Xfoil Free Download
Etta Lesniak
I am working on some airfoil optimization using XFOIL and recently ran into a lot of trouble with convergence. As part of my troubleshooting, I decided to run the same airfoil in XLFR5 to try to determine how to refine my results to get better convergence. Upon doing this, I noticed that for the exact same airfoil, and same operating conditions, I am getting different results from XLFR5 than if I just use XFOIL. Does anybody know why this may be? For the airfoil I used an S809 with 66 panels (I have tried using 160 and this does change the results at higher alpha, but for alpha=0 there is still a descrepancy).
There may be two reasons
- xflr5 is based on xfoil v6.94. Later additions to xfoil have not been implemented.
- more importantly, xfoil is written in fortran, and xflr5 in C; I've written this in the guidelines : It may be found, in some cases, that one of the two programs may not converge where the other will, or that the path to convergence is different from one to the other. This is due to the different manner in which floating point numbers and calculations are processed by the two compilers. Having said this, the converged results are always close, and any differences within the convergence criteria set in the XFoil source code.
I've built xfoil, which is a supersonic airfoil analysis tool and avl, which is an fixed wing aircraft stability analysis tool. These tools were both written a combination of C and Fortran 77, and are well trusted tools in aerospace. They both have similar cli interfaces and feature interactive plotting tools. I've successfully built and used each on other (non arch) linux systems, but I am having difficulty getting the plotting functionality to work properly on my (relatively) new arch install.
No, the build failed when I used the AUR package. It looked like gfortran version 10 was flagging something as an error that had previously only been a warning, so I edited the makefiles to use gfortran-9 instead.
[Solved]
I'm not 100% sure what I did, but let me explain my methodology. On my last system where I had each of these programs working, I had both i3 and cinnamon installed, so I looked through the dependencies for cinnamon and added the packages that were missing from my current installation that seemed relevant. After rebooting (just to be sure), everything seems to be working.
That was what I thought at first, but installing xorg fonts and related packages didn't seem to fix the problem. If I had to guess, it was one of the dependencies of muffin (cinnamon's wm), which isn't a dependency of i3. I'm not certain of this, but it's my best guess.
I don't think so. Unless there were ttf or otf packages that were dependencies of files I did install and didn't notice, the only font files I installed to try to fix this were xorg-fonts-100dpi xorg-fonts-75dpi xorg-fonts-misc xorg-fonts-encodings and xorg-fonts-type1.
I ordered one yesterday with the surf thing! Cant afford those jet surfs and fliteboards. It is a new product, so I was skeptical at first, so I called them and asked more about the parent company, seems legit so they must know what they are doing. And speaking of manufacturing, even Iphone is made in china so that is not concerning to me. Also it looks sporty and cool!
I tried to reach out to the xFoil CEO, Paul Lowchareonkul as well. As an early backer of Waydoo, I reviewed their product and have had good communication with the team. It would be great if XFoil is a success, but poor communication and no updates on the campaign page nor updates to backers is a red flag. Curious if they reach out to you Jetsurfingnation as you have established yourself as an authority in the efoil and jetboard space.
I am xfoil backer and communications are as good as any other small company. Staff is limited so you might not get in touch being in a different time zone, try Email? They are hesitant to give concrete info yet but I have researched the company and their Indiegogo history. As an independent reviewer, you should wait till customers start to get their products. The competition will only things better. Keep on surfin mate.
Copyright (c) 2011, Gus Brown with Modification by Louis Edelman 2015
All rights reserved.
-xfoil-interface
Generates a command script to rapidly run Xfoil for a designated airfoil coordinates file, NACA airfoil, or coordinates matrix. Give the flexibility to pull detailed data (Cp, Cf, H, etc) or just the polar data for a single alpha or vector of alphas. All data is stored as a structured data set with the first left hand operator corresponding to the polar data and the second the detailed results.
Note that you need to have Xfoil 6.99 ( ) in the same directory to run this code.
If not requested as an output, parsing the detailed results will be skipped to save on cost.
Outputs can be manipulated as standard double precision vectors or matrices using standard structured data calls.
Added a version of the function that targets specific Cl values instead of alpha. This is virtually identical to the origninal script and I wrote it a few years back when I did the original. I'm 90% sure it is debugged, but some probably still exist.
Xfoil is a powerful tool for designing airfoils and is freely available for download. While the xfoil community is very supportive, I recently had a hard time properly formatting an airfoil data file in such a way that xfoil would load it. After many hours of working through it I decided to document what I found here. The main xfoil website is here:
We have C and Fortran installed, so I don't think that's the problem -- it actually looks like a problem with the xfoil package itself. When I create a virtualenv on my own Linux machine, and try to pip install into it, I get exactly the same error. Perhaps it's worth raising an issue against the package?
Thanks very much Conrad! Yes- gfortran is located in the directory /usr/bin/gfortran. I updated the makefile accordingly and the SBDART compiled correctly. Hopefully no further issues from this point! Cheers,
This package was originally a fork of pyXLIGHT (which has since been renamed to CMPLXFOIL), but has since undergone some development to introduce new features. The version of XFOIL that this package wraps is that of the xfoil_light project.
This code actually wraps two versions of Mark Drela's XFOIL code, one of which may be used to compute sensitivities using the complex step method. The complex step enabled version of XFOIL may be called by appending _cs to the end of each functions name. Note that there is no interaction between the two versions of XFOIL wrapped by this package, so if you wish to use the complex step version of the code you must use the functions that end with _cs.
It appears that "xfoil-osmap.patch" doesn't do anything useful. If you grep the xfoil binary to look for "osmap.dat", the only result is "/var/local/codes/orrs/osmap.dat". The only place where "/var/local/codes/orrs/osmap.dat" appears in the xfoil 6.99 source code is in osrc/osmap.f. Are we patching the wrong file? Should we be patching osrc/osmap.f instead of orrs/src/osmap.f?
Many of the airfoils have polar diagrams which can be viewed in the details and comparison sectionsections of the site. These show the change in lift coefficient (Cl), drag coefficient (Cd) and pitching moment (Cm) with angle of attack (alpha). There is also a graph of lift coefficient (Cl) against drag coefficient (Cd) which gives the theoretical glide angle of the airfoil.
All the polar diagrams currently available have been produced using Xfoil, an application created by Mark Drela and Harold Youngren for the design and analysis of subsonic airfoils. There is more information and details on the limitations of the analysis on the Xfoil page.
I wanted to create polar diagrams for all the airfoils in the database for a range of Reynolds numbers and ncrit values that would typically be applicable for model or light aircraft or small wind turbines. The polars are keyed by three values.
- Reynolds number - These range from 50,000 to 1,000,000 in approximatly logarithmic steps. The Reynolds number is a dimensionless value that depends on the velocity, wing chord and fluid. There is more information on the Reynolds number calculator page.
- Ncrit value - This is used to model of the turbulence of the fluid or roughness of the airfoil. The Xfoil documentation has a section explaining the method and also the table (reproduced below) of suggested values:- SituationNcritsailplane12 to 14motorglider11 to 13clean wind tunnel10 to 12average wind tunnel9dirty wind tunnel4 to 8
- Mach number - This has been left at the default value of zero.
Xfoil has a command line user interface and this was automated using an expect script running under Cygwin on a Windows PC. The airfoil dat files are run through the parser to convert them to a Selig format and remove any extra text so they could be read by Xfoil. The commands to load the dat file and set up the session was fairly straight forward but it was more difficult to handle the user interaction when the iterative calculations failed to converge and restart Xfoil when it froze.
The commands for a typical scripted Xfoil session to generate a polar are below. The xfoil ALFA command was used for each individual angle of attack rather than the ASEQ as it was easier to automate, determine the succcess of the last calculation calculation and "step over" any failures.The polars were generated stating at ALFA = 0 in first a positive and then a negative direction. If a solution was found the next ALFA value was immediatley calculated.If no solution was found an INIT command was run before moving on to the next ALFA command.
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