Kitesurfers School | Kiteboarding Lessons

Make Your Own DIY Kiteboarding Kite

In the early days, kite designing and making was an art exclusive to a small group of people who are gifted with a tremendous amount of aerodynamic knowledge, skillful in drafting, sewing, and other handy works.

Table of Contents

Not anymore! With the help of modern kite design fundamentals, kite design software, a database of airfoils, sample kite designs, almost all kiters can make their own kite. Let’s take a look at all those elements one by one and see where we are with the art of kite making:

Kite Design Fundamentals for Kiteboarders

Kites, especially sled kites, are very complex aerodynamic devices (as complex as if not more than airplane wings). If you are not familiar with airfoil, profile, wing, and the associated terminology, read some airfoil primer introduction before continuing. Now let’s take a quick look specifically at those that apply for kites.

Forces and Torques on a Kite

[Read this now if you are ready; otherwise, just read the summary  or you can skip the whole thing now and read it later.]

Like an airplane wing, a kite can fly due to various forces acting on it. The main differences are that an airplane has thrust while a kite has line tension and an airplane is balanced by its weight around its Center of Gravity (CoG) while a kite is balanced by its effective tow points (which can be adjusted automatically by the kite or manually by the kiter) and its weight at CoG. Let take a quick look at all the force and torque players:

Like an airplane wing, a kite can fly due to various forces acting on it. The main differences are that an airplane has thrust while a kite has line tension and an airplane is balanced by its weight around its Center of Gravity (CoG) while a kite is balanced by its effective tow points (which can be adjusted automatically by the kite or manually by the kiter) and its weight at CoG. Let take a quick look at all the force and torque players:

  • Wind Generated Forces:
    • Lift: This is the vertical force upward perpendicular to the wind that provides lift to the kite. The Lift of the kite is proportional to the Lift Coefficient (Cl) of the airfoil which varies dependent on the angle of attack (AoA) of the kite.  From 0 to around 20 degrees (most dominant AoA range for kiting), Cl increases as AoA increases.  After the peak is around 15 to 20 degrees, Cl will decrease.
    • Drag: (or profile Drag) is the horizontal force in the same direction as the wind that drags the kite rearward.  Similar to Lift, the Drag force is proportional to the Drag Coefficient (Cd) which varies dependent on the AoA. Cd normally increases as AoA increases
    • Lift/Drag (L/D) ratio: The L/D ratio shows how Lift changes as compare to Drag. The faster Lift increases compare to Drag or the slower Lift decreases compare to Drag, the higher the L/D ratio. From 0 to around 20 degrees (the most dominant AoA range for kiting), the L/D ratio is inverse proportional to AoA: low AoA means high L/D, and high AoA means low L/D.
    • Induced Drag: Induced Drag is the drag occurred when a physical wing or kite is flying.  The total Drag of the kite is the sum of the profile Drag and the induced Drag. Induced Drag is proportional to the square of Cl (Lift Coefficient), inverse proportional to the Aspect Ratio (AR) of the kite, and also inverse proportional to the shape of the kite (Induced Drag is minimum for an elliptical planform).
    • Moment (or Torque): this is the rotational force that either flips the kite over its nose (for the traditional airfoil, negative moment) or over its tail (for the reflex airfoil, positive moment).  The point along the chord where Moment force is constant for all AoAs is called the Aerodynamic Center. History and experiments have shown that for most subsonic airfoils, the “quarter-chord” point at 25% of the chord from the leading edge has a fairly constant Moment (for AoAs from -5 to 20 degrees, the range of AoA most important for airplanes and kites) and most if not ALL modern data are measured using the quarter-chord point as the AC. Moment is proportional to Moment Coefficient (Cm) and the chord of the airfoil. 
    • There are TWO MATHEMATICAL MODELS used by designers to consider how the Lift, Drag forces and the Moment act on the airplane or kite:
      • The AC and Moment model:  In this model, the Lift, Drag forces, and the Moment are considered acting at the AC. The Moment, if negative will flip the kite over the nose around the AC  (traditional airfoil), and if positive will flip the kite over the tail around the AC (reflex airfoil).
      • The Center of Pressure (CoP) model:  In this model, there are only Lift and Drag forces acting at a single point on the chord line called the Center of Pressure (CoP).  Since the CoP is not necessary at the same location as the AC, the Lift and Drag forces (the sum of Lift and Drag forces component that are perpendicular to the chord line; let’s call it Fcop) will generate a torque around the AC. Since the torque around the AC is constant, the CoP is close to the AC when the force Fcop is high (large AoA), and the CoP is far from the AC when the force is small (small AoA).
        For traditional airfoil, the Moment is negative, therefore, the CoP moves along the rearward side of AC (from 25% of the chord to the rear).
        For reflex airfoil, the Moment is positive, therefore the CoP moves along the frontward side of AC (from 25% of the chord to front).
        Since the Moment is constant, it moves either along the front side or rear side of the AC (dependent on the airfoil type) and will NEVER cross the AC.

Both the AC/Moment and the CoP mathematical models are useful and can be used in different situations in the wing and kite design process.  For some reasons, airplane designers are more comfortable with the AC/Moment model (this is one of the main reasons why airplanes have tail-wing to counterbalance the Moment of the main wing) and kite designers are more comfortable with the CoP model (it is easier to deal with 1 force than with a force and a moment).  In any event, from these 2 models, one can approximately determine the position of the CoP mathematically as:
          CoP position = AC – Cm/Cl
The exact equation is:
          CoP position = AC – Cm/( Cl(Cos(AoA) + Cd(sin(AoA) )
So at any AoA, once Cl, Cd, and Cm are known (normally measured in the wind tunnel at the quarter-chord point), we can determine the position of CoP at 0.25 – Cm/Cl of the chord from the leading edge. Please note the minus sign, if Cm is negative, the CoP is on the rear side of the quarter-chord point (traditional airfoils normally used in LEI) and if Cm is positive, the CoP is on the front side of the quarter-chord point (reflex airfoil normally used in Arc).

Why is CoP so important to a kite designer? The CoP is important to the kite designer because it is the location of the kite that the effective tow point has to be at or the bridle system has to support during the flight of the kite. Since CoP of the kite is changing during flight, the effective tow point of the kite has to change accordingly (either support statically via bridle line tensions, change automatically via a spherical shape, or change manually via the back and front lines of a spherical shape).

  • Gravity Force:

The kite weight is centered at its Center of Gravity.  The Lift of the kite must be larger than the weight of the kite for it to fly.  A kite is an unbalanced device and won’t be able to fly by itself unless:

  1. It has a “thrusters system” that pushes it forward to counterbalance the Drag force and some mechanism to counterbalance the Moment (e.g., tailplane.  For airplane without a tailplane, it needs to use a reflex profile and place its CoG in front of the main wing). This is the simple model for an airplane.
  2. Has a tether line placed at an appropriate location to counter-react the Drag force and the Moment. This is the model for a kite.
  • Line Tension:

The line tension is the main force component of the kite that acts similar to the thrust force of an airplane.  While the thrust force is an active force, Line tension is a static force.  The effective tow point is a location along the chord line that the line tension acts on. A tow point can be a single fixed tow point, a bridled tow point, a dynamic sled tow point, or a full control sled tow point.

  • Single fixed tow point: the tether line is connected directly to the kite. This is almost never used in a traction kite.
  • Bridled tow point: the effective tow point is determined by a bridle system consisting of multiple connections to the kite. While the built-in effective tow point is the most optimum location for a bridle system to counter-react the lift from the kite, the bridle system can accommodate some variation around the built-in effective tow point during flight by automatically adjusting the tension on various parts of the bridle lines.
  • Dynamic sled tow point:  Using a spherical form, a sled intrinsically has a dynamic tow point configuration for the kite (more for the central part, less for the wingtip) where the effective tow point can vary quite a range dynamically while the kite is flying (this is the case of an original 2 line LEI as described in Bruno’s LEI patent).
  • Full control sled tow point: Using a spherical form and a system of front lines and back lines, a 4 line sled has a dynamic fully controllable configuration where the effective tow point is dynamically readjusted during the fly and also be fully manipulated by the kiter (this is the case of a 4 line sled, LEI or Arc).

When a kite is balanced on the sky, all the forces and torques acting on it must be equal.  This means:

  1. The Lift of the kite has to be larger than the weight of the kite; the leftover Lift will create line tension to generate pull and also “thrust” ( this thrust force T is equal to (L-W)*Tan(AoA)  when the kite is fully balanceddue to the inclination of the line to move the kite forward (only if this “thrust” is larger than the sum of Profile Drag and Induced Drag).
  2. Using the AC and Moment model, the line tension and the weight of the kite has to balance the Moment of the kite about its AC or quarter-chord point.  Normally when a kite is flying (especially a traction kite), the lift is much higher than weight and the Moment about the AC is higher than the torque created by the weight of the kite. The effective tow point should be rearward of the AC (25% of the chord) for traditional airfoil (which has negative Moment) and frontward of the AC for reflex airfoil (which has positive Moment). 
  3. Using the CoP model, the difference of the Lift force at CoP and the kite weight at CoG is a force L1 slightly less than Lift and very close to CoP (since Lift is normally much larger than Weight; otherwise, we won’t feel any force on the line).  Let’s call this spot CoPg.  If CoP is frontward of CoG, CoPg is slightly rearward of CoP and if CoP is rearward of CoG, CoPg is frontward of CoP.

    The kite is balanced longitudinally when the effective tow point is around the CoPg.  For a bridle system, the CoPg should be within the range supported by the bridle system.  For a dynamic sled tow point system (2 line LEI), the kite will rotate and change the effective tow point to match that of the CoPg (the kite line will point straight to the CoPg).  For a full control sled, the kite can readjust the tow point automatically or the kiter can do it manually. While the kite is flying the CoP is changing and the kite balances its two point correspondingly to keep longitudinal balance. 

    Balancing the tow point will change the kite AoA to the wind (more drastically with sled) depending on the shape of the kite.  For example, for a typical AR 5 sled (with a kite angle of 50 degrees – read the Sphere theory for kite angle), decrease the tow point to 1% of the chord is equal to increase the AoA 0.5 degree and vice and versa). So for a sled using a traditional airfoil (LEI), during the flight path, the wind direction changes, and the AoA increases, the CoP will decrease and the kite will rotate itself to increase the AoA further. In this case, the kite amplifies the AoA increase so the kite designer has to make sure that at all places along its path, the kite will not luff nor stall due to this additional automatic adjustment from the kite. 

    This phenomenon from sled kite using traditional airfoil (for LEI only as Arc uses mostly reflex airfoil due to concern about wingtip or shoulder collapsing) makes it an excellent performer as it accelerates the Lift during the growth phase (AoA from 0 to around 20) and decelerates the Lift loss during the decline phase (AoA from 20 and above)

    For AoA from minus 5 to 20:
    AoA increases during flight path  -> CoP moves frontward -> Tow point follows CoP frontward -> AoA further increases -> Even more Lift

    For AoA from 20 and above:
    AoA increases during flight path -> CoP moves rearward -> Tow point follows CoP rearward -> AoA decreases -> Hang on to the Lift as long as possible.

    This effect is called “Sled Boosting” effect and is the reason why many kiters feel that they can jump easier and higher with LEI and LEI won the battle over foil in the early days of kitesurfing.

    For sled using reflex airfoil (such as Arc or LEI using reflex airfoil), the “Sled Boosting” effect is reversed, which means that it would protect the kite from exposing itself to very large or very small AoA. This means that for Arc, the kite will try to retain within a range AoA with an excellent L/D ratio.  So this type of kite will be fast and leverage power from speed instead of lift like the case of LEI.

    Furthermore, with a 4 line sled, the kiter can adjust the effective tow point (adjusting the length of the front line and backline) when the AoA becomes too little or too much.  This is what depower really means for a 4 line sled.  At any CoP position, a kiter can adjust the front line and backline such that the kite will fly certain degrees of AoA smaller or larger than the case of a 2 line sled kite.

    The kite will fly properly once it reaches longitudinal balance and will continue to adjust its longitudinal balance automatically (or the kiter can help manually) during the flight.

  4. The kite will stop flying when its “thrust” force is equal to the sum of all the drag forces (Profile Drag and Induced Drag).  So the wind window and the AoA of the kite at the wind window are determined by the kite itself (the airfoil characteristics).  The built-in effective tow point should be selected accordingly to be as close as the wind window CoP as possible (via bridle setting for bridle kite and via Profile Attachment Points for sled kite).


  1. A kite has Lift and Drag similar to an airplane.
  2. CoP of a kite varies dependent on AoA. CoP is closer to AC (25% of chord from leading edge) for large AoA and farther from AC for small AoA. For traditional foils, CoP is normally around 27% (AoA around 20 degrees) to 55% (AoA around 0) of the chord from the leading edge. For reflex airfoil (Arc), the CoP is normally frontward from 0 to 25% of the chord.
  3. The tow point of the kite should either statically (bridled kite) or dynamically (sled kites) support the range of variation of the CoP when the kite is flying across the wind window.  In the case of sled kite, it is automatic.  By following the CoP automatically, a sled kite using a traditional airfoil (such as LEI) “amplifies” the acceleration of Lift and sustains the peak.  This “Sled Boosting” effect is one of the main reasons why an LEI kite jumps higher and easier to jump.
  4. The Lift, Weight, and Drag of the kite determine the wind window and the AoA of the kite at the wind window.

Important Kite Design Parameters

The most easy to manipulate and highly visible kite parameters are Aspect Ratio (AR), Airfoil Profile and built-in Angle of Attack (AoA) of the kite:
Aspect Ratio
  • Aspect Ratio is approximately Span/Chord of the kite or more exactly Span*Span/Area.  Since AR determines the shape of the kite it is the most visible kite design parameter that the user will see. Higher AR kites have less induced drag (upwash and tip vortex effects)  than Lower AR kites of the same characteristics. Induced drag is inverse proportional to AR.  So when stationary at the wind window, a low AR kite can generate the same amount of pull as a higher AR kite (of the same characteristics) but as soon as we need to move the kite for more power (for jumping or underpowered situation), a higher AR kite can accelerate faster, therefore, get more power sooner than a low AR kite.  As a rule of thumb, a higher AR kite has a larger Power Window (the difference between min power and max power) and a lower AR kite has a smaller Power Window. Following are the recommended AR ranges:
Kite TypeVery Low ARLow ARModerate ARHigh ARVery High AR
Inflatable / Arc3-4567+
  • Inflatable and Arc have spherical shape, a natural stable form, therefore their ARs are normally higher than foil’s. 
  • Airfoil Profile
  • Airfoil has a lift but also a drag. A profile with the highest lift when stationary will give the strongest pull when stationary at the wind window (AoA around 5 degrees). A profile with the highest lift/drag ratio will accelerate faster and will generate the strongest pull when flying across the power zone. A high lift airfoil is sometimes labeled a “tractor” airfoil as it will pull like a tractor at the wind window.  A high lift/drag airfoil is labeled a “speed” airfoil as it flies very fast across the power zone and generates a tremendous amount of pull while doing so.  A speed airfoil may generate a lot of pull at the wind window but may not be necessary as much as a tractor airfoil.  The following table shows the recommended lift and lift/drag ratio ranges:
Very LowLowModerateHighVery High
Lift Coefficient (at AoA = 5)0.5-0.70.911.1+ (Tractor)
Lift/Drag40-507090110+ (Speed)
  • Please note that these Lift/Drag ratios are the calculated ratio and not included Induced Drag. In reality, the “real world” L/D ratios are reduced by a factor of 6 or 7.
  • It’s best to use an airfoil design program to design, analyze and select the airfoil profile to use for the kite (for kiting purposes, the Reynolds number is around 1,000,000 to 2,000,000).

Some kite designers being shy from the complexity of airfoil design and analysis uses the rule of thumb method of changing the profile thickness/camber for changing the lift and lift/drag characteristics of a profile.  This method is not accurate but may be acceptable for kites. As a general rule of thumb, increase the profile thickness/camber to increase lift at the wind window and decrease the profile thickness/camber to increase the speed of the kite.  The following table shows the range of profile thickness/camber used for most kites:

Foil and ArcInflatable
Thin Profile (Speed): 14% or lessThin Profile (Speed): 8% - 9%
Moderate Profile: 15%Moderate Profile: 10%
Thick Profile: 16%Thick Profile: 11%
Thicker Profile: 17%Thicker Profile: 12%
Thickest Profile (Tractor): 18% or moreThickest Profile (Tractor): 13% - 14%
Built-in AoA
  • A kite get more lift with a higher Angle of Attacked (AoA) to the wind (more surface projected to the wind and also from 0 to 16 degrees of AoA, the Lift Coefficient of an airfoil normally increase to an optimum value).  Each kite has a “neutral” built-in AoA for the center of the kite and the wing tip when it is at the wind window straight over-head (with front lines and back lines of equal length). The range of the built-in AoA is normally from 0 to 5 degrees. Note that the wind-window angle is around 85 degrees such that the in-flight AoA of the center profile at the wind window is the sum of the built-in AoA and 5 degrees (or 90 – 85). Note that changing the built-in AoA of the kite may also change the wind window angle such that the two will “amplify” each other to have a “double AoA” effect. E.g., changing the built-in AoA from 2 to 0 may make the wind window angle change from 85 to 86; therefore the in-flight AoA of the kite at the wind window is now 4 degrees instead of 7.

    It is interesting to read Peter Lynn’s Myth 1 and 2 in which he stated that the Lift or pull of the kite at the wind window is proportional to the AoA of the kite and the L/D of a kite is inverse proportional to the AoA of a kite (AoA here means AoA within the “dominant AoA” range of 0 to around 20 degrees which are directly influenced by the built-in AoA of the kite).

    • A kite with a lower built-in center AoA has a larger wind window but can over-fly & luff easily and does not pull much at the wind window (a Speed kite should have a lower built-in AoA around 0 degrees). These types of kites must have instantaneous AoA control for the kiter to prevent luffing and also for the kiter to “sheet-in” to get more power at the wind window if needed.
    • A kite with a higher built-in center AoA has a smaller wind window but generate more pull at the wind window and hard to luff (a Tractor kite may have a higher built-in AoA around 3 to 5 degrees for more pull at the wind window)
    • An all-around kite may have a built-in AoA of 2 to 3 degrees.
    • Due to the upwash and the wing vortex phenomena, the built-in wingtip AoA of a kite can be 1 or 2 degrees higher than the center AoA.  The upwash effect reduces the AoA of the wingtip a bit so add 1 or 2 degrees to the wingtip AoA to counterbalance that effect.
    • For inflatable and Arc, due to their geometry, the wingtip AoA varies much different than the center AoA and therefore the built-in wingtip AoA can be designed independently from the center AoA and the designer should add 1 or 2 degrees to the desired built-in AoA to counterbalance the up-wash and the tip vortex effects.
Very Low AoALow AoAModerate AoAHigh AoAVery High AoA
Range (in degrees)0-12 - 345+
Kite TypeRacingSpeedAll-aroundWaveTractor (Wake Style)
The following tables provide the summary of the AR, Airfoil, AoA parameters:
ARSmall POWER WindowLarge POWER Window
Lift (at wind window)Weak pull at wind windowStrong Pull at Wind Window
Lift/Drag RatioSlowFast
Built-in AoALarge WIND Window
Small AoA at wind window (less pull)
Luff Easily
Small WIND Window
High AoA at wind window (more pull)
Hard to Luff

And their uses in different types of kite:

Kite Type/WindLight Wind
(6 - 15 Knots)
Moderate Wind
(12 - 27 Knots)
Strong Wind
(27+ Knots)
Sled Kite Size (Foil)16 m2 (10 m2) & Larger8 - 16 m2 (5 - 10 m2)8 m2 (5 m2) & Smaller
School (Stable, Low Lift, Slow)Moderate AR
High Lift
High Lift/Drag
Moderate AoA
Low AR
Low Lift
Moderate - Low Lift/Drag
Low AoA
Very Low AR
Very Low Lift
Very Low Lift/Drag
Moderate - Low AoA
Tractor (Wake Style, Wave, Gusty Wind)Moderate AR
Very High Lift
High Lift/Drag
High AoA
Moderate - Low AR
High Lift
Moderate Lift/Drag
High - Very High AoA
Low AR
Moderate Lift
Low Lift/Drag
Moderate - High AoA
All AroundHigh AR
High Lift
Very High Lift/Drag
High AoA
Moderate AR
Moderate Lift
High - Moderate Lift/Drag
Low AoA
Moderate - Low AR
Low Lift
Moderate - Low Lift/Drag
Moderate AoA
Speed (High Jump, Freestyle)Very High AR
High Lift
Very High Lift/Drag
Moderate - Low AoA
High AR
Moderate Lift
High Lift/Drag
Low - Very Low AoA
Moderate AR
Low Lift
Moderate - Low Lift/Drag
Low AoA

Other Kiting Design Fundamentals

  • Center profile should be selected for optimum lift and optimum lift/drag ratio (optimum as according to the type of kite requirements specified in the tables above)
  • Wingtip profile should be selected for maximum luff resistance (e.g., reflex profile).
  • For sled kites (Inflatable or Arc in spherical form):
    • A sled kite has a similar projected surface of around 63% (2/pi or 2/3.14159) of the flat surface regardless of any other parameters of the kite (AR, Tip/Center chord ratio, etc.)
    • If the wingtips are wide enough (effective tow points of the back lines are larger than 80% of the center chord), one can reverse relaunch an inflatable or Arc by pulling on the back lines.
    • For LEI (using traditional airfoil), if the wingtip is wide enough and the effective tow point of the front lines is so forward (normally less than 15% of the chord) that it reduces the AoA drastically, the kite will not fly on the front lines alone (100% depower)

Flat LEI

A Flat LEI has similar structure with a classic LEI except for the following differences:
  • A flatter canopy design (however most still have a deep canopy curve compared to regular foil, to take advantage of the Sled Boosting effect)
  • A bridle system consisting of a simple but somewhat elaborated bridle system for the front lines and a very simple bridle system for the back lines.  The front bridle system has multiple connection points to the leading edge to support the leading (therefore Flat LEIs are also referred to as Support Leading Edge, SLE, kites)
The canopy is more or less equivalent to the center part of the classic LEI canopy (around 3/4 of the classic LEI canopy) and the bridle system is equivalent to the sides of the classic LEI canopy (about 1/4 or 1/8 of the canopy on each side).

One of the more popular commercial Flat LEIs.

Besides the differences above, a Flat LEI design should be somewhat similar to a classic LEI in theory. It is then just a matter of properly design the canopy and the towing points via the new bridle systems.

Unfortunately, current version of Surfplan does not provide full calculation and analysis of the two points of the bridle for Flat LEI. So in the meantime, you have to design a flat LEI with some manual processes. Also, if you are interested in flat LEI kite design.

Airfoil Database For Kiteboarders

Most kite design or foil design software comes with some airfoil database; however should you want more, there are other airfoil databases and one of the most extensive airfoil databases is UIUC Airfoil Coordinates Database.

Kite Design Software

The most popular kite design software for inflatable kites is currently SurfPlan (Surf stands for Surface). has a “Pseudo” Surfplan User Manual for LEI kite designers at the end of this page.

Foil designers may want to use something similar to FoilMaker which was around before Surfplan and was very popular among foil enthusiasts.  FoilMaker had its complete user manual and the website also offered some kite design samples.

Kite Design Samples

It’s better to make your first kite using an existing kite design sample.  The best place for inflatable kite design samples was; however, the site is no longer in operation. Fortunately, the archive is still available at*/ In the beginning, it’s wise to play with only a few somewhat “harmless” parameters and once you feel more comfortable with the software, read the “Pseudo” Surfplan User Manual and play with more complex parameters such as kite shape, profile shape, rib shape, leading-edge and trailing edge shape, etc.

KitesurfingSchool.Org Kite Design Sample Database

So go design your kites, make them (or have them made for you), test them, send us your designs and photos and comments for the KitesurfingSchool.Org Kite Design Sample Database for future readers:
Theory & R&D Kites:

Kite Sewing Methodologies

Alex Stelios has released complete instructions on how to sew and make one of his “almost production” homemade kites.  The page includes a whole complete instruction set as well as the plan for the Ikaros kite (version 2). 

Another place to learn the method to sew your own inflatable kite is the Zeroprestige archive at*/

Bruno's Post on Kitesurf Group

In the message at one of Yahoo Kitesurf groups, Bruno mentioned that one can design a new LEI kite by simply changing the AR parameter. This message was the catalyst for Stelios to develop the Sphere Theory for designing LEI kites.

From: Bruno Legaignoux
Date: Thu Aug 3, 2000 2:44 am
Subject: Bruno Legaignoux’s message


I’m Bruno Legaignoux. For those who don’t know my name, we are, with my brother Dominique the inventors of the inflated kite in the shape of a gore. This message is to try to put the numerous rumors off.

My brother and I were sailors (French Junior champions, cruising boat skippers, sailing instructors, surfers, windsurfers, etc…). We tried to develop very efficient sails and boats and finally, we became interested in kites when seeing Jacob’s Ladder, a catamaran pulled by Flexifoils, although we never flew a dual line kite. It was in 1984. After some research, we understood that no water re-launchable kite existed so it became obvious to us that we had to create one.  After one year of work, we were sailing with water skis and demonstrating the device during the 1985 Brest International Speed Week. We also applied for a patent. The project was to find one or several licensees within 2 years but windsurfing was at its acme and no windsurf company was interested.

We never stopped believing in this sport so we had 10 years of a VERY HARD time, continuing the project without money, looking for new markets, for licensees, then creating our own company and producing in France in 1993-94… at a too high cost (please don’t cry !)

Then Windsurfing declined and Kiteboarding time came. I am proud to see that we were the main actors of kiteboarding birth but for sure we were not alone. For example, Cory Roeseler with the Kiteski device or Andreas Kuhn with a paraglider and a kind of wakeboard helped too with international media exposure.

In 1995-96 we went in very serious talks with Neil Pryde. Finally they renounced but they accepted to produce small quantities for us and we started selling these kites in July 1997 under Wipika brand mark. Then we found another manufacturer in Asia.
In 1998, Don Montague and Robby Naish came to us asking for a license. As it was our original goal, we agreed and told them that both of us needed a software to be able to make new designs quickly. I came to Hawaii and gave all my knowledge to Don Montague and their programmers. One year later, the program was working. We shared it. With it, everybody can make a new good kite in 30 seconds, just changing one parameter. For example, change AR = 2.5 (the default value) with 8 and you will appear as a genius designer!

Some people hate this way. I think that when you are a well-organized company in a market where products
evolve very quickly, the patent is just a waste of money and energy. But if you are a “small” independent inventor, you have no chance against large companies if you don’t protect your ideas: they won’t even give you just credit for that!

Who on this list is against intellectual property (music, literature, etc…)?
Our motivation was kept during the hard years because of the patent.

Seen by my side, there are only 3 kinds of kites :
  • the ones which are far from ours, like ram air kites, delta kites, etc…
  • the ones which are very close to ours: if they got a license contract like Naish, they are licensees; if not, they are infringing copies whether or not there are patented improvements on.
  • there are kites designed with a sole goal: to use our concept but escaping the patent by modifying the kite after studying the patent and looking for weak points in it. In this case, it is more difficult for me to get justice admitting the infringement but I’ll try each time I think I can win.
Obviously, I beat the infringers and already stopped a few ones. Something interesting to be known is that I have no obligation starting legal action immediately, that means that I can start even when they will have invested a lot of energy and money in their product. This is to explain that it is probably more risky for them to infringe that what they generally think. 
Yes, we are open to give other licenses but to companies which are able to bring something to the market, not to companies with short term view or which sole way to get market shares is to discount their kites. In 2000-2001 a few high image companies will enter the market.

– who invented kiteboarding? several people did it on their side without knowing that other people previously made something close. Ourselves we started in 1984 with windsurfing boards because we were surfers and windsurfers but not waterskiers. We built several boards for that purpose. As our kites were very unstable at that time, we mainly used waterskis because the water start was easier, but the patent talks about windsurfing board type too. We also tested any kind of boats and many other “things” that you can’t even imagine and a patent drawing shows a guy on two 40cm “water skates” (photos in the History page of We made and sailed them. It was fun. I’m sure that we’ll soon see advanced pilots trying this kind of skates.

– Who “invented” high AR inflated kite? In 1985 we made a 17m kite with aspect ratio 6 and with 100% double-skin (photos on Wipika web site… and a short video soon). With it, we waterskied with 6 to 12 knots of wind and, during the 1886 International Brest Speed Week, we were clocked at 14.5 knots (average speed during a 500m run) while the best world-class windsurfers reached 10 knots. This is registered. We also made kites with 20%, 30%, 40%, 60%, 80%, 100% double skin, what was already described in the 1984 patent, and kites made of clear mylar with scrim. Probably you will see this kind of “improvement” in the next months or years.

– Who “invented” inflated “struts” without an inner tube? A competitor? No, in the past, we used 2 different construction methods for inflated struts: airtight fabric and mylar fabric with inner tube. These ways are described in the original patent.

– Who invented 4 line straight bar with both front lines meeting at a “main line” going to the harness and with the bar sliding along the “main line”? a competitor? No, we own a patent on this device since 1995. I first used this device for buggying and won some races thanks to it. Seasmik uses without any license the exact device we described so we’ll have to sue them.

– Who invented 4-line inflated kite? A competitor? No, the above patent also describes how to settle inflated kites with 4 lines by cutting the edges for example (there are other ways). I always used “cut tip” kites with the 4 line straight bar. I explained all these things to Don Montague in 1998. Why didn’t we apply these improvements earlier? There are 2 main reasons :

Firstly, when you settle a company and you have no money, especially in France, you have to work 80 hours a week to have it working properly. So I had no time for R&D. It’s why in 1999 I looked for people to take care of Wipika and get myself more time in R&D. I also moved in early 2000 to the Dominican Republic which is really a perfect place for R&D.

Secondly, the market was not ready for more evolved kites. In the “early ages”, we made very efficient kites then we understood that we had to make simple, stable, and safe. In 1998, 100% of the users were beginners – there are not so many markets like this one! In 1999, still, 90% were beginners but the 10 other percent were starting to ask for more efficient kites so we prepared the Free Air AR3.3 range and started sales in early 2000. But because of Naish AR5, our new range is already old-fashioned if you believe a few ones. My main concern is safety and when I hear that some beginners directly purchase AR5 kites, I’m scared. Firstly they are more difficult to relaunch but above all they are fast. That makes them dangerous for beginners in the state of the market (almost no schools nor well-informed retailers…).

We are starting a competition to efficiency, just like windsurfing manufacturers did. Remember: “Hey guy, how many cambers do you have ? Only six ? … and your board, what size ? 2.26m ? Too bad! mine is 2,195m !”. Windsurfing is dying for this reason. And us, when? A fact: the Wipika riders Franz Olry and Christopher Tasti, which actually win some events, don’t want to use too high AR kites because they are so fast and unstable that they can’t make the kind of tricks they do with more stable kites. They don’t want a 20 kite quiver. They want simplicity. Same for Lou Wainman, Mauricio Abreu, and some other ones. If you see them using high AR kites, it’s because competition pushes in this way, not because they prefer (except in light winds). To resume, if we go too quickly, we’ll burn our wings. All the people involved in kiteboarding should take care of that.


Any kind of commercial/strategical agreement was never made. Both companies are completely independent/free of mutual contracts. Both are Legaignoux licensees with the same contract terms.


Wipika supplies the Classic kites since July 1997 with additional webbing so that all the Classic can be settled with 4 lines. That means that we believe the 4 line use since a long while but 99% of the customers didn’t want to hear about it last year. There are several ways to settle your Classic as a 4 line kite, I’ll come back on this matter in another message. Very soon, the Classic kites will be sold with a second webbing, like the Free Air, to simplify transformation. Classic and Free Air will also receive long velcros to fold the tips. Many new Wipika items will be available in the next weeks and months, including an interesting 4 line bar. We’ll keep you informed. You are welcome to use abstracts of this message for public use as long as it is in good faith. Please don’t expect that I’ll react to the messages which could follow mine, I’m still too busy to do it. Sorry!

Thank you for your time and…
Best winds to all of you,

Peter Lynn's Myths on Kitesurf Group

Make Your Own DIY Kitesurfing Kite

When Peter released these myths, it created many controversial debates and one of the reasons was that it’s not clear what Peter meant by “angle of attack”.  Note that Peter talked about kite design here so the “angle of attack” he referred to probably meant the “built-in AoA” and/or the “dominant AoA” (from 0 to 20 degrees) and not all the AoAs of the kite when it flies.

From: “Ian Young” <>
Date: Thu Aug 3, 2000  7:34 pm
Subject: Peter Lynn’s Six Aerodynamic Myths of Kite Traction  


Food for thought from Peter Lynn for those of you who don’t get his newsletter …

The Six Aerodynamic Myths of Kite Traction.

Myth One.
That the upwind performance (that is, lift/drag ratio) of kites is primarily a function of profile and aspect ratio.
Wrong. The strongest determinant of L/D is the angle of attack. Low angles of attack yield high L/D in an inverse relationship, profile and aspect ratio have comparatively little effect.

Myth Two.
That the Lift Coefficient (power for size) of a kite is primarily determined by its profile and aspect ratio.
Wrong. The angle of attack is again by far the strongest determinant of pull for the area, and by close to a direct linear relationship in the range that matters for kites.

Myth Three.
That high aspect ratio equates to high performance.
Correct in theory but misleading for kites in practice. Aspect ratio (defined as span squared divided by area) is a strong determinant of induced drag, the dominant form of drag at low speeds for efficient airfoils- but kites are not efficient airfoils by any definition, so aspect ratio determined induced drag is not the major drag component for kites. It would be possible to make a square wing (A.R=1.0) that is more efficient than the highest aspect ratio high-performance kite currently available- (but making it useable as a kite would be another matter).

Myth Four
That Thin sections are “better” than fat sections.
Wrong. Unless your kite is to fly at something approaching the speed of sound anyway. Sections as fat as 16% (maximum thickness as a proportion of chord) lose nothing by L/D or lift to thinner sections, up to 300km/hr or so, and are less prone to stalling and luffing.

Myth Five.
That double skin wings (ie three-dimensional airfoils) are more powerful than cambered single-skin wings.
Wrong. Cambered single-skin wings will generally have higher lift coefficients than fully shaped 3-dimensional wings because they can work at higher angles of attack without stalling. 3 D forms will be more luff resistant and can have higher L/D but they won’t be more powerful.

Tanstafl. (There ain’t no such thing as a free lunch.)
The fundamental design conflict is between one and two above. Traction kites require a high angle of attack to have desirable power for size characteristics but a low angle of attack for good upwind performance.

Some kitesurfing tips:
*Early this year we added an extra valve near the wingtips on Arcs to speed their inflation and to make them more resistant to tip collapse in the case that inflation leaks develop. We aren’t sure that this was necessary but added them just in case. Being near the tips, the disadvantage of these extra valves is that they can ingest water during relaunching. If this is a problem for you just seal them off internally with double-sided tape- they can then easily be reopened if ever necessary. Thank you to Nick Grant for this.

*If you’re going to break things, it is not a good idea to do so when against wind and tide and far from land. In Tahiti last week Mike Holland broke a line in such circumstances and was unable to re-rig, and relaunch so spent one day of his South Pacific holiday swimming in. Thank you Mike for this tip.
*When you are using our wrist leash velcroed to the bar end so that it doesn’t get twisted up in spins, lash it on with knitting wool in addition to the velcro so that it doesn’t come off prematurely but will still release when required- just like wool ties on a yacht spinnaker. Thank the sheep for this one.

New things this month- Nothing!, Which is the first time ever, except that there is something but I’m just not talking about it until we hear back from our traveling testers. It was what Mike was testing in Tahiti when he had
a line break and the long swim.

And a little gossip to round off: Andy Reid; windsurfer, kitesurfer, board maker, and (with Justin), our kite test rig operator, finishes his BEng. this year and goes to work at Team New Zealand for the next defense of America’s Cup. Our loss, their gain- congratulations Andy.

Peter Lynn, Ashburton New Zealand, July 31, 2000.

Ian Young

Update: Making a DIY kiteboarding kite is still around! If you want to get started as soon as possible, this video might be of inspiration for you. Enjoy!

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