{
 "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": "wig-hull-steps-hydrofoils",
 "name": "WIG hulls: steps, hydrofoils and hydroskis",
 "kind": "standard",
 "category": "Aircraft design",
 "group": "Ground-effect design",
 "year": null,
 "question": "How do WIG craft get off the water?",
 "tags": [
  "vehicle design",
  "ground-effect design",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "wig hull",
  "ekranoplan hull step",
  "wig hydrofoil",
  "hydroski",
  "wig takeoff from water",
  "ground effect boat hull",
  "stepped hull wig",
  "rc ekranoplan hull",
  "wig sponsons"
 ],
 "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/wig-hull-steps-hydrofoils/",
 "sheet_txt": "https://xemstudio.com/objects/wig-hull-steps-hydrofoils/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": [
   "WIG craft must break free of water drag before flying. Designs used hull steps (m-Sky 2), front and stern hydrofoils to soften water landing (Lippisch X-114), bow hydroskis for pitch stability (Lockheed 1963) and aft ski structures to trim take-off and landing (Douglas DAW-S) (Rozhdestvensky).",
   "Weiland proposed hydroskis as an alternative to power augmentation, and the Hoverwing HW20 used a static air cushion with retractable skirts only for take-off (Rozhdestvensky). KM operated in waves up to 3 m at take-off (Rozhdestvensky).",
   "Used on: Lippisch X-114, m-Sky 2, Douglas DAW-S, Hoverwing HW20.",
   "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": [
    [
     "Lippisch X-114",
     "two front hydrofoils + one stern",
     "Rozhdestvensky 2006"
    ],
    [
     "Lockheed wingship study",
     "V-shaped landing hydrofoil, 4.64 m span",
     "Rozhdestvensky 2006"
    ],
    [
     "m-Sky 2",
     "step on centre-body bottom",
     "Rozhdestvensky 2006"
    ],
    [
     "KM take-off wave height",
     "up to 3 m",
     "Rozhdestvensky 2006"
    ],
    [
     "Hoverwing HW20",
     "static cushion, retractable skirts for take-off",
     "Rozhdestvensky 2006"
    ]
   ]
  }
 },
 "sheet_text": "WIG hulls: steps, hydrofoils and hydroskis — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/wig-hull-steps-hydrofoils/  (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- WIG craft must break free of water drag before flying. Designs used hull steps (m-Sky 2), front and stern hydrofoils to soften water landing (Lippisch X-114), bow hydroskis for pitch stability (Lockheed 1963) and aft ski structures to trim take-off and landing (Douglas DAW-S) (Rozhdestvensky).\n- Weiland proposed hydroskis as an alternative to power augmentation, and the Hoverwing HW20 used a static air cushion with retractable skirts only for take-off (Rozhdestvensky). KM operated in waves up to 3 m at take-off (Rozhdestvensky).\n- Used on: Lippisch X-114, m-Sky 2, Douglas DAW-S, Hoverwing HW20.\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\nLippisch X-114  two front hydrofoils + one stern  Rozhdestvensky 2006\nLockheed wingship study  V-shaped landing hydrofoil, 4.64 m span  Rozhdestvensky 2006\nm-Sky 2  step on centre-body bottom  Rozhdestvensky 2006\nKM take-off wave height  up to 3 m  Rozhdestvensky 2006\nHoverwing HW20  static cushion, retractable skirts for take-off  Rozhdestvensky 2006\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Progress in Aerospace Sciences (K.V. Rozhdestvensky, 2006): Wing-in-ground effect vehicles (review) — web — Publisher's page; dimensions are facts — https://www.hassanhameed.com/wp-content/uploads/2016/01/wingingroundeffectvehicles-130120003005-phpapp01.pdf\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/wig-hull-steps-hydrofoils/index.json\nAPI: https://xemstudio.com/api/geometry?object=wig-hull-steps-hydrofoils\n",
 "sources": [
  {
   "publisher": "Progress in Aerospace Sciences (K.V. Rozhdestvensky, 2006)",
   "title": "Wing-in-ground effect vehicles (review)",
   "url": "https://www.hassanhameed.com/wp-content/uploads/2016/01/wingingroundeffectvehicles-130120003005-phpapp01.pdf",
   "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": [
  "ground-effect-height-span-ratio",
  "ground-effect-height-chord-ratio",
  "lippisch-reverse-delta-wig",
  "ekranoplan-wing-tail-layout",
  "tandem-wig-configuration",
  "power-augmented-ram-par"
 ],
 "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": "What hull helps a WIG model unstick?",
   "a": "A stepped hull or hydrofoils/hydroskis, all used on full-size craft (Rozhdestvensky)."
  }
 ],
 "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": "wig-hull-steps-hydrofoils-hull",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/wig-hull-steps-hydrofoils/wig-hull-steps-hydrofoils-hull.step",
   "stl": "https://xemstudio.com/files/hardware/wig-hull-steps-hydrofoils/wig-hull-steps-hydrofoils-hull.stl",
   "note": "stepped hull, 600 × 150 mm, deadrise 20°, 1 steps (sections illustrative, scale to your boat)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/wig-hull-steps-hydrofoils/index.md"
}