{
 "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-2421-airfoil",
 "name": "NACA 2421 airfoil",
 "kind": "standard",
 "category": "Airfoils",
 "group": "NACA 4-digit",
 "year": null,
 "question": "What is the exact shape of the NACA 2421 airfoil, and what do the digits mean?",
 "tags": [
  "airfoil",
  "naca",
  "wing section",
  "rc plane",
  "aerodynamics",
  "cambered airfoil"
 ],
 "aliases": [
  "NACA 2421",
  "NACA 2421 airfoil",
  "NACA 2421 coordinates",
  "NACA 2421 dat",
  "NACA 2421 profile",
  "NACA 2421 DXF",
  "NACA 2421 STEP",
  "NACA 2421 STL",
  "perfil NACA 2421",
  "Profil NACA 2421",
  "naca2421",
  "NACA 2421 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-2421-airfoil/",
 "sheet_txt": "https://xemstudio.com/objects/naca-2421-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 2421: 2 % camber at 40 % chord, 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",
     "0.930",
     "3.422",
     "1.570",
     "-3.176"
    ],
    [
     "2.5",
     "2.073",
     "4.798",
     "2.927",
     "-4.314"
    ],
    [
     "5",
     "4.458",
     "6.666",
     "5.542",
     "-5.728"
    ],
    [
     "7.5",
     "6.905",
     "8.005",
     "8.095",
     "-6.646"
    ],
    [
     "10",
     "9.387",
     "9.047",
     "10.613",
     "-7.297"
    ],
    [
     "15",
     "14.417",
     "10.554",
     "15.583",
     "-8.117"
    ],
    [
     "20",
     "19.499",
     "11.528",
     "20.501",
     "-8.528"
    ],
    [
     "25",
     "24.610",
     "12.108",
     "25.390",
     "-8.670"
    ],
    [
     "30",
     "29.738",
     "12.373",
     "30.262",
     "-8.623"
    ],
    [
     "40",
     "40.000",
     "12.150",
     "40.000",
     "-8.150"
    ],
    [
     "50",
     "50.103",
     "11.195",
     "49.897",
     "-7.306"
    ],
    [
     "60",
     "60.177",
     "9.733",
     "59.823",
     "-6.178"
    ],
    [
     "70",
     "70.212",
     "7.855",
     "69.788",
     "-4.855"
    ],
    [
     "80",
     "80.200",
     "5.607",
     "79.800",
     "-3.385"
    ],
    [
     "90",
     "90.133",
     "2.996",
     "89.867",
     "-1.774"
    ],
    [
     "95",
     "95.075",
     "1.549",
     "94.925",
     "-0.910"
    ],
    [
     "100",
     "100.000",
     "-0.000",
     "100.000",
     "0.000"
    ]
   ]
  }
 },
 "sheet_text": "NACA 2421 airfoil — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/naca-2421-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 2421: 2 % camber at 40 % chord, 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  0.930  3.422  1.570  -3.176\n2.5  2.073  4.798  2.927  -4.314\n5  4.458  6.666  5.542  -5.728\n7.5  6.905  8.005  8.095  -6.646\n10  9.387  9.047  10.613  -7.297\n15  14.417  10.554  15.583  -8.117\n20  19.499  11.528  20.501  -8.528\n25  24.610  12.108  25.390  -8.670\n30  29.738  12.373  30.262  -8.623\n40  40.000  12.150  40.000  -8.150\n50  50.103  11.195  49.897  -7.306\n60  60.177  9.733  59.823  -6.178\n70  70.212  7.855  69.788  -4.855\n80  80.200  5.607  79.800  -3.385\n90  90.133  2.996  89.867  -1.774\n95  95.075  1.549  94.925  -0.910\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-2421-airfoil/index.json\nAPI: https://xemstudio.com/api/geometry?object=naca-2421-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-2408-airfoil",
  "naca-2410-airfoil",
  "naca-2411-airfoil",
  "naca-2412-airfoil",
  "naca-2414-airfoil",
  "naca-2415-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 2421?",
   "a": "Maximum thickness 21.00 % of chord at 30.0 % chord: 21.00 mm on a 100 mm chord."
  },
  {
   "q": "Where is the NACA 2421's camber?",
   "a": "Maximum camber 2.00 % of chord at 40.0 % chord."
  },
  {
   "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-2421-airfoil-section-100mm-chord",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/naca-2421-airfoil/naca-2421-airfoil-section-100mm-chord.step",
   "stl": "https://xemstudio.com/files/hardware/naca-2421-airfoil/naca-2421-airfoil-section-100mm-chord.stl",
   "note": "NACA 2421 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-2421-airfoil/index.md"
}