Lift-induced drag

About: Lift-induced drag is a research topic. Over the lifetime, 2861 publications have been published within this topic receiving 41094 citations.

Formation Flying Commercial Aircraft - Assessment Using a New Approach - Wing Span Load and Camber Control

Abstract: The idea of flying commercial aircraft in formation to reduce fuel usage, has been around for some time. There are many results available using idealized approaches e.g. vortex lattice formulations. In view of the greater importance being attached to environmental aspects, the need has arisen to evaluate the possible advantages and disadvantages. This paper steps up the analysis level exploiting a recently developed design method that allows span loading and camber control on wings with without winglets. The method has been adapted to assess the aerodynamics of wings in formation and then to redesign them to eliminate induced roll effects. From a limited number of flight formation configurations assessed so far, the method predicts induced drag reductions of near 30%, affording overall drag reductions of the order of 15%. The benefits may well be larger, using other formation spacing parameters. Limited results using an Euler solver reflect benefits of the same order. The technique has proved to be easy and robust in use. It is enlightening as it gives, at every stage, a feel for what is happening in terms of camber development, pressure distributions and Centre of Pressure location. Favourable characteristics of the configuration can be enhanced whereas those that are not beneficial can be minimised or avoided as the design progresses Several avenues of further work and development have arisen.

CFD Study of an Annular-Ducted Fan Lift System for VTOL Aircraft

Abstract: The present study aimed at assessing a novel annular-ducted fan lift system for VTOL aircraft through computational fluid dynamics (CFD) simulations. The power and lift efficiency of the lift fan system in hover mode, the lift and drag in transition mode, the drag and flight speed of the aircraft in cruise mode and the pneumatic coupling of the tip turbine and jet exhaust were studied. The results show that the annular-ducted fan lift system can have higher lift efficiency compared to the rotor of the Apache helicopter; the smooth transition from vertical takeoff to cruise flight needs some extra forward thrust to overcome a low peak of drag; the aircraft with the lift fan system enclosed during cruise flight theoretically may fly faster than helicopters and tiltrotors based on aerodynamic drag prediction, due to the elimination of rotor drag and compressibility effects on the rotor blade tips; and pneumatic coupling of the tip turbine and jet exhaust of a 300 m/s velocity can provide enough moment to spin the lift fan. The CFD results provide insight for future experimental study of the annular-ducted lift fan VTOL aircraft.

Approach to induced drag reduction with experimental evaluation

Abstract: An approach to minimize the induced drag of an aeroelastic configuration by means of multiple leading- and trailing-edge control surfaces is investigated. A computational model based on a boundar ...

Calculations, and comparison with an ideal minimum, of trimmed drag for conventional and canard configurations having various levels of static stability

Abstract: Classical drag equations were used to calculate total and induced drag and ratios of stabilizer lift to wing lift for a variety of conventional and canard configurations. The Flight efficiencies of such configurations that are trimmed in pitch and have various values of static margin are evaluated. Classical calculation methods are compared with more modern lifting surface theory.