{ "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": "clark-y-airfoil", "name": "Clark Y airfoil", "kind": "standard", "category": "Airfoils", "group": "Airfoils", "year": null, "question": "What is the Clark Y airfoil?", "tags": [ "vehicle design", "airfoils", "rc design", "aerodynamics", "guide" ], "aliases": [ "clark y", "clark y airfoil", "clark y coordinates", "clark y dat", "flat bottom airfoil", "clark y rc", "clark y cl max", "clark y airfoil template", "clark y vs naca 2412", "classic model airfoil" ], "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/clark-y-airfoil/", "sheet_txt": "https://xemstudio.com/objects/clark-y-airfoil/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": [ "The Clark Y has a maximum thickness of 11.7% and a lower surface flat from 30% chord aft (Mason, Virginia Tech, citing Riegels). The flat bottom makes it easy to build on a flat board.", "NACA tested it widely, including TR-431 on very low aspect ratios (0.5-3), which found stall delayed and maximum lift increased at aspect ratios around 1 (NACA TR-431).", "NASA's 1979 PAR ground-effect model used a 12% Clark-Y section (NASA TM-78793).", "Used on: NASA PAR WIG test model (TM-78793)." ], "table": { "columns": [ "parameter", "value or range", "source" ], "rows": [ [ "Max thickness", "11.7% chord", "Mason (Virginia Tech)" ], [ "Lower surface", "flat from 30% chord aft", "Mason (Riegels 1961)" ], [ "Low-AR tests", "AR 0.5-3; CLmax higher near AR 1", "NACA TR-431" ], [ "Coordinates source", "Mason / Riegels; NACA R 427, 428, 431", "Mason" ] ] } }, "sheet_text": "Clark Y airfoil — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/clark-y-airfoil/ (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- The Clark Y has a maximum thickness of 11.7% and a lower surface flat from 30% chord aft (Mason, Virginia Tech, citing Riegels). The flat bottom makes it easy to build on a flat board.\n- NACA tested it widely, including TR-431 on very low aspect ratios (0.5-3), which found stall delayed and maximum lift increased at aspect ratios around 1 (NACA TR-431).\n- NASA's 1979 PAR ground-effect model used a 12% Clark-Y section (NASA TM-78793).\n- Used on: NASA PAR WIG test model (TM-78793).\n\nparameter value or range source\nMax thickness 11.7% chord Mason (Virginia Tech)\nLower surface flat from 30% chord aft Mason (Riegels 1961)\nLow-AR tests AR 0.5-3; CLmax higher near AR 1 NACA TR-431\nCoordinates source Mason / Riegels; NACA R 427, 428, 431 Mason\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Virginia Tech (W.H. Mason): Airfoil definitions (Configuration Aerodynamics notes) — web — Publisher's page; dimensions are facts — https://archive.aoe.vt.edu/mason/Mason_f/C23AirfoilDefinitions.pdf\n- NACA (C.H. Zimmerman): Characteristics of Clark Y Airfoils of Small Aspect Ratios, NACA TR-431 (1933) — web — Publisher's page; dimensions are facts — https://ntrs.nasa.gov/citations/19930091504\n- NASA Langley / DTNSRDC (Thomas, Paulson & Margason): Powered Low-Aspect-Ratio Wing in Ground Effect (WIG) Aerodynamic Characteristics, NASA TM-78793 (1979) — web — Publisher's page; dimensions are facts — https://ntrs.nasa.gov/api/citations/19790022970/downloads/19790022970.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=clark-y-airfoil\n", "sources": [ { "publisher": "Virginia Tech (W.H. Mason)", "title": "Airfoil definitions (Configuration Aerodynamics notes)", "url": "https://archive.aoe.vt.edu/mason/Mason_f/C23AirfoilDefinitions.pdf", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "NACA (C.H. Zimmerman)", "title": "Characteristics of Clark Y Airfoils of Small Aspect Ratios, NACA TR-431 (1933)", "url": "https://ntrs.nasa.gov/citations/19930091504", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "NASA Langley / DTNSRDC (Thomas, Paulson & Margason)", "title": "Powered Low-Aspect-Ratio Wing in Ground Effect (WIG) Aerodynamic Characteristics, NASA TM-78793 (1979)", "url": "https://ntrs.nasa.gov/api/citations/19790022970/downloads/19790022970.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": [ "selig-s1223-airfoil", "eppler-e387-airfoil", "mh32-airfoil", "ag35-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": "Why is Clark Y popular with builders?", "a": "Its lower surface is flat from 30% aft, so ribs sit on a flat board (Mason)." } ], "files_license": null, "offers": [], "markdown": "https://xemstudio.com/objects/clark-y-airfoil/index.md" }