{
 "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": "naca-0021-airfoil",
 "name": "NACA 0021 airfoil",
 "kind": "standard",
 "category": "Airfoils",
 "group": "NACA 4-digit",
 "year": null,
 "question": "What is the exact shape of the NACA 0021 airfoil, and what do the digits mean?",
 "tags": [
  "airfoil",
  "naca",
  "wing section",
  "rc plane",
  "aerodynamics",
  "symmetric airfoil"
 ],
 "aliases": [
  "NACA 0021",
  "NACA 0021 airfoil",
  "NACA 0021 coordinates",
  "NACA 0021 dat",
  "NACA 0021 profile",
  "NACA 0021 DXF",
  "NACA 0021 STEP",
  "NACA 0021 STL",
  "perfil NACA 0021",
  "Profil NACA 0021",
  "naca0021",
  "NACA 0021 wing section"
 ],
 "overall_mm": {
  "length": 100,
  "width": 20,
  "height": 21
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/naca-0021-airfoil/",
 "sheet_txt": "https://xemstudio.com/objects/naca-0021-airfoil/sheet.txt",
 "sheet": {
  "basis": "Computed from the NACA equations (Report 460 / Report 610, restated in NASA TM-4741)",
  "overall_mm": {
   "length": 100,
   "width": 20,
   "height": 21
  },
  "notes": [
   "NACA 0021: symmetric, 21 % thick.",
   "NACA 4-digit: first digit = maximum camber in % of chord, second = its position in tenths of chord, last two = maximum thickness in % of chord (NACA Report 460).",
   "Ordinates are in % of chord from the leading edge, computed from the published equations with the closed-trailing-edge thickness coefficient (−0.1036, as in NASA TM-4741). The original reports use an open trailing edge (−0.1015); the difference is under 0.03 % of chord near the trailing edge.",
   "The file is a 100 mm chord section, 20 mm deep: scale it uniformly to your chord, or import the STEP and sweep or loft it into a wing. Thickness scales with chord; the shape is the same at any size."
  ],
  "table": {
   "columns": [
    "x (% chord)",
    "upper x",
    "upper y",
    "lower x",
    "lower y"
   ],
   "rows": [
    [
     "0",
     "0.000",
     "0.000",
     "0.000",
     "0.000"
    ],
    [
     "1.25",
     "1.250",
     "3.314",
     "1.250",
     "-3.314"
    ],
    [
     "2.5",
     "2.500",
     "4.576",
     "2.500",
     "-4.576"
    ],
    [
     "5",
     "5.000",
     "6.221",
     "5.000",
     "-6.221"
    ],
    [
     "7.5",
     "7.500",
     "7.350",
     "7.500",
     "-7.350"
    ],
    [
     "10",
     "10.000",
     "8.195",
     "10.000",
     "-8.195"
    ],
    [
     "15",
     "15.000",
     "9.354",
     "15.000",
     "-9.354"
    ],
    [
     "20",
     "20.000",
     "10.040",
     "20.000",
     "-10.040"
    ],
    [
     "25",
     "25.000",
     "10.396",
     "25.000",
     "-10.396"
    ],
    [
     "30",
     "30.000",
     "10.501",
     "30.000",
     "-10.501"
    ],
    [
     "40",
     "40.000",
     "10.150",
     "40.000",
     "-10.150"
    ],
    [
     "50",
     "50.000",
     "9.251",
     "50.000",
     "-9.251"
    ],
    [
     "60",
     "60.000",
     "7.957",
     "60.000",
     "-7.957"
    ],
    [
     "70",
     "70.000",
     "6.359",
     "70.000",
     "-6.359"
    ],
    [
     "80",
     "80.000",
     "4.500",
     "80.000",
     "-4.500"
    ],
    [
     "90",
     "90.000",
     "2.389",
     "90.000",
     "-2.389"
    ],
    [
     "95",
     "95.000",
     "1.232",
     "95.000",
     "-1.232"
    ],
    [
     "100",
     "100.000",
     "-0.000",
     "100.000",
     "0.000"
    ]
   ]
  }
 },
 "sheet_text": "NACA 0021 airfoil — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/naca-0021-airfoil/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Computed from the NACA equations (Report 460 / Report 610, restated in NASA TM-4741)\nCatalog version: 2026-10-20\n\nOverall (mm): length 100.0, width 20.0, height 21.0\n- NACA 0021: symmetric, 21 % thick.\n- NACA 4-digit: first digit = maximum camber in % of chord, second = its position in tenths of chord, last two = maximum thickness in % of chord (NACA Report 460).\n- Ordinates are in % of chord from the leading edge, computed from the published equations with the closed-trailing-edge thickness coefficient (−0.1036, as in NASA TM-4741). The original reports use an open trailing edge (−0.1015); the difference is under 0.03 % of chord near the trailing edge.\n- The file is a 100 mm chord section, 20 mm deep: scale it uniformly to your chord, or import the STEP and sweep or loft it into a wing. Thickness scales with chord; the shape is the same at any size.\n\nx (% chord)  upper x  upper y  lower x  lower y\n0  0.000  0.000  0.000  0.000\n1.25  1.250  3.314  1.250  -3.314\n2.5  2.500  4.576  2.500  -4.576\n5  5.000  6.221  5.000  -6.221\n7.5  7.500  7.350  7.500  -7.350\n10  10.000  8.195  10.000  -8.195\n15  15.000  9.354  15.000  -9.354\n20  20.000  10.040  20.000  -10.040\n25  25.000  10.396  25.000  -10.396\n30  30.000  10.501  30.000  -10.501\n40  40.000  10.150  40.000  -10.150\n50  50.000  9.251  50.000  -9.251\n60  60.000  7.957  60.000  -7.957\n70  70.000  6.359  70.000  -6.359\n80  80.000  4.500  80.000  -4.500\n90  90.000  2.389  90.000  -2.389\n95  95.000  1.232  95.000  -1.232\n100  100.000  -0.000  100.000  0.000\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- NACA (NASA Technical Reports Server): Report 460: The characteristics of 78 related airfoil sections from tests in the variable-density wind tunnel (Jacobs, Ward, Pinkerton, 1933) — web — Publisher's page; dimensions are facts — https://ntrs.nasa.gov/citations/19930091108\n- NASA: TM-4741: Computer program to obtain ordinates for NACA airfoils (Ladson, Brooks, Hill, Sproles, 1996) — web — Publisher's page; dimensions are facts — https://www.pdas.com/refs/tm4741.pdf\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/naca-0021-airfoil/index.json\nAPI: https://xemstudio.com/api/geometry?object=naca-0021-airfoil\n",
 "sources": [
  {
   "publisher": "NACA (NASA Technical Reports Server)",
   "title": "Report 460: The characteristics of 78 related airfoil sections from tests in the variable-density wind tunnel (Jacobs, Ward, Pinkerton, 1933)",
   "url": "https://ntrs.nasa.gov/citations/19930091108",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "NASA",
   "title": "TM-4741: Computer program to obtain ordinates for NACA airfoils (Ladson, Brooks, Hill, Sproles, 1996)",
   "url": "https://www.pdas.com/refs/tm4741.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": [
  "naca-0006-airfoil",
  "naca-0008-airfoil",
  "naca-0009-airfoil",
  "naca-0010-airfoil",
  "naca-0012-airfoil",
  "naca-0015-airfoil"
 ],
 "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 thick is the NACA 0021?",
   "a": "Maximum thickness 21.00 % of chord at 29.9 % chord: 21.00 mm on a 100 mm chord."
  },
  {
   "q": "Where is the NACA 0021's camber?",
   "a": "None: it is symmetric (upper and lower surfaces mirror)."
  },
  {
   "q": "How do I use it for my wing?",
   "a": "Scale the 100 mm section to your chord (e.g. 180 mm chord = 180 % scale), then extrude or loft between root and tip sections. For a tapered wing, scale a root and a tip copy and loft between them."
  }
 ],
 "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": "naca-0021-airfoil-section-100mm-chord",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/naca-0021-airfoil/naca-0021-airfoil-section-100mm-chord.step",
   "stl": "https://xemstudio.com/files/hardware/naca-0021-airfoil/naca-0021-airfoil-section-100mm-chord.stl",
   "note": "NACA 0021 section, 100 mm chord × 20 mm span, closed trailing edge, 160 points from the equations (scale to your chord)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/naca-0021-airfoil/index.md"
}