RC Wing Designer — Complete User Guide

RC Wing Designer — Complete User Guide

Design RC aircraft wings from scratch — no CAD skills required. From your first rectangular wing to complex tapered, swept, polyhedral designs ready for laser cutting or 3D printing.

rcplanediy.com · Wing Designer · All Build Types

Contents

Overview

Introduction

The RC Wing Designer is a browser-based parametric wing design tool built specifically for RC aircraft builders. Whether you prefer traditional balsa rib-and-spar construction, laser or CNC cutting, or fully 3D-printed wings, the tool generates production-ready output files in minutes — no CAD software, no engineering degree required.

You describe the wing you want using familiar RC building language: chord length, span, dihedral, washout, spar positions. The tool handles all the geometry, curve interpolation, and file export automatically. The output is accurate to fractions of a millimetre and accounts for dihedral and washout angles when sizing spar notches.

What you can design

  • Straight, tapered, swept, elliptical, or any custom planform shape
  • Flat, dihedral, polyhedral (gull-wing / cranked), or anhedral wings
  • Any NACA 4-digit airfoil, or upload a custom profile from airfoiltools.com
  • Span-wise thickness variation (thinner at tip)
  • Per-rib washout (twist) for improved stall behaviour
  • Complete spar/stringer/jig layouts for traditional balsa construction
  • Solid shell or lattice-infill structures for FDM 3D printing

Output formats

  • PDF — tiled across A4/letter pages, print and cut by hand
  • SVG / DXF — send to a laser cutter or CNC router
  • STL — import into a slicer (Cura, PrusaSlicer, Bambu Studio) and 3D print
This guide covers every tab, parameter, spar type, and export option. If you are completely new to RC construction, read sections 1–4 carefully. Experienced builders can jump straight to the Spars section or Tips & Techniques using the navigation above.
Getting Started

Getting Started

Interface Layout

The Wing Designer has three main regions:

  1. Sidebar (left) — All design parameters organised into tabs. This is where you configure everything.
  2. Viewport (centre/right) — Live 3D, Planform, or 2D cut-out preview that updates automatically as you change settings.
  3. View switcher and export buttons (top-right) — Switch between views and download files.
🖼️ Screenshot: Full interface overview Annotated screenshot showing sidebar, viewport, and view-switcher controls

Sidebar Tabs

The sidebar is divided into tabs, each controlling a distinct aspect of the wing. They are worked through roughly top-to-bottom when designing a new wing:

TabWhat it controls
General SettingsBuild method, units, span, chord, rib count, rib thickness, airfoil
Leading EdgeLE sweep angle and shape along the span
Trailing EdgeTE sweep angle, shape, and washout along the span
WashoutPer-rib wing twist angles for stall characteristics
DihedralVertical angle of each wing panel, polyhedral breakpoints
Wing ThicknessSpan-wise chord thickness scaling
Rib SpacingCustom rib positioning along the span (hidden for Solid3D)
Spars & MoreAdd and configure spars, stringers, combs, and jigs (hidden for Solid3D)
The Rib Spacing and Spars & More tabs are only visible when the Build Method is set to a rib-and-spar type. They are hidden for Solid 3D Print builds.

Designing Your First Wing

Here is the fastest path to a usable wing file:

  1. Open the tool at rcplanediy.com. A default rectangular wing is already loaded.
  2. In General Settings, set your Unit (cm or inches), Wing Span, Root Chord, and Rib Count.
  3. Choose a Build Method — start with Planar Ribs & Spars (2D) if you are building with balsa or cutting on a laser.
  4. Enter the four digits of your chosen NACA airfoil (e.g. 2412 for a classic trainer profile).
  5. Switch to the Spars & More tab and add a main spar and a leading-edge spar.
  6. Click the 2D Cut Outs view tab to see all ribs laid out.
  7. Click Download PDF and print at 100% scale.
All dimensions are output in millimetres (mm) regardless of which unit you work in. Always print PDF at 100% scale / actual size — do not let your printer scale to fit the page.
Tab 1

General Settings

The General Settings tab is your starting point. It defines the fundamental geometry and construction method for the wing.

🖼️ Screenshot: General Settings tab Shows Build Method dropdown, Unit selector, Wing Span slider, Root Chord slider, Rib Count, Rib Thickness, and NACA digit selectors

Build Method

This is the most important setting. It determines what the tool generates and which other tabs and views are available.

Build MethodDescriptionBest For
Planar Ribs & Spars (2D) Generates individual 2D rib and spar profiles. Each rib is a flat cut-out with notches for the spars. Laser cutting balsa/plywood, hand cutting from printed templates
3D Print — Solid Generates a solid 3D shell of the entire wing surface. Internal structure can be Skin Only, LE/TE Diamond, or Full Diamond Lattice. FDM 3D printing (PLA, PETG, LW-PLA)
3D Print — Separate Parts Generates individual 3D-printable ribs and spars as separate objects, assembled after printing. Large wings where printing a single piece isn’t practical
3D Print — One Piece Like Separate Parts but all ribs are fused into a single monolithic print. No spar notches — structure is one body. Small, stiff wing panels for micro aircraft
For Solid3D builds, a Structure Type sub-option appears. Skin Only is the lightest but least rigid — suitable for foam-infill cores. Skin and Inner Diamond Structure creates a lattice of internal triangular struts that dramatically stiffens the wing without adding a solid infill. This is the recommended option for bare 3D-printed wings.

Units

OptionNotes
Centimetres (cm)Most common for metric RC builders. Sliders display in cm.
Inches (in)For imperial builders. Sliders display in inches.
Regardless of the unit you choose, all exported files (PDF, DXF, SVG, STL) contain geometry in millimetres. This is important when importing DXF into CAM software.

Wing Dimensions

ParameterRangeStepDescription
Wing Span12 – 1250.5 Total tip-to-tip span of the wing panel. For a full aircraft, this is typically half-span (root-to-tip of one panel) unless you are designing a full symmetric wing.
Root Chord2 – 1200.1 The chord length at the wing root. For tapered wings, the root is always the widest point.
Rib Count3 – 201 Number of ribs along the span. More ribs provide better shape definition and more attachment points for sheeting, but increase cutting time and weight. For a typical 1-metre trainer, 8–12 ribs is common.
Rib Thickness0.02 – 20.01 The thickness of each rib and spar material. This should match your actual material thickness — e.g. 0.3 cm for 3 mm balsa sheet. Spar notch widths are calculated from this value. For Solid3D builds this controls wall thickness.
A good starting rib count for a 1-metre trainer is 10 ribs. For a high-aspect-ratio glider, use 14–16 ribs. For a delta or flying wing with a short span, 5–8 is usually enough.
Rib Thickness drives the width of every spar notch in the 2D output. If you laser-cut with a kerf of 0.1–0.15 mm, reduce your Rib Thickness by that amount (e.g. set 2.85 mm instead of 3 mm) for a tight push-fit.

Airfoil

The cross-sectional shape of every rib in the wing. You can use the built-in NACA 4-digit generator or upload a custom profile.

NACA 4-Digit Airfoil

NACA 4-digit airfoils are described by four numbers. Each digit is set individually with a selector (0–9).

DigitMeaningPractical Guidance
1st digitMaximum camber as % of chord0 = symmetric (aerobatic). 2–4 = typical trainer/sport. Higher = more lift at lower speed.
2nd digitPosition of max camber (tenths of chord)4 = max camber at 40% chord. Most trainers use 4.
3rd & 4th digitsMaximum thickness as % of chord12 = 12% thick. Thicker wings are more stable and easier to cover. Common range: 08–15.

Common profiles for RC aircraft:

  • NACA 2412 — classic all-rounder, great for trainers and sport flyers
  • NACA 4412 — higher lift, slower stall speed, good for slow flyers
  • NACA 0012 — symmetric, zero lift at zero angle of attack — aerobatic and 3D
  • NACA 0009 — thin symmetric, used for tail surfaces
  • NACA 6412 — high camber, high lift, flying wing/delta designs

Custom Airfoil Upload

To use a non-NACA profile (e.g. Clark Y, Eppler, or a proprietary airfoil):

  1. Visit airfoiltools.com and find your desired airfoil.
  2. Download the coordinate file in Selig format (.dat file).
  3. In the General Settings tab, click Upload Custom Airfoil and select the .dat file.
  4. The viewer will update immediately to show the new profile.
  5. To revert to the NACA profile, click the Reset button.
🖼️ Screenshot: NACA digit selectors and custom airfoil upload button
Clark Y and Eppler 193 are popular choices for RC trainers and are available on airfoiltools.com. They provide better low-speed characteristics than an equivalent NACA profile.
Tab 2

Leading Edge

The Leading Edge tab defines the sweep curve of the wing’s front edge as it travels from root to tip. Instead of a single fixed angle, the tool lets you define a curve — you can have a straight panel near the root that sweeps into a more aggressive tip, for example.

🖼️ Screenshot: Leading Edge tab Shows the sweep slider, tension slider, Root and Tip reference points, and the Add Cue button

Sweep

ParameterRangeDescription
LE Sweep–50° to +180° The angle of the leading edge relative to the root at each reference point. 0° = straight (perpendicular to fuselage). Positive values sweep the LE backwards. Negative values sweep it forward.

Common sweep configurations:

  • 0° — Straight rectangular wing (easiest to build)
  • 5°–15° — Mild sweep for aesthetic and slight aerodynamic benefit
  • 20°–45° — Sport/performance sweep, reduced induced drag
  • 45°–90° — Delta-like leading edge
  • Negative values — Forward-swept wing (unusual, advanced)

Tension (Curve Smoothness)

ParameterRangeDescription
LE Tension0.01 – 1.0 Controls how the sweep curve interpolates between reference points. 1.0 = very smooth, gradual curve. 0.01 = very sharp corners at each reference point (almost straight-line segments). Think of it as the “springiness” of the curve.
For most wings, leave Tension at the default (0.5). Lower it to 0.1–0.2 for a sharply tapered tip like a cranked glider LE. Set it to 0.8–1.0 for a continuously curved, organic elliptical-style planform.

Reference Points (Cues)

Reference points, called cues, are the backbone of every curve in this tool. A cue is a specific location along the span where you define an exact sweep value. The tool smoothly interpolates the curve between all cues.

There are always two fixed cues: Root (0% span) and Tip (100% span). You can add intermediate cues between them. Each intermediate cue has:

Location (%)
Where along the span this cue sits, expressed as a percentage of total span. E.g. 50 = midspan.
Offset (Y)
The actual lateral offset at this location relative to the root chord. This is an absolute distance (in your chosen units), not an angle.
You can create a cranked or “gull” leading edge by placing a cue at the panel break location (e.g. 40%) with a sharp tension value. This is essential for flying wings with two different sweep zones on the same panel.
Tab 3

Trailing Edge

The Trailing Edge tab mirrors the Leading Edge tab but also includes a per-point washout control. The TE defines the rear edge of each rib’s chord.

🖼️ Screenshot: Trailing Edge tab Shows sweep slider, tension, washout slider, and Root/Tip reference points

Sweep

ParameterRangeDescription
TE Sweep–100° to +100° Same concept as LE sweep, but for the trailing edge. The combination of LE and TE sweep determines the overall planform shape.

Planform shapes by sweep combination:

  • Rectangular: LE = 0°, TE = 0°
  • Tapered: LE = 5°, TE = –5° (both edges angle inward toward the tip)
  • Swept: LE = 20°, TE = 15° (both sweep backward, LE more than TE)
  • Delta / Flying wing: LE = 55°+, TE = 0° or very slight
  • Reverse taper: TE sweeps more than LE (seen on some gliders)

Washout (TE Tab)

ParameterRangeDescription
TE Washout–15° to +15° Geometric twist of the trailing edge at each reference point. Positive washout rotates the TE upward (decreasing angle of attack at the tip). Negative washout twists the tip nose-down (washin).
For more granular per-rib control, use the dedicated Washout tab instead. The TE washout here is best used when you want a simple, uniform twist applied smoothly across the span.
Tab 4

Washout Tab

Washout is the aerodynamic twist built into a wing — the tip ribs are rotated relative to the root ribs so the tip flies at a lower angle of attack than the root. This is one of the most important stall-safety features for RC trainers and gliders.

🖼️ Screenshot: Washout tab Shows rib location cues with washout angle values, and the Add Cue button

Why Washout Matters

Without washout, a wing stalls roughly uniformly from root to tip. The tip stalling first is particularly dangerous in RC aircraft because it causes an abrupt roll (a spin entry) with little warning. Washout ensures the root stalls first — you feel the buffet in pitch before you lose roll control.

  • Trainers: 2°–4° positive washout at the tip
  • Sports aircraft: 1°–2° washout
  • Aerobatic: 0° (symmetric handling, intentional stall entry)
  • Flying wing: 3°–6° washout, critical for pitch stability

Setting Washout per Rib

ParameterRangeDescription
Washout Angle–15° to +15° Positive = trailing edge rotates upward (reduces AoA at that span location). Negative = washin (increases AoA — avoid on outboard sections).
Span Location (%)0 – 100% Where along the span this cue applies. 0% = root, 100% = tip.
Washout affects spar notch geometry. The tool calculates each notch’s width and angle accounting for the local rib’s washout angle, so all spar pieces should slide together cleanly even with significant twist.
Tab 5

Dihedral

Dihedral is the upward angle of the wing panels relative to horizontal. It provides roll stability — a dihedral wing naturally returns to level flight when disturbed. This tab lets you define dihedral as a curve along the span, enabling polyhedral, gull-wing, and inverse dihedral (anhedral) designs.

🖼️ Screenshot: Dihedral tab Shows dihedral angle cues, tension slider, and planform preview reflecting dihedral
ParameterRangeDescription
Dihedral Angle–45° to +80°Upward tilt of the wing at each cue point. 0° = flat. Positive = dihedral (tips up). Negative = anhedral (tips down).
Dihedral Tension0.01 – 1.0Curve smoothness between dihedral cue points. Low tension = sharp break (polyhedral). High tension = smooth gull-wing curve.
Span Location (%)0 – 100%Where along the span this dihedral cue applies.

Polyhedral Wings

Polyhedral is two (or more) dihedral angles joined at a break point — common in gliders and high-wing trainers. To create polyhedral:

  1. Set root dihedral to 0° (flat inner panel).
  2. Add an intermediate cue at the break point (e.g. 50% span) with the outer panel angle (e.g. 15°).
  3. Set tip to 15° as well (flat outer panel).
  4. Lower Tension to 0.05–0.1 for a sharp break, or leave at 0.5 for a rounded gull-wing transition.
For a traditional RC trainer with a dihedral break at the midspan, use two cues: root at 0° and tip at 10°–15° with a break cue in the middle. This gives about 5°–7° effective dihedral — plenty of self-levelling stability.
Tab 6

Wing Thickness

Real aircraft wings taper in thickness toward the tip — not just in chord but in absolute height. This saves weight, reduces drag at the tip, and creates a more realistic-looking section. The Wing Thickness tab lets you scale the thickness of each rib as a percentage of the root rib’s thickness.

🖼️ Screenshot: Wing Thickness tab Shows root and tip thickness cues and the tension slider
ParameterRangeDescription
Thickness (%)0 – 100% The height of the airfoil at this span location as a percentage of the root chord height. 100% = same absolute thickness as the root. 60% = 60% of root height.
Thickness Tension0.01 – 1.0 Smoothness of the thickness taper curve between cue points.
A realistic taper for a sport aircraft is root at 100% and tip at 70%–80%. Avoid going below 40% at the tip as the ribs become too thin to cut reliably.
Thickness scaling applies only to the rib cross-section height. It does not change the chord width — use the Trailing Edge and Leading Edge tabs to taper the planform.
Tab 7

Rib Spacing

By default, ribs are distributed evenly along the span. The Rib Spacing tab lets you pin specific ribs to exact span locations, with the remaining ribs auto-distributing evenly in the gaps between pinned ribs.

🖼️ Screenshot: Rib Spacing tab Shows span location inputs for each rib index, with auto-distribute arrows between them

Why Custom Spacing Matters

Even rib spacing is rarely optimal. You will want denser ribs:

  • At the wing root, where bending loads are highest
  • At control surface hinge lines (aileron, flap), to provide a clean cutout edge
  • At undercarriage attachment points
  • At the wingtip, to define the tip shape precisely

Setting Rib Positions

Each rib can be given a span position as a percentage (0–100%). If you only define some ribs, the tool automatically distributes the rest evenly in the gaps.

Example: 10-rib wing with custom spacing for an aileron bay:

  • Rib 1: 0% (root)
  • Rib 7: 55% (inboard aileron hinge rib)
  • Rib 8: 57% (tightly spaced for aileron horn clearance)
  • Rib 10: 100% (tip)
  • Ribs 2–6 and 9 distribute evenly in the gaps
When designing for an aileron servo mount, place two ribs very close together (1–2% span apart) at the outboard servo bay boundary. This creates a strong servo mounting bay without adding ribs to the entire span.
Tab 8

Spars & More

This is the most powerful tab in the tool. It lets you define all structural and assembly elements: main spars, leading-edge reinforcements, trailing-edge stock, cap strips, spar doublers, stringers, and assembly jigs. You can add as many elements as your wing requires.

🖼️ Screenshot: Spars & More tab Shows the Add Spar dropdown, and a list of existing spars each with their configuration options expanded

Common Properties (All Spar Types)

PropertyDescription
Start RibThe rib index where this element begins. Rib 1 is the root.
End RibThe rib index where this element ends. Set to the last rib for a full-span element.
WidthThe cross-sectional width of the spar (or slot width for Comb/Stringer). In your selected units.
Height / RadiusCross-sectional height (for rectangular shapes) or radius (for circular shapes).
ShapeThe cross-section profile of the spar slot cut into the rib (see below).

Spar Shapes

ShapeUse Case
Square / RectangleStandard balsa strip, carbon rod, or square carbon tube. Most common.
DiamondDiamond-oriented square — used for round carbon rods where the notch needs to be rotated 45° for easier insertion.
CylinderRound spar — carbon or fiberglass tubes. The notch is circular.
Half CylinderA semi-circular notch — used when you want the spar to rest on a cradle rather than being fully enclosed.

Spar (Support)

The main structural element of any rib-and-spar wing. The Spar type creates a rectangular or round section running span-wise through the wing, cutting notches in each rib it passes through. This is the element you use for your primary carbon tube spar, main balsa spar, or any internal reinforcement rod.

🖼️ Screenshot: Spar (Support) configuration panel Shows Shape dropdown, Width, Height, Start/End rib, and vertical offset sliders
PropertyRangeDescription
Start Index0.01 – 0.99 The chord-wise position of the spar as a fraction of chord length. 0.0 = leading edge, 1.0 = trailing edge. 0.25 = quarter-chord (typical main spar location).
End Index0.01 – 0.99 The chord-wise end position of the spar on the last rib. Can differ from Start Index to allow the spar to run at an angle through a tapered wing.
Start Vertical Offset–0.1 to +0.1 Moves the spar vertically (Z-axis) at the start rib. 0 = centred on the chord line. Positive = above centreline.
End Vertical Offset–0.1 to +0.1 Vertical offset at the end rib. Differ from Start Offset to create a spar that rises or dips through the wing.
ShapeSquare, Diamond, Cylinder, Half CylinderCross-section of the spar notch in each rib.
Width0.1 to chord/4Width of the spar cross-section.
Height0.1 to chord/10Height of the spar cross-section (rectangular only).

RC Construction Context

In traditional balsa construction, the main spar typically runs at 25–35% chord. Placing it at the quarter-chord minimises the twist loads transferred to the fuselage. Common spar materials:

  • Balsa strip spar: 3–5 mm wide × 5–8 mm tall, at 25–30% chord, Square shape
  • Carbon rod: 3–8 mm diameter, at 25% chord, Cylinder shape
  • Carbon tube: 6–10 mm diameter, 30% chord, Cylinder shape

For heavily loaded wings, add a secondary spar at 60–70% chord to resist trailing-edge bending loads.

Leading Edge Spar

The Leading Edge spar type snaps automatically to the leading edge of every rib. It is used to represent the leading-edge stock — the shaped balsa piece that runs the full span at the front of the wing.

🖼️ Screenshot: Leading Edge spar configuration Shows Shape, Width, Height options and the Slope Overwrite toggle
PropertyDescription
ShapeUsually Square or Half Cylinder. Half Cylinder models a round LE dowel. Square models a balsa block that will be sanded to shape.
WidthThe width of the LE stock. For a typical trainer, 5–8 mm is common.
HeightHeight of the LE notch. Match to your LE stock thickness.
Slope OverwriteToggle between Auto and a manual angle. Auto calculates the correct tangent angle to the leading edge.

RC Construction Context

  • Balsa triangle stock: Shape = Square. Width and height match the triangle cross-section. Sand to an aerodynamic shape after assembly.
  • Round dowel: Shape = Cylinder or Half Cylinder.
  • Hard LE sheeting (D-box): Use the Comb element at full depth instead — cuts a flat-face notch for ply or hard balsa LE sheeting.

Trailing Edge Spar

The Trailing Edge spar type attaches to the trailing edge of each rib. It is used for trailing-edge stock — the shaped piece running span-wise at the TE.

🖼️ Screenshot: Trailing Edge spar configuration
PropertyDescription
ShapeSquare for balsa strip TE stock. Diamond for a tapered wedge profile.
Width / HeightMatch to your TE stock. For a tapered trailing edge, height is small (1–2 mm).
Slope OverwriteAuto is recommended unless you need a specific TE bevel angle.

RC Construction Context

  • Balsa tapered wedge: 2–3 mm thick × 10–15 mm wide, Diamond shape.
  • Balsa strip: 1.5 mm × 5 mm, Square shape, trimmed to a wedge after assembly.
  • Carbon fibre flat strip: 0.5–1 mm × 10 mm for a rigid, lightweight TE on a high-performance wing.

Comb

The Comb is one of the most versatile and underutilised elements in the tool. Unlike a round or square spar that passes through the rib, a Comb is a flat element that runs between two chord-wise positions on the rib, cutting a slot that spans part or all of the rib depth.

🖼️ Screenshot: Comb configuration panel Shows Side (top/bottom), Start Index, End Index, Width, and Comb Depth slider
PropertyRangeDescription
SideTop / Bottom Whether the comb enters the rib from the top surface or the bottom. Top cuts a slot opening downward from the top edge of the rib. Bottom cuts opening upward from the bottom edge.
Start Index0.01 – 0.99Chord-wise start position as a fraction of chord. 0.0 = LE, 1.0 = TE.
End Index0.01 – 0.99Chord-wise end position.
Width0.1 to chord/4Thickness of the Comb element — the width of the slot cut into the rib. Match to your material thickness.
Comb Depth (%)1 – 100% How deep the slot cuts into the rib. 100% = all the way through (full depth). 50% = halfway through. 1% = a surface-level groove (see Advanced tip below).
Slope OverwriteAuto / –45° to +45°Angle of the slot relative to the rib surface. Auto follows the local airfoil tangent.

What a Comb Produces

The Comb generates a 2D flat profile in the cut-outs view. This flat profile is the spar itself — it slots into the notches cut into each rib. Think of it like the comb of a hair comb: the rib notches are the teeth-gaps, and the Comb profile is the backbone strip.

The Comb as a Spar Doubler: Setting Comb Depth to approximately 1% creates a near-zero depth slot on the rib — the Comb’s 2D profile becomes a flat strip whose full height spans the top-to-bottom distance of the rib between the Start and End Index positions. This produces a spar-cap or spar-doubler strip that runs the full height of the rib web. Use this to model a ply spar doubler: set Start Index = spar position − small offset, End Index = spar position + small offset, Side = Top, Width = ply thickness, Comb Depth = 1%. The resulting profile is a flat strip as tall as the spar web at each rib station — cut from 1 mm ply and glue to the face of the main spar at each rib bay.

RC Construction Patterns with Comb

  • Sheet spar (D-box front): Start = 0.0, End = 0.3, Side = Top, Depth = 100%. Models a D-box front spar sheet covering the first 30% of chord.
  • Spar cap / doubler: Depth = 1%, span the main spar chord-wise position. Creates a ply face-on strip for shear reinforcement.
  • Aileron bay spar: Start = 0.6, End = 0.9, Side = Bottom, Depth = 80%. Creates a deep rear spar for the aileron control surface.
  • Wing sheeting slot: Shallow depth (20–30%), full span, Side = Top. Models a slot for 0.8 mm balsa sheeting that rests on top of the ribs.

Stringer

A Stringer is a thin element that runs along the surface of the airfoil — it follows the curve of the top or bottom of the wing rather than passing through the rib at a fixed chord position. Stringers are used for cap strips, surface-parallel reinforcements, and balsa top/bottom sheeting support runners.

🖼️ Screenshot: Stringer configuration panel Shows Side, Start Index, End Index, Width, Height, and Slope Overwrite
PropertyRangeDescription
SideTop / BottomWhether the stringer runs on the upper or lower surface of the airfoil.
Start Index0.01 – 0.99Chord-wise start of the stringer on the airfoil surface (fraction of chord from the LE).
End Index0.01 – 0.99Chord-wise end of the stringer on the surface.
Width0.1 to chord/4Width of the stringer notch (matches your stringer material width).
Height0.1 to chord/10How deep the notch cuts into the rib edge. Matches stringer thickness.
Slope OverwriteAuto / manualAuto follows the airfoil surface tangent.

RC Construction Context — Cap Strips

A cap strip is a thin strip of balsa (typically 1.5–3 mm × 3–6 mm) that runs chord-wise on top or bottom of each rib. It sits in a shallow notch on the rib edge and provides a bonding surface for the wing covering material.

To model cap strips:

  • Side: Top | Start: 0.05 | End: 0.95 | Width: 0.3 cm | Height: 0.15 cm
  • Repeat with Side: Bottom for a lower cap strip
Add two Stringer elements — one Top, one Bottom — spanning the full chord for a traditional cap-strip wing. This is a hallmark of classic balsa construction and significantly stiffens each rib against bending.

Jig

The Jig element is unique — it is not a structural part of the wing. Instead it generates an assembly fixture that you cut from a flat piece of material (typically scrap ply or MDF) and place on your build table. The ribs, spars, and spar combs all register against the jig to ensure the wing builds straight and true.

🖼️ Screenshot: Jig element in 2D cut-outs view Shows the jig profile alongside the rib cut-outs, with the flat table reference line visible
PropertyDescription
Start Rib / End RibThe span extent of the jig. Typically the full span (Rib 1 to Rib N).
Start Index / End IndexThe chord positions that the jig references — usually the main spar position.
Comb Depth (%)Depth of the rib notches in the jig. 50% is typical — ribs slot halfway in, providing alignment without being locked.
Table OffsetVertical offset of the jig’s flat base below the bottom surface of the wing, so the jig sits flat on the building board.

How to Use the Jig

  1. Add a Jig element referencing the same chord position as your main spar.
  2. Export the 2D cut-outs as PDF or DXF — the jig profile appears alongside the ribs.
  3. Cut the jig from a flat piece of 3 mm MDF or ply.
  4. Pin the jig to your building board.
  5. Slot each rib into the jig notches — this holds all ribs at the correct height and angle.
  6. Thread the main spar through, apply glue, and let it cure.
  7. Remove the jig once the glue has set. The jig is not glued in — it is discarded after assembly.
A jig is invaluable for dihedral and washout wings where each rib sits at a slightly different angle. Without a jig, holding all ribs at the correct twist while glue dries requires many clamps. With a jig, it is automatic.
Visualisation

Views & Visualisation

The Wing Designer offers three distinct views, accessible from the tab switcher in the top-right of the viewport. Each view gives you a different perspective on the wing geometry and has its own export options.

3D View

The 3D view renders an interactive three-dimensional model of the complete wing. You can rotate, pan, and zoom to inspect the wing from any angle.

🖼️ Screenshot: 3D View Shows a tapered, dihedral wing with ribs and spars visible, rendered in 3D

Navigation

  • Left-click + drag — Rotate the model
  • Shift + drag — Pan the view
  • Scroll wheel — Zoom in/out

What the 3D View Shows

  • All ribs as transparent or solid profiles
  • All spar elements as coloured 3D bodies passing through rib notches
  • Dihedral, washout, and taper correctly applied in three dimensions
  • For Solid3D builds: the full wing shell with internal structure

Export from 3D View

  • STL — Full-resolution 3D mesh for 3D printing. May take 10–30 seconds to generate.
  • DXF — 3D DXF export for CAD software import.
The real-time 3D preview uses a reduced rib count for performance. The STL download always generates at full resolution (80 ribs for Solid3D). Do not judge surface smoothness from the live preview — the exported file will be smoother.

Planform View

The Planform view shows the wing from above — a top-down projection that reveals the overall shape: leading edge, trailing edge, rib positions, and spar outlines.

🖼️ Screenshot: Planform View Shows top-down wing outline with all rib lines and a page-size overlay

What the Planform View Shows

  • The LE and TE curves spanning root to tip
  • Vertical lines at each rib station
  • Horizontal lines indicating spar positions
  • A page-size overlay indicating the print area

Page Size Setting

You can adjust the page/material size (width × height) that the overlay represents. Useful to check whether the wing fits on a particular sheet of laser-cut material. Default is A4 (21 × 29.7 cm).

Export from Planform View

  • DXF — 2D CAD drawing of the planform, ready for import into Fusion 360, AutoCAD, or similar.
Use the Planform view to verify your taper and sweep look correct before committing to export. The LE and TE curves should look smooth and the rib spacing should appear consistent with your Rib Spacing tab settings.

2D Cut Outs View

The 2D Cut Outs view is the primary production view. It shows all rib profiles, spar flat profiles, and jig shapes laid out flat — exactly as they will be cut. This view is only available for rib-and-spar build types.

🖼️ Screenshot: 2D Cut Outs View Shows multiple rib profiles with spar notches, spar flat profiles, and a jig, all laid out on a virtual sheet

What You See

  • Each rib as a flat outline with spar notches cut out
  • Comb elements as flat profiles with rib notches
  • Stringer elements as shallow notches on rib edges
  • Leading/Trailing edge notches on rib edges
  • Jig profiles (if a Jig element is defined)
  • A page-size overlay grid for multi-page tiling

Navigation

  • Shift + drag — Pan the cut-out layout
  • Zoom buttons (+/–) — Zoom in and out

Export from 2D View

  • PDF — Tiled multi-page PDF. Print at 100% actual size.
  • SVG — Vector file. Suitable for Inkscape, Illustrator, or direct laser-cutter import.
  • DXF — CAD/CAM format for CNC routers and laser cutters with CAM software.
In the PDF export, pieces are placed to minimise page count, but the packing is automatic. Some pieces may be split across pages. Always check page boundaries before cutting.
The 2D cut-outs do not include labels for each rib. Keep your ribs in the order they appear in the layout. Mark them lightly with pencil after cutting while still on the template sheet.
Export

Export & Download

The Wing Designer exports directly from the browser — no server upload required. All geometry is computed locally.

PDF

Available from: 2D Cut Outs view. Generates a multi-page document with all cut-out shapes at true scale (1:1).

  • Print settings: Always print at Actual Size or 100% Scale. Do not select “Fit to Page”.
  • Verification: After printing, measure a known dimension (e.g. root chord) with a ruler. It should match your Wing Designer setting exactly.
  • Multi-page: For large wings, pieces tile across multiple pages. Cut pages and tape together precisely at alignment marks.

SVG

Available from: 2D Cut Outs view. Best format for laser cutters with built-in SVG import (e.g. LightBurn, K40 Whisperer, Glowforge).

  • All cut lines are vector paths — no rasterisation.
  • Import at 1:1 scale. In LightBurn, set import units to millimetres.

DXF

Available from: 2D Cut Outs view, Planform view, 3D view. Universal format for CAD and CAM software.

  • All geometry is in millimetres. Confirm your CAD software is set to mm when importing.
  • Curves are approximated as polylines at sufficient resolution for manufacturing.

STL

Available from: 3D view. Standard format for 3D printing.

  • Generating the STL uses high-granularity computation (80 ribs for Solid3D). This may take 10–60 seconds.
  • Import into your slicer (Cura, PrusaSlicer, Bambu Studio) and verify dimensions in mm.
For LW-PLA 3D-printed wings, export as STL with Solid3D, choose Skin and Inner Diamond Structure, set wall thickness to 1.0–1.5 mm, and slice with 0% infill.
Workflows

Build Method Deep-Dive

Planar Ribs & Spars (2D) — Balsa / Laser Cutting

This is the traditional RC construction method and the tool’s most capable output mode.

Workflow

  1. Design: Configure your wing in all tabs. Add spars matching your materials.
  2. Export PDF or SVG: From the 2D Cut Outs view. PDF for hand-cutting, SVG or DXF for laser/CNC.
  3. Cut ribs: Laser-cut or hand-cut the rib profiles. Typical: 1.5–3 mm balsa or 1.5 mm ply for high-stress ribs.
  4. Cut spars: Spar Comb profiles are in the cut-outs. Cut from appropriate material.
  5. Assemble on jig: If you added a Jig element, cut it first, pin to board, slot ribs in, thread spars through.
  6. Glue: CA glue at rib/spar interfaces, epoxy for carbon tube sockets.
  7. Cover: Once structure is complete and sanded, cover with film (Monokote, Oracover) or tissue and dope.

Material Recommendations

PartRecommended MaterialThickness
RibsBalsa sheet (trainer), Ply (high-load)1.5–3 mm
Main sparPultruded carbon strip, ply strip2–3 mm
LE stockBalsa triangle6–10 mm
TE stockBalsa tapered wedge2–3 mm
Spar comb (D-box)Hard balsa or 0.8 mm ply0.8–1.5 mm
JigMDF or scrap ply (discarded after assembly)3–6 mm

3D Print — Separate Parts

Prints individual ribs and spars as separate 3D objects, assembled after printing — a 3D-printed version of the balsa rib-and-spar approach.

  • Each rib is printed as a flat object; spars as their cross-sectional profiles
  • Ribs and spars slot together then bonded with CA or epoxy
  • Best for large wings where a solid shell is impractical
  • Allows mixing materials: printed ribs + carbon tube spars
Print ribs flat on the bed with two perimeter walls and 10–15% gyroid infill for a lightweight but stiff rib. Standing ribs produce the strongest layer structure for span-wise loading.

3D Print — Solid

Generates the entire wing as a single closed mesh for direct 3D printing. Internal structure is controlled by the Structure Type setting.

Structure Types

  • Skin Only: A hollow shell. Minimal weight. Suitable for foam-core wings.
  • LE/TE Diamond Structure: Diamond lattice at the LE and TE zones only.
  • Skin + Full Diamond: Diamond lattice throughout. Maximum rigidity. Best for small high-performance wings.

Print Settings

  • Material: LW-PLA (lightest), PLA (rigid), PETG (outdoor durability)
  • Wall thickness: Set Rib Thickness to 1.0–1.5 mm. Use 2–3 perimeter walls in your slicer.
  • Infill: 0% — the diamond lattice provides internal structure.
  • Orientation: Print chord-wise (root face down). Split large wings at 50% span and join with a carbon joiner rod.
The Solid3D preview uses 30 ribs for performance. The exported STL uses 80 ribs. The live preview will look faceted — this is normal. The STL will be smooth.
Advanced

Tips & Techniques

Practical techniques and patterns for getting the most out of the Wing Designer. Each one exploits the tool’s flexibility in a non-obvious way.

Spar as Doubler (Comb Depth Trick)

A spar doubler is a thin strip of hard material (typically 1–1.5 mm ply) glued to the flat face of a main balsa spar to reinforce it. Model this with a Comb element set to minimal depth:

  1. Add a Comb element.
  2. Set Start Index = main spar position minus a small offset (e.g. if spar is at 0.25, set Start to 0.22).
  3. Set End Index = main spar position plus a small offset (0.28).
  4. Set Side = Top (or Bottom for the lower doubler).
  5. Set Width = thickness of your doubler ply (e.g. 0.1 cm for 1 mm ply).
  6. Set Comb Depth = 1%.

Result: The Comb profile in the 2D export is a flat strip whose full height spans the vertical extent of the spar web at each rib. Cut from 1 mm ply and glue to the face of the main spar at each rib bay.

🖼️ Diagram: Spar doubler comb profile vs main spar Shows a rib with a main spar notch and adjacent thin Comb profile representing the doubler strip

Cap Strips with Stringers

Model cap strips with two Stringer elements (one Top, one Bottom):

  • Side: Top | Start: 0.05 | End: 0.95 | Width: 0.25 cm | Height: 0.12 cm
  • Side: Bottom | Start: 0.05 | End: 0.95 | Width: 0.25 cm | Height: 0.12 cm

Each rib will get a shallow notch on its top and bottom edges. Cut 2.5 mm × 1.2 mm balsa strips and slot them in before covering.

For a competition-grade finish, use 3 mm × 1.5 mm hard balsa cap strips. They add very little weight (~2 g per rib) but visibly stiffen the wing and give an excellent surface for iron-on film adhesion.

Polyhedral and Gull Wings

Sharp Polyhedral (Classic Glider)

  1. In the Dihedral tab, set the root cue to 0°.
  2. Add an intermediate cue at your break point (e.g. 40% span) with the outer panel angle (e.g. 12°).
  3. Set the tip cue to the same 12°.
  4. Set Tension to 0.05 for a sharp break with almost no rounding.

Smooth Gull Wing

  1. Set root cue to –5° (slight anhedral on the centre section).
  2. Add a cue at 30% span: 0°.
  3. Set tip cue: 12°.
  4. Set Tension to 0.7–0.9 for a continuously curved transition.
After designing a polyhedral wing, use the Rib Spacing tab to place a rib exactly at the break point. This ensures a clean, sharp physical fold line in the built wing.

Rib Spacing for Control Surfaces

Control surfaces (ailerons, flaps, elevons) require careful rib placement to define their inboard and outboard boundaries cleanly.

  • Place two ribs very close together (1–2% span apart) at each hinge line. This gives you a firm edge to cut against and a full-thickness rib for the hinge attachment.
  • Add a secondary spar at 65–70% chord from the inboard aileron rib to the tip. This forms the front face of the aileron bay and the hinge spar.
  • Add a Comb at 65–70% chord, Side = Bottom, Depth = 80–100% for the aileron spar web.
  • Space ribs more densely in the aileron bay (every 8–10% span) for smooth shape and good control force distribution.
🖼️ Diagram: Rib spacing layout for an aileron wing Shows dense inner ribs, tight double-rib at the hinge line, and aileron bay ribs

Custom Airfoil Workflow

  1. Go to airfoiltools.com and search for your airfoil (e.g. “Clark Y”, “Eppler 193”, “SD7037”).
  2. Click the airfoil name, scroll down and click Download coordinates.
  3. Select Selig format (.dat) — a plain text file with X/Y coordinates normalised to chord = 1.
  4. In Wing Designer, open General Settings and click Upload Custom Airfoil.
  5. Select the .dat file. The viewer updates immediately.
  6. To return to NACA, click Reset.
Popular choices by aircraft type: Trainers: Clark Y, NACA 2412. Gliders: SD7037, E193. Pylon racers: NACA 64A010. Aerobatic: NACA 0012. Flying wing: MH45, S5010.

Getting the Most from the Assembly Jig

  • Reference the main spar: Set the Jig’s Start and End Index to match your main spar position so spar and ribs all align on the same baseline.
  • Cut the jig from thicker material: 4–6 mm MDF prevents the jig from bowing under the weight of the wing.
  • Ribs don’t get glued to the jig: The jig is a registration fixture only — only the spars get glue. The jig is removed and discarded after assembly.
  • For dihedral wings: The jig accommodates dihedral angles automatically — each rib notch is at the correct vertical position for that rib’s dihedral height.
  • Reuse the jig for symmetric panels: Both wing panels use the same jig profile since they are mirror images.
🖼️ Photo: Assembly jig in use on a building board Shows MDF jig pinned to cork board with ribs slotted in and main spar threading through

RC Wing Designer · rcplanediy.com · Guide version 1.0 · All output dimensions in millimetres.