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After several years of development (preliminary version in 2005), Laboratori d'envol presents in 2010 "LEparagliding 1.0" paraglider design program, that follow the laboratory concepts and techniques, and allows improved design for the new gliders. With the help of LEparagliding 1.0 has been possible to design the gnuLAB2 paraglider in 2010.

The latest version released is LEparagliding 3.15 (January 2021),
which contains many enhancements over the previous versions.


- Scale factor to design different sizes
- Elastic corrections in the lines, depending on the load
- Plans prepared for printing on paper (amateur use) or for computer cutting table (professional use).
- Design aids to facilitate the work of sewing
- Support for the division of the sail panels in colors (testing)
- Horizontal straps
- V-ribs (two cells without lines)
- VH-ribs (three cells without lines, in testing)
- Rotation of triangles in space for single surface paragliders (choice of double "ds" or simple surface "ss" paraglider! in testing). BHL paragliders design.
- In general, better presentation of the plans, although there is still much room for improvement
- 2D steering allowed (two or more main brake lines)


- Improvements in the shape of single skin sawtooth profiles
- lines.txt human-readable list of lines
- new type of wing "pc", special for parachute design


- Eighth column, in section 2, is now used in single paragliders (useless in double skin). More control in rotation of triangles.
- Other minor corrections

2.40 (2015-09-04):

leparagliding 2.40
LEparagliding 2.40 using "full continous diagonal rib"

Distance between equidistant points of control seam at the bottom of the profiles, improved (fixed a bug). Thanks to Scott from Utah - USA.
-  Few improvements in the drawing number 6 of 2D drawings "Calage estimation". The calculation of the angle of attack of the wing (alpha) and angle of the airfoil chord with respect horizon (theta) or "assiette", now is drawn correctly (fixed a bug). Thanks to Yuri from Crimea. More info in excell file: Balance_calculus.xls
- Changed executable name from a.out or a.exe to lep-2.40.out or lep-2.40.exe (optional)
- V-ribs "type 3" now possible
- V-ribs "type 5" new type "full continous diagonal rib" includes parabolic and elliptical holes (very especial thanks to Scott for supporting leparagliding developement)
- In lep-out.txt output file added summary of ribs and panel lenghts differences
- Preprocessor 1.2 version "Gurzuf" with more info written in the output file (area, span)
- Graphical user interface (first ideas)

2.41 (2015-09-19):

 - Attachements points marks in intrados panels (Scott request).
- Increased number of ribs with color marks, from 20 to 100 (per side). (Thanks to
Paweł from Poland)
- Now possible draw color marks also in intrados panels. Use same format for data that in extrados.
- Now
is possible define and draw trailing edge "miniribs" ("minicabs") in non "ss" paragliders: Simply define minirib length (in %) in column number 8 of section "2. AIRFOILS". If column 8 values are "0" or "1", miniribs are not draw and these values used only in "ss" paragliders, according manual 2.41.

2.48 (2016-04-17):

          - Using new reformatting option (fully adjustable) for high accuracy in length between panels and ribs,
             corrections in lenght and distorsion. And many others improvements.
          - Using DOUBLE PRECISION real variables and double precision trigonometric functions in Fortran code
          - Special thanks to Scott from Utah (USA), which has made possible this new version.
- Read README.txt file for details

2.49 (2016-04-24):

- V-rib type 6 is fully functional. Type 6 is a general diagonal. It's very simple. A trapezoidal diagonal ranging from rib number i to rib number i+1. But the rib is totally configurable in size and position. It has been designed to develop competition paragliders CCC types, which need to jump between 4 and 5 cells without lines. But it can also serve to design simplest paragliders, and replacing some of the types of diagonals described above. It is also very useful to define transverse horizontal strips located in all parts of the wing (the tapes have not necessarily coincide  with the anchor points).
- In final report lep-out.txt, area and span, calculated also in ft2 and ft
- Improved location of decimal numbering of all V-ribs types.
- Read section 10 of the manual: (...) "i11" indicates rib number "i", where anchor the top line of the brakes. This number, usually an integer. Nevertheless, some versions ago was added an interesting and not documented feature. Is possible define a decimal which means the displacement of the anchoring point between the rib "i" and the rib and "i+1". For example, 8.4 means anchor the line in the trailing edge, between rib 8 and 9, and 40% from the rib 8. This effect is now visible in 2D and 3D

version "Utah" (2016-05-09)
- Added the possibility of using "middle unloaded ribs". Very easy to use: In section "2. AIRFOILS" at the last column use the parameter "100", means to place a complete unloaded rib in the middle of the panel, and the left corresponding rib. Similarly, as defined in the mini-ribs. But the parameter "100" activates a new specific programation. New plan numbered "1-6" with the new middle ribs numbered and marked.
- "Mini-ribs" are redefined, and now in section "2. AIRFOILS" at the last column, if you use the parameter "15", means to place a 15% mini-rib in the middle of the panel, and at the LEFT of the corresponding rib. Previously, mini-rib it was placed on the RIGHT. But it is better set at the left, so you can specify a minirib the center of the wing (Mini-rib specified in the left first rib). And this is consistent with the new middle unloaded ribs.
- Applied little optional displacement (to the center of the wing) in the points marking the position of the miniribs. Third parameter in the line of section "7. MARKS" of the datafile. Before, this displacement was set to default to zero.
- All 2D-plans renamed whit the notation "i-j" that means row "i" and column "j".

2.52 (2016-08-18)

Added new option. Set automatic washin angles from center airfoil to wingtip.
At request from Yuri (Crimea).
How to use: Below line 21 in leparagliding.txt data file:

* Alpha max and parameter
3.5   2  -1.0

- First number "3.5" is the angle of attack (degres) in wingtip airfoil
- Second number "2" is a control parameter that means case "2", ie, add new number indicating the angle of attack of the central airfoil
- Third number "-1.0" is the angle of attack (degres) of the central airfoil

The distribution angles of attack is made proportional to the wing chord (similar to case "1"). See "lep-out.txt" to view the result.

2.52++ version "Utah" (2016-08-27)

1) Added new option in V-ribs "type-3", at request from Yuri.
Diagonal rib type 3, indicated by 10 numbers.
Previously, the columns 9 and 10, were not used. And set to "0".
Now (in version 2.52++ and following), if the column 9 is set to "1", this means that the radius
defined in columns 7 "r-" and 8 "r+" , are now defined in % of the chord of the profile, not in cm.
This allows definition of the diagonals widths automatically, and proportional to the profile chord.
Thus, it is achieved a perfect match in the widths of the contiguous diagonals and chord proportionality.

2) Internal fortran subroutine "vredis" (vector redistribution) improved, because in some cases
(when used very small widths in V-ribs) were errors in the forms of V-ribs. Now fixed.

3) Version 2.52++ packs version 1.4 of the pre-processor.

2.60 version "Les Escaules" 2016-12-12

1) Corrected some problems using an even number of cells
When we define paragliders using an even number of cells, the central profile has a coordinate x = 0.0 along span, and program use internally a "virtual centrall cell" with a zero thickness.
This can cause some numerical errors when calculating angles or divisions by zero. The result is usually an unreadable DXF file. Now, if the central profile located at x = 0.0, the program adds internally +0.01 cm (a tenth of a millimeter) and it seems that there are no numerical errors. [Section 4.2 in source code file .f].

2) The labels of the lines now automatically written on the schematic drawing in the form of tree. This prevents errors, and had to The labels of the lines now automatically written on the schematic drawing in the form of tree. This prevents errors, and had to draw them manually. :)

3) Added more geometric parameters in lep-out.txt report

2.71 (2018-06-17) to 2.99 (2019-08-24):

Since version 2.71 LEparagliding has an expanded data file structure with respect to the previous version 2.60. Sections 1 to 18 of version 2.60 are the same as those of versions greater than 2.71. But new version has addicitonal sections numbered 19,20,21 ... up to 31. To convert a file from version 2.60 to higher version, just add the new sections at the end of the archive leparagliding.txt. Program versions greater than 2.71 are the result of working intensively in the source code of LEparagliding. There is a lot of invisible work in subroutines and code improvements.

Most of the data included in the new sections can be considered as "invariant parameters", sections 19,20,24,25,28,30,31. That is, they can be used as default values for any new model.  The new parameters allow for greater control of the DXF results and add some new features. Extension of the DXF-2D plans to an array 4 rows x of 7 columns (28 plans). Plan 1-7 used for rods. New plan 4-7 includes general text notes for constructor. New sections save a lot of drawing work with CAD, and now the paraglider is almost finished from the program. Section 31 allows skin tension with control of up to 100 points and applicable individually to each panel.

3.10 version "Pirineus" (2020-05-02):

Main features added in lep-3.10 over precedent version:

Data file leparagliding.txt:
Section 29. 3D-shaping active.
Section 20.  Marks types, activated type8 which allows control of position and size of roman numerals
New plans added in file leparagliding.dxf:
Box (1,8) Intermediate and ovalized airfoils (*)
Box (-1,3) and (-1,5) extrados panels with 3D cuts
Box (0,3) and (0,5) intrados panels with 3D cuts
New graphics in lep-3d.dxf: intermetiade and ovalized airfoils are draw if desired.
New three informative sections added in lep-out.txt file:
Section 9. 3D internal calculus values, informative (**)
Section 10. The quotient between the lengths of the panel and ribs, for extrados and intrados.
Section 11. Counting of points in all profiles, informative

(*) Plan (1,8) shows median airfoils between rib i and i-1 and the corresponding ovalized median airfoil, including marks of the points j1,j2,j3,j4,j5,j6,j7 used in the defintion of the 3D-shaping.
(**) Section 9, with the length ot the arch of airfoil (d1) and the arch of the ovalized airfoil (d2), the differences of longitude (d2-d1) calculated automatically in each zone, and the amplitude value (f) applied consistently to each cut using the values (d2-d1) of the adjacent zones and the coefficient aof depth of the 3D effect. According to theoretical study.


The use of the program remains "cryptic", but very powerful and "easy". Thus is only recommended for people accustomed to work with text files containing sorted data, and CAD systems. No graphical user interface, but its mode of operation does not need. Is necessary, a pre-processing of data in CAD systems (or equivalent analytical tools) and a CAD post-process of the DXF resulting files, for printing or for the automated cutting table.

The program works by reading some data files:

 leparagliding.txt that contains all the geometric description of the glider
 and files of profiles gnua.txt gnuat.txt or others.

Then the program calculates and draws the glider in 2D and 3D in a few seconds. The results are obtained in the following files:

leparagliding.dxf containing drawings to be interpreted and plotted with a CAD program (Use LibreCAD if AutoCAD20XX do not open)
lep-3d.dxf containing 3D drawings model of the glider and lines
lep-out.txt containing the summary of the geometric and aerodynamic parameters calculated, and the length of all lines.
lines.txt human-readable list of lines
lep-3d-surface.dxf (wing surface in dxf format, not ready yet)
lep-3d-surface.stl (wing surface in slt format, not rady yet)

Program works in GNU/Linux, Windows all versions, and possible in MAC but not tested.


LEP user manual (english version)
LEP user manual (russian version)
FAQ leparagliding
Informative notes about cygwin .dll's libraries used in Windows versions
Informative notes about source code compilation optional.
About the Graphical User Interface
About the pre-processor

Updates_log.txt (cumulative list of changes in versions)
License GNU GPL 3.0

Download the source code and executable files for your system:
Source code
Linux version
Windows version
MAC version
Classic version
3.14++ "Pirineus"
leparagliding.f lep-3.14++lin-64bit lep-3.14++win-64bit
3.15 "Canigó"
leparagliding.f lep-3.15-lin-64bit lep-3.15-win-64bit
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