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LEPARAGLIDING 2.52

USER MANUAL

1. INTRODUCTION

2. GENERAL CONCEPTS

3. FILES ASSOCIATED WITH THE PROGRAM

4. HOW TO WORK WITH THE PROGRAM

5. COMPOSITION OF THE AIRFOIL FILE

6. COMPOSITION OF THE INPUT DATA FILE leparagliding.txt

    SECTION 1: GEOMETRY
    SECTION 2: AIRFOILS
    SECTION 3 : ANCHOR POINTS
    SECTION 4: LIGHTENING IN THE RIBS (RIB HOLES)
    SECTION 5: SKIN TENSION
    SECTION 6: SEWING ALLOWANCE
    SECTION 7: SEWING MARCAGE
    SECTION 8: ESTIMATING THE GENERAL ANGLE OF ATTACK
    SECTION 9: DESCRIPTION OF LINES
    SECTION 10: BRAKES
    SECTION 11: RAMIFICATIONS LENGTH
    SECTION 12: H V and VH RIBS
    SECTION 15: EXTRADOS COLORS
    SECTION 16: INTRADOS COLORS
    SECTION 17: ADITIONAL RIB POINTS
    SECTION 18: ELASTIC LINES CORRECTION

7. RESULTS


Interpretacions of lines labels in lines.txt

8. FUTURE DEVELOPMENTS

FIGURE INDEX

Figure 1: How to work with the program
Figure 2: Airfoils definition
Figure 3: Washin
Figure 4: Axes and coordinates
Figure 4+. Miribs definition
Figure 5. Hole type 1, ellipse
Figure 6. Hole type 2, ellipse or circle with central strip
Figure 7. Hole type 3 triangle
Figure 8. Skin tension
Figure 9. Ripstop elasticity
Figure 10. Sewing corrections
Figure 12: General AoA estimation
Figure 13: Suspension lines matrix
Figure 14. Brake distribution
Figure 15: Ramifications length
Figure 16. Mini-rib 1 (horizontal strap)
Figure 17. Mini-rib 2 (V-rib)
Figure 18. Mini-rib 3 (full V-rib)
Figure 19. Mini-rib 4 (VH-rib)
Figure 20. Full continous V-ribs type 5 using parabolic holes
Figure 21. Full continous V-ribs type 5 using elliptical holes
Figure 22. V-rib type 6 general diagonal
Figure 23. Extrados colors


1. INTRODUCTION


This manual describes the use of the "leparagliding 2.52" created by Laboratori d'envol for the design of paragliders. The author of the program provides no other information as described in the web. There is no warranty for the correct operation of the program. You assume the full consequences of use of the program.

LEparagliding is very "cryptic" to use, "FORTRAN style", but very powerfull...!

The program implements the theoretical developed in the book "Paraglider Design Handbook", which is advisable to study, because many of the contents are complementary.

I apologize, because this manual provides explanations in a style slightly rough. It is possible that some subjects are poorly explained. I will be happy to provide further clarification by pm. The program is not perfect, but it works.

Please, forgive my writings in English, not good enough, beacuse is not my usual language!


2. GENERAL CONCEPTS


LEparagliding is a calculation engine written in g77 FORTRAN language, that performs the reading the data of the input files, and writes the results to the output files.
 

    Input files:

        leparagliding.txt

Contains detailed geometric definition of the entire paraglider. The designer must edit this text file to achieve the desired results.

        airfoil1.txt
        airfoil2.txt
        ...

They contains coordinate files of the profiles, taking a unit chord. Can be assigned a specific profile name of each rib. However the most common is a general airfoil aplied to tthe entire wing and a zero thickness airfoil for the last profile of the wingtip,

Output files:

        leparagliding.dxf

Contains drawings in DXF format to be visualized. analyzed and edited with a CAD program (LibreCAD, Autocad, Microstation...)

        lep-3d.dxf


Dxf file created automatically by the program and contains 3D model (use 3D CAD program to view)

        lep-out.txt

Text output file with the main parameters calculated on the wing (span, area, aspect ratio, finenesse, ...) and the ordered list of the lengths of all lines in the wing (main line plans and brakes).

        lines.txt

Text output file including the list of all lines labeled in a human readable format
.


3. FILES ASSOCIATED WITH THE PROGRAM

    leparagliding.f

File program source code, written in language "GNU Fortran 77". This file is not necessary for the end user. Is included for developers who want to make modifications, improvements and extensions to the code, or for students. These changes are completely free under the principles and conditions of the GNU General Public License 3.0 (http://www.gnu.org) which is distributed the program.

The author of the file leparagliding.f program keeps it evolving and improving, as are several important aspects to implement and enlarge the use and possibilities of the program. Adjustments are also made to particular designs.

    leparagliding.txt

Text file that contains the main geometric definition of the glider model, whose detailed description is made below.

    gnulab2.txt, airplan.txt

Text files containing the coordinates of the profile used. There may be many files you want to profile (possible apply a different profile in each rib, although that is not common)

    lep-2.52.out (Linux) or 2.52.exe (Windows)

Executable program that must be activated to read the data and obtain graphical and numerical results.

    leparagliding.dxf

Dxf file created automatically by the program and contains all drawings of the wing panels with patterns ready to print or further postprocess in a CAD program.

    lep-3d.dxf

Dxf file created automatically by the program and contains 3d model.

    lep-out.txt

Text file with the numerical results of the program.

     lines.txt

Text output file including the list of all lines labeled in a human readable format.
Note that some paragliders require experimental adjustments of the lengths of the lines compared the theoretically calculated (BHL is the case).
 

4. HOW TO WORK WITH THE PROGRAM

Working with LEparagliding consists of the following phases:

    1. Pre-process

It is the initial phase of design, whether CAD or pencil and graph paper and calculator. It defines the shape in plan, the lobe or vault and the desired inclination of the ribs. Note that the pre-process work with paper, pencil, calculator and definition of discrete analytic functions, enables the same precision as with CAD.

An analytical pre-processor
is available (is optional, and
not strictly necessary), but very practical.

    2. Edit data file

    Descibed below in detail. Complete sections 1 to 18. It is the most important operation, and the overall design of the glider itself

    3. Program execution (seconds)

   GNU/Linux: run ./lep-2.52.out in a terminal

    Windows: execute lep-2.52.exe including compatible cygwin1.dll in the same directory.

    Mac OSX: compile sorce code in a terminal: " f77 leparagliding.f" and run "./lep-2.52.out" in terminal as in linux
   (compiler name will be f77, g77, gfortran, or equivalent). Not tested yet.

Note: since version 2:35 recommend executable files renamed with "lep" + "-" + "X.XX"  being X.XX the version number, instead old names a.out or a.exe. So a.out and a.exe files have been renamed lep-2.52.out and lep-2.52.exe

    4. Viewing the drawings (CAD)

  The program CAD displays the results dxf file. Please use 'zoom_extension' command.

    5. Iteration from stage 1. to achieve the desired layout.

    6. Post-process CAD

    Drawings can be edited by the CAD program to improve the presentation. They should position the panels and ribs on a reference template and print the templates in an array of A4/A3 size paper or plotter.

leparagliding
FIGURE 1: How to work with the program.
Since 2.23 version and additional file lines.txt is in the output.


5. COMPOSITION OF THE AIRFOIL FILES


The file of the profile data must have the following structure:

Line 1: name of the profile (do not use spaces in the name)
Line 2: total number of points defining the profile
Line 3: number of points that form the extrados (upper surface)
Line 4: number of points that form the opening (if any)
Line 5: number of points that form the intrados (lower surface)
Following lines:
X coordinate Y coordinate of each point of the airfoil
The coordinates are ordered starting at the trailing edge, covering the top surface, passed through the leading edge and coming through the lower surface and
again ending at the trailing edge.

Important: The endpoint of the extrados must exactly match the start in% of the opening (air inlet), and the starting point of the intrados must exactly match the end in% of the opening (air outlet). Therefore the airfoil must be processed prior in a CAD program to achieve this. Therefore if you want to vary the start and end points of the air openings  along span, you must detail specific profiles for this. Init and end points of openings declared in leparagliding.txt file must be consistent with the selected airfoils.

airfoil leparagliding
FIGURE 2: Airfoils definition


For gnulab2 two profiles have been defined eg for gnulab2.txt wing and airplan.txt  to the end profile.

It is essential that the number of points of extrados, openings, and intrados, and all are exactly the same for all profiles defined in a wing model.

Zero-thicknees wingtip airfoil:

Usually, you must define a profile of zero thickness for the final profile of the wingtip. It is advisable to move the end of the panel's top surface (upper panel) to 0% of the profile, and keep the same number of points for each item (upper panel "extrados", air intakes, bottom panel "intrados")

Closed cells:

The program apparently only works with open cells. But it also draws all caps cloth inlets that can be added manually (with a CAD program), the underside of the panels. Thus, any cell can be closed or converted to a special opening of any geometric shape.


6. COMPOSITION OF THE INPUT DATA FILE leparagliding.txt

Designing the paraglider is simplified to editing the file leparagliding.txt either creating it from scratch or by editing an existing model.

All lines that begin with the symbol "*" are comments that are not used by the program, although you must maintain it to keep the sequence of reading.

The units of work planned for the data file are centimeters (cm), except sewing allowances expressed in mm.

Next, and by section, we define the parameters to enter in the data file. Only are explained the line to complete, because the lines that begin with the asterisk symbol * are comments that should be maintained as are, so that the reading order is right.

First, it indicates the type of data to enter (integer, real , text, or boolean (1 or 0)). Then, following the ":" , indicates the object's data to write. It is essential using the sample file leparagliding.txt to understand. The order, data type, and number of rows is essential for a correct reading of the data file.

SECTION 1: GEOMETRY

By lines, and regardless of the lines beginning with * which are comments or notes for help.

text  :   Brand name (between "  ")
text  :  Wing name (between "  ")
real  :  Drawing scale (1.0 usual value)
real  :   Wing scale (1.0 usual value)
integer :    Cells number
integer :   Ribs number
real, integer, real : Maximum torsion angle (washin) between central airfoil and tips, an integer parameter set to 0-1- 2, and a real number for the angle of attack in the center used only in case "2".

If the integer parameter is set to "0" the washin will be done manually.  (Figure 3).
If the integer parameter is set to "1" then washin will be done proportinal to the chord, being maximun and positive at the tip, using only the first real.
If the integer parameter is set to  "2", then automatic washin angles are set from center airfoil to wingtip. The first real is the washin in wingtip, then set "2", and the last real is the washin in the central airfoil.

Example about 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.

text, boolean : Paraglider type "ds", "ss", or "pc", and parameter set to 0 or 1. If 1 then leading edge triangles will be no rotated (only ss paragliders)
integer + 8 reals:

    For each of the ribs, and considering an orthonormal system of axes XYZ (Figure 4) .
    oriented in the following way:
    X axis along the wingspan
    Y axis along the central chord
    Z axis growing vertical from the wing to the pilot

They are shown in a horizontal line the following parameters:

integer : rib number
real : rib X coordinate
real : Y coordinate of the leading edge
real : Y coordinate of the trailing edge
real : X' coordinate of the rib in its final position in space
real : Z coordinate of the rib in its final position in space
real : the angle "beta" of the rib to the vertical (degres)
real : RP percentage of chord to be held on the relative torsion of the airfoils
real : washin in degrees defined manually (if parameter is set to "0")

These parameters can not be defined without a previous drawing, preferably in a file of computer aided design CAD, in which the desired plant is drawn to an appropriate scale, form lobe in elevation, and inclination of the ribs. This drawing is one of the most basic and important design (pre-process).

It would be possible to generate this drawing by a geometric preprocessor to read basic data from the wing desired number of cells, separation, size, shape, edge and trailing by a few parameters defined to create elliptical shapes. This pre-processor has been implemented (june 2013), but not inside the main program, because we prefer to keep this important part of design with a CAD program, to allow total freedom of the shape of the leading edge, trailing edge, and in the elevation, and inclination of the profiles. Any design is possible, normal wings, or bionic type, with peaks in leading edge or ...

There is a limitation of not being able to define airfoils in the center of symmetry. To remedy this situation can be defined a virtual central cell's with almost zero thickness.

washin
Figure 3. Washin

wing definition
Figure 4. Axis and main paraglider geometric design

Instructions for selecting the type of paraglider (parameters "ds" "ss" "pc" listed above):

"ds": means that the design and calculation parameters are adjusted to create paragliders and parachute of double surface airfoils (intrados and extrados)
"ss":  means that the design and calculation parameters are adjusted to create single skin paragliders and parachutes, Surfaces corresponding to the intrados are not draw. But it is not enough to indicate this parameter to create single skin paraglider. It is necessary to define an special intrados sawtooth profile (or parabolic shaped), so that the vertices of the triangles are located exactly at the point where% is defined the anchor points. As a general rule, we use covers of the air intakes, as part of the sigle skin profile.
"pc": means that the design and calculation parameters are adjusted to create parachutes using double surface airfoils (intrados and extrados).

SECTION 2: AIRFOILS

In an orderly manner for each rib, are written in a horizontal line:

integer : Number of rib
text : Name the file containing the airfoil assigned to that rib
real : Percentage of chord start of the air inlet
real : Percentage of chord end of the air  inlet
boolean : Value 1 or 0 to create closed cells, at the left of rib ("0" indicates closed-cell, "1" open)
real : Displacement in cm of the rib perpendicular to the chord, and in the plane of the rib itself. Serves to improve the position of the ribs without suspension lines. Value is usually 0
real: Relative weight of the chord, in relation to the load. Value is usually 1.
real:
It has two meanings:

1) If values is "0" or "1", only used in single skin paragliders (useless in double skin). More control in rotation of triangles. Real value "1" (or "1.") means that the triangles are rotated automatically in the corresponding profile. "0" means that the triangles are not rotated, but they are set according to the angle "beta" specified in Section 1.

2)
If the numerical value greater than 1.0 is possible define and draw trailing edge "miniribs" ("minicabs") in non "ss" paragliders: The value, simply define the minirib length (in %).

miniribs minicabs
                Figure 4+. Miribs definition in lep  <  2.50 (in lep-2.50 minirib "i" was set at LEFT, between "i-1" an "i")


Note: init and end points of the air openings are not fully implemented yet in the program, and is in the profile itself obliged to include it means of the integer numbers that describe the end of the top surface and the beginning of the intrados (in each airfoil).

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 (lep < 2.50), 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.

SECTION 3: ANCHOR POINTS

In an orderly manner for each rib, are shown in a horizontal line:

integer : Number of rib
integer : Number of anchors in the rib
real : Anchor position A as% of rib
real : Anchor position B as% of rib
real : Anchor position C as% of the rib
real : Anchor position D as% of rib
real : Anchor position E as% of rib
real : Anchor position F as% of rib

Note: A, B, C, D, E anchorages. F brakes.


SECTION 4: LIGHTENING IN THE RIBS (RIB HOLES)

By Rows:

integer : Number of configurations of lightening
integer : Initial rib for first lightening configuration
integer : Final rib for first lightening configuration
integer : Number of holes for the first lightening configuration

Definition of each hole in a horizontal line. There are three possible types of holes. Type 1 = elliptical holes (including circulars), type 2 = elliptical holes central band, type 3 =  triangular holes with smooth corners.

If the hole is type 1, type in a horizontal line:

integer : 1
real : Distance from LE to hole center in% chord
real : Distance from the center of hole to the chord line in% of chord
real : Horizontal axis of the ellipse as% of chord
real : Ellipse vertical axis as% of chord
real : Rotation angle of the ellipse
real : 0. (not used)
real : 0. (not used)
real : 0. (not used)

hole 1
Figure 5. Hole typoe 1, ellipse

If the hole is type 2, type in a horizontal line:

integer : 2
real : Distance from LE to hole center in% chord
real : Distance from the center of hole to the chord line in% of chord
real : Horizontal axis of the ellipse as% of chord
real : Ellipse vertical axis as% of chord
real : Rotation angle of the ellipse
real : central strip width
real : 0. (not used)
real : 0. (not used)

Hole 2
Figure 6. Hole type 2, ellipse or circle with central strip

Not use holes type 2 beacuse yet no implemented !

If the hole is type 3, type in a horizontal line:

integer : 3
real : Distance from LE to triangle in% chord
real : Distance from the center of the triangle corner to the chord line in% of chord
real : Traingle base as% of chord
real : Triangle heigth as% of chord
real : Rotation angle of the base
real : Radius of the smoothed corners
real : 0. (not used)
real : 0. (not used)

hole 3
Figure 7. Hole type 3 triangle

Continue:

integer : Initial rib for second lightening configuration
integer : Final rib for second lightening configuration
integer : Number of holes for the second lightening configuration

Definition of each hole in a horizontal line, as before.

And so on... (repeat pattern for all types of lightening configurations)


SECTION 5: SKIN TENSION

The tension of the top surface and lower surface panels is achieved by creating tapers in the panels. The program allows you to define "over-wides" in 6 points along the edge of the panels. The transition between basis points of overwide is linear.

In each of the six lines are defined to indicate consecutively:

real : Distance in% of chord on the leading edge of extrados
real : Extrados over-wide corresponding in % of chord
real : Distance in% of chord on trailing edge
real : Intrados over-wide corresponding in% of chord

skin tension
FIGURE 8: Skin tension

Then add two more lines with the following parameterr (new in leparagliding 2.0):

 real : 0.0114 (strain in mini-ribs).

The justification for this value is obtained from the theory of elasticity. Leave the default value in case of doubt.

Ripstop elasticity
Figure 9. Ripstop elasticity

integer, real : Number of points np, k coeficient 0.0 to 1.0

The justification for this line is complex. There are two possibles interpretations:

First interpretation)

If first number in NOT set to "1000",
the values are used to make adjustments to the shape of the leading edge for easy sewing. However is and old feature and actually is not recomended. Study conducted at the request of a manufacturer of paragliders.
The second number is used to adjust the intensity of the modification (1.0=maximal effect, 0.0= no effect).

Justification of the line in the figure below:

sa
Figure 10. Sewing corrections

And the explanation:

When three panels are sewn at the same time, with different curvatures to side... problems may arise:

The left panel (i="izquierda") has a concave curvature, while the right panel (d="derecha") has a convex curvature.

The lengths of seam lines (line dashed) should be exactly the same. However, the outer edge of the fabric, which is 15 mm from the seam line, is shorter in the left case (inner radius) than the right (outer radius). The program calculates the difference in length of the leading edge in the area of "np" points od airfoil of greatest curvature from air inlet (np defined by user).

With the calculated length difference (1d2d-1i2i), the program modifies the plan shape of the left panel, extending its inner side. Thus, when the seam is made, there are fewer problems ...

The second control parameter, "k" between 0. and 1. is the coefficient to be applied to the difference (1d2d-1i2i). Then 0.0 = no effect. 1.0 = total effect. Then sewing corrections:

integer, real : Number of points np, k coeficient 0.0 to 1.0

Another explanation for the same, but in French: Étude des courbures panneaux-nervures (PDF)
Many builders prefer not to take into account this effect, then select the parameter as k=0.0

Second interpretation) Recommended:

Set the parameters of the line to the values:
1000     1.0

First number "1000" (integer) is only a convention than signifies force the program to use maximal precision, reformating panels to achieve accuraccy better than 0.1 mm (lengths differences beetween rib and panels located at left and right).
Second number is a coefficient (real) between 0.0 and 1.0 that sets the intensity of the correction. If coefficient is set to "0.0" then is no correction. If the coefficient is set to "1.0" the accuracy is maximal, aprox < 0.01 mm.

The description of the geometrical problem and the solution, is decribed here.

In file lep-out.txt is a report in section 6, indicating the final lenghts of the panel at left, rib, panel at right, and maximal difference and distorsions in mm.

SECTION 6: SEWING ALLOWANCES

3 reals : Edge seam (mm) in upper panels,  LE, TE
3 reals : Edge seam (mm) in lower panels, LE, TE
real : Edge seam (mm) in ribs
real : Edge seam in V-ribs

SECTION 7: SEWING MARCAGE

Indicate the spacing in centimeters and the radius of the point, to make marks on ribs and panels to match all items as accurately and thus able to control that there is no slippage during sewing.

real, real, real : marks spacing, point radius, point displacement

SECTION 8: ESTIMATING THE GENERAL ANGLE OF ATTACK

This section defines the basic length of the lines and provides the general draft of the wing, estimating the center of pressure and angle of glide.

Be entered on lines below:

real : Finesse goal, according to the general proportions of the wing.

real : Position of the wing center of pressure estimated as % of central cord

real : Calage in% (distance from the leading edge point to the perpendicular to the central chord from the pilot position)

real : Riser basic length

real : Basic length of lines (maillons - sail)

real : Separation between main carabiners

calage
FIGURE 12: General AoA estimation


SECTION 9: DESCRIPTION OF LINES


It defines the following concepts by lines:

integer : Control parameter with the following meanings

0 = lower branches lined only by geometric mean of the anchor points
1 = lower branches lined by weighting type 1 (not fully implemented yet)
2 = lower branches lined by weighting type 2 (not fully implemented yet)

integer : Line plans number (2,3,4...)


Denotes the number of plans of lines that start from each of the risers of the glider. Will be considered as many plans as risers. The "plans" do not necessarily have lines in a plan, and may have different alignments anchors in various rows (pyramid lines)


integer : Paths number for first plan

11 integers : i1, i2, i3, i4, i5, i6, i7, i8 ,i9, i19, i11 Ramifications and levels

(i1) number of branches (ramifications) of the path

(i2) branching level 1
(i3) order at level 1

(i4) level of ramification 2
(i5) order at level 2

(i6) level of ramification 3
(i7) order at level 3

(i8) branching level 4
(i9) order at level 4

(i10) anchor line (1 = A, 2 = B, 3 = C, 4 = c 5 = D, 6 = brake)
(i11) anchor rib number

- These are considered the ramifications from to the bottom to up. The main riser are considered the branch level "1", the next line that starts from maillons "2", the one above is the "3" ... and so on.
- Within a branch level are numbered consecutively in the same lines from left to right 1,2,3,
- Path: Is any path through the ramifications, upward, started in the main carabiner and ended in a sail anchor.
- With these definitions, this section should be written the array of lines for each plan
- The first section number indicates the number of planes to be considered.
- The next number indicates the total number of different paths in the plane.
- Each line of the matrix is a "path"
- If there is no level 3 or 4 is denoted by "0"
- It is only allowed up to 4 levels of branching.

integer : Paths number for second plan

11 integers : i1, i2, i3, i4, i5, i6, i7, i8 ,i9, i19, i11 Ramifications and levels
...

Do likewise with the other plans of the paraglider line design. The example of clear matrix writing is exposed in gnuLAB2 data file.

lines

FIGURE 13: Suspension lines matrix


SECTION 10. BRAKES

real : brake lenght

integer : number of paths brake plane

The first number is the length in cm for the main brake cable, and second number indicates the number of paths brake plane.

11 integers : i1, i2, i3, i4, i5, i6, i7, i8 ,i9, i10, i11 Ramifications and levels

Matrix writes like for the rest of the lines, taking into account that now the level "1" corresponds to the main brake cable.

NOTE:  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.

Brakes distribution:

4 real : s1, s2, s3, s4, s5 (lengths along vault and from center wing)

4 real : d1, d2, d3, d4, d5 (lengths increments in brake line)

brake distribution
Figure 14. Brake distribution


SECTION 11. RAMIFICATIONS LENGTH

Indicates the upper branch lengths to the anchors in sail, by rows:

integer, real :  3 , Distance branching from third ramification to sail (l2)

integer, real, real :  4, Distance branching third to sail (l3), Distance beginning of fourth branching to sail (l2)

integer, real :  3, Distance beginning of third brake branch to sail (l2)

integer, real, real : 4, Distance beginning of third brake branch to sail (l3), Distance brakes start fourth branching to sail (l2)

ram
FIGURE 15: Ramifications length

SECTION 12: H V and VH RIBS

integer : mini-ribs number

real, real : x-spacing, y-spacing (when drawing mini-ribs)

Then, for each mini-rib, and in a row:

integer, integer, integer, integer, integer, integer, real, real real, real, real :

with the following meanings,

If it is a mini-rib horizontal ribbon type:

1
Figure 16. Mini-rib 1 (horizontal strap)

If it is a "V-rib" mini-rib  type:

2
Figure 17. Mini-rib 2 (V-rib)

If it is a "full V-rib" type 3:

3
Figure 18. Mini-rib 3 (full V-rib

If it is a "VH-rib" type 4: (partially implemented!)

4
Figure 19. Mini-rib 4 (VH-rib)

If it is a "VH-rib" type 5:

VRF
Figure 20. Full continous V-ribs type 5 using parabolic holes (if t<100%)

VRF
Figure 21. Full continous V-ribs type 5 using elliptical holes (if t>100%)


If it is a "VH-rib" type 6:

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).

Type 6
Figure 22. V-rib type 6 general diagonal

Parameters:

n = number of V-rib (consecutive order)
6 = define V-rib "type 6"
i = number of initial rib
x1 = starting position as a percentage of the chord of the profile
h1 = initial height in percent of the local thickness profile
r1 = radius backwards (cm)
r1- = radius forward (cm)
i +1 = number of final rib
x2 = starting position as a percentage of the chord of the profile
h2 = initial height in percent of the local thickness profile
r2+ = radius backwards (cm)
r2- = radius forward (cm)

Type 6 uses 12 parameters, while the other V-ribs types, use only 10 parameters. This is no problem. The program can read the data file correctly. Simply, interpret the scheme. Try and see the results. Type-6 is now working and fully implemented.

Very important: The pieces "Type 6", must be defined consecutively, and line by line. With the following order: From the leading edge to the trailing edge, and from the center of the wing, to the wingtip. That is, first define all the pieces consecutively in rib number "i", before defining pieces in a rib greater than "i".

SECTION 15: EXTRADOS COLORS

integer : number of ribs with marks

integer, integer : first rib number, number of marks

integer, real, 0. : first mark, distance % from TE, 0.

integer, real, 0. : second mark, distance % from TE, 0.
                                ...

integer, integer : second rib number, number of marks

integer, real, 0. : first mark, distance % from TE, 0.

integer, real, 0. : second mark, distance % from TE, 0.
                                ...
and so on...

colors
Figure 23. Extrados colors

SECTION 16: INTRADOS COLORS

Like extrados colors, works from version >= 2.41. Fopr example write the minimal configuration:

1
1    1
1    0.    0.

SECTION 17: ADITIONAL RIB POINTS

With this option, auxiliary points can be drawn in the ribs.
Typically
to mark mylars, or start and end points of the nylon rods.

integer : number of points

real, real : x-coordinate % of chord, y coordinate % of chord (first point)
                  ....
real, real : x-coordinate % of chord, y coordinate % of chord (last point)


SECTION 18: ELASTIC LINES CORRECTION

Option to estimate the elastic elongation of the lines in normal flight configuration. These elongations are subtracted from strictly geometric length, so that in flight, are the exact lengths of project. Option fully functional but still under development. To calculate the elongation, we take into account the loads on each line, and the rigidly coefficient of each line, the elongation estimated by Hook's law: F = kˇdx

real : load in flight (kg)

real, real : % load distribution in 2 lines rib

real, real, real : % load distribution in 3 lines rib

real, real, real, real : % load distribution in 4 lines rib

real, real, real, real, real :  % load distribution in 5 lines rib

integer, real, real, real, realp, d1, d2, d3 where

p = number of lines per rib (p 1 to 5)
d1 = deformation in lower level with 10 kg
d2 = deformation in medium level with 10 kg
d3 = deformation in higher level with 10 kg


7. RESULTS

INTERPRETATION OF THE LINE LABELS IN FILE lines.txt

In file lines.txt lines will be labeled like this:   [integer]-[letter]-[integer]

Examples: 1A1, 2A1, 2A2, 4A14,..., 1B1, 2F2, ....

First integer indicates "line level" from below to above. Then level "1" is the riser, level "2" main lines, level "3"
following branching above main lines, and so on.

The middle letter indicates:

-
Lines that belong to the riser (or brake) of the same letter A, B, C, D, F (in the case of the lines belonging lower levell of to two or three branches system)
-
Or the final destination row A, B, C, D, F, in upper ramifications of the case of 4 levels or more

The final integer indicates:

- Line order in the same level, counting from center to tips
- Final rib destination number, 
if the line is for the highest level, anchored under sail

This nomenclature may seem strange, but studying the examples is clear and justified. The name of the line indicates in which part of the glider was inserted. Naturally, it is essential to have the sketch lines, with each line label, drawn at the appropriate place. This is a simplification of the nomenclature already provides the file lep-out.txt file for each line.


8. FUTURE DEVELOPMENTS

The author of the program maintains the files leparagliding.f and leparagliding.txt constantly evolving, and improvements will be added in future releases.


- Optional pre-processor for basic geometry (planform and vault). Done.
- Dynamic definition of points of entry and exit of air inlets, directly from the data file without having to coordinate with the definition from the airfoil files. Pending
- Improving VH ribs design (three cell). Done.
- V-rib (full). Done.
- Mini-ribs in the leading edge. Done
-
Anchor brake lines to intermediate points between ribs. Done.
- Improvements on lines elastic calculus
- Much better plans presentation
-
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.
- Graphical user interface GUI
-...

It is very recommended reading and understanding the file example file leparagliding.txt, following this guide, and others examples in the laboratori gliders.

FAQ leparagliding.

Current version of LEparagliding is 2.52 "Utah"
And pre-processor is 1.3 "Utah"

Pere Casellas
pere at laboratoridenvol dot com
Teiŕ, Barcelona, August 2016

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