– Reference Table
Version 0.1 – Working Draft
This reference table provides cross-linked helmet design terminology, organized to show relationships between terms and concepts.
Category Key:
- AE: Aerodynamic Elements
- DE: Design Elements
- DP: Design Process
- SE: Structural Elements
- TE: Technical Elements
- TS: Testing & Standards
| Term | Definition | Category | See Also |
|---|---|---|---|
| Airdam | A foil or aerodynamic device. | AE | Spoiler, Windsplit, Flow chines |
| Arc bones | Primary raised lines that radiate longitudinally across the shell surface, providing structural reinforcement while defining major design elements. | SE | Bone line, Arc streaks, Structural lines |
| Arc streaks | Subtle surface lines that follow the helmet’s curvature, primarily decorative but suggesting motion and flow. | DE | Arc bones, Speed streaks, Flow chines |
| Attitude | When a helmet has a noticeable demeanor and is said to be aggressive, playful, intimidating, etc. Can also describe the helmet’s overall relationship to wearer. | DE | Gesture, EyeMood, Noble, Profile Line |
| Axes | In locating points on a helmet body, designers use conventional 3-axis reference lines. X (front to back), Y (side to side), Z (top to bottom). Key reference points include nose bridge, ear openings, and occipital base. | TE | Zero line, Zero point, Package |
| Backlights/Exhaust Vents | Rear ventilation openings designed for air outflow. | AE | Vent, Ventilation Matrix, Vent slices |
| Badge engineering | The practice of applying different nameplates to helmets with identical or very similar shells. ODM. | DP | Facelift, One-off, Platform |
| Bakeoff | A showdown between design proposals, usually held in the form of a show with clay models from rival studios or designers. | DP | Mockup, Prototype, Theme |
| Blocking | Preliminary arrangement of major design elements and proportions. | DP | Theme, Line drawing, Proveout model |
| Bone line | A hard, raised longitudinal peak in a shell. Usually along the side of a helmet shell more massive than a character line. | DE | Arc bones, Character line, Peak |
| Bowl | A partial or full surface, affixed to the underside of a helmet EPS, forming the interior base structure. | SE | Shell, Onion, Headliner |
| Brow | A raised or protruding area above or around an arch, like a headvent or an ear cove. | SE | Forehead Vent, Earcove, Profile Line |
| Bugback | A rear of a helmet that curves downward without interruption, like a VW Beetle. Typical skateboard helmet, rounded back. | DE | Fastback, Notchback, Quarter panel |
| Burntab | The descending tab of the helmet in front of the earcove. Sideburns. The hard point mounting location for the helmet straps. | SE | Quarter tab, Hard points, Retention System |
| Buttresses | Cross-supporting structural elements bridging between remaining shell sections around vent slices, preventing material spread during impact and maintaining shell integrity. | SE | Pillar, Impact Zone, Ventilation Matrix |
| Centerline | A hypothetical line drawn longitudinally through the center of a developing helmet body, also known as the X axis. | TE | Axes, Zero line, Profile Line |
| Chamfer | The juncture of two angled or beveled flat surfaces. | DE | Fillet, Spline, Coved |
| Character line | A raised or indented, creased or peaked line on a smooth surface that adds stronger-than-normal interest to the helmet’s aesthetics. | DE | Bone line, Crease battans, Arc streaks |
| Cheat | To exaggerate a design feature in a sketch or model in order to improve the helmet’s appearance or proportions. | DP | Sweeten, Mockup, Rendering |
| Coved | Recessed, protected zone, like ear cove. | DE | Fillet, Chamfer, Spline |
| Crease battans | Flexible design lines that help define transitional surfaces between major helmet sections. | DE | Character line, Spline, Arc streaks |
| Crown | A domed area. Also a subtle rise or convexity in a surface to make it look straight or flat instead of sunken. | DE | Dome, Overcrown, Tumblehome |
| Cutline | The line around an openable body panel. | TE | Section, Template, Hard points |
| Dash | The lines defined by the various testing standards that define where structural parts of the helmet should lie. | TS | Testing Lines, Zero line, Platform |
| Daylight opening (DLO) | The perimeter of any helmet window. | DE | Goggle Window, Sightlines, Profile Line |
| Deck | The upper surface of the rear of the helmet. | SE | Bugback, Fastback, Quarter panel |
| Dome | The upper portion of the helmet shell that forms the primary protective structure over the crown of the head. | SE | Crown, Shell, Impact Zone |
| Earcove | Curved arch opening in half shell helmet for ears. | SE | Brow, Burntab, Quarter panel |
| Elevation | As seen in front, rear or side views. A side elevation, for example, is a side view. | TE | Plan view, Section, Profile Line |
| Envelope body | A helmet body whose sides have no visual or actual side-surface interruptions or breaks. | DE | Organic, Muscular, Tension |
| EyeMood | In the analogy of the two front vents to the eyes on a face, the shape and the character of the vents conveyed. | DE | Attitude, Gesture, Noble |
| Facelift | Design changes that make a familiar style or ornament look fresh and different. | DP | Badge engineering, One-off, Theme |
| Fast | A word used to describe the angle or tilt of a windshield or backlight. The “faster” the angle, the more nearly horizontal it is. | DE | Rake, Fastback, Profile Line |
| Fastback | A body shape in which the roof slopes downward at the rear and blends into the deck with no notch or visual break. | DE | Bugback, Notchback, Deck |
| Fillet | A concave, transitional surface that fills, mates or blends two intersecting surfaces. Similar to Chamfer but rounded. | DE | Chamfer, Spline, Organic |
| Flow chines | Sharp-edged longitudinal lines that cut through the surface geometry, typically serving both aerodynamic and aesthetic purposes. | AE | Windsplit, Arc bones, Speed streaks |
| Forehead Vent | Primary front-facing ventilation intake, typically positioned above the brow line. | AE | Vent, Ventilation Matrix, EyeMood |
| Gesture | When a helmet has implied motion in its styling lines and shapes. | DE | Attitude, EyeMood, Rifling |
| Goggle Window | The shape under the brim of a helmet that matches the shape of the goggle. | DE | Daylight opening, Sightlines, Profile Line |
| Hard points | Specific locations of points that have to be adhered to when designing surfaces, including chin strap mounts. | TE | Burntab, Quarter tab, Testing Lines |
| Headliner/headlining | The inner trim lining of a helmet. | SE | Bowl, Onion, Stack Height |
| Helmond | A raw shape that a helmet would be cut from, a word that combines helmet and almond. | DP | Mockup, Prototype, Platform |
| Highlight | Light that bounces noticeably off a peak or line or convex surface. | DE | Peak, Crown, Character line |
| Impact Zone | Specifically designed areas of the helmet that are engineered to absorb and distribute crash forces. | SE | Buttresses, Shell, Testing Lines |
| Line drawing | An outline sketch without shading or color. | DP | Blocking, Rendering, Tape drawing |
| Lip molding | Ornamental bright trim that outlines and visually reinforces a helmet perimeter cut. | DE | Chamfer, Fillet, Character line |
| Louver | A slit or narrow opening to let air, light or water in or out. | AE | Vent, Scoop, Vent slices |
| Mockup | A representation, usually of the final shape of a styled or engineered body. Can be made of wood, fiberglass, metal or any combination. | DP | Prototype, Bakeoff, Helmond |
| Monocoque | A type of body construction in which the skins are stressed to form part of the supporting structure. | SE | Shell, Impact Zone, Platform |
| Mule | A prototype helmet, usually built with new cosmetics over an existing foam and headform basis. | DP | Prototype, One-off, Helmond |
| Muscular | When a design mimics human and animal forms. The designs surfaces are handled in a way that has muscle-like definition. | DE | Organic, Envelope body, Tension |
| Noble | When a helmet overall aesthetic and proportions commands attention, suggest financial success and social distinction. | DE | Attitude, Gesture, Profile Line |
| Notchback | A helmet style in which a relatively upright backlight joins a more horizontal rear deck, the join forming a notch. | DE | Bugback, Fastback, Deck |
| Occipital Coverage | The extent and shape of protection provided to the lower rear of the skull. | SE | Impact Zone, Shell, Testing Lines |
| One-off | A one-of-a-kind helmet, body style or body type. | DP | Facelift, Mule, Prototype |
| Onion | Describing the layers of surfaces that are cut into and revealed for aesthetics. Also the stack of surfaces on the interior of a helmet that describe headform, padding, foam protection surfaces, etc. | SE | Bowl, Headliner, Stack Height |
| Organic | When surfaces are made to blend together seamlessly. Forms that appear to have grown biologically. | DE | Muscular, Envelope body, Fillet |
| Overcrown | To raise above the surrounding crowned surface. | DE | Crown, Dome, Highlight |
| Overhang | The amount of helmet shell structure, as seen in side view ahead of the forehead and behind the earcove centerline. | SE | Brow, Earcove, Profile Line |
| Package (the) | A drawing or series of specifications that tell where a helmet’s “hard points” must be. | TE | Hard points, Platform, Testing Lines |
| Peak | A sharp ridge stamped into a body surface, usually directed upward. | DE | Highlight, Bone line, Character line |
| Pillar | An upright/latitudinal bridge between two ribs or body sections. | SE | Buttresses, Impact Zone, Arc bones |
| Plan view | As seen from the top. | TE | Elevation, Section, Working drawings |
| Platform | The engineering basis for a helmet, including head form specifications, testing standard requirements, foam density requirements, and molding technology constraints. | TE | Package, Hard points, Testing Lines |
| Profile Line | The characteristic side view outline that defines the helmet’s primary shape and attitude. | DE | Gesture, Attitude, Elevation |
| Prototype | A realistic, full sized three dimensional representation of an entire helmet, usually made of CNC foam, abs or a combination. | DP | Mockup, Mule, Proveout model |
| Proveout model | A model made to confirm that a drawing or numerical model appears as expected. | DP | Prototype, Mockup, Working drawings |
| Quarter panel | That part of a helmet bodyside comprising the rear panel from the earcove opening backwards. | SE | Deck, Bugback, Earcove |
| Quarter tab | Hard point for mounting the chin straps, the corner behind the ear cove, also called dogknee. | SE | Burntab, Hard points, Retention System |
| Rake | Angle of “attack” at front of helmet, the steeper the angle the more “rake”. | DE | Fast, Profile Line, Attitude |
| Raw Shell | The finished but unmounted and unpainted shell, ready for graphics and final assembly. | SE | Shell, Monocoque, Platform |
| Rendering | A drawing or illustration that includes shading and detail. | DP | Line drawing, Mockup, Tape drawing |
| Retention System | The complete system of straps, adjusters, and buckles that secure the helmet to the head. | SE | Hard points, Quarter tab, Testing Lines |
| Rifling | Spiral or wrapped surface patterns that flow around the helmet shell, typically serving aesthetic purposes. | DE | Speed streaks, Flow chines, Gesture |
| Scoop | An open-fronted area of the body designed to let in air. | AE | Louver, Vent, Ventilation Matrix |
| Section | Representation of a body or part of a body as if it were cut and viewed at 90 degrees. | TE | Plan view, Elevation, Template |
| Shell | The outer protective layer of the helmet, typically made of composite materials or high-grade plastics. | SE | Monocoque, Raw Shell, Impact Zone |
| Sightlines | Theoretical lines from the wearer’s eyes to objects inside the helmet and also beyond or outside the helmet. | TE | Goggle Window, Daylight opening, Profile Line |
| Speed streaks | Surface patterns that represent trails of water swept back by the rush of wind at speed. | DE | Arc streaks, Rifling, Flow chines |
| Spline | A gently curved or arched surface. Also refers to a long metal or wooden strip used to form a curve or arch. | DE | Fillet, Chamfer, Organic |
| Spoiler | An upward lift of the surfaces at the rear of a helmet, simulating aerodynamic downward force. | AE | Airdam, Windsplit, Flow chines |
| Stack Height | The measured distance from the wearer’s head to the outer surface of the shell. | SE | Shell, Onion, Platform |
| Sweeten | In design, to smooth and improve the aesthetic flow of a surface or line. | DP | Cheat, Rendering, Character line |
| Tape drawing | Full-sized “drawings” of side and end helmet-body elevations made with long, thin strips of flexible adhesive tape. | DP | Line drawing, Mockup, Working drawings |
| Template | A hard, cut-out representation of a body surface at a certain section. | DP | Cutline, Section, Working drawings |
| Tension | A purposefully imperfect design feature. A conflicting set of themes combined to generate interest and controversy. | DE | Gesture, Attitude, Muscular |
| Testing Lines | Defined boundaries established by safety certification standards that determine minimum coverage areas and impact protection zones. | TS | Dash, Zero line, Impact Zone |
| Theme | A loose design idea, usually in sketch or model form, that captures the essence of a project goal. | DP | Blocking, Bakeoff, Package |
| Tumblehome | The inward tilt or angle of the roof from the beltline up as seen in front or rear view. | DE | Turn-under, Organic, Profile Line |
| Turn-under | The inward curvature of a helmet body below roughly beltline as seen in front or rear view. | DE | Tumblehome, Organic, Profile Line |
| Vent | An opening for air passage. | AE | Louver, Scoop, Vent slices |
| Vent slices | Wedge-shaped voids cut through the shell and liner for ventilation, typically angled for aerodynamic efficiency and water management. | SE | Vent, Ventilation Matrix, Buttresses |
| Ventilation Matrix | The planned arrangement of intake and exhaust vents designed to optimize airflow through the helmet. | AE | Vent, Backlights, Vent slices |
| Windsplit | A raised crease that runs longitudinally along a body surface. A windsplit is lower than a fin. | AE | Flow chines, Airdam, Arc bones |
| Working drawings | The mechanical drawings used to complete the body engineering drafts. | DP | Template, Section, Package |
| Zero line (horizontal) | A locating line at the bottom of the testing lines as seen in side view. Also called “datum line.” | TE | Axes, Zero point, Testing Lines |
| Zero line (vertical) | A locating line at the center of the midpoint point of the headform or established at the front of the helmet. | TE | Axes, Zero point, Centerline |
| Zero point | A point that serves to locate all other parts and surfaces of the body. The zero point is often at the very center of the front of the helmet. | TE | Axes, Zero line, Platform |