{
 "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": "inverted-v-tail",
 "name": "Inverted V-tail (anhedral V)",
 "kind": "standard",
 "category": "Aircraft design",
 "group": "Tail configurations",
 "year": null,
 "question": "What is an inverted V-tail and why use it?",
 "tags": [
  "vehicle design",
  "tail configurations",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "inverted v-tail",
  "inverted v tail",
  "anhedral v tail",
  "upside down v tail",
  "inverted v tail drone",
  "inverted v tail pusher",
  "proverse yaw tail",
  "lambda tail",
  "inverted v vs v tail"
 ],
 "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/inverted-v-tail/",
 "sheet_txt": "https://xemstudio.com/objects/inverted-v-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": [
   "An inverted V-tail points its two surfaces downward. Its rudder input produces proverse rather than adverse roll/yaw coupling: Stackhouse notes 'an inverted V-tail results in a proverse yaw', the reverse of the upright V whose yaw input rolls the aircraft the wrong way (Kitplanes V-Tails).",
   "Stackhouse adds that it has 'so many other drawbacks' that an upright V is usually preferred; the downward panels also bring the surfaces nearer the ground.",
   "Size it like an upright V: effective areas are 2S cos^2(a) and 2S sin^2(a) (McCombs). McCombs also notes negative ('cathedral') V-tail angles can help duration models because of a restoring effect.",
   "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": [
    [
     "Effective horizontal / vertical area",
     "2S cos^2(a) / 2S sin^2(a)",
     "McCombs 1994"
    ],
    [
     "Reference build",
     "same as V-tail example, panels angled downward (32.3 deg)",
     "computed"
    ]
   ]
  }
 },
 "sheet_text": "Inverted V-tail (anhedral V) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/inverted-v-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- An inverted V-tail points its two surfaces downward. Its rudder input produces proverse rather than adverse roll/yaw coupling: Stackhouse notes 'an inverted V-tail results in a proverse yaw', the reverse of the upright V whose yaw input rolls the aircraft the wrong way (Kitplanes V-Tails).\n- Stackhouse adds that it has 'so many other drawbacks' that an upright V is usually preferred; the downward panels also bring the surfaces nearer the ground.\n- Size it like an upright V: effective areas are 2S cos^2(a) and 2S sin^2(a) (McCombs). McCombs also notes negative ('cathedral') V-tail angles can help duration models because of a restoring effect.\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\nEffective horizontal / vertical area  2S cos^2(a) / 2S sin^2(a)  McCombs 1994\nReference build  same as V-tail example, panels angled downward (32.3 deg)  computed\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Charles River Radio Controllers (D. Stackhouse): V-Tail Adverse Yaw (1999) — web — Publisher's page; dimensions are facts — https://charlesriverrc.org/articles/design-and-construction/aircraft-design/tail-design-and-structure/vtail-adverse-yaw/\n- Kitplanes (B. Wainfan): Design Process: V-Tails (2022) — web — Publisher's page; dimensions are facts — https://www.kitplanes.com/design-process-v-tails/\n- Model Aviation (AMA), W.F. McCombs: Wing and Tail Dihedral for Models (Dec 1994) — web — Publisher's page; dimensions are facts — https://library.modelaviation.com/article/wing-and-tail-dihedral-models\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/inverted-v-tail/index.json\nAPI: https://xemstudio.com/api/geometry?object=inverted-v-tail\n",
 "sources": [
  {
   "publisher": "Charles River Radio Controllers (D. Stackhouse)",
   "title": "V-Tail Adverse Yaw (1999)",
   "url": "https://charlesriverrc.org/articles/design-and-construction/aircraft-design/tail-design-and-structure/vtail-adverse-yaw/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Kitplanes (B. Wainfan)",
   "title": "Design Process: V-Tails (2022)",
   "url": "https://www.kitplanes.com/design-process-v-tails/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Model Aviation (AMA), W.F. McCombs",
   "title": "Wing and Tail Dihedral for Models (Dec 1994)",
   "url": "https://library.modelaviation.com/article/wing-and-tail-dihedral-models",
   "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",
  "cruciform-tail",
  "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 is an inverted V-tail less common?",
   "a": "It gives proverse yaw but brings 'many other drawbacks' so upright Vs are usually preferred (Stackhouse, CRRC)."
  }
 ],
 "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": "inverted-v-tail-tail",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/inverted-v-tail/inverted-v-tail-tail.step",
   "stl": "https://xemstudio.com/files/hardware/inverted-v-tail/inverted-v-tail-tail.stl",
   "note": "inverted v layout: horizontal span 250 × chord 112, vertical 0 × 0 mm on a 500 mm boom, NACA 0009 surfaces"
  }
 ],
 "markdown": "https://xemstudio.com/objects/inverted-v-tail/index.md"
}