A Multi-Lifting-Line-Method for design and analysis of non-planar wing configurations
LIFTING-LINE
Calculation of the flow around a parabola skeleton with an angle of attack alpha
The flow around a parabolically cambered plate with an angle of attack alpha can be replaced by the superposition of the flow around a flat plate with the angle of attack alpha, with the flow around the parabolically cambered plate in a chord-parallel flow or by the superposition of the flow around a flat plate with the angle of attack (alpha - alpha_0) and with the flow around the parabolically cambered plate with an angle of attack of alpha_0.
The multiple lifting line method LIFTING_LINE is a potential-flow-theory based program, which computes the aerodynamic coefficients of a given configuration consisting of one or more nearly arbitrarily arranged lifting surfaces. It can be used in case of inviscid, incompressible flow conditions, provided that the airfoils are thin and therefore –according to the thin airfoil theory–able to be modeled as flat plates. A Göthert compressibility correction has been added to extend the range of applications to compressible, subsonic flow.
LIFTING_LINE was developed in 1987 by Prof. Dr.-Ing K. H. Horstmann for his PhD thesis (see DFVLR FB 87-51). The primary objective was the determination of the induced drag of non-planar wing configurations with an accuracy comparable to lifting surface methods. Over the years, LIFTING_LINE has been continually enhanced and extended. Nowadays, combined with the increased performance of modern PCs, it permits to conduct extensive parametric variation studies within a very short amount of time. The program is very flexible with respect to the variety of calculable geometric shapes and benefits from a relatively simple geometry input.
Key features
Example of a lift-distribution, computed with LIFTING_LINE
Changes of a lift distribution, caused by a deflection of the red marked flap (with its trailing edge) around 10° downwards.
simulation of systems of arbitrarily arranged, thin wings
consideration of airfoil camber and control surface deflections
modeling of propeller slipstream effects
symmetric and asymmetric flow cases (Angle of attack, angle of sideslip, quasi-steady rotations)
Göthert Compressibility correction
local and global force and moment coefficients
investigation of the flow field around the aircraft
Area of applications
The LIFTING_LINE method is well-suited for a rapid investigation of a wide range of aircraft concepts under subsonic flow conditions during the aircraft design process. Effects from viscosity and transonics, however, have to be calculated and added to the results separately–just as the influence of fuselages. Using LIFTING_LINE it is possible to create large aerodynamic performance maps (including damping derivatives and control surface deflections) over a wide range of the flight envelope and to provide them to investigations on flying qualities and flight performance. On the other side, the local investigation of coefficients and flow field for single operating points permits the optimisation of the geometry and the estimation of aerodynamic loads for structural sizing.
License notice
The LIFTING_LINE program is published under the terms of version 2 of the GNU General Public License and is with kind permission of Prof. Dr. Horstmann provided on request by the institute to interested persons. Please enquire using the contact button below.
