CPL PoF Drag Revision 2

Skin friction drag is caused by

• Sheer stress between successive layer of air

• The mixing between converging airflows at the junction of various aircraft surfaces

• The pressure differential between the forward are rear facing surfaces

• Wingtip vortices

Interference drag is caused by:

• The pressure differential between the forward and rear facing surfaces

• The shear stress between successive layers of air

• The mixing between converging airflows at the junctions of various aircraft surfaces

• Wingtip vortices

Form drag is caused by:

• The shear stress between successive layers of air

• The pressure differential between the forward and rear facing surfaces

• Wingtip vortices

• The mixing between converging airflows at the junctions of various aircraft surfaces

What type of drag does streamlining reduce

• Induced

• Form

• Skin friction

• Interference

How does streamlining reduce drag

• By increasing the pressure differential between forward and rear facing surfaces

• By decreasing the pressure differential between the forward and rear facing surfaces

• By increasing the pressure differential between the upper and lower surfaces

• By decreasing the pressure differential between the upper and lower surfaces

Which of the following would be used to reduce interference drag?

• Winglets

• Flush riveting

• Flying faster

• Filleting

By increasing an aircrafts speed you would (Select all that apply)

• Increase form drag

• Increase interference drag

• Increase induced drag

• Decrease skin friction drag

To decrease skin friction drag you should:

• Keep the boundary layer laminar for as long as possible

• Laminar/turbulent boundary layer doesn't effect skin friction

• Make more of the boundary layer turbulent

• Fly as fast as you can

Select all that effect skin friction drag

• Size

• Surface area

• Shape

• AoA

• Colour

What is fineness ratio?

• Ratio between the length of a body to is depth

• Ratio between the width of a body to its length

• Ratio between the width of a body to its length

• Ratio between the shape and width of a body