

• Phenomena

• Formula