{
 "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": "rear-spoiler",
 "name": "Rear spoiler (vs rear wing)",
 "kind": "standard",
 "category": "Car design",
 "group": "Car aero",
 "year": null,
 "question": "What is the difference between a rear spoiler and a rear wing?",
 "tags": [
  "vehicle design",
  "car aero",
  "rc design",
  "aerodynamics",
  "guide"
 ],
 "aliases": [
  "spoiler vs wing",
  "rear spoiler",
  "ducktail spoiler",
  "lip spoiler",
  "trunk spoiler",
  "difference between spoiler and wing",
  "boot spoiler",
  "Gurney spoiler car",
  "rc car spoiler",
  "NASCAR spoiler",
  "wing or spoiler"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "not-scanned",
 "les": false,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/rear-spoiler/",
 "sheet_txt": "https://xemstudio.com/objects/rear-spoiler/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 spoiler is a lip or dam on the body's trailing edge that 'spoils' unfavourable flow over the body (Sportwing); a wing is a separate airfoil with air passing over both surfaces, creating a pressure difference (CompetitionX).",
   "Spoilers have lower aerodynamic efficiency than wings (Garry & Le Good, cited in SAE 2018-01-0725), although a NASCAR PIV study found a spoiler made more downforce than a wing because it deflects more flow.",
   "On a 35% DrivAer racing model, spoiler downforce rose with angle from 20 to 60 deg, with the optimum between 40 and 60 deg; 60 deg cost 8.2% more drag than 40 deg for only 3.5% more downforce.",
   "Used on: NASCAR stock cars (spoiler vs wing study)."
  ],
  "table": {
   "columns": [
    "parameter",
    "value or range",
    "source"
   ],
   "rows": [
    [
     "Spoiler lengths tested (35% model)",
     "40, 80, 120 mm",
     "Cranfield / SAE 2018-01-0725"
    ],
    [
     "Spoiler angles tested",
     "20, 40, 60 deg; optimum between 40 and 60 deg",
     "Cranfield / SAE 2018-01-0725"
    ],
    [
     "Downforce ratio at peak ride height",
     "1.61 (20 deg), 1.89 (40 deg), 1.95 (60 deg)",
     "Cranfield / SAE 2018-01-0725"
    ],
    [
     "60 vs 40 deg",
     "+3.5% downforce, +8.2% drag",
     "Cranfield / SAE 2018-01-0725"
    ],
    [
     "1/12 RC pan car spoiler limit",
     "max 25 mm high, 35 mm long",
     "EFRA"
    ]
   ]
  }
 },
 "sheet_text": "Rear spoiler (vs rear wing) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/rear-spoiler/  (sheet CC BY 4.0)\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 spoiler is a lip or dam on the body's trailing edge that 'spoils' unfavourable flow over the body (Sportwing); a wing is a separate airfoil with air passing over both surfaces, creating a pressure difference (CompetitionX).\n- Spoilers have lower aerodynamic efficiency than wings (Garry & Le Good, cited in SAE 2018-01-0725), although a NASCAR PIV study found a spoiler made more downforce than a wing because it deflects more flow.\n- On a 35% DrivAer racing model, spoiler downforce rose with angle from 20 to 60 deg, with the optimum between 40 and 60 deg; 60 deg cost 8.2% more drag than 40 deg for only 3.5% more downforce.\n- Used on: NASCAR stock cars (spoiler vs wing study).\n\nparameter  value or range  source\nSpoiler lengths tested (35% model)  40, 80, 120 mm  Cranfield / SAE 2018-01-0725\nSpoiler angles tested  20, 40, 60 deg; optimum between 40 and 60 deg  Cranfield / SAE 2018-01-0725\nDownforce ratio at peak ride height  1.61 (20 deg), 1.89 (40 deg), 1.95 (60 deg)  Cranfield / SAE 2018-01-0725\n60 vs 40 deg  +3.5% downforce, +8.2% drag  Cranfield / SAE 2018-01-0725\n1/12 RC pan car spoiler limit  max 25 mm high, 35 mm long  EFRA\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Cranfield University / SAE: On the Aerodynamics of an Enclosed-Wheel Racing Car (Soares et al., SAE 2018-01-0725) — web — Publisher's page; dimensions are facts — https://dspace.lib.cranfield.ac.uk/server/api/core/bitstreams/9b476386-44d0-4c0f-a49e-c3372274d351/content\n- Sportwing: Rear Spoiler vs Rear Wing: What's the Difference? — web — Publisher's page; dimensions are facts — https://sportwing.com/blog/rear-spoiler-vs-rear-wing\n- CompetitionX: RC Wings Explained — web — Publisher's page; dimensions are facts — https://www.competitionx.com/?p=489\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\nNo true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.\nAPI: https://xemstudio.com/api/geometry?object=rear-spoiler\n",
 "sources": [
  {
   "publisher": "Cranfield University / SAE",
   "title": "On the Aerodynamics of an Enclosed-Wheel Racing Car (Soares et al., SAE 2018-01-0725)",
   "url": "https://dspace.lib.cranfield.ac.uk/server/api/core/bitstreams/9b476386-44d0-4c0f-a49e-c3372274d351/content",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Sportwing",
   "title": "Rear Spoiler vs Rear Wing: What's the Difference?",
   "url": "https://sportwing.com/blog/rear-spoiler-vs-rear-wing",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "CompetitionX",
   "title": "RC Wings Explained",
   "url": "https://www.competitionx.com/?p=489",
   "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": "not-scanned",
  "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": "Which is more efficient?",
   "a": "A wing; spoilers have lower aerodynamic efficiency (Garry & Le Good via SAE 2018-01-0725)."
  },
  {
   "q": "Can a spoiler make more downforce than a wing?",
   "a": "It can: a NASCAR PIV study found the spoiler deflected more flow and made more downforce, at higher drag."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/rear-spoiler/index.md"
}