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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TL;DR: In this paper, the tumbling motion of freely falling plates with aspect ratio ranging from 2 to 10 was studied using both experimental measurement and simplified lifting line theory, where the trajectories of plates were recorded by high-speed video camera and analyzed to obtain instantaneous and average kinematic and aerodynamic parameters, including the descent angle, rotating speed, descent velocities, lift and drag coefficients, and their fluctuation spectrums.
Abstract: The tumbling motion of freely falling plates with aspect ratio ranging from 2 to 10 is studied using both experimental measurement and simplified lifting line theory. The trajectories of plates are recorded by high-speed video camera and analysed to obtain instantaneous and average kinematic and aerodynamic parameters, including the descent angle, rotating speed, descent velocities, lift and drag coefficients, and their fluctuation spectrums. A double period rotation with period doubling is observed here for some range of aspect ratio and the double frequency is determined from a Fourier analysis. By adding a correction from the inducing effect of trailing vortices and wing-tip vortices to the corresponding two-dimensional force and torque expressions, a simplified kinematic model is obtained which successfully predicts the qualitative influence of aspect ratio on the averaged kinematics, that the descent angle and the vertical descent velocity component are decreasing functions of the aspect ratio, while the rotation speed and horizontal velocity component are increasing functions of the aspect ratio. For decreasing aspect ratio, the induced drag due to the trailing and tip vortices reduces the lift to drag ratio and thus increases the descent angle, while the dissipative torque due to translational induced drag decreases the rotation speed.
24 citations
Patent•
05 Mar 1997
TL;DR: In this article, a fixed-wing aircraft that can be automatically converted to a roadway vehicle within seconds while driving in the highway, comprising a one-piece wing rotatably mounted on top of the fuselage.
Abstract: A fixed wing aircraft that can be automatically and rapidly converted to a roadway vehicle within seconds while driving in the highway, comprising a one-piece wing rotatably mounted on top of the fuselage The aircraft features a 3-horizontal-surface design allowing good pitch stability and damping in a very short fuselage, stall-resistant feature and reduction in induced drag at cruise speed The aircraft's wing is enlargeable with additional wing tip segments allowing boost in aspect ratio hence improving efficiency at high loads The vehicle has low center of gravity, four wheels with independent suspension, nose-height leveling for take-off and landing, and anti-sway mechanism in order to prevent roll-over in a tight turn Ground propulsion is by both a ducted fan and hydraulic rear wheel drive allowing rapid accleration in the roadable mode
24 citations
TL;DR: A high lift-to-drag ratio is considered crucial for high-altitude and long-endurance hypersonic vehicles and one of the simplest and most useful methods is to install an aerospike in front of the vehi...
Abstract: A high lift-to-drag ratio is considered crucial for high-altitude and long-endurance hypersonic vehicles. One of the simplest and most useful methods is to install an aerospike in front of the vehi...
24 citations
Patent•
22 Jul 1968
TL;DR: In this article, the stabilizing fins and the drag brake were deployed to a position perpendicular to the missile axis to produce aerodynamic drag, as well as rotate the stabilising fins to rotate them.
Abstract: Retractable stabilizing fins and drag brake apparatus having coactive connection between the stabilizing fins and drag brakes. The stabilizing fins when deployed to a position perpendicular to the missile axis present an edge to air stream. The drag brakes when deployed to a position perpendicular to the missile axis produce aerodynamic drag as well as rotate the stabilizing fins to a position to produce aerodynamic drag.
24 citations
TL;DR: In this article, a simple method is given for calculating, in incompressible flow, the spanwise and chordwise loadings on thin swept wings with symmetrical aerofoil sections and of moderate and large aspect ratios.
Abstract: A simple method is given for calculating, in incompressible flow, the spanwise and chordwise loadings on thin swept wings with symmetrical aerofoil sections and of moderate and large aspect ratios. The present note is based on, and continues, the investigation described in an earlier paper. The design of swept wings with given spanwise and chordwise load distributions, obtained by modifying the plan form of the wing or by adding camber and twist, is briefly considered, as well as the design of swept wings which give minimum induced drag.
24 citations