{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "gull-wing",
 "name": "Gull wing",
 "kind": "standard",
 "category": "Aircraft design",
 "group": "Wing planforms",
 "year": null,
 "question": "What is a gull wing and why was it used?",
 "tags": [
  "vehicle design",
  "wing planforms",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "gull wing",
  "gull wing aircraft",
  "gull wing seaplane",
  "gull wing rc plane",
  "gull wing glider",
  "pbm mariner wing",
  "bent wing aircraft",
  "gull wing dihedral",
  "gull wing flying boat"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/gull-wing/",
 "sheet_txt": "https://xemstudio.com/objects/gull-wing/sheet.txt",
 "sheet": {
  "basis": "Design rules and figures from the cited sources; example geometry by Xem Studio",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A gull wing rises steeply from the root, then flattens outboard. On the PBM Mariner flying boat the gull wing 'kept the vulnerable engines out of the salt spray' and avoided the external bracing a parasol wing like the Catalina's needed (Smithsonian NASM).",
   "Wainfan notes changes at the wingtips matter more for lateral stability than changes near the root, and part-span dihedral needs slightly more outer-panel dihedral to match a constant-dihedral wing (Kitplanes).",
   "Used on: Martin PBM Mariner.",
   "The file is a reference example built by Xem Studio from the numbers above. Sizes the sources do not fix are illustrative; scale the example to your own vehicle."
  ],
  "table": {
   "columns": [
    "parameter",
    "value or range",
    "source"
   ],
   "rows": [
    [
     "PBM Mariner wing",
     "gull wing on deep hull; engines above spray",
     "Smithsonian NASM"
    ],
    [
     "Part-span dihedral rule",
     "outer panels need slightly more dihedral",
     "Kitplanes (Wainfan)"
    ],
    [
     "Reference build angles",
     "illustrative (no published angle fetched)",
     "illustrative"
    ]
   ]
  }
 },
 "sheet_text": "Gull wing — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/gull-wing/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Design rules and figures from the cited sources; example geometry by Xem Studio\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A gull wing rises steeply from the root, then flattens outboard. On the PBM Mariner flying boat the gull wing 'kept the vulnerable engines out of the salt spray' and avoided the external bracing a parasol wing like the Catalina's needed (Smithsonian NASM).\n- Wainfan notes changes at the wingtips matter more for lateral stability than changes near the root, and part-span dihedral needs slightly more outer-panel dihedral to match a constant-dihedral wing (Kitplanes).\n- Used on: Martin PBM Mariner.\n- The file is a reference example built by Xem Studio from the numbers above. Sizes the sources do not fix are illustrative; scale the example to your own vehicle.\n\nparameter  value or range  source\nPBM Mariner wing  gull wing on deep hull; engines above spray  Smithsonian NASM\nPart-span dihedral rule  outer panels need slightly more dihedral  Kitplanes (Wainfan)\nReference build angles  illustrative (no published angle fetched)  illustrative\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Smithsonian National Air and Space Museum: Martin PBM-5A Mariner — web — Publisher's page; dimensions are facts — https://si.edu/object/martin-pbm-5a-mariner:nasm_A19730270000\n- Kitplanes (B. Wainfan): Wind Tunnel: Roll's role in lateral stability (2008) — web — Publisher's page; dimensions are facts — https://www.kitplanes.com/wind-tunnel-135/\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/gull-wing/index.json\nAPI: https://xemstudio.com/api/geometry?object=gull-wing\n",
 "sources": [
  {
   "publisher": "Smithsonian National Air and Space Museum",
   "title": "Martin PBM-5A Mariner",
   "url": "https://si.edu/object/martin-pbm-5a-mariner:nasm_A19730270000",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Kitplanes (B. Wainfan)",
   "title": "Wind Tunnel: Roll's role in lateral stability (2008)",
   "url": "https://www.kitplanes.com/wind-tunnel-135/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "rectangular-wing",
  "tapered-wing",
  "elliptical-wing",
  "swept-wing",
  "forward-swept-wing",
  "delta-wing"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [],
 "faq": [
  {
   "q": "Why did flying boats use gull wings?",
   "a": "To raise engines above the spray without parasol bracing (Smithsonian NASM, PBM Mariner)."
  }
 ],
 "files_license": {
  "name": "Xem Studio Design License",
  "holder": "Xem Studio",
  "url": "https://xemstudio.com/license/",
  "note": "Xem Studio's own design: free to use, print, modify and sell things made from it; not to be republished or redistributed as files."
 },
 "offers": [
  {
   "file": "gull-wing-wing",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/gull-wing/gull-wing-wing.step",
   "stl": "https://xemstudio.com/files/hardware/gull-wing/gull-wing-wing.stl",
   "note": "gull planform: span 1000, root 200, tip 120 mm, LE sweep 0°, dihedral 5°, NACA 2412"
  }
 ],
 "markdown": "https://xemstudio.com/objects/gull-wing/index.md"
}