{
 "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": "side-skirts",
 "name": "Side skirts (ground-effect sealing)",
 "kind": "standard",
 "category": "Car design",
 "group": "Car aero",
 "year": null,
 "question": "What do side skirts do on a ground-effect race car?",
 "tags": [
  "vehicle design",
  "car aero",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "side skirts",
  "sliding skirts",
  "ground effect skirts",
  "skirt seal",
  "rocker panel skirts",
  "side skirt aero",
  "lotus 78 skirts",
  "venturi skirts",
  "underbody seal",
  "rc side skirts"
 ],
 "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/side-skirts/",
 "sheet_txt": "https://xemstudio.com/objects/side-skirts/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": [
   "Side skirts seal the gap between the car's sides and the road so that low pressure built under the floor is not destroyed by air leaking in from the sides (Wikipedia, Ground effect (cars)).",
   "Lotus sealed inverted-aerofoil sidepods to the ground with flexible skirts on the Lotus 78 (1977) and 79 (1978); the advantage was so large that sliding skirts and then ground-effect floors were banned, with flat bottoms mandatory from 1983.",
   "Used on: Lotus 78, Lotus 79, Chaparral 2J.",
   "The file is a reference example built by Xem Studio from the numbers above (Dimensions illustrative; no skirt-gap figure in source.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle."
  ],
  "table": {
   "columns": [
    "parameter",
    "value or range",
    "source"
   ],
   "rows": [
    [
     "Lotus 78 season",
     "1977, five wins",
     "Wikipedia"
    ],
    [
     "Lotus 79",
     "1978, six wins and the drivers' title",
     "Wikipedia"
    ],
    [
     "Chaparral 2J (fans + skirts)",
     "end of 1970; led to movable-aero ban",
     "Wikipedia"
    ],
    [
     "Flat-bottom rule",
     "mandatory from 1983",
     "Wikipedia"
    ],
    [
     "Ground effect returns to F1",
     "2022",
     "Wikipedia"
    ]
   ]
  }
 },
 "sheet_text": "Side skirts (ground-effect sealing) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/side-skirts/  (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- Side skirts seal the gap between the car's sides and the road so that low pressure built under the floor is not destroyed by air leaking in from the sides (Wikipedia, Ground effect (cars)).\n- Lotus sealed inverted-aerofoil sidepods to the ground with flexible skirts on the Lotus 78 (1977) and 79 (1978); the advantage was so large that sliding skirts and then ground-effect floors were banned, with flat bottoms mandatory from 1983.\n- Used on: Lotus 78, Lotus 79, Chaparral 2J.\n- The file is a reference example built by Xem Studio from the numbers above (Dimensions illustrative; no skirt-gap figure in source.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.\n\nparameter  value or range  source\nLotus 78 season  1977, five wins  Wikipedia\nLotus 79  1978, six wins and the drivers' title  Wikipedia\nChaparral 2J (fans + skirts)  end of 1970; led to movable-aero ban  Wikipedia\nFlat-bottom rule  mandatory from 1983  Wikipedia\nGround effect returns to F1  2022  Wikipedia\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Ground effect (cars) — web — Publisher's page; dimensions are facts — https://en.wikipedia.org/wiki/Ground_effect_(cars)\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/side-skirts/index.json\nAPI: https://xemstudio.com/api/geometry?object=side-skirts\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Ground effect (cars)",
   "url": "https://en.wikipedia.org/wiki/Ground_effect_(cars)",
   "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": [
  "rear-wing-single-element",
  "rear-wing-dual-element",
  "swan-neck-wing-mount",
  "gurney-flap-wickerbill",
  "wing-endplates",
  "front-splitter"
 ],
 "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": "Are road-car side skirts the same?",
   "a": "Styling skirts follow the shape but rarely seal to the ground; the race-car function described here relies on a minimal gap to the road (Wikipedia)."
  }
 ],
 "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": "side-skirts-side-skirt",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/side-skirts/side-skirts-side-skirt.step",
   "stl": "https://xemstudio.com/files/hardware/side-skirts/side-skirts-side-skirt.stl",
   "note": "Side skirt 2000 mm long with a horizontal flange (illustrative section)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/side-skirts/index.md"
}