Cruciform tail (stabiliser part-way up the fin) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/cruciform-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
- 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.

parameter  value or range  source
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

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- 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
- 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
- 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
- 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

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