le-ge
[en] [fr] [de] [ru]

BHL7
BARRETINA HYPER LITE 7
 
BHL7 comparative
Figure 1. BHL7 sizes 22 and 10 comparative

1. DESCRIPTION

BHL7 is the name of the new single skin paraglider 2022 of the Laboratory. At first glance, it is a BHL2-evo model, because its basic geometry is exactly the same. However, we have added some experimental improvements, and with the aim of not creating more confusion with the BHL2 model versions, we have named this 7, which is the next corresponding number in the hyperlight series. The changes are as follows:

1. Nose modified airfoil

Based on a classic four-triangle BHL2 profile, the profile nose has been modified, making the lower surface exit angle above the horizontal. That is, it is an "epsilon" angle profile (as explained in the BHL3 paragliding studies). With this, less aerodynamic drag is expected. This modification of the profile nose has also been applied to the 16 m2 Suluk2, and to the size 33 m2 of the BHL5. The profile of the 2016 BHL3 also had a similar modification.

nm airfoil BHL2
Figure 2. Nose modified airfoil with with an epsilon angle above the horizontal, at the nose exit edge.
Includes an optional nylon rod above the "D" triangle to minimize wrinkles in this area

2. Progressive rotation of profiles around the "Z" axis

This is not an aesthetic curiosity. During the summer of 2021 we studied in detail that rotating the planes of the profiles in three axes X, Y, Z can be achieved that these are perfectly oriented with the flight path. That is, the profiles work with their highest aerodynamic efficiency. And, especially in the case of single-skin paragliders, allows the triangles to offer the minimum resistance due to exposure to airflow. That is, this alignment with the flow is more important in single skin paragliders, than in double surface paragliders where the diagonals are perfectly faired inside the double surface.

This alignment allows us to calculate more accurately the angle of attack "seen" by the profiles in relation to the flight path, and at the same time allows us to reduce the maximum geometric torsion (washin). Angles washin and Rot_z used in BHL7 (printed in section 3 of lep-out.txt):

 Rib - Chord - washin - beta - Rot_z
 -------------------------------------------------
 1     262.65   0.000   1.53   0.22
 2     261.53   0.028   4.31   0.61
 3     259.27   0.084   7.23   1.02
 4     255.90   0.167  10.15   1.43
 5     251.39   0.279  13.00   1.82
 6     245.72   0.419  17.10   2.38
 7     238.90   0.588  21.21   2.93
 8     230.88   0.786  25.05   3.43
 9     221.59   1.016  28.90   3.92
10     210.01   1.303  32.74   4.39
11     195.90   1.652  36.59   4.84
12     179.24   2.064  41.19   5.34
13     160.02   2.540  47.35   5.97
14     138.42   3.074  53.11   6.49
15     114.55   3.665  59.33   6.99
16      88.44   4.311  75.16   7.86
17      59.85   6.500  89.34   8.13

washin ---> airfoil rotation around X axis
beta ---> airfoil rotation arount Y axis
Rot_z ---> airfoil rotation arounf Z axis

Note that in this paraglider we have used a maximum washin angle of 6.5, while the BHL2 and BHL-evo use angles of 10 and higher. The BHL3 paraglider used an washin angle of only 4.5 with no tendency to fold ears during flight, and a slight tendency during the inflation phase. Here we have preferred to increase a little. The rotation angles in Z "Rot_z" fron 0.22 to 8.13 are the ones recommended by the program to achieve the best alignment of the profiles. See the results in the
lep-out.txt) file section 12.

Rot Z BHL7
Figure 3. The cyan lines represent the Z-rotations of each profile.

Rot Z detail
Figure 4. Wingtip detail. Maximun Z rotation 8.13.


3.
Calculation of lines according to theory number "3".

The calculation of line alignments in space is done by calculating the weighted average of the relative weights of the anchor points and the chord length variations along the span. Remember that the previous BHL2s were calculated with the theory number "0" which only considers the geometric means of the anchor points. View first parameter in section 9 of leparagliding.txt

Lines models
Figure 5. Lines models using case "0" (orange), case "3" with 35-35-20-10 distribution (green), and case "3" with 32-32-22-14 distribution (magenta).
BHL7 uses magenta case. View values set in section 18 of
leparagliding.txt

Detail
Figure 6. BHL7 uses magenta model. The aim is to predict a distribution of forces as close as possible to reality, and thus a uniform tension throughout the sail.


2. TECHNICAL ESPECIFICATIONS BHL7


Mini
M
Model
BHL7-10
BHL7-22
Surface
10 m2
22 m2
Flat span
7.04 m
10.44 m
Flat AR
4.96
4.96
Panels
33
33
Closed cells
2 in wingtip, with one elliptical inlet
Weight range
-
70-90 kg
Anchors per rib
4
Risers
3
Top surface
ripstop 40 gr/m2
Ribs
ripstop 40 gr/m2 hard
Certification
No. Use only for
ground handling.
No


3. DATA FILES AND PLANS

LEparagliding-3.17 input and output files and DXF files


BHL7-10
BHL7-22
Airfoils
bhlnm-4p.txt   gnuPSFtube.txt
bhlmn-4p.txt gnuPSFtube.txt
Input file
leparagliding.txt
leparagliding.txt
Output txt files
lep-out.txt lines.txt
lep-out.txt lines.txt
PDF descriptive plans
BHL7-10
BHL7-22
PDF A4
Panels
Ribs
Pockets
Panels 01-07 Panels 08-17
Ribs 01-06 Ribs 07-17
Pockets
All files in one zip including DXF plans
BHL7-10.zip  (version 2022-01-09)
BHL7-22.zip  (version 2022-01-09)

Version 3 m2 here: BHL7-3.zip (version 2022-01-16)

Panels
Figure 7. Panels ready to print in A4 (BHL7 10m2)

Ribs
Figure 8. Ribs ready to print in A4 (BHL7 10m2)

Pockets
Figure 9. Rod pockets and straps ready to print in A4 (BHL7 10m2)

4. SCREENSHOTS

1
Figure 10. Top view

2
Figure 11. 3D view

3
Figure 12. Front view

5. CONSTRUCTION

Jeremy Paxson has begun construction of the 10 m2 prototype in Germany.

1
1. Jeremy has used the technique of using a large format plotter and printing the plans directly on the ripstop fabric.
He has even printed the Laboratory logo!

1
2. CAD designed Lineshoe for Sewing the lines.
"Lots of 3d printed parts this time"
7
3.
7
4.
7
5.
7
6.


7
7.
7
8.
7
9.
7
10.


LAB NOTE: Build a paraglider at home is a very complicated task (even simple skin), and requires many hours of work. Previous experience is required, and very inventive. As always remember that: The free flight implies risks that can only be known and they can be controled with a suitable formation on the part of a recognized school. Not test wings without knowing their functioning. The construction and test of experimental wings without certifying requires deep knowledge of what is being made.

index