# Y-tail (V-tail with ventral fin)

> What is a Y-tail?

- Category: Aircraft design › Tail configurations
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/y-tail/ · JSON: https://xemstudio.com/api/geometry?object=y-tail · Plain text: https://xemstudio.com/objects/y-tail/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- Bhattacharya et al. describe the Y-tail as a V-tail with a rudder added at the rear, which improves yaw stability and has less interference drag than a conventional tail.
- Its performance depends on the V dihedral and the length of the vertical stub (Bhattacharya et al.). The ventral fin takes over pure yaw control, easing the coupled ruddervator problem of a plain V-tail (FAA PHAK ch.6).
- Their maritime UAV design used NACA 2412 for the horizontal elements and NACA 0024 for the vertical, with a 105 cm tail arm on a 165 cm fuselage.
- Used on: LearAvia Lear Fan 2100, MQ-9 Reaper, Waiex.
- 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.

## Sizes

| parameter | value or range | source |
|---|---|---|
| Example UAV tail arm / fuselage length | 105 cm / 165 cm | Bhattacharya et al. |
| Example vertical tail area | 0.1568 m^2 on 0.549 m^2 reference area | Bhattacharya et al. |
| Example airfoils | NACA 2412 (horizontal), NACA 0024 (vertical) | Bhattacharya et al. |
| Reference build | V panels as V-tail example plus 80 mm ventral fin | computed |

## Where the files are

- engrXiv (Bhattacharya et al., ICMMM 2023): [Design and Computational Analysis of Y-tail Configuration for Maritime UAV](https://engrxiv.org/preprint/download/6582/10812/9153) — web — Publisher's page; dimensions are facts
- FAA: [Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), Ch. 6 Flight Controls](https://www.faa.gov/sites/faa.gov/files/08_phak_ch6.pdf) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/y-tail/index.json · license: https://xemstudio.com/files/hardware/y-tail/LICENSE.md

- y-tail-tail: [STEP](https://xemstudio.com/files/hardware/y-tail/y-tail-tail.step) · [STL](https://xemstudio.com/files/hardware/y-tail/y-tail-tail.stl) — y tail layout: horizontal span 250 × chord 112, vertical 80 × 90 mm on a 500 mm boom, NACA 0009 surfaces

## Questions

**Which aircraft use a Y-tail?**

Bhattacharya et al. list the LearAvia Lear Fan 2100 and MQ-9 Reaper among others.

## Fits with

- [Tail volume coefficient (horizontal and vertical tail sizing)](https://xemstudio.com/objects/tail-volume-coefficient/)
- [Tail moment arm (tail lever arm ratios)](https://xemstudio.com/objects/tail-moment-arm/)
- [Conventional tail (low-mounted stabiliser and single fin)](https://xemstudio.com/objects/conventional-tail/)
- [T-tail (stabiliser on top of the fin)](https://xemstudio.com/objects/t-tail/)
- [Cruciform tail (stabiliser part-way up the fin)](https://xemstudio.com/objects/cruciform-tail/)
- [V-tail (butterfly tail with ruddervators)](https://xemstudio.com/objects/v-tail/)