Activity for André
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André posted a comment on discussion Open Discussion
There won't be any new development for xflr5. In fact v6.62 is intended to be the last version before the project closes formally at the end of the year. Please consider upgrading to flow5 which can handle asymmetric configurations.
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Hi everyone, v6.62 is intended to be the last version of xflr5, barring any new major bug which would need fixing. The plan is to close the project at the end of 2026. Please consider upgrading to flow5. All xflr5 features except for inverse foil design have been ported to the new application. André
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Mixed inverse design - aoa or Cl selection
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closed in version 6.62
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Sideslip simulation problem on version v6.61
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Fixed in version 6.62
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tagging version 6.62
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releasing v6.62
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OK, the operating points take graded colours when the style of the parent plane or polar is changed. There is no option exposed in xflr5 to change this behaviour. I recommend that you upgrade to flow5 where the option is disabled by default and can be set in the preferences.
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Preferences/Display Options/Flow down changes....
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Preferences/Display Options/Flow down cganges....
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Dis this literally more than 20 years ago, so I don't really remember the reasoning. Also I used XFoil as a black box, so I may not have made the best choices. André
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As of January 1st 2026, flow5 is public and open-source.
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A blank screen is usually the sign that something is wrong with the OpenGl settings. Try to launch from the command line with xflr5 -o 21 for a 2.1 context xflr5 -o 31 for a 3.1 context and finally xflr5 -o 41 for a 4.1 context which is the highest that macOS supports.
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A blank screen is usually the sign that somthing is wrong with the OpenGl settings. Try to launch from the command line with xflr5 -o 21 for a 2.1 context xflr5 -o 31 for a 3.1 context and finally xflr5 -o 41 for a 4.1 context which is the highest that macOS supports.
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In the Analysis/advanced settings, there is an option to store or not unconverged points "Store points outside the polar mesh". The option used to be activated by default, however I was unconfortable with the storage of potentially erroneous points, so the option is now deactivated by default. I recommend to keep it deactivated since the potential method reaches or even oversteps its limits near stall angles.
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The PANE and CADD commands modify the panels and not the operating conditions. You should double check the Reynolds, Mach, NCrit and forced transitions settings in XFoil. In xflr5 the XFoil settings in are accessed in the menu "Analysis/XFoil advanced settings"
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Xfoil has no settings. It comes with a documentation which explains various options which can be set once the program is launched. The convergence depends mostly on the foil's panelling which is set with the PANE and CADD commands.
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Make sure that you are in the operating point view (F5) Click on the operating point in the left tree view, and activate the cross in the third column In the operating point view deactivate "Show current Operating Point only" Reset the scales (R)
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flow5 horizontal tail volume coefficient bug
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Not an xflr5 bug.
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There isn't any option to access forces and aerodynamic coefficients for each wing, only for the plane. You can however export the operating points and do some post-processing of your own.
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There isn't any option to access forces and aerodynamic coefficients for each wing, only for the plane. You'll can however export the operating points and do some post-processing.
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yes the wing is rotated around the leading edge point of its root section. André
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There is a secret handle to drag between the list of foils and the polar types.
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Repanel the airfoil (F3)
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The display scales for drag and lift are not the same. This is a design choice otherwise the drag would be barely visible. The central arrow is the overall lift.
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Nice work. Please restore the copyright notice and export it to pdf, and I'll be happy to host it on the flow5 website. André
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In non-viscous theories, the lift depends on the velocity but not the lift and drag coefficients which are normalized to be independent of velocity, fluid density and plane scale. Viscous effects can modify slightly the lift coefficient, something which you can observe in 2d using XFoil or in 3d with the non-linear LLT method.
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Re = chord x Velocity / kinematic_visc. or Re = chord x velocity x density / dynamic_visc In 2d analysis the reference point for Cm is the 1/4 chord location. In 3d it's the CoG location defined in the "inertia" tab of the analysis form F = 1/2 rho V² S Cl For the moments the reference lengths are defined in the guidelines
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The polar mesh does not exdend to high Re numbers http://www.xflr5.tech/docs/Point_Out_Of_Flight_Envelope.pdf
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What if you reset the graph's scales?
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No option for that. xflr5 is intended to be a GUI driven application.
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minor things
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xflr5 implements NACA TN 1269 for the non linear LLT and NASA Contractor report 4023 "Program VSAERO theory document" in the case of the panel method. There are a number of online documents covering the subject of the VLM, but you can start with the wikipedia page. Lastly there is Mark Drela's "Flight Vehicle Aerodynamics" which covers a lot of theoretical ground.
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It is tricky to compare glide ratios because the division amplifies differences in CL and CD. You should try to compare separately CL and CD to the values of table 6. The authors seem to use the k-epsilon model which implies fully developed turbulence, whereas xflr5 uses XFoil's mixed laminar/turb model. You can change the turbulence model in XFoil using the NCrit and forced transition parameters. André
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This means that one of the foils used to define the main wing is not found in the list of foils. This can occur if the foil was renamed or deleted after it has been selected in the wing design form. Check that "NACA 6409" and the other foils still exist in the 2d module, or click on the foil name in the wing's design form to get the updated list of foil names. André
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Looks good as far as I can tell. xflr5 ignores compressibility effects. Yes, xflr5 can be used for underwater flow analyses, such as in the case of hydrofoils. The main issue is likely to be the evaluation of the viscous drag. I've heard that NCrit=2 or 3 instead of 9 should be used for flow transitions in 2d. André
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Export the operating point to a text file.
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Solved?
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I suppose so. xflr5 calculates whatever foil is provided in input.
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Flow5 v7.26 don't even start in Windows64
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Please post flow5 related requests in the Q&A section of the flow5 website. André
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added an option to edit QSSpec in XInverse
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code cleaning
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This may be the best that XFoil can do on this non-conventional airfoil shape. Repanelling locally and globally may help. André
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Unfortunaly the option is bugged. You can still export the results to a text file to be read in a spreadsheet. André
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Click on the coloured line next to the foil's name.
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fixed an OpenGL compatibility issue with Wayland
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xflr5 builds the surface by constructing sets of points on each side of the panel. The points are spaced according to a COSINE distribution, then linked two by two. You can see how it's done by visualizing the mesh which is built in the same way. André
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added an option to discard spurious Xfoil operating points
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code cleaning
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The lengths are exported in meters. At this late stage I don't really want to change interfaces and add unit conversions which could be a problem for all users who have written data processing routines. André
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Check that the wing flaps are defined with a flapped foil on each side Check that the flaps are visible in the 3d view I've checked that if they are properly defined, the flaps show up in the "Control parameters" page of the analysis form. André
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Check that the wing flaps are defined with a flapped foil on each side Check that the flaps are visible in the 3d view I've checked that if they are properly defined, the flaps show up in the "Control parameters" page of the analysis form. André
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Try to import the airfoi from another database or generator Modify the coordinates manually Use the splines in the direct design module to smooth the geometry Use inverse design to smooth the geometry André
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code cleaning
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I had missed something which should be fixed with the latest commit. André
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code cleaning
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code cleaning
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code cleaning
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The reason is that the end-of-line character used in your .dat file is "\r" instead of "\r\n" or "\n". It is not recognized by the Qt libraries. André
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Sideslip simulation problem on version v6.61
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fixed with commit 1493
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fix for bug 213
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code cleaning
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Not sure that I understand. The tip panels are flat and perpendicular to the wing when using the thick panel method. There are alternative methods in flow5 to increase the panel density and the shape of the tip, but it turned out it doens't make much difference if any. André
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code cleaning
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Sideslip simulation problem on version v6.61
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Bug confirmed.
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Numeric values are displayed in the graphs top right corner. In the Preferences/Display options/All graph settings/Fonts and background, increase the margin size André
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Sideslip simulation problem on version v6.61
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The likely explanation is that there is an area of locally high pressure at the wing tip. Try to change the scale of the color map. André
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This may help too https://sourceforge.net/p/xflr5/code/HEAD/tree/trunk/xflr5/doc/Abbreviations-en-fr-de.odt
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The only export option is to xml. In the wing editor, user "Other", etc. André
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If you look closely at the TE, the bottom surface crosses the top surface at x=0.986 André
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The y-positions of the wing section must be in crescending order. André
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The polars should be the same. Try to run XFoil from the command line to be sure. André
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The polars houild be the same. Try to run XFoil from the command line to be sure. André
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Behaviour in the stall region can be erratic and exhibit sudden changes in lift and drag for small changes to the aoa. Also near the stall region XFoil may converge towards different operating points depending on how the analysis was initialized and run. André
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The panel methods in xflr5 assume inviscid flow and do not predict stall. Only the LLT to some extent predicts non-linear effects. André
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It means that XFoil predicts opposite pressures at the T.E. It's within the margin of error of the predictions. I wouldn't worry about it. André
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No, won't work. André
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Hello, The script function is limited to the analysis of foils. Plane scripting has only been implemented in flow5. To launch from the command line, make sure that the path to xflr5.exe is in the system PATH, or type in the absolute path to the executable. André
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No option to export them all. André
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The orders of magnitude of ther T5 polars look good as far as I can tell and are consistent with the results of both flow5 and AVL. The signs of Cn and Cl in xflr5 are wrong. flow5 is OK https://flow5.tech/docs/flow5_doc/Validation/Stability.html
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The orders of magnitude of ther T5 polars look good as far as I can tell and are consistent with teh results of both flow5 and AVL. The signs of Cn and Cl in xflr5 are wrong. flow5 is OK https://flow5.tech/docs/flow5_doc/Validation/Stability.html
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The option OpPoint/Current OpPoint/Export of a T7 polar exports the eigenvalues among other things Export of the curve title as the run case is intentional. I do not wish to change it at this late stage
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For historical reasons linked to the development and to the different axes conventions, the signs of lateral derivatives may not be totally consistent in xflr5. I don't plan to change them however because it would require a considerable code ovehaul which I'm not willing to do right now.
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the validity of results may be affected for large angle of attack and thick airfoils Not sure where you have read this. In xflr5, this is true in 3d at high aoa, i.e. near the stall angles. In 2d, XFoil is known to give reasonable results in the stall region, even for thick airfoils with "normal" shapes. However at even higher angles, I don't know, and there is little published experimental data to compare. André
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It's in the error file you attached. André
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The vortex core size should be one order of magnitude smaller than the smallest triangle edge. It can be adjusted using the menu option Analysis/3d analysis settings/vortex. In the future please post the questions related to flow5 in the Q&A section of the flow5 site. André
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Mixed inverse design - aoa or Cl selection
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Fixed with commit 1490
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Fixes for ticket 212
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Mixed inverse design - aoa or Cl selection
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