Topic
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.
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01 Jan 2011
TL;DR: In this paper, the theoretical foundations of static longitudinal stability and controllability are presented and applied to the box wing aircraft, and the results are interpreted and put into practice with the help of a medium range box-wing aircraft based on the Airbus A320.
Abstract: The induced drag of box wing aircraft is assessed with the help of literature data. The theoretical foundations of static longitudinal stability and controllability are presented and applied to the box wing aircraft. The results are interpreted and put into practice with the help of a medium range box wing aircraft based on the Airbus A320. Stability in cruise is attained by increasing the ratio CL,1/CL,2 to a value of 1,74, which is the ratio of lift coefficients of the forward and the aft wing. According to biplane theory this results in a 3,4 % increase of induced drag. Applying aerodynamic theory for closed wing systems no increase would be expected. With the stated ratio of lift coefficients results a relatively small envelope for the center of gravity (CG). Consequently the aircraft is designed to be well balanced with regard to its CG. The individual CGs of the airframe, engines, fuel and payload are all located approximately at the same position. Hence the CG shift is minimized for different payload and fuel quantities.
17 citations
01 Mar 1971
17 citations
TL;DR: In this paper, a method for predicting the drag increment caused by the installation of a blade-type vortex generator (VG) on a transonic-transport airplane is discussed, where the original Nash and Bradshaw magnie cation concept of roughness drag is extended to cover compressible e ows and then is applied to estimate the VG installation drag on an airplane.
Abstract: A method is discussed for predicting the drag increment caused by the installation of a blade-type vortex generator (VG) on a transonic-transport airplane. The original Nash and Bradshaw magnie cation concept of roughness drag is extended to cover compressible e ows and then is applied to VG blades to estimate the VG installation drag on an airplane. Thedrag of a VG blade placed on a wing will beamplie ed dueto thegrowth of the boundary layerwith distance along thewing surface. Nash and Bradshaw showed that thedegree of magnie cation cannot be approximated simply by the ratio of local to freestream dynamic pressure ( q effect). To demonstrate the magnie cation effects, some VG installation drag analyses for transonic-transport airplane models are performed using the new magnie cation factor formula. It can be seen that the agreement between these predicted drag increments and the wind-tunnel test results is good, but the drag increment based on the q effect is seriously underestimated.
17 citations
TL;DR: In this article, the authors discuss the formulation of models for sail forces and moments as needed for the prediction of performance of a given yacht, and show that the effects of heel angle may be accurately accounted for using a simple geometric construction.
17 citations
Patent•
18 Apr 1977
TL;DR: The stowable airfoil as discussed by the authors is a tapered, high aspect ratio, retractable and foldable wing for aircraft which provides minimum aerodynamic drag during launch and minimum space for ground storage.
Abstract: The stowable airfoil structure is a tapered, high aspect ratio, retractable and foldable wing for aircraft which provides minimum aerodynamic drag during launch and minimum space for ground storage. The airfoil utilizes a forward leading edge box section to which is attached a plurality of spanwise channels hinged together for movement in a chordwise direction. Retraction of these elements takes place by the utilization of suitable actuators so as to move the hinged elements forwardly in a nested position thereby substantially reducing the width of the wing or airfoil which is then folded to lie along side the fuselage of an aircraft.
17 citations