Why GNU gliders?
This article is written
about the conference given
by Dr. Richard Stallman (President of the Free
in Barcelona, 10 may 2012 (Universitat
Politècnica de Catalunya,
Auditori de l'Edifici Vèrtex). We had planned to show and
discuss a GNU wing,
but the conference ended
too soon, and this time
it was not possible. I wrote this text
which try to justify
the GNU name
attached to many of my
projects. Experts on
system, also will
understand why. However, many
are unaware of the
of free flight. This
tries to give more details about this curious
consists mainly of flying gliding wings capable of takeoff and landing on foot, from high places and without
assistance. Wings are
light, and easily collapsible and portable.
The most popular free flight wings are hang
gliders and paragliders.
It is difficult to determine
precisely where the free
flight originated. No doubt converge several places with people
working independently without knowing almost nothing
of each other.
One of the major development sites, there is no doubt on the coast of California in the early 70's. Some manufacturers, including "hippies",
built their own wings
in plastic and bamboo.
They fly in dunes and
cliffs above the beaches.
There are no sufficiently
and design and construction
are "home made".
Quickly, bamboo is replaced by aluminum and plastic nylon. The designs are improved, and
manufacturers are beginning
to appear. A free flight historian could give more details.
Some articles have appeared in magazines such as "Low
and Slow" and "Popular
Mechanics" show some plans to build yourself your own wings. Other exchanges of drawings are produced by post or by
photocopy. There is a tradition of amateur
builders who enjoy not only flying but building their own models, from small RC planes,
kites, wood gliders... But it was not always easy to
get good plans...
In the case of paragliding,
this is started in the late 70's when a Frenchs skydivers fly with their canopys from
some peaks of the Alps.
Soon added to the
new sport climbers, mountaineers,
... and history repeats
itself. The undeniable advantages of the paragliders
(minimum weight and volume, ease of transport and use ...) facilitates rapid
progress to achieve
2. SOURCES OF INSPIRATION
I will mention three
sources of inspiration for the wings GNU:
1 - The model
of mathematics and physics.
Can be easily understood that
the mathematics and physics
that we learned, are
free, because it published
in countless books for study
and can be used wherever
necessary, whether in
programming, the design of wings, or in the bridges ...
2 - The work of
the Californian Michael Sandlin, a pioneer of free flight, which has been
publishing for many years (even before
me) complete plans of gliders in tube and fabric. His plans are freely available in CAD format and picture format. Contain much
detail and are of great
quality. Furthermore, the
same Sandlin has
built and flown their
models, demonstrating the success
3 - The GNU concept of freedom.
The model of freedom-respecting software licensing
with the GNU General Public License (GPL),
is applicable to other fields of engineering.
In particular, in the case of the design of
free flying wings, the source code, is
comparable to the plans in vectorial format
It is not easy to copy
a wing, but it is easy to copy a DXF file. A DXF file
can describe, so completely and accurately, a creation as a paraglider or hang glider.
3. THE GNU WINGS
Since 1999 I
have published on
the web, various wing
designs completely free. The plans are available for free study and
copy. Some designs do not
move from the conceptual
idea or a sketch,
others are detailed in
DXF, and even physically materialized.
Many of my designs are prefixed with "gnu" It's
fun and remember that
the design is free and
published under a license like the GPL. Other wings are not called gnu but follow the same concept (like many GPL programs which need not necessarily
start with the letter "g"
These are some of the
why GNU wings?
The interest of publishing
wings under GNU concept.
There are several reasons,
depending on the particular model, though subsisting always the idea of sharing and not unnecessarily close to work.
For gnupwing, the goal is clearly to share code (plans),
so that others can study it
or make replies.
Also returning to the public domain the
original plans of a NASA-kite I took
as a model.
For gnuLAB (later called gnuLAB1)
is very important. Surely
the first glider totaly
published online for your free copy. The main objective was precisely
to have someone copy,
and so save me the work of building ...
The case of gnuLAB2 is the project design and
complete construction, showing that the wing GNU flies perfectly.
BHL's case is
different. In mid-2011 a major and leading manufacturer of paragliders (perhaps the "Apple" of the paragliding), present a model
very light and
"revolutionary" and shrouded in
secrecy ... Looking
at some pictures of
this model, the concept reminds me the gnuswing,
so recognizing the
beauty of the idea, I decided to
go a step further and make
an improved version also
published as GNU. To carry out the project,
I have even the support of a Spanish manufacturer
of paragliders. Perhaps
will be the first GNU glider built in series
(currently in beta testing).
Its original name is just
and the version of the final model may be another. A Russian designer has also
released recently and
quite independently, its own model, including software
for the design.
4. DOCUMENTATION AND SOFTWARE
a complement to the wings, I
added two very important pillars:
PDH "Paragliding Design Handbook".
book, I'm still writing,
which exhibits all the
paragliders design technique.
Other articles on the web
complement the art.
program that I built from scratch to design my gliders. Programmed entirely in gnuFortran.
Read text files with the data, and generates
DXF files with 2D and 3D plans, and other text file listings. You do not need graphical
environment. Undoubtedly, the code is not everything
refined it should be,
but it works (I follow the
rule of simplicity UNIX, which is to
make the machine work, instead of the programmer time). I love the Fortran! I
learned Fortran on the old VAX terminals of the university, and I still
5. DERIVATIVE WORKS
great success for GNU glider would see how an outside manufacturer
copies it improves if necessary, and put it into production.
Until now, only I have news
for some amateur models to scale and the BHL case
Also some surprises,
which I have not worked
- A doctoral thesis of an aeronautical engineer
study of deformations
in a paraglider. It needed an accurate model and took the
gnuLAB2 as a model:
A flight simulator that
also takes gnuLAB2 model:
Conclusion: to encourage young engineers / scientists in the field of
programming or in other very different fields, to release
free their work. It is
absurd to hide the
principles of mathematics and physics.
Pere Casellas, Teià May 13, 2012
Laboratori d'envol home
to improve the english translation here: pere at laboratoridenvol dot