# All-moving tail (stabilator)

> What is a stabilator (all-moving 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/all-moving-stabilator/ · JSON: https://xemstudio.com/api/geometry?object=all-moving-stabilator · Plain text: https://xemstudio.com/objects/all-moving-stabilator/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

- A stabilator is a one-piece horizontal tail that pivots about a central hinge; it is very sensitive to control input (FAA PHAK ch.6).
- An antiservo tab on its trailing edge moves in the same direction as the stabilator, increasing stick force to prevent over-control, and a balance weight is usually placed ahead of the main spar (PHAK ch.6).
- RC sailplanes use the same idea: Drela's Bubble Dancer has a 'horizontal all moving tail' on a V-mount (CRRC).
- Used on: Bubble Dancer (RC sailplane).
- 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 |
|---|---|---|
| Antiservo tab direction | same direction as stabilator | FAA PHAK ch.6 |
| Mass balance | weight ahead of main spar | FAA PHAK ch.6 |
| Bubble Dancer tail airfoil | ht21 (horizontal and vertical) | CRRC |
| Reference build | Sh 40,000 mm^2 pivoting surface | computed |

## Where the files are

- 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
- Charles River Radio Controllers (M. Drela designs): [Bubble Dancer 3m RES sailplane](https://charlesriverrc.org/articles/on-line-plans/mark-drela-designs/bubble-dancer/) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/all-moving-stabilator/index.json · license: https://xemstudio.com/files/hardware/all-moving-stabilator/LICENSE.md

- all-moving-stabilator-tail: [STEP](https://xemstudio.com/files/hardware/all-moving-stabilator/all-moving-stabilator-tail.step) · [STL](https://xemstudio.com/files/hardware/all-moving-stabilator/all-moving-stabilator-tail.stl) — all moving layout: horizontal span 400 × chord 100, vertical 140 × 114 mm on a 500 mm boom, NACA 0009 surfaces

## Questions

**Why do stabilators need an antiservo tab?**

They are so sensitive that the tab adds feel force to prevent over-controlling (FAA PHAK ch.6).

## 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/)