{
 "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": "slotted-flap",
 "name": "Slotted flap",
 "kind": "standard",
 "category": "Aircraft design",
 "group": "Wing features",
 "year": null,
 "question": "How does a slotted flap work?",
 "tags": [
  "vehicle design",
  "wing features",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "slotted flap",
  "single slotted flap",
  "double slotted flap",
  "slotted flap rc",
  "slotted flap how it works",
  "flap gap",
  "slotted vs plain flap",
  "high lift flap"
 ],
 "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/slotted-flap/",
 "sheet_txt": "https://xemstudio.com/objects/slotted-flap/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 slotted flap opens a gap between wing and flap so high-pressure air from below energises the flap's upper surface; it raises the lift coefficient significantly more than plain or split flaps and is the most popular type today (FAA PHAK ch.6).",
   "Its section CLmax increment is about 1.3 vs 0.9 for a plain flap (Arnedo, Franchini data); large aircraft use double or triple slots (FAA).",
   "The file is a reference example built by Xem Studio from the numbers above. Sizes the sources do not fix are illustrative; scale the example to your own vehicle."
  ],
  "table": {
   "columns": [
    "parameter",
    "value or range",
    "source"
   ],
   "rows": [
    [
     "Section delta-CLmax",
     "1.3",
     "Arnedo (Franchini)"
    ],
    [
     "Wing delta-CLmax",
     "0.92 x dCl x (Sflapped/S) x cos(sweep)",
     "Arnedo"
    ],
    [
     "Typical CLmax/cos(sweep), slotted flap",
     "1.5-1.7 takeoff (20 deg) / 1.8-2.2 landing (40 deg)",
     "Arnedo"
    ],
    [
     "Typical CLmax/cos(sweep), double slotted",
     "1.7-1.95 takeoff (20 deg) / 2.3-2.7 landing (50 deg)",
     "Arnedo"
    ],
    [
     "Reference build",
     "chord 100, 25% flap, 40 deg",
     "Arnedo landing setting"
    ]
   ]
  }
 },
 "sheet_text": "Slotted flap — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/slotted-flap/  (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- A slotted flap opens a gap between wing and flap so high-pressure air from below energises the flap's upper surface; it raises the lift coefficient significantly more than plain or split flaps and is the most popular type today (FAA PHAK ch.6).\n- Its section CLmax increment is about 1.3 vs 0.9 for a plain flap (Arnedo, Franchini data); large aircraft use double or triple slots (FAA).\n- The file is a reference example built by Xem Studio from the numbers above. Sizes the sources do not fix are illustrative; scale the example to your own vehicle.\n\nparameter  value or range  source\nSection delta-CLmax  1.3  Arnedo (Franchini)\nWing delta-CLmax  0.92 x dCl x (Sflapped/S) x cos(sweep)  Arnedo\nTypical CLmax/cos(sweep), slotted flap  1.5-1.7 takeoff (20 deg) / 1.8-2.2 landing (40 deg)  Arnedo\nTypical CLmax/cos(sweep), double slotted  1.7-1.95 takeoff (20 deg) / 2.3-2.7 landing (50 deg)  Arnedo\nReference build  chord 100, 25% flap, 40 deg  Arnedo landing setting\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- FAA: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), Ch. 6 Flight Controls — web — Publisher's page; dimensions are facts — https://www.faa.gov/sites/faa.gov/files/08_phak_ch6.pdf\n- LibreTexts (Arnedo, Fundamentals of Aerospace Engineering; data from Franchini et al.): 3.4.3 Increase in CLmax (high-lift devices) — web — Publisher's page; dimensions are facts — https://eng.libretexts.org/Bookshelves/Aerospace_Engineering/Fundamentals_of_Aerospace_Engineering_(Arnedo)/03%3A_Aerodynamics/3.04%3A_High-lift_devices/3.4.03%3A_Increase_in_CLmax\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/slotted-flap/index.json\nAPI: https://xemstudio.com/api/geometry?object=slotted-flap\n",
 "sources": [
  {
   "publisher": "FAA",
   "title": "Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), Ch. 6 Flight Controls",
   "url": "https://www.faa.gov/sites/faa.gov/files/08_phak_ch6.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "LibreTexts (Arnedo, Fundamentals of Aerospace Engineering; data from Franchini et al.)",
   "title": "3.4.3 Increase in CLmax (high-lift devices)",
   "url": "https://eng.libretexts.org/Bookshelves/Aerospace_Engineering/Fundamentals_of_Aerospace_Engineering_(Arnedo)/03%3A_Aerodynamics/3.04%3A_High-lift_devices/3.4.03%3A_Increase_in_CLmax",
   "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": [
  "plain-flap",
  "split-flap",
  "fowler-flap",
  "leading-edge-slat-slot",
  "gurney-flap",
  "leading-edge-cuff"
 ],
 "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": "Does the slot matter?",
   "a": "Yes; the gap flow lets the flap deflect further without separating, giving about 1.3 vs 0.9 dCLmax (Arnedo)."
  }
 ],
 "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": "slotted-flap-wing-segment",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/slotted-flap/slotted-flap-wing-segment.step",
   "stl": "https://xemstudio.com/files/hardware/slotted-flap/slotted-flap-wing-segment.stl",
   "note": "slotted flap: wing segment 100 mm chord × 300 mm, 25 % chord surface deflected 40°"
  }
 ],
 "markdown": "https://xemstudio.com/objects/slotted-flap/index.md"
}