{
 "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": "wing-endplates",
 "name": "Wing endplates / side dams",
 "kind": "standard",
 "category": "Car design",
 "group": "Car aero",
 "year": null,
 "question": "What do endplates on a car wing do?",
 "tags": [
  "vehicle design",
  "car aero",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "wing endplates",
  "end plates",
  "side dams",
  "wing side plates",
  "endplate size",
  "rc wing side dams",
  "wing tip vortex plate",
  "endplate design",
  "car wing end plate",
  "spoiler side plates"
 ],
 "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/wing-endplates/",
 "sheet_txt": "https://xemstudio.com/objects/wing-endplates/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": [
   "Endplates limit air spilling around the wing tips from the high-pressure side to the low-pressure side, which raises downforce and efficiency (HPA).",
   "UIUC tests found a larger endplate raised CL by about 0.096 at constant angle and cut drag 13.7% at constant CL (Jasinski & Selig).",
   "HPA's ballpark for home-built plates is to extend twice as far below the wing as above it. RC classes cap side-dam size in their rules, e.g. 40 x 20 mm on 1/10 touring cars (AARCMCC) and 80 x 80 mm on 1/10 off-road buggies (EFRA).",
   "Used on: Champ Car endplate (UIUC test).",
   "The file is a reference example built by Xem Studio from the numbers above (1/10 touring-car limits: 190 mm width, 40 mm chord, 20 mm side dam.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle."
  ],
  "table": {
   "columns": [
    "parameter",
    "value or range",
    "source"
   ],
   "rows": [
    [
     "Endplate proportion (rule of thumb)",
     "2x as far below as above, e.g. 100 mm above, 200 mm below",
     "HPA rear wing"
    ],
    [
     "Larger endplate effect",
     "+0.0958 CL at constant alpha; -13.7% CD at constant CL",
     "Jasinski & Selig (UIUC)"
    ],
    [
     "1/10 touring car side dam",
     "max 40 mm wide x 20 mm high",
     "AARCMCC"
    ],
    [
     "1/10 track car endplates",
     "25 mm above body x 100 mm deep",
     "AARCMCC"
    ],
    [
     "1/10 off-road side dam",
     "must fit an 80 x 80 mm rectangle",
     "EFRA"
    ],
    [
     "1/12 pan car side dam",
     "max 72 mm high",
     "EFRA"
    ]
   ]
  }
 },
 "sheet_text": "Wing endplates / side dams — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/wing-endplates/  (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- Endplates limit air spilling around the wing tips from the high-pressure side to the low-pressure side, which raises downforce and efficiency (HPA).\n- UIUC tests found a larger endplate raised CL by about 0.096 at constant angle and cut drag 13.7% at constant CL (Jasinski & Selig).\n- HPA's ballpark for home-built plates is to extend twice as far below the wing as above it. RC classes cap side-dam size in their rules, e.g. 40 x 20 mm on 1/10 touring cars (AARCMCC) and 80 x 80 mm on 1/10 off-road buggies (EFRA).\n- Used on: Champ Car endplate (UIUC test).\n- The file is a reference example built by Xem Studio from the numbers above (1/10 touring-car limits: 190 mm width, 40 mm chord, 20 mm side dam.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.\n\nparameter  value or range  source\nEndplate proportion (rule of thumb)  2x as far below as above, e.g. 100 mm above, 200 mm below  HPA rear wing\nLarger endplate effect  +0.0958 CL at constant alpha; -13.7% CD at constant CL  Jasinski & Selig (UIUC)\n1/10 touring car side dam  max 40 mm wide x 20 mm high  AARCMCC\n1/10 track car endplates  25 mm above body x 100 mm deep  AARCMCC\n1/10 off-road side dam  must fit an 80 x 80 mm rectangle  EFRA\n1/12 pan car side dam  max 72 mm high  EFRA\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- High Performance Academy: Aerodynamic performance devices for club level cars: rear wing theory — web — Publisher's page; dimensions are facts — https://www.hpacademy.com/courses/aerodynamics-fundamentals/aerodynamic-performance-devices-for-club-level-cars-rear-wing-theory\n- University of Illinois / SAE: Experimental Study of Open-Wheel Race-Car Front Wings (Jasinski & Selig, SAE 1998) — web — Publisher's page; dimensions are facts — https://m-selig.web.engr.illinois.edu/pubs/JasinskiSelig-1998-MSEC-SAE-Trans-V107-S6.pdf\n- AARCMCC: Section 3: Electric On Road, Technical Rules (Oct 2006) — web — Publisher's page; dimensions are facts — https://www.rctech.net/forum/attachments/australian-racing/180184d1162811203-aarcmcc-online-tech-road-oct-06.pdf\n- EFRA: EFRA Handbook 2010, Appendix 3: Electric Cars — web — Publisher's page; dimensions are facts — https://www.efra.ws/wp-content/uploads/2010/03/Handb10App3.pdf\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/wing-endplates/index.json\nAPI: https://xemstudio.com/api/geometry?object=wing-endplates\n",
 "sources": [
  {
   "publisher": "High Performance Academy",
   "title": "Aerodynamic performance devices for club level cars: rear wing theory",
   "url": "https://www.hpacademy.com/courses/aerodynamics-fundamentals/aerodynamic-performance-devices-for-club-level-cars-rear-wing-theory",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "University of Illinois / SAE",
   "title": "Experimental Study of Open-Wheel Race-Car Front Wings (Jasinski & Selig, SAE 1998)",
   "url": "https://m-selig.web.engr.illinois.edu/pubs/JasinskiSelig-1998-MSEC-SAE-Trans-V107-S6.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "AARCMCC",
   "title": "Section 3: Electric On Road, Technical Rules (Oct 2006)",
   "url": "https://www.rctech.net/forum/attachments/australian-racing/180184d1162811203-aarcmcc-online-tech-road-oct-06.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "EFRA",
   "title": "EFRA Handbook 2010, Appendix 3: Electric Cars",
   "url": "https://www.efra.ws/wp-content/uploads/2010/03/Handb10App3.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": [
  "rear-wing-single-element",
  "rear-wing-dual-element",
  "swan-neck-wing-mount",
  "gurney-flap-wickerbill",
  "front-splitter",
  "splitter-tunnels-front-diffuser"
 ],
 "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": "Do endplates add drag?",
   "a": "In the UIUC test a larger endplate actually reduced drag at constant lift by 13.7% (Jasinski & Selig)."
  }
 ],
 "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": "wing-endplates-rear-wing",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/wing-endplates/wing-endplates-rear-wing.step",
   "stl": "https://xemstudio.com/files/hardware/wing-endplates/wing-endplates-rear-wing.stl",
   "note": "single rear wing: span 190 × chord 40 mm at 6°, endplates 20 mm, inverted NACA 4412 section (mounts from below)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/wing-endplates/index.md"
}