H-tail / twin fin tail — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/h-tail-twin-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 H-tail puts two fins at the ends of the horizontal stabiliser. Bhattacharya et al. list redundancy and fins less affected by wing/fuselage downwash and fuselage turbulence as benefits, with propwash drag and boom weight as costs.
- The stabiliser end-plates the fins in the same way a T-tail's stabiliser end-plates a single fin (Kitplanes T-Tails), and splitting the fin area keeps each fin short.
- Arnedo describes twin (H) tails as 'much less common' than conventional, cruciform and T-tails.
- Used on: Consolidated B-24, B-25 Mitchell, Avro Lancaster, Handley Page Halifax, Petlyakov Pe-2.
- 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
Fin area split  total Sv shared by two fins (each 8,000 mm^2 in reference build)  computed from Vv 0.04
Reference build  Sh 40,000 mm^2, two fins 100 x 80 mm  computed

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- engrXiv (Bhattacharya et al., ICMMM 2023): Design and Computational Analysis of Y-tail Configuration for Maritime UAV — web — Publisher's page; dimensions are facts — https://engrxiv.org/preprint/download/6582/10812/9153
- 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
- Kitplanes (B. Wainfan): Design Process: T-Tails (2022) — web — Publisher's page; dimensions are facts — https://www.kitplanes.com/design-process-t-tails/
- 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/h-tail-twin-tail/index.json
API: https://xemstudio.com/api/geometry?object=h-tail-twin-tail