{
 "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": "t-tail",
 "name": "T-tail (stabiliser on top of the fin)",
 "kind": "standard",
 "category": "Aircraft design",
 "group": "Tail configurations",
 "year": null,
 "question": "What is a T-tail and why do aircraft use it?",
 "tags": [
  "vehicle design",
  "tail configurations",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "t-tail",
  "t tail aircraft",
  "t-tail deep stall",
  "t-tail vs conventional tail",
  "t tail rc plane",
  "high tail",
  "t-tail advantages disadvantages",
  "why gliders have t-tails",
  "t-tail flutter",
  "t tail sailplane"
 ],
 "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/t-tail/",
 "sheet_txt": "https://xemstudio.com/objects/t-tail/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 T-tail mounts the horizontal stabiliser on top of the fin, which keeps the elevator above most propeller downwash and wing/fuselage wake and clear of engine exhaust (FAA PHAK ch.6). The horizontal surface also end-plates the fin, so the fin can be slightly smaller (Kitplanes T-Tails; Scholz 2021).",
   "The penalty is deep stall: at high angle of attack the tail can drop into the stalled wing's wake, and FAA notes deep stalls are more likely on T-tails (PHAK ch.6). The BAC Trident was lost to an unrecoverable deep stall (Kitplanes).",
   "Putting the stabiliser's mass at the fin tip raises flutter loads, so the fin must be stiffer and the structure 'significantly heavier' than a conventional tail (PHAK ch.6; Kitplanes). With no propwash on the tail, more elevator is needed to raise the nose at low speed (PHAK ch.6).",
   "Used on: BAC Trident, DC-9, C-141, C-5, C-17, Piper PA-32RT-300 Lance II, Grob G-109, Piper PA-44 Seminole.",
   "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": [
    [
     "Tail volume reduction allowed for T-tail",
     "about 4%",
     "Scholz 2021"
    ],
    [
     "Horizontal arm vs vertical arm on T-tails",
     "about 23% longer",
     "Scholz 2021"
    ],
    [
     "Sailplane Vh / Vv (T-tails nearly universal on sailplanes)",
     "0.50 / 0.02",
     "HAW Hamburg Table 2.1; Kitplanes T-Tails"
    ],
    [
     "Reference build",
     "Sh 38,400 mm^2 (Vh 0.50 less 4%), Sv 15,360 mm^2, arm 500 mm",
     "computed"
    ]
   ]
  }
 },
 "sheet_text": "T-tail (stabiliser on top of the fin) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/t-tail/  (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 T-tail mounts the horizontal stabiliser on top of the fin, which keeps the elevator above most propeller downwash and wing/fuselage wake and clear of engine exhaust (FAA PHAK ch.6). The horizontal surface also end-plates the fin, so the fin can be slightly smaller (Kitplanes T-Tails; Scholz 2021).\n- The penalty is deep stall: at high angle of attack the tail can drop into the stalled wing's wake, and FAA notes deep stalls are more likely on T-tails (PHAK ch.6). The BAC Trident was lost to an unrecoverable deep stall (Kitplanes).\n- Putting the stabiliser's mass at the fin tip raises flutter loads, so the fin must be stiffer and the structure 'significantly heavier' than a conventional tail (PHAK ch.6; Kitplanes). With no propwash on the tail, more elevator is needed to raise the nose at low speed (PHAK ch.6).\n- Used on: BAC Trident, DC-9, C-141, C-5, C-17, Piper PA-32RT-300 Lance II, Grob G-109, Piper PA-44 Seminole.\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\nTail volume reduction allowed for T-tail  about 4%  Scholz 2021\nHorizontal arm vs vertical arm on T-tails  about 23% longer  Scholz 2021\nSailplane Vh / Vv (T-tails nearly universal on sailplanes)  0.50 / 0.02  HAW Hamburg Table 2.1; Kitplanes T-Tails\nReference build  Sh 38,400 mm^2 (Vh 0.50 less 4%), Sv 15,360 mm^2, arm 500 mm  computed\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- Kitplanes (B. Wainfan): Design Process: T-Tails (2022) — web — Publisher's page; dimensions are facts — https://www.kitplanes.com/design-process-t-tails/\n- INCAS Bulletin / HAW Hamburg (D. Scholz): Empennage sizing with the tail volume complemented with a method for dorsal fin layout (2021) — web — Publisher's page; dimensions are facts — https://www.fzt.haw-hamburg.de/pers/Scholz/Aero/AERO_PUB_INCAS_TailVolume_Vol13No3_2021.pdf\n- HAW Hamburg (Aircraft Design and Systems Group): Empennage sizing: tail lever arm as % of fuselage length (thesis; Table 2.1 typical tail volume coefficients) — web — Publisher's page; dimensions are facts — https://www.fzt.haw-hamburg.de/pers/Scholz/arbeiten/TextMcDavid.pdf\n- LibreTexts (Arnedo, Fundamentals of Aerospace Engineering): 2.2.3 Empennage — web — Publisher's page; dimensions are facts — https://eng.libretexts.org/Bookshelves/Aerospace_Engineering/Fundamentals_of_Aerospace_Engineering_(Arnedo)/02%3A_Generalities/2.02%3A_Parts_of_the_aircraft/2.2.03%3A_Empennage\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/t-tail/index.json\nAPI: https://xemstudio.com/api/geometry?object=t-tail\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": "Kitplanes (B. Wainfan)",
   "title": "Design Process: T-Tails (2022)",
   "url": "https://www.kitplanes.com/design-process-t-tails/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "INCAS Bulletin / HAW Hamburg (D. Scholz)",
   "title": "Empennage sizing with the tail volume complemented with a method for dorsal fin layout (2021)",
   "url": "https://www.fzt.haw-hamburg.de/pers/Scholz/Aero/AERO_PUB_INCAS_TailVolume_Vol13No3_2021.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "HAW Hamburg (Aircraft Design and Systems Group)",
   "title": "Empennage sizing: tail lever arm as % of fuselage length (thesis; Table 2.1 typical tail volume coefficients)",
   "url": "https://www.fzt.haw-hamburg.de/pers/Scholz/arbeiten/TextMcDavid.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "LibreTexts (Arnedo, Fundamentals of Aerospace Engineering)",
   "title": "2.2.3 Empennage",
   "url": "https://eng.libretexts.org/Bookshelves/Aerospace_Engineering/Fundamentals_of_Aerospace_Engineering_(Arnedo)/02%3A_Generalities/2.02%3A_Parts_of_the_aircraft/2.2.03%3A_Empennage",
   "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": [
  "tail-volume-coefficient",
  "tail-moment-arm",
  "conventional-tail",
  "cruciform-tail",
  "v-tail",
  "inverted-v-tail"
 ],
 "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 do most gliders have T-tails?",
   "a": "The single main wheel and slim aft fuselage would put a low tail on the ground when the glider rests wing-down (Kitplanes T-Tails)."
  },
  {
   "q": "What is a deep stall?",
   "a": "At high angle of attack the wing wake blankets the T-tail, removing pitch-down authority so the aircraft can stay stalled (FAA PHAK ch.6)."
  }
 ],
 "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": "t-tail-tail",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/t-tail/t-tail-tail.step",
   "stl": "https://xemstudio.com/files/hardware/t-tail/t-tail-tail.stl",
   "note": "t tail layout: horizontal span 384 × chord 100, vertical 140 × 110 mm on a 500 mm boom, NACA 0009 surfaces"
  }
 ],
 "markdown": "https://xemstudio.com/objects/t-tail/index.md"
}