Lift-induced Drag
Summary
- Drag due to Lift
- Selected References
This type of drag is due to the vorticity produced by a lifting wing (induced drag or vortex drag) and is expressed as momentum deficiency in the wake. This type of drag can be a drawback of high-lift systems. Typically, a strong vortex is released at the tip.
The dissipation of this vortex farther downstream is one of the source of
loss, but this is of viscous nature. The inviscid nature of the drag is also due to
the downwash created in the slipstream, which on turns is related to an induced angle
of attack.
Methods used for the minimization of the induced drag make use of techniques to
diffuse this vortex and redistribute the wing loading. The methods include:
Reduction Methods
For lifting wings some of the devices commonly designed are the following
The methods listed above are used for the reduction of the vortex drag produced at the tip.
Selected References
- Hoerner SF. Fluid Dynamic Drag, Hoerner Fluid Dynamics, 1965.
- AGARD. Special Course on Concepts for Drag Reduction, AGARD Report R-654, 1977.
- AGARD. Special Course on Subsonic/Transonic Aerodynamic Intereference for
Aircraft, AGARD Report R-712, 1983.
- AGARD. Aircraft Drag Prediction and Reduction, AGARD Report R-723, 1985.