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LEPARAGLIDING 2.60/2.88 "Baldiri"



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 2.88 (January 2019),
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 (only ideas, yet not functional)

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

2.50 (2016-05-09)

LEparagliding 2.50 version "Utah" (2016-05-09)

- MIDDLE UNLOADED RIBS: 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. These ribs have been reformatted to achieve a perfect match with high precision, with the corresponding panels. In the center of the panels, are marked equidistant points in correspondence with the middle unloaded ribs. In addition, in the 2D-planform (plan "1-1"), also drawn in gray new ribs. Planned to draw in 3D (for reference) but not yet done. Important: To define holes in the ribs (elliptical or circles), add in section "4. AIRFOIL HOLES" a new hole type "11" that is defined exactly as the type "1" (hole type "1" and type "11" are exactly the same but the type "11" used exclusively by the middle unloaded ribs). In this case the initial rib number and end rib number with holes type "11" should be the same, and greater than the maximum number of ribs on one side, for example, use "50" . See the attached example "leparagliding.txt". All new programation in section 9.9 of the source code.

- "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".

- (!) CRITICAL ERROR found :( and solved :) when using V-ribs "Type 3" and wing scale different from 1.0. Solved. Caution! because V-ribs "Type 3", defined in earlier versions may be incorrect.

- A strange line, which appeared in the wingtip rib if zero thickness airfoil and wing type "pc" erased! :)

- Please, see and test attached 2.50 example.

LEparagliding 2.51 version "Utah" (2016-06-05)
            WARNING: Update 2.50 to 2.51 beacuse version 2.50 may done some errors in the lines list (!)

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.

LEparagliding 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.

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) Lines labels

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.draw them manually. :)

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

However, the use of the
program remains "cryptic", even more than the previous version, 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.

The program reads the data, calculates and draws the glider in 2D and 3D in a few seconds. The results are obtained in four 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

I'm still working on several improvements (mainly intended to reduce the post-process working):

         - Improved 3D-shaping notes here
         - Virtual skin tension in vents
         - Dynamically define airfoils vents (
integrated program ac)
         - Glue automatically vents in the upper or lower panel
         - Nylon rods and mylars
         - For computerized plotters,
choose puntual marks between puntual dots or small circles
- For computerized plotters, move DXF graphical objects to specific layers
         - Graphical interface
- Better detail the internal code of the program (schema structure, list of variables, drawings with the explanation of algorithms). With the aim that others can understand and further develop the program.

          VERSION 2.60 (classic version 2016-12-12)
User manual 2.60  Very interesting! recommended
lep-2.60-linux Linux version
lep-2.60-win Windows version
lep-2.60-mac MAC OSX Version

VERSION 2.88 (version
User manual 2.88

License GNU GPL 3.0
FAQ leparagliding
Simple instructions. How working with the program?
Programming LEP