{
 "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": "cruciform-tail",
 "name": "Cruciform tail (stabiliser part-way up the fin)",
 "kind": "standard",
 "category": "Aircraft design",
 "group": "Tail configurations",
 "year": null,
 "question": "What is a cruciform tail?",
 "tags": [
  "vehicle design",
  "tail configurations",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "cruciform tail",
  "cross tail aircraft",
  "mid tail",
  "cruciform empennage",
  "stabilizer mounted halfway up fin",
  "cruciform vs t-tail",
  "cruciform tail rc",
  "cross shaped tail plane"
 ],
 "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/cruciform-tail/",
 "sheet_txt": "https://xemstudio.com/objects/cruciform-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 cruciform tail mounts the horizontal stabiliser part-way up the fin, forming a cross when seen from behind (Arnedo).",
   "It is used to keep the horizontal surfaces out of the engine wake while avoiding many of the T-tail's drawbacks (Arnedo), such as the heavy, flutter-prone fin needed to carry a stabiliser at its tip (FAA PHAK ch.6).",
   "Because it is neither fully out of the wing wake nor carried at the fin tip, sizing sits between the conventional and T-tail cases; the published coefficients are for conventional tails and T-tails (Scholz 2021).",
   "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 basis",
     "use conventional class values (e.g. homebuilt 0.50 / 0.04)",
     "HAW Hamburg Table 2.1"
    ],
    [
     "Reference build",
     "same areas as conventional example; stabiliser at mid-fin",
     "computed"
    ]
   ]
  }
 },
 "sheet_text": "Cruciform tail (stabiliser part-way up the fin) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/cruciform-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 cruciform tail mounts the horizontal stabiliser part-way up the fin, forming a cross when seen from behind (Arnedo).\n- It is used to keep the horizontal surfaces out of the engine wake while avoiding many of the T-tail's drawbacks (Arnedo), such as the heavy, flutter-prone fin needed to carry a stabiliser at its tip (FAA PHAK ch.6).\n- Because it is neither fully out of the wing wake nor carried at the fin tip, sizing sits between the conventional and T-tail cases; the published coefficients are for conventional tails and T-tails (Scholz 2021).\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 basis  use conventional class values (e.g. homebuilt 0.50 / 0.04)  HAW Hamburg Table 2.1\nReference build  same areas as conventional example; stabiliser at mid-fin  computed\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\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- 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- 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\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/cruciform-tail/index.json\nAPI: https://xemstudio.com/api/geometry?object=cruciform-tail\n",
 "sources": [
  {
   "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
  },
  {
   "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": "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
  }
 ],
 "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",
  "t-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 choose a cruciform tail?",
   "a": "To lift the stabiliser out of engine wake without the T-tail's structural and deep-stall penalties (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": "cruciform-tail-tail",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/cruciform-tail/cruciform-tail-tail.step",
   "stl": "https://xemstudio.com/files/hardware/cruciform-tail/cruciform-tail-tail.stl",
   "note": "cruciform layout: horizontal span 400 × chord 100, vertical 140 × 114 mm on a 500 mm boom, NACA 0009 surfaces"
  }
 ],
 "markdown": "https://xemstudio.com/objects/cruciform-tail/index.md"
}