Expert: Paul Soderman - 5/19/2006

Question
direction of drag and lifting forces on an aircraft wing?

the flow patteren and pressure distribution across the surface of the wing?

Answer
Lloyd

By definition, aircraft lift is perpendicular to the fight vector and drag is parallel to the flight vector.  That said, aerodynamicists know that the lift vector is tilted downstream by the wake induced angle of attack, which results in a component called drag due to lift.  So drag has two components - one caused by viscosity and one caused by lift.   However, we still refer to the resultant lift and drag as the forces perpendicular and parallel to flight, respectively.

The flow pattern and pressure distributions around a wing is too complex for me to discuss effectively, but can be seen in any basic aerodynamics book.

Paul