Inverted V-tail (anhedral V) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/inverted-v-tail/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Catalog version: 2026-10-20

Sizes: see table below
- 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.

parameter  value or range  source
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

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- 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/
- Kitplanes (B. Wainfan): Design Process: V-Tails (2022) — web — Publisher's page; dimensions are facts — https://www.kitplanes.com/design-process-v-tails/
- 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

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/inverted-v-tail/index.json
API: https://xemstudio.com/api/geometry?object=inverted-v-tail