{
 "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": "polyhedral-wing",
 "name": "Polyhedral wing",
 "kind": "standard",
 "category": "Aircraft design",
 "group": "Wing planforms",
 "year": null,
 "question": "What is polyhedral and why do RC gliders use it?",
 "tags": [
  "vehicle design",
  "wing planforms",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "polyhedral wing",
  "polyhedral dihedral",
  "polyhedral rc glider",
  "polyhedral vs dihedral",
  "rudder elevator glider wing",
  "equivalent dihedral",
  "polyhedral angle",
  "tip dihedral",
  "three piece wing dihedral"
 ],
 "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/polyhedral-wing/",
 "sheet_txt": "https://xemstudio.com/objects/polyhedral-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": [
   "Polyhedral breaks the dihedral at more than one point, with tip panels steeper than the inner panels; McCombs calls it common on duration models.",
   "Because outer panels are farther out, they count more: McCombs combines breaks as an equivalent V-dihedral EVD = A + k*B, and Wainfan notes tip changes affect lateral stability more than root changes (Kitplanes).",
   "Rudder-only RC models need roughly 9 deg total effective dihedral to turn with rudder and recover (McCombs).",
   "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": [
    [
     "EVD formula",
     "EVD = A + k*B (+ k*C ...)",
     "McCombs, Model Aviation 1994"
    ],
    [
     "Worked example",
     "A = 6 deg, B = 20 deg -> EVD 15.0 deg",
     "McCombs 1994"
    ],
    [
     "Rudder-only RC total effective dihedral",
     "about 9 deg",
     "McCombs 1994"
    ],
    [
     "Hand-launched glider EVD",
     "12-17 deg",
     "McCombs 1994"
    ],
    [
     "Nordic towline glider EVD",
     "9-12 deg",
     "McCombs 1994"
    ],
    [
     "Reference build",
     "span 1500, inner 6 deg (tips steeper)",
     "McCombs example"
    ]
   ]
  }
 },
 "sheet_text": "Polyhedral wing — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/polyhedral-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- Polyhedral breaks the dihedral at more than one point, with tip panels steeper than the inner panels; McCombs calls it common on duration models.\n- Because outer panels are farther out, they count more: McCombs combines breaks as an equivalent V-dihedral EVD = A + k*B, and Wainfan notes tip changes affect lateral stability more than root changes (Kitplanes).\n- Rudder-only RC models need roughly 9 deg total effective dihedral to turn with rudder and recover (McCombs).\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\nEVD formula  EVD = A + k*B (+ k*C ...)  McCombs, Model Aviation 1994\nWorked example  A = 6 deg, B = 20 deg -> EVD 15.0 deg  McCombs 1994\nRudder-only RC total effective dihedral  about 9 deg  McCombs 1994\nHand-launched glider EVD  12-17 deg  McCombs 1994\nNordic towline glider EVD  9-12 deg  McCombs 1994\nReference build  span 1500, inner 6 deg (tips steeper)  McCombs example\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Model Aviation (AMA), W.F. McCombs: Wing and Tail Dihedral for Models (Dec 1994) — web — Publisher's page; dimensions are facts — https://library.modelaviation.com/article/wing-and-tail-dihedral-models\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/polyhedral-wing/index.json\nAPI: https://xemstudio.com/api/geometry?object=polyhedral-wing\n",
 "sources": [
  {
   "publisher": "Model Aviation (AMA), W.F. McCombs",
   "title": "Wing and Tail Dihedral for Models (Dec 1994)",
   "url": "https://library.modelaviation.com/article/wing-and-tail-dihedral-models",
   "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": "How much polyhedral for a rudder-only glider?",
   "a": "Aim for about 9 deg total effective dihedral (McCombs); hand-launched gliders use 12-17 deg EVD."
  }
 ],
 "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": "polyhedral-wing-wing",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/polyhedral-wing/polyhedral-wing-wing.step",
   "stl": "https://xemstudio.com/files/hardware/polyhedral-wing/polyhedral-wing-wing.stl",
   "note": "polyhedral planform: span 1500, root 180, tip 120 mm, LE sweep 0°, dihedral 6°, NACA 2412"
  }
 ],
 "markdown": "https://xemstudio.com/objects/polyhedral-wing/index.md"
}