Flying sailplanes


Contents :


  • Flying wings.
  • F3i : towed sailplane
  • Scale sailplanes.
  • Electric flying.
  • Hang and cliff gliding.
  • HLG.

  • 2.Tips and technic
  • Kite towing :
    a windy experience...
  • The "débattomètre" (What !?)
    Dowloads (JC Etiemble)
  • The soft "Mean Aerodynamic Chord".
  • Tracfoil : to plot every airfoils !

  • 3.Aerodynamics / Flight mechanic

  • MIAReX, a program for multi-airfoil wing calculation
  • Flight dynamics : eigen modes location
  • Aerodynamic tuning of a Nimbus 4D model.
  • Low Reynolds airfoil polar.
  • Speed task : F3i, F3b or F3f.
  • Understanding "dynamic soaring".
  • Miscellaneous calculation.

  • 4.Miscellaneous

  • A short 3-language gliding terms
  • Links.

  • Click for further in formation in the same page.

    You are my XXX th visitor, thanks !!
    since 13th may 2000, when the counter last broke...

    I am a student, then there is still
    some articles for french reader only, excuse me...


    Flying wings.

    1. The Paoli wing.
         It is a pure flying wing, without any fin. Simple as it may seem, it works well, and the building is really easy.

    2. Titine : a bungee flying wing
         Here is a small flying wing, launched with bungee, that flies on a soccer area field.

    3. The NicAile : a performance flying wing, designed par Nicolas Quendez
         During a training period at ONERA (french research center for aeronautics), Nicolas quendez studied aerodynamics optimisation applied to flying wings. He defined some design rules concerning thoise tailless aircraft, that were practically verified through the building of the NicAile.
         We both built a NicAile, and I felt in love with the conccept.
      Do you want to know more ?

    4. The Minus-Kiool MAV
         This is not really a flying wing, but it looks like...
         Here is presented the MAV we design in a student team for the first MAV contest. The result is a really Tiny aircraft, whose weight is only 56gm with a camera onboard.

    5. Docs about flying wings.    I propose you some books dealing with flying wings.

    6. Airfoils to be used on flying wings.
         Many flying wings airfoils does exist, but they are not all as much well known

    7. My links about flying wings :


    F3i : towed sailplanes

       F3i is a FAI rule for sailplanes with span larger than 3500mm, that uses aerotowing to start. It is a "speed - duration" event.
       For me it's a project at school, too.

    Come and have a look at this project.
    1. Presentation.
    2. Calculation.
    3. Airfoils.
    4. Building Jade sailplane.


    Scale sailplanes.

    Come to discover scale sailplanes !

    Including : a list of 3-views drawing and other docs, some unusual subjects, links...
                Displayed :
    1. My ASK-13.
    2. A logo for Duo-Discus.
    3. Docs.
    4. Do you have ever hear about Scimitar sailplanes ?
    5. The PW-5, world class glider.
    6. Links - Best of sites for the scale sailplane addict...


    Electric flying.

    1. La Sitelle (the nuthatch) :
         I have designed my first electrical powered glider. The building is quite simple and wholly inexpensive, and the flight is efficient. Come and see !!
    2. Excepting the description of this glider, some tips concerning electric flight are displayed.
      Come in the world of electrons !!


    Hang and cliff gliding.

       I am from Normandy in France, and this countryside is not famous for its sun and nice wether. Whereas there is nice cliffs here, that are really flyable !



       I had already built a Slider and a personnal model(Mostiko, plan encarté RCM n°190). here is a large HLG, for calm days at the slope.
       It is here displayed ready to fly. It can really fly into small and weak thermals, but it is quite lazy to handle !

    For checking the accuracy of my Excel polar calculator, I computed polar and L/D ratio according to speed for this HLG, with S4083 airfoil. It is quite realistic, even if a little bit optimistic.


    2.Tips and technic

    Kite towing : a windy experience...

       Have you ever tow a glider with a kite ?
       When two hobbies join together, you can do interesting things.

    You want to know more about this ? Only one answer : read the page !!


    The "débattomètre"

       This untranslatable term hides a simple device which will allow you to trim your sailplanes more easily.

    Have a look to this page, and within 20 minutes, you will own a new tool !


    The soft "Mean Aerodynamic Chord"

       Programmed by Jean-Claude Etiemble, this small soft will make your modelers life easier. It computes for you the mean aerodynamic chord and the CG for wing with up to 5 panels !
       Both in metric and non-metric system.

    GO on its page,and download it !


    Tracfoil, a genuine airfoil plotter

       The state of the art, by Jean-Claude Etiemble !
       This soft plots every *.dat airfoil, and draws spar, leading edge and other features on the ribs. It also plots template for foam cutting. It worths at least "compufoil", but it is far cheaper !

    NEW : buy tracfoil license online to its author !

    check its page, and download a 45 days test version !


    3.Aerodynamics / Flight mechanic

    MIAReX, a program for multi-airfoil wing calculation

    Here is a very useful and interesting program, that compute polar for multi-airfoil wing. The calculation method used is based on lifting line theory, généralised to non linear behaviour of airfoil section.

    More information about MIAReX

    Download MIAReX

    Flight dynamics : eigen modes location.

    AVL from Harold Youngreen & Mark Drela is an aerodynamic (VLM) tool, but it also computes rigid eigen mode of a glider.
    A pair of models of glider were evaluated through this tools, allowing to get some knowledge about what can be hoped, eigen mode speaking, for a sailplane model.

    Here are some commented examples :

    Aerodynamic tuning of a Nimbus 4D model.

       I got my Nimbus as a second owner, but I was really disappointed not to fly and trim it properly at the first place.
       I did some deep investigation, that leads to some aerodynamic improvement. this was successful since now it flies much better !

    More information about this aerodynamic tunnig

    Low Reynolds airfoil polars

       Xfoil is a code that allows calculation with viscosity effects. Then the polars are quite accurate for models aifoils.
       Here are some result for different Re number.

  • F3I airfoils :
  • Typical F3B airfoils
  • Marcel Guwang's airfoils (F3F, 60 inches) :
  • Others :

        Olivier Bordes also plots some polars, for F3F airfoils.


    Speed flight : F3i, F3b or F3f.

       I made some calculation about speed flight in glider event. At first according to energetical ideas, but it did not fit really well. And then I studied Helmu Quabeck's book : "Design, Leistung und Dynamic von Segelflugmodellen". I took his ideas for the calculation, and I add some personnals ideas too.
       It seems to give pretty close accurate results, at least for F3i.
        This is summed up into an excel sheet (in french curently). Some parameters are taken into accompt :

       Here is display the calculation that allowed to build this sheet (in french at the moment).

    As usually, there are some restriction to calculation. Hopefully those choosen are quite accurate, but don't forget to keep CRITICAL in front of strange result.


    Understanding "dynamic soaring".

       DSing is quite widespread today. It is an extraordiar way to fly faster and faster. It is even quite magique, and I wanted to know from where all this energy comes.
       So I made an excel sheet (once again...) to compute this, and to understand what are the main parameters for DSing. I had to make some simplification, but you can have an idea of the ideal path according to the glider and the wind.

    Main hypothesys are :

    1. The pilot flies in such a way that the flight path is a plan circle
    2. Wind is zero under a separation line, and is parallele to it over this line. So the frontier between calm and windy areas is infinitely thin.
    3. Ground speed is continuous (mathematically speaking)
    4. Only wind gust is considered, not lift due to rising air.

    You can download this excel sheet. Don't forget to read the instructions.

    Also some interesting links on DS :


    Miscellaneous calculation.

       Here at SUPAERO school, I am taught to calculate many things on plane. So I apply this to all what worries me, and I make some excel sheets.
    You have to keep aware that all those calculations have an "area of accuracy". Don't forget to read instructions.

    1. Calculation of glider's polar.
         I is quite simple to calculate lift, but drag is much moire difficult. Here is displayed some evalutation of Cd for sailplane, giving an idea of glider's polar.
    2. Roll speed :
      You can compare roll speed for a wing of a fixed area, in relation to aspect ratio, for full span or classic rudder.
      download this study of roll !
    3. Reverse polar speed to Cz-Cx:
      One can easily find on Internet speed polar for full size sailplanes, which give Vz according to speed V. But seldom one finds the polar giving Cz according to Cx.
         Thanks to this small sheet, you will be able, while re-entering 10 points on the speed polar, to very quickly obtain the Cz and the Cx of this sailplane.
      Download the Excel file inverting polars.
    4. That's all, folks (for the moment) !!!

       Here are some adresses displying free CFD code :



    A short 3-language gliding terms vocabulary

    Rather than a genuine dictionary, here is displayed a short vocabulary. Terms are given from english, to french and german, according to different topics.



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