Chapter 2: Wings & Membranes — Span, Bones, Folds, Feather Fans

Created by Sarah Choi (prompt writer using ChatGPT)

Wings & Membranes — Span, Bones, Folds, Feather Fans Reads

Limbs, Wings, Fins & Tails for Creature Concept Artists

Wings are some of the most iconic appendages you can give a creature. A single silhouette of outstretched wings can signal:

  • Function – flight, gliding, hovering, leaping boosts, shielding.
  • Status – divinity, mutation, corruption, elite or boss tier.
  • Personality – elegant, monstrous, ragged, disciplined.

But wings are also some of the trickiest appendages to design and animate. Span, bone layout, membrane folds, and feather fans all have to work together in motion, across multiple poses and camera angles.

For creature concept artists, understanding wings as appendage classes with distinct functions is essential on both sides of the pipeline:

  • On the concepting side, you’re designing silhouettes that tell players how this creature moves and fights.
  • On the production side, you’re creating wing systems that can be rigged, animated, and read clearly at gameplay scale.

This article will walk through wings and membranes in depth:

  • Wing types and appendage classes.
  • Span and bone structure logic.
  • Membrane reads: folds, tension, tatters.
  • Feathers and feather fans as big‑shape language.
  • Practical tips for game‑ready wing designs.

1. Wing Appendage Classes & Functions

First, treat wings like any other limb: define their class and job.

1.1 Primary Wing Functions

A wing can be:

  • Flight engine – main lift and thrust provider.
  • Glider / parachute – for controlled falls and long drifts.
  • Stabilizer / rudder – small wings for steering, not main lift.
  • Display surface – for intimidation, mating, faction markings.
  • Shield – used to block attacks.
  • Weapon – with claws, spines, edge blades.

Most creatures will have one or two primary wing functions and several secondary ones. Decide up front:

What is this wing primarily for in gameplay? Flight, glide, display, shield, weapon, or some mix?

This will guide choices about span, bone robustness, and membrane/feather structure.

1.2 Limb Integration Classes

Wings can be integrated into the body in different ways:

  • Arm‑wings – wing shares the same limb as the forearm and hand (bat/dragon style).
  • Shoulder‑wings – separate limbs attached to the torso (bird/angel style).
  • Back fins / gliding membranes – non‑muscular or semi‑muscular sheets (sugar glider, flying squirrel).
  • Insect wings – plate or membrane wings attached to thorax segments.

Each integration class affects:

  • How many joints animators must manage.
  • Whether the wing can double as an arm/hand for climbing, striking, or gripping.

2. Span & Proportions — How Big is “Big Enough”?

Wing span is one of the first things players read. It communicates power, maneuverability, and role.

2.1 Functional Span Considerations

Very roughly:

  • Short, stubby wings → bursts, jumps, glide assist, not true sustained flight.
  • Medium wings (comparable to or a bit larger than body length) → strong, agile fliers.
  • Huge wings (much wider than body length) → powerful gliders, dramatic silhouettes.

In games, realism can bend, but the read still matters:

  • Tiny wings on a massive body usually read as magical or vestigial.
  • Oversized wings on a small body read as floaty, agile, or unstable.

Decide:

  • Does the creature actually need to fly in gameplay, or just in cinematics?
  • Is flight its main locomotion, or a special move (short glides, leaps)?

Align wing span with that answer so players aren’t confused.

2.2 Silhouette Span Reads

Wings also frame the creature in composition:

  • Horizontal span widens the silhouette, making the creature feel dominant and territorial.
  • Vertical span (wings raised) creates a towering, dramatic shape.

Use span changes as expressive beats:

  • Closed/folded: compact, reserved, stealthy.
  • Half‑open: cautious, ready, blocking.
  • Fully open: threat display, takeoff, ultimate ability.

For production, plan at least two or three key spans for animation targets, and design shapes that look good at each.

3. Bone Structure — The Underlying Logic

Even if you stylize heavily, your wings will feel more believable if the underlying bone logic is clear.

3.1 Arm‑Wing Bones (Bat/Dragon‑Style)

Arm‑wings usually follow this structure:

  • Shoulder joint – attaches to torso.
  • Upper arm (humerus equivalent).
  • Elbow joint.
  • Forearm.
  • Wrist and extended “finger” bones supporting the membrane.

Key design choices:

  • How many primary wing digits support the membrane (one long finger vs several spines).
  • How far the hand extends beyond the wing edge (claws at wing tips for climbing or slashing).

Readable cues:

  • A few strong, clear bones create clean fold lines and simple rigs.
  • Too many tiny spines can make the silhouette noisy and harder to animate.

3.2 Bird‑Style Wings (Feathered)

Bird‑like wings also arise from arm bones, but feathers take over much of the structural role:

  • Upper arm and forearm segments are mostly covered by covert feathers.
  • Hand bones support the primary and secondary feather fans.

Design focus:

  • Emphasize the primary feather fan (outermost) as the main indicator of shape.
  • Keep internal bone hints subtle, using feather layering to imply structure.

For production:

  • Rigs often control a handful of major feather clusters rather than individual feathers.

3.3 Insect & Plate Wings

Insect wings pivot from the thorax:

  • No obvious arm bones; instead, a base plate at the body.
  • Wing veins act as supporting struts.

Design approach:

  • Use vein patterns or structural lines to indicate hinge and stiffness.
  • For armored plate wings, treat the first segment as a rigid shield, with secondary membranes or plates behind.

3.4 Hybrid Wing Skeletons

Fantasy lets you mix types:

  • Arm‑wings with feathered fans.
  • Insect thorax wings with vertebrate arm segments.

To keep readability:

  • Choose one primary structural logic (arm or plate) and let the other be aesthetic.
  • If the wing can fold tightly, ensure bones or plates are arranged so that fold is physically imaginable.

4. Membranes — Folds, Tension & Tatters

Membranous wings sell texture and mood: fleshy, leathery, ghostly, or tattered.

4.1 Membrane Attachment Points

Membranes can stretch between:

  • Arm/wing bones and body (classic bat/dragon).
  • Multiple limbs (wing attached to torso and leg, forming a web).
  • Spines or fin rays (fish‑like or cephalopod‑like wings).

Design considerations:

  • Where does the membrane start and end? Chest, hip, tail?
  • Does it connect to the side of the body (larger surface) or only to arm bones?

Silhouette cues:

  • Membranes anchored to legs and torso create big, kite‑like shapes.
  • Membranes only between fingers create more delicate, lacy wings.

Production note:

  • More anchor points = more complex deformation.
  • Simpler anchor layouts are easier to rig and animate.

4.2 Fold Logic & Rest Shapes

Membranes look very different folded vs stretched.

Folded state:

  • Membrane compresses into pleats along bones.
  • Edges may droop, wrinkle, or sag under gravity.

Stretched state:

  • Membrane is taut between supports.
  • Veins or structural lines become more visible.

For concepting:

  • Always design at least two states: folded and fully extended.
  • Make sure folds align with your bone layout—no random creases that ignore structure.

For production:

  • Folds can be suggested by texture and normal maps rather than modeled geometry.

4.3 Membrane Condition: Fresh, Scarred, Tattered

Membrane state also tells story:

  • Smooth, clean membranes → youthful, divine, precise, advanced tech.
  • Scarred membranes with stitched repairs → veteran or patched‑together creatures.
  • Torn/tattered edges → undead, cursed, battle‑worn.

Readability at distance:

  • Big, deliberate tears read better than many tiny irregularities.
  • Consider balancing tattered edges with some intact sections for contrast.

Production considerations:

  • Extreme tatters can create lots of small, thin geometry—expensive to animate.
  • Use alpha masks or texture tricks where possible.

5. Feathers & Feather Fans — Big Shape Language

Feathers are your main shape‑control elements on feathered and hybrid wings.

5.1 Feather Layers & Families

Wing feathers come in broad categories:

  • Primary flight feathers – long outer feathers controlling lift and thrust.
  • Secondary flight feathers – nearer the body, help with lift.
  • Coverts – shorter feathers covering the bases.

For design, you don’t need ornithology detail, but you should:

  • Define a primary fan – usually the outermost set.
  • Define a secondary fan – closer to the body.

These two fans give you large, graphic shapes.

5.2 Feather Fan Silhouettes

Play with primary fan shapes:

  • Straight, even fan → disciplined, engineered, orderly.
  • Curved, scimitar‑like fan → aggressive, slicing.
  • Ragged fan with varied lengths → wild, corrupted, weathered.

Angle and spread of the fans signal mood:

  • Closed fan – feathers stacked, low profile, stealth or rest.
  • Half spread – ready state, balanced, controlled.
  • Full spread – display, threat, launch.

Visually, think of feather fans as blades of light that can radiate or slice across the composition.

5.3 Feather Texture: Smooth vs Ruffled

Smooth feathers:

  • Implies grooming, discipline, or high status.

Ruffled feathers:

  • Implies agitation, damage, or wild nature.

Use feather condition to align with character arcs:

  • A fallen angel might have one wing smooth, the other ruffled or partially burned.

Production:

  • Fine feather detail is made in textures; rigging mostly controls overall fan shapes.

6. Wing Reads in Motion — Flap, Glide, Hover

Wing function becomes clear when you imagine how they move.

6.1 Flapping Fliers

Flap motion:

  • Large vertical arcs.
  • Leading edge slices air; membranes/feathers flex.

Design considerations:

  • Joints must allow upstroke and downstroke arcs.
  • Membranes shouldn’t collide with body every frame.

Read in silhouette:

  • Long, clear arcs read well in side or 3/4 view.

6.2 Gliders & Divers

Glide posture:

  • Wings locked in extended position.
  • Minimal active flap.

Design traits:

  • Larger span, thinner profiles.
  • Strong, simple bone layout to hold shape.

Silhouette:

  • Crisp, clean lines; ideal for high‑altitude shots and key art.

6.3 Hoverers & Flickers

Hover wing motion:

  • Rapid, small flaps; often wings blur.

Design cues:

  • Smaller wings, sometimes multiple sets.
  • May incorporate insect wing logic even on larger creatures.

Production:

  • With high flap frequency, wings may be partially faked with motion blur or FX.

7. Wings as Shields & Weapons

Wings are not just for movement.

7.1 Shield Wings

Shield behavior:

  • Creature wraps wings around body.
  • Leading edge or outer surfaces act as armor.

Design:

  • Reinforced bones/plates along leading edge.
  • Membranes with thicker, opaque sections.

In silhouette:

  • Creature becomes a more solid shape; wings close gaps and negative spaces.

Production:

  • Important for block animations; ensure wings can fully cover hitboxes without messy intersections.

7.2 Weapon Wings

Weaponized wings might have:

  • Spurs at joints.
  • Claws at tips.
  • Bladed edges along the span.

Strike reads:

  • Side swipes using the whole wing.
  • Downward slams with reinforced edges.

Concepting:

  • Design at least one hero striking pose per wing type.
  • Emphasize the path of the weaponized edge in the silhouette.

Production:

  • Rigs must support both flight poses and attack poses without contorting geometry unnaturally.

8. Concept vs Production: Constraints & Collaboration

8.1 Concept‑Side Considerations

As a concept artist:

  • Choose one main class per wing set (flight engine, shield, weapon, display).
  • Design wings to look good in at least three states: folded, half‑open, fully open.
  • Think about camera angles: will the wings be readable from top‑down, third‑person, or isometric views?

Ask:

  • Does this wing design support the character’s role in game?
  • Can I clearly see how bones and membranes/feathers deform between poses?

8.2 Production‑Side Considerations

Closer to production, refine designs by:

  • Simplifying bone counts and membrane anchor points.
  • Standardizing wing logic across faction families so rigs and animations can be reused.
  • Avoiding extreme shapes that always intersect other geometry.

Communicate with rigging and animation:

  • Provide callouts of bone analogs and fold directions.
  • Specify which poses are essential (idle, glide, fold, attack).

9. Practical Workflow for Designing Wings & Membranes

Step 1 – Define Wing Class & Function

Write a one‑line brief:

“Massive dragon‑bat arm‑wings used for short‑burst flight and heavy shield blocks.”

From that brief, pick:

  • Integration type (arm‑wing, shoulder‑wing, plate wing).
  • Primary function (flight, glide, shield, display, weapon).

Step 2 – Block in Bone Structure & Span

Rough in:

  • Shoulder placement.
  • Upper arm, forearm, and main wing digits or plates.
  • Overall span relative to body.

Check that:

  • Span feels appropriate to the role.
  • Bones align in a way that allows folded and extended poses comfortably.

Step 3 – Add Membrane or Feather Fans

Design:

  • Membrane attachment lines.
  • Primary and secondary feather fans.

Ensure that:

  • Membranes have clear tension directions.
  • Feather fans create bold, readable outer edges.

Step 4 – Draw Key Poses

At minimum, sketch:

  • Folded wings (rest/idle).
  • Half‑open (ready/glide/guard).
  • Fully open (takeoff, display, or roar).

Silhouette test each pose:

  • Fill in black, shrink down, and check readability.

Step 5 – Add Condition & Story

Decide if wings are:

  • Pristine vs scarred vs tattered.
  • Natural vs cybernetic vs magical.

Add a few story marks: scars, missing feathers, stitched membranes, faction symbols.

Step 6 – Annotate for Production Handoff

On a final sheet:

  • Label bone analogs and joints.
  • Show fold directions with arrows.
  • Indicate which surfaces are weapon edges or shield faces.

This turns your wing design into a usable blueprint for 3D and animation.

10. Exercises for Creature Concept Artists

Exercise 1 – Three Wing Classes on One Body

Take a single base creature body and design three wing variants:

  1. True flight wings.
  2. Glide/display wings.
  3. Shield/weapon wings.

Keep attachment points the same; change bone structure, span, and membrane/feather treatments. Compare how the role read changes.

Exercise 2 – Membrane Fold Sheet

Design a bat/dragon‑style wing and create a sheet showing:

  • Fully extended.
  • Half‑folded.
  • Fully folded.

Mark fold lines, tension directions, and any scars or tatters.

Exercise 3 – Feather Fan Language

Explore a page of primary feather fans:

  • Straight, curved, ragged, asymmetric.

Under each, note what it implies: elegance, aggression, corruption, etc. Use these fans as swappable “wing tips” in multiple creature designs.

11. Closing Thoughts

Wings and membranes are among the most expressive appendages in creature design. They frame the body, control huge chunks of silhouette, and instantly communicate function and status.

As a concept‑side creature artist, treating wings as appendage classes with clear functions helps you:

  • Design silhouettes that tell players what a creature can do.
  • Build coherent wing logic across species and factions.
  • Create dramatic, memorable moments in key art and exploration pages.

As a production‑side concept artist, clear thinking about span, bones, folds and feather fans helps you:

  • Deliver designs that rigs and animations can actually support.
  • Reduce rework from impossible fold patterns or overcomplicated membranes.
  • Provide strong, reusable patterns for entire families of winged creatures.

Next time you add wings to a design, ask:

  • What class of appendage is this wing—engine, glider, shield, weapon, or display?
  • Does the span and bone logic support that role?
  • How do membranes or feather fans read in folded, half‑open, and fully open states?

If your answers are clear and your silhouettes hold up from thumbnail to close‑up, your wings won’t just look cool—they’ll feel like believable, game‑ready appendages integrated into the creature’s movement and combat systems.