Deutsch: README.de.md

Wingdesigner

Browser application for designing wings of radio-controlled (RC) model aircraft.

• Lofts one half wing as a NURBS (non-uniform rational B-spline) surface through 2 to 20,000 airfoil sections.
• Models the half wing at y ≥ 0; the other half is its mirror image at the plane y = 0.
• Exports models as STEP (Standard for the Exchange of Product model data), STL (stereolithography) and 3MF (3D Manufacturing Format).
• Saves the project as JSON (JavaScript Object Notation).
• Imports the main wing or the horizontal stabilizer from XFLR5 files (.xfl, .xml). XFLR5 is a program for the analysis of airfoils and wings.
• Projects, airfoil files and XFLR5 files are not sent to a server.

Resource	Address	Published by
App	https://subtilitas.github.io/Wingdesigner/	ci.yml, push to main, after all other continuous integration (CI) jobs pass; HTTP 200 on 2026-09-29
Wiki start page (English and German)	https://github.com/subtilitas/Wingdesigner/wiki	docs.yml, push to main that changes docs/wiki/ or docs.yml, or manual run; reachability: not verified

Topic	English	German
Workflow, controls, XFLR5 import dialog, export options	User Guide	Benutzerhandbuch
Airfoil curves, sections, guide curves, surface	Geometry	Geometrie
Airfoil files, checks, project JSON, XFLR5 import, STEP, STL, 3MF	File Formats	Dateiformate
Airfoil sources and licenses	Airfoil Sources	Profilquellen
Architecture, build, tests, CI	Development	Entwicklung

Functions

Function	Behaviour	Limits and defaults
Sections	Each section places an airfoil with its leading edge at (x, y, z), scales it to the chord and rotates it by the twist, in its section plane.	2 to 20,000 sections, warning above 200 (see Project size); y 0 to 1,000,000 mm, all y distinct; x and z −1,000,000 to 1,000,000 mm; chord 1 to 100,000 mm; twist −360 to 360°. The Sections table clamps typed values to these limits; planform drags stay within them.
Airfoil curve	Cubic B-spline through every point of the airfoil file.	Parametrization: centripetal (default), chord length, uniform. With chord length or uniform, airfoil errors in Checks add a hint to use centripetal.
Chordwise resampling	All sections are resampled at the same chord fractions, cosine-spaced towards leading and trailing edge.	16 to 200 stations per surface, default 60
Section planes	Mitred (default): the root section is vertical, a section between two panels lies in the bisector plane of the two panels, the tip section is square to the last panel, and each airfoil is stretched in thickness by 1/cos of the angle between its plane and the panel, as in XFLR5. The wing is as thick across every panel as its airfoil. Vertical: every section in a plane y = const; across a panel with dihedral δ the wing is cos δ as thick (81.9 % at 35°).	Stretch at most 2 (60° between a section plane and its panel) and no fold between neighbouring planes: build errors. Smooth blending builds vertical planes, with an info line. Project files of format version 1 open vertical.
Spanwise blending	Linear: each section value (airfoil, chord, twist, position) blends linearly along the panel (panel: span interval between 2 adjacent sections), kinks at the sections. Straight panels: straight lines between points of equal chord fraction of 2 adjacent sections, as XFLR5 builds its panels; no guide curves. Smooth: natural cubic spline through the section values.	Default linear; the XFLR5 import sets straight panels; smooth needs 3 or more sections (with 2 sections the blend is linear)
Spanwise stations	With a guide curve or smooth blending: N stations per panel (section included), cosine-spaced towards the panel ends. With linear blending and mitred section planes: N stations in every panel whose two sections lie in planes of different roll. Otherwise: stations only at the sections. Extra stations are inserted where the loft surface deviates from the intended profile by more than 0.5 mm or 10 % of the local chord, whichever is smaller (3D distance). Compared points: leading edge, upper trailing-edge point and 5 chord stations per surface (at the default 60 chordwise stations). Extra stations lie at check positions: 257 evenly spaced span positions, the stations and every guide-curve control point and knot. Each extra station keeps at least 1e-6 of the span from every other station.	N = 3 to 40, default 8; up to 32 extra stations. Loft grid: (N × D + (sections − 1 − D) + 1) × (2 × stations per surface + 1) points before the extra stations; D = sections − 1 with a guide curve or smooth blending, otherwise the linear panels between mitred planes of different roll. Settings shows Loft grid: … points under Resolution; above 60,000 points the note adds the time and memory of each change, and the Large project warning lists the grid. Above 5,000,000 grid points N is lowered to the largest value that keeps the grid within 5,000,000, with a warning. When 1 station per panel still exceeds 5,000,000 grid points, the build stops with an error; remedies named in the message: fewer stations per surface, fewer sections. Linear blending without a guide curve and without rolled panels (60 stations per surface, 1 station per section): warning from 496 sections on; N is never lowered (20,000 sections: 2,420,000 grid points). With a guide curve or smooth blending at the default N = 8: warning from 63 sections on; N lowered from 5167 sections on; 20,000 sections: N = 2.
Wing surface	Tensor-product B-spline surface through all stations.	Degree 3 chordwise; spanwise degree 1 (no panel with intermediate stations) or 3; linear blending with intermediate stations: degree 2 or 1 when the grid limit lowers N to 2 or 1
Guide curves	Nose line (leading edge) and end line (trailing edge) in the planform. Each is a NURBS curve through points (curve parameter proportional to y) or from control points, stretched to the root-to-tip span.	Off by default; degree 1 to 5, default 3; 2 to 20,000 points (Add point is disabled at 20,000); warning above 500 points in an enabled guide curve, and from 500 points on the title of Add point names the time and memory of each change with one more point; y strictly increasing; x within ±1,100,000 mm (covers the trailing edge x + chord of every valid section), y within ±1,000,000 mm; drags and typed x values are clamped to ±1,100,000 mm. Error when a control point of the curve lies beyond x = ±1,200,000 mm; through-point curves over points unevenly spaced in y reach this. Remedies named in the message: points spaced more evenly in y, control-point mode.
Trailing edge	As in the airfoil files, closed, or a fixed thickness in mm.	Default mode: as in the airfoil files; default thickness value 0.4 mm. Wizard: fixed thickness max(0.3 mm, 0.2 % of root chord). Sample wing: fixed 0.5 mm. Limited to 5 % of the local chord, with a warning (no warning in the last panel of a Pointed tip).
Wing tip	Flat: the wing ends at the tip section. Pointed: tip profile scaled to 1/N of the chord at the second-to-last section, at least 1 mm. In the last panel the chord stays ≥ this tip chord. Converging guide curves end in the scaled profile.	Default flat; N = 100 to 1000, default 200. The Sections table shows the tip chord; (min.) marks the 1 mm floor.
Mirror	Display toggle Show mirrored half (y < 0) in Settings. Exports use the export option Wing halves. Statistics always cover both halves.	Display toggle default: on
Airfoil import	Selig, Lednicer, 3-column table (x, upper y, lower y), XML (Extensible Markup Language), HTML (HyperText Markup Language) pages (coordinates in <pre> blocks or tables). Reads decimal commas, percent coordinates, UTF-8 (Unicode Transformation Format, 8-bit) and Windows-1252. Input: dropped files, Choose files or pasted text. Shows outline, NURBS curve and check messages before the airfoil is added. Consecutive points closer than 1e-9 chord to the previous point are removed. An airfoil with an error, including a failed NURBS interpolation, cannot be added (Cannot add (errors)). The preview (upload and View) draws the NURBS curve with the project's profile parametrization. An XFLR5 project or an XFLR5 plane or wing file is refused as an airfoil with the hint to use Open; Check pasted text does not test for it.	Choose files filter: .dat, .txt, .cor, .xml, .htm, .html, .csv and plain-text files; dropped files: any extension; 5 to 100,000 points, warning below 20 and above 5000 (… points (warning above 5,000): the checks and the first build of a wing that uses the airfoil take … s.); at most 5,000,000 characters; files above 20 MB are rejected before reading, an XFLR5 project with the hint to use Open; a name line above 10,000 characters is cut to its first 10,000. Per project: at most 10,000 airfoils and 1,000,000 airfoil points in all; warning above 200 airfoils and above 100,000 airfoil points. Project files: the same point and airfoil limits. At 10,000 airfoils the Airfoils tab opens no preview and shows The project holds 10,000 airfoils, the limit; "Remove unused" frees places.; an airfoil that takes the project above 1,000,000 points is refused in the same way.
NACA generator	NACA (National Advisory Committee for Aeronautics) 4-digit and 5-digit airfoils from the equations of NACA Report 824. Also reflexed 5-digit airfoils (third digit 1). Open or closed trailing edge.	17 presets; 81 points per surface
Wizard	Inputs: 7 numbers (see Wizard inputs), planform (straight or elliptic), tip (flat or pointed), root and tip NACA code. Output: evenly spaced sections; the elliptic planform adds nose and end guide curves. Last section: tip airfoil; all others: root airfoil.	6 presets: Trainer, Sport (preselected), Glider, Swept flying wing, Plank, Tail surface. Elliptic with flat tip: taper < 1. Pointed tip: tip chord 1/200 of the second-to-last section chord, at least 1 mm.
Checks	Lists errors and warnings, then info lines. Planform: span, wing area (dm²), aspect ratio, mean aerodynamic chord (MAC), MAC position (y, leading-edge x), 25 % MAC x, root and tip chord. Surface: degrees, control-point counts, trailing edge open or closed. Span = 2 × y of the tip section; area and MAC: 5-point Gauss-Legendre quadrature of the intended planform between root, tip, the sections and every guide-curve knot and control point; an interval is halved while the halves change an integral by more than 1e-10 of its scale, at most 12 times.	Export of STEP, STL and 3MF is blocked while errors exist. Section and guide values beyond the project limits are errors; autosave does not store such a project, and Open rejects it. Root section off y = 0: the gap between the halves counts to the span, not to the area.
Project size	Above a warning threshold the wing builds as usual. Checks adds one warning: Large project: …, listing each size above its threshold with (warning above …), followed by the estimated time and browser memory of each change (Each change takes … and … of browser memory.). When the first build (Open, restored autosave, a change of Profile parametrization) takes at least 1 s longer than a change, the warning adds Opening it or changing the profile parametrization takes ….; estimate: time of a change plus 4.4 ms per airfoil that a section uses plus 30 µs per point of these airfoils (Node.js 24; 20,000 linear sections at 16 stations per surface and 10,000 airfoils of 99 points: about 83 s). A message shows the same text when an edit, Open or the restored autosave takes a size above its threshold. Estimates: linear fits to measurements in Chromium 141 (see Current limitations).	Warning above: 200 sections, 200 airfoils, 5000 points in one airfoil, 100,000 airfoil points in all, 500 points in an enabled guide curve, 60,000 loft grid points, 2,000,000 export triangles or 1,000,000 STEP control points (export dialog), 200 characters in a name. Hard limits, where a desktop browser tab runs out of memory or a change takes about a minute: 20,000 sections, 10,000 airfoils, 100,000 points in one airfoil, 1,000,000 airfoil points in all, 20,000 points per guide curve, 5,000,000 loft grid points, 10,000,000 export triangles, 3,000,000 STEP control points, 10,000 characters in a name, 200 characters in an id, 2000 characters in an airfoil source text, 100 MB per project file. Lists and messages show the first 200 characters of a name followed by ….
Input	Mouse, touchscreen, keyboard. 3D view: drag rotates, wheel or pinch zooms, right button or 2 fingers pan. 2D views (planform, previews): drag a point to move it, drag the background to pan, wheel or pinch zooms, 2 fingers pan, double-click fits.	Undo: Ctrl+Z or Cmd+Z; redo: Ctrl+Shift+Z, Cmd+Shift+Z, Ctrl+Y or Cmd+Y. Shortcuts are ignored while an input field has focus or a dialog is open. Undo history: at most 100 steps and at most 64,000,000 characters of serialized project (undo and redo together); a project above 640,000 characters keeps fewer steps, at least 1. One drag forms 1 undo step, however long it pauses; an action that changes nothing adds no undo step.
Storage	Autosave to browser local storage after every change that passes project validation, with the rebuild in the next animation frame; a pending save is written at once when the page is hidden or left (reload, closing the tab). A stored project that fails to load is kept under wingdesigner.project.v1.rejected, and the wizard opens. Nothing is saved while the first-run wizard is open. Save downloads the project JSON. Open opens a project file or an XFLR5 file (row XFLR5 import). When browser storage refuses the project, a message says so and the status bar shows Autosave off: use Save until an autosave succeeds.	Local storage unavailable: the project stays in memory only. Browser storage: about 5,000,000 characters per site. Open: files above 100 MB are rejected before reading; an .xfl file is read up to 2,000 MB.
XFLR5 import	Open reads an XFLR5 project (.xfl) or an XFLR5 plane or wing file (.xml) and imports one surface from it: the main wing or the horizontal stabilizer (XFLR5 calls it the elevator). A dialog offers the plane, the surface and one airfoil for every airfoil name, and shows a report of what is applied, changed and dropped. Import replaces the project in one undo step; Cancel changes nothing. Section values: y and z from the span positions (XFLR5 measures them along the panels) and the panel dihedral angles; x from the leading-edge offset; the chord; the twist about the quarter chord. The tilt angle and the position of the wing in the plane are applied. A section whose airfoil has a frame (position of the leading edge and chord length in the airfoil coordinates) is moved and scaled by it, so that the airfoil lies where XFLR5 draws it. Airfoils of the .xfl project, uploaded .dat files, NACA airfoils and NACA sections of the current project (from the NACA generator or the NACA presets of the Airfoils tab, the wizard and the sample wing) have a frame; library airfoils and the other airfoils of the current project have none. Settings of the imported project: Twist pivot (fraction of chord) 0.25, Straight panels, Mitred section planes, Flat tip, trailing edge As in the airfoil files. A tilted part imports with Vertical section planes, which keep the folded tilt angle exact, and stores the angle in the project; so does a part whose mitred planes would fold the surface or stretch an airfoil more than 2 times. An .xfl project holds the airfoil coordinates. An XML file holds airfoil names only: the dialog matches each name against uploaded .dat files, the current project, Library, the NACA generator and similar names, and Import stays disabled while a name has no airfoil.	Files: .xfl projects of format 200001 (XFLR5 6.10.01 to 6.43) and 200002 (6.44 to 6.62); XML plane files (<explane version="1.0"> with <Plane>; XFLR5 6.11 to 6.62) and XML wing files (XFLR5 6.41 to 6.62). Refused with a message: .wpa projects (XFLR5 6.09 and older), flow5 7.x files, .xfl projects without a plane, XML wings that are fins. One surface per import. Not imported: the second wing, the fin, the other surface, the body, masses, analyses and results, colours, left-side airfoils, flap deflections. The Open file chooser lists .json, .xfl and .xml. Size: .xfl up to 2,000 MB (read in windows of 4,194,304 bytes), other files up to 100 MB. Per file: at most 10,000 planes, 20,000 sections per wing, 10,000 airfoils and 2,000,000 airfoil points read from an .xfl. Lengths in XML files: the unit of the file (mm, cm, dm, m, in, ft), converted to mm; XFLR5 rounds lengths in metre XML files to 1 mm. Angles: degrees. The dialog lists 200 airfoil rows and 200 report lines. Section values must meet the project limits (x and z within ±1,000,000 mm, y 0 to 1,000,000 mm, chord 1 to 100,000 mm, twist within ±360°); a chord below 1 mm is raised to 1 mm with a warning; sections at one y_position that differ are moved apart by up to 0.5 mm with a warning; of identical ones only the outer one is kept. Details: File Formats, section XFLR5 import.
Language	English and German, chosen with Language / Sprache in the first group of Settings. The texts switch without a reload: top bar, tabs, tooltips, Checks with the build errors and warnings, airfoil check messages, size warnings. Later notices and dialogs opened later use the new language. A notice that is showing at the switch is removed; an error notice stays in its language until it fades. Numbers follow the language (German 1.234,5). Number fields read a decimal comma or a decimal point in both languages (0,7 and 0.7 are 0.7) and digit groups of the language (1500 comes from 1,500 in English, from 1.500 in German). Not translated: file contents, airfoil names, attributions, license identifiers.	Starts with the stored choice; without one in German when the first language of the browser is German, otherwise in English. Stored in the browser under wingdesigner.language. Project, selection and undo history stay. File names of downloads write umlauts out in both languages (ü becomes ue). Details: User Guide, section Language.

Wizard inputs

Wizard input	Range	Unit
Span (both halves)	100 to 20,000	mm
Root chord	10 to 3000	mm
Taper (tip / root chord)	0.1 to 1.5	—
Sweep of the 25 % line	−45 to 60	°
Dihedral per half	−60 to 60	°
Tip twist (negative = washout)	−15 to 15	°
Number of sections	2 to 8	—

Coordinates and units

Quantity	Definition	Unit
x	Chordwise, positive towards the trailing edge	mm
y	Spanwise, positive towards the right tip; the half wing lies at y ≥ 0	mm
z	Up	mm
Section origin	Leading edge = point of minimum x on the interpolated airfoil curve	mm
Chord	x distance from the leading edge to the trailing-edge midpoint of the interpolated airfoil	mm
Twist	Rotation about the twist pivot; positive = leading edge up	°
Twist pivot	Fraction of the chord from the leading edge, 0 to 1, default 0.25	— (fraction of chord)

Exports

File name, derived from the project name:

1. German umlauts written out: ä → ae, ö → oe, ü → ue, Ä → Ae, Ö → Oe, Ü → Ue, ß → ss.
2. Other accents removed (é → e, ñ → n).
3. Each run of characters other than A-Z a-z 0-9 . _ - becomes one _.
4. Leading and trailing _ removed.
5. Cut to the first 120 characters.
6. Empty result: wing.

The rule is the same in the English and the German interface.

Example: Flügel V2 (neu) → Fluegel_V2_neu.step.

Format	File	Content	Verification
STEP, Application Protocol 214 (AP214), ISO (International Organization for Standardization) 10303-21 text	.step	One closed B-rep (boundary representation) solid per half. Faces: upper and lower B-spline surface (the exact loft surface), ruled trailing-edge face (open trailing edge only), planar root and tip caps.	CI: scripts/validate_step.py reads 12 test wings with OpenCascade (cadquery-ocp 8.0.1). Pass: shapes valid, shells closed and oriented, volume within 0.05 % of the mesh volume, cap edges within 1e-6 mm of their planes.
STL, binary	.stl	Closed triangle mesh; one shell per body.	Unit tests: every directed edge occurs once and its reverse once; volume from the parsed float32 file within 0.0005 % of the mesh volume.
3MF	.3mf	Same meshes; one object per shell; unit millimetre.	Unit tests: 3 package parts, unit millimetre, 1 object and 1 build item per shell, vertex count. CI: scripts/validate_3mf.py reads the 12 test wings with lib3mf 2.5.0 in strict mode. Pass: no warnings while reading, triangle count per object as written, every object manifold and oriented. Slicer software: not tested.
Project JSON	.json	Airfoil coordinates, sections, guide curves, settings. Derived NURBS data, only when the wing builds without errors. When the file with the derived data would exceed 100 MB, Save and the JSON export leave it out and show The file leaves out the derived NURBS data: with it, the file would exceed 100 MB, the largest project file Open reads. Open recomputes it; STEP export writes the exact surfaces. Derived data: curve of every airfoil used by a section, each enabled guide curve (null when off), spanwise stations, wing surface (degrees, knots, control points). Import ignores the derived data and recomputes it.	Unit tests: write, read back and rebuild gives the same sections, guide curves, airfoil points and surface control points; validation of every field.

Export option	Values	Effect
Wing halves	Both halves as separate bodies (default)	2 bodies in every format
	Full wing as one body	STL and 3MF: 1 shell, only when the root section lies at y = 0, otherwise 2 bodies. STEP: 2 solids.
	Right half only	1 body
Mesh density	Normal (default), Fine (4x triangles)	STL and 3MF only. A note below the options gives the triangle count and file size of the chosen format, halves and density: … million triangles, file about … MB. Above 2,000,000 triangles it adds The export takes … and … of browser memory. Above 10,000,000 triangles Download is disabled; the note names the limit and the remedies: Normal density, one half, fewer stations per surface or per panel.
Fusion 360 fix: Y up (also SolidWorks) (STEP, STL, 3MF)	off (default), on	On writes every point (x, y, z) as (x, z, −y): the upper surface faces +Y, the chord stays along X, the span runs along Z. For CAD programs with Y as the up axis, which show a Z-up file on its side. The checkbox starts as it was at the last export (browser storage). The project JSON keeps the axes of the app.
Format STEP	–	A note gives the control points and file size of the chosen halves: … control points, file about … MB. Above 1,000,000 control points it adds the time and browser memory; above 3,000,000 Download is disabled and the note names the limit and the remedies: one half, fewer stations per surface or per panel.

Airfoil data and licenses

• NACA 4-digit and 5-digit airfoils are computed in the browser from the published equations. No coordinate file is used for them.
• The bundled airfoil library (public/airfoils/) holds 6 coordinate files. Library lists them after the 17 NACA presets, each with category, use, author and license identifier.
• Adding a library file copies author (as attribution, editable in the preview), license identifier, source address and terms address into the source of the project airfoil.
• Source, legal basis with quotes, conditions and attribution text per file: public/airfoils/NOTICE.md.

Airfoil	Source	License identifier	Basis
Clark Y	NACA Report No. 502, Table I; section by Virginius E. Clark	public-domain	Work of the United States Government; United States copyright term expired
NACA 8-H-12	NACA Technical Note 1998, Table I	public-domain	Work of the United States Government
NACA M-6	NACA Report No. 221, Table XXIX	public-domain	Work of the United States Government; United States copyright term expired
RAF 34	Royal Aircraft Establishment (RAE) table in NACA Report No. 286	public-domain	United States copyright term expired; table reprinted in a work of the United States Government
S9104	Michael Selig, University of Illinois Urbana-Champaign	CC-BY-4.0	Creative Commons Attribution 4.0 International license (CC BY 4.0) from the designer
USA 35B	NACA Report No. 233, Table XXXVI	public-domain	Work of the United States Government; United States copyright term expired

• Status of the 5 public-domain files outside the United States: not established.
• RAF 34: 7 values of the source scan are uncertain by up to 0.20 % of chord (listed in NOTICE.md).
• The expansions of "RAF" and "USA" in the section names are unknown; the sources checked do not give them.
• The .dat download and the STEP, STL and 3MF exports carry no attribution. NOTICE.md gives the attribution text for a shared file made with S9104.
• Not bundled: aerodesign.de and mh-aerotools.de (personal use allowed, redistribution restricted), UIUC (University of Illinois Urbana-Champaign) Airfoil Coordinates Database (no license stated). The app links to these sources.
• Not bundled either: share-alike data (Creative Commons Attribution-ShareAlike 4.0), sections by Mark Drela under the GNU General Public License (GPL) version 2 or later, the PROFOIL test sections. Decisions: RECORD.md.
• Terms and quotes: Airfoil Sources, Profilquellen.
• Uploaded airfoils keep their name and attribution in the project JSON.
• Airfoils imported from an XFLR5 project (.xfl) keep their name and the file name in the project JSON (source.kind xflr5). The name rule below fills the attribution for HS and MH names. The app does not check the rights to these airfoils; whoever imports the file is responsible for them.
• The airfoil preview fills the Source / attribution field. Library file: the author from index.json. Other airfoils: from the airfoil name; the match ignores case and leading spaces.

Name starts with	Attribution filled in
HS + space or hyphen	Hartmut Siegmann, www.aerodesign.de
MH + optional space or hyphen + digit	Martin Hepperle, www.mh-aerotools.de

Current limitations

Limitation	Condition
Smooth blending builds vertical section planes.	With Mitred section planes and smooth blending, every section lies in a plane y = const; across a panel with dihedral δ the wing is cos δ as thick as the airfoil. The Checks tab says so in an info line.
Section planes follow the section positions only.	Mitred planes take their rolls from the positions (y, z) of the sections. A roll per section cannot be typed. An XFLR5 import whose airfoil frames move sections builds rolls that differ from XFLR5's: 3.90° and 4.88° instead of 4.5° and 6° on the untilted worked example, within 0.1 mm at its trailing edges.
A chord below 1 mm is not possible.	Chord below 1 mm at any span position is an error. Checked at 257 evenly spaced span positions, every loft station and every guide-curve control point and knot. A chord of the fitted surface below 0.9 mm (measured along the intended chord direction) is an error; it is checked at the same positions and at 0.25, 0.5 and 0.75 of every interval between fitted stations. A Pointed tip ends in a profile scaled to 1/100 to 1/1000 of the second-to-last section chord, at least 1 mm.
Smooth blending can overshoot.	Error when an interpolated value (leading-edge x and chord where no guide curve sets them, z, twist or a profile point height) lies more than 2 × the range of its section values outside that range, or when the blended profile thickness is below 0. Checked at the same span positions as the chord. The overshoot message names the quantity, the span position and the smallest gap between sections. Remedies named in the messages: linear blending, evenly spaced sections, removing sections that lie close together, more sections.
A wing beyond ±1,200,000 mm or with a chord above 100,000 mm between the sections is not possible.	Error when, at a span position of the chord check, leading-edge x, trailing-edge x or z lies beyond ±1,200,000 mm or the chord exceeds 100,000 mm. Causes: smooth blending, also within the overshoot bound, for example sections at y = 0, 100 and 1000 mm with x = 0, 1,000,000 and 0 mm (leading-edge x 1,211,902 mm at y = 125 mm); nose line and end line more than 100,000 mm apart. The message names the span position, leading-edge x, z and chord. Remedies named in the message: checking the guide curves, linear blending.
A closed or fixed-thickness trailing edge can make upper and lower surface cross.	Occurs where the airfoil is thinner inside than its trailing-edge gap. The upper surface then passes below the lower one; this is an error. Use As in the airfoil files or a larger thickness.
The loft follows the guide curves exactly only at the spanwise stations.	Warning when the loft surface still deviates from the intended profile (leading edge, upper trailing-edge point, 5 chord stations per surface at 60 chordwise stations) by more than 0.5 mm (or 10 % of the local chord, if smaller) after the extra stations (up to 32 in 6 rounds, 1 round above 60,000 loft grid points). Of the fits before and after each round the build keeps the one with the smallest largest deviation relative to its tolerance, the first one on a tie: 2 sections with a nose-line bump 4 mm high and 0.06 mm wide deviate 3.67 mm without extra stations and 18,797 mm after 32; the build keeps the first fit and warns. The warning uses the check positions of the chord check only. The warning names more spanwise stations per panel (up to 40) as the remedy; its effect on a wing with this warning is not measured. When the grid limit lowers N (Functions, Spanwise stations), a higher setting adds no stations. The wizard presets with pointed tip build without this warning; Glider with pointed tip (elliptic planform, 8 stations per panel): 5 extra stations, largest deviation 0.263 mm. Within 2 mm of a pointed elliptic tip the leading and trailing edge x deviate at most 0.031 mm (wizard presets); the other profile points there are not measured, and the warning does not cover them. Local thickness of the fitted surface at the compared chord stations below 0 ("turns inside out") or at most 0.001 % chord between 1 % and 99 % chord ("has zero thickness") is an error. Checked at the check positions and at 0.25, 0.5 and 0.75 of every interval between fitted stations. Causes named in the message: guide curves that change fast, unevenly spaced sections in smooth mode.
The loft surface is tested for self-crossing on selected rows only.	A surface row (in the plane of its station) that crosses itself between the resampled points is an error ("The loft surface crosses itself at y = … mm near x = … mm"; remedy named in the message: more stations per surface). Tested rows: every section, halfway between adjacent sections and halfway across the 64 widest intervals between fitted stations. Rows in the other station intervals are not tested.
Trailing-edge gaps below 0.01 mm are opened to 0.01 mm.	Applies unless every station has a closed trailing edge. Stations with a gap below 0.01 mm are opened to 0.01 mm (at most 5 % of the local chord). A warning gives the number of opened stations. Its text names closed and open stations also when every station is open with a gap below 0.01 mm.
Guide curves set x and chord only.	z (dihedral) and twist always follow the section values.
Inclined airfoils are not rotated back.	Twist refers to the x axis of the file. Warning when the line from leading edge to trailing edge is inclined by more than 0.5°. The bundled Clark Y (1.97°) and USA 35B (1.51°) give this warning.
STEP files carry no colours, no face names and no assembly structure.	Applies to every STEP file.
The 25 % MAC point is a geometric reference.	Shown in Checks as "25 % MAC (geometric reference)". No neutral-point or centre-of-gravity calculation.
A project within all limits can exceed the 100 MB of a project file.	Names and source texts near their limits: 10,000 airfoils with 10,000-character names hold 100,000,000 name characters (with 5 points per airfoil: 100.8 MB). Save writes no file and shows Save failed: the project takes 100.8 MB as a file, above the 100 MB that Open reads. Projects with shorter names and source texts fit: 1,000,000 airfoil points take about 40 MB.
Browser support is tested in Chromium only.	Playwright tests at 1280 x 720 and in the Pixel 7 phone profile. Firefox and Safari: not tested.
Time and memory estimates come from one desktop computer.	The Large project warning, the warning for airfoils above 5000 points, the titles of + and Add point, the loft grid note in Settings and the export note use linear fits to measurements in Chromium 141 on 4 cores of a 2.1 GHz server CPU. Measured: JavaScript time without drawing the 3D view; the 3D view adds its drawing time. The first-build sentence of the Large project warning adds a term measured in Node.js 24 only.
Flaps of XFLR5 airfoils are imported undeflected.	An .xfl project stores the base shape and the flap parameters. The import uses the base shape and cuts no control surface. Report: info for a flap at 0°, warning for another angle. A 0.5° flap with its hinge at 50 % of the chord puts the trailing edge 1.61 mm off XFLR5's at 368 mm chord.
A tilted XFLR5 part keeps vertical section planes.	The import folds the tilt angle into the section values, which is exact for vertical planes only. Across a panel with dihedral δ the thickness is then cos δ times the XFLR5 value: 99.9 % at 3°, 98.5 % at 10°, 82 % at 35° (a V-tail modelled as an elevator); the import warns above 10° and below −10°. Set to Mitred, the part lies up to 0.75 · chord · sin(tilt) · sin(roll) off XFLR5's (0.45 mm on the worked example, about 1.6 mm on a 35° V-tail with 3° tilt), with a warning in Checks. Projects of the XFLR5 import of format version 1 hold no stored tilt and give no such warning.
The imported wing is not identical to the surface XFLR5 builds.	Compared with the STL files that the code of XFLR5 6.62 wrote for 93 surfaces of 15 real projects: 35 lie within 0.1 mm, 80 within 0.6 mm; the others are 4 tilted V-tails (2.87 mm), 8 wings with a 0.5° flap (2.43 and 2.65 mm) and 1 wing with a 33-point Clark YS (0.88 mm). XFLR5 joins the airfoil points with straight segments, Wingdesigner with a smooth curve (largest part on 58 surfaces); XFLR5 shears the airfoil of a twisted section, Wingdesigner rotates it as a rigid shape (0.37 mm at 3° twist and 300 mm chord); XFLR5 skews the panels next to a flap. Details: section "Differences from XFLR5" of File Formats.
Library airfoils and airfoils of the current project have no frame, except NACA sections of the current project (they get the frame of the generated section of their NACA code).	The XFLR5 coordinates of the name are not known. The report names bundled airfoils whose leading edge lies, in their own coordinates, more than 2 % of the chord from 0 in x or y: Clark Y 3.55 %, USA 35B 2.87 %; and airfoils of the current project from an XFLR5 import or an upload, whose own coordinates are not stored. Uploading the .dat file that XFLR5 used places the sections as XFLR5 does.
The phone file pickers with the .xfl filter are untested.	Whether the file pickers of Android and iOS list .xfl files with the filter of Open is unknown. The Playwright tests (Chromium on the desktop and in the Pixel 7 profile) check the accept attribute and hand the file to the chooser; no phone picker is opened.
The XFLR5 import dialog is untested with screen readers.	Upload .dat in the dialog announces its result in a status line that only screen readers show. No screen reader was run against the dialog.
Wing computation time and memory use on phones: not measured.	—

Quick start

1. Open the app. On the first visit the wizard opens with the Sport preset. Pick a preset, edit the values, click Create design. Skip (open sample wing) loads "Sport wing 1500": 1500 mm span, 3 sections, NACA 2412 and 2410.

   

2. Airfoils: enter a NACA code and click Preview, click Preview next to a Library entry, or drop airfoil files on the drop zone or click Choose files. Review the preview, then click Add to project.

3. Sections: choose the airfoil in the Airfoil column. Set y, x, z, chord and twist of each section. + inserts a section after the row (disabled at 20,000 sections; from 200 sections on, its title names the time and memory of each change with one more section). When no span position lies between the row and the next section, + shows a message and inserts nothing. × deletes the row (disabled at 2 sections).

4. Planform: tick Use guide curve for the nose line or the end line. Drag the points.

5. Checks: read errors, warnings and planform figures.

6. Export: choose format, wing halves and mesh density (for Fusion 360 set to Y up: Fusion 360 fix), then click Download. A note gives the triangle count (STL, 3MF) or control point count (STEP) and the file size; above 10,000,000 triangles or 3,000,000 control points Download is disabled.

Offline use

Each GitHub release (tag v*) carries wingdesigner-<tag>-site.zip, the built site (1.0 MB zipped: 0.75 MB of code with the styles, a 3.7 MB source map, the bundled airfoil files and LICENSES.txt).

1. Unzip it.
2. Open index.html in the browser. The app runs from the file without a web server and without network access; the airfoil library is part of the code, and autosave keeps the project across reloads. Tested in Chromium 141; Firefox and Safari: not tested.

A static web server on the unzipped folder works as well, e.g. python3 -m http.server and then http://localhost:8000/.

Development

Requires Node.js 24 (.nvmrc; package.json engines >=24). STEP and 3MF validation: Python 3.12 (as in CI), 3.11.15 in a local run on 2026-09-30; other Python versions not tested. Version history: CHANGELOG.md. Verified state and open items: RECORD.md. Where the work stands, next steps and the working agreements with the owner: docs/Handover.md.

npm ci
npx playwright install chromium   # browser for end-to-end (e2e) tests and screenshots (or set PW_CHROMIUM=/path/to/chrome)
npm run dev              # development server on http://localhost:5173
npm test                 # 546 unit tests (Vitest)
npm run lint             # ESLint
npm run build            # production build into dist/
npm run preview          # serve dist/ on http://localhost:4173
npm run e2e              # production build, then 179 Playwright tests on desktop 1280 x 720 and Pixel 7 (358 runs)
npm run coverage         # unit tests with coverage report in coverage/
npm run coverage:readme  # write the coverage tables into README.md and README.de.md
npm run coverage:check   # exit code 1 when a README coverage table differs from coverage/
npm run airfoils:check   # validate the bundled airfoil library and the NACA presets
npm run step:cases       # write 12 STEP files, 12 3MF files and cases.json to step-check/
npm run screenshots      # rebuild and regenerate docs/wiki/images/
npm run docs:check       # check page pairs, wiki links, images, coverage markers and the release texts in CHANGELOG.md
npm run counts:check     # compare the test counts in README, RECORD and wiki with the suites
npm run i18n:check       # check the German translation of every text
pip install cadquery-ocp==8.0.1.0.0 lib3mf==2.5.0         # Python 3.12
python scripts/validate_step.py step-check/cases.json   # validate the STEP files with OpenCascade
python scripts/validate_3mf.py step-check/cases.json    # validate the 3MF files with lib3mf (strict mode)

Test coverage

Update: npm run coverage && npm run coverage:readme. CI runs npm run coverage:check and fails on a difference. The Playwright tests run the DOM (Document Object Model) code; its coverage is not measured.

Statements	Branches	Functions	Lines
98.3 %	95.3 %	98.8 %	99.0 %

Unit tests (Vitest, V8 coverage) over src/, excluding the DOM code in src/ui/ and src/main.js.

Authors

Julian (subtilitas) created Wingdesigner, with Claude (Anthropic) as co-creator.

License

MIT License (named after the Massachusetts Institute of Technology), see LICENSE. Airfoil coordinate data keeps the terms of its source.

The build writes LICENSES.txt next to index.html: this license and the license texts of the libraries in the bundle, three.js and fflate (both MIT). Help links to it.