# Aileron

> How big should ailerons be?

- Category: Aircraft design › Control surfaces
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/aileron/ · JSON: https://xemstudio.com/api/geometry?object=aileron · Plain text: https://xemstudio.com/objects/aileron/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

- Ailerons on the outboard trailing edges move in opposite directions to roll the aircraft; the down-going aileron's drag yaws the nose away from the turn (adverse yaw), worst at low speed and large deflection (FAA PHAK ch.6).
- Sadraey's typical values: aileron area 5-10% of wing area, span 20-30% of wing span, chord 15-25% of wing chord, inboard edge at 60-80% semispan, max deflection about 30 deg, though he recommends keeping it under 25 deg to avoid aileron stall.
- A Cessna 182 uses 20% chord ailerons from 46% to 95% semispan with 20 deg up / 14 deg down (Sadraey Table 12.1).
- Used on: Cessna 182, Air Tractor AT-802, Gulfstream 200.
- 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 |
|---|---|---|
| Sa/S | 0.05-0.10 | Sadraey ch.12 |
| ba/b | 0.20-0.30 | Sadraey ch.12 |
| Ca/C | 0.15-0.25 | Sadraey ch.12 |
| Inboard edge bai/b | 0.6-0.8 | Sadraey ch.12 |
| Max deflection | ~30 deg; keep < 25 deg up and down | Sadraey ch.12 |
| Cessna 182 | Ca/C 0.2, 0.46-0.95 semispan, 20/14 deg | Sadraey Table 12.1 |
| Reference build | chord 200, 20% aileron, 300 mm long, 20 deg | Sadraey ranges |

## 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
- Universidad de Sevilla course files (Sadraey, Aircraft Design, Ch. 12): [Design of Control Surfaces (Aileron)](https://aero.us.es/adesign/Slides/Extra/Stability/Design_Control_Surface/Chapter%2012.%20Desig%20of%20Control%20Surfaces%20%28Aileron%29.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/aileron/index.json · license: https://xemstudio.com/files/hardware/aileron/LICENSE.md

- aileron-wing-segment: [STEP](https://xemstudio.com/files/hardware/aileron/aileron-wing-segment.step) · [STL](https://xemstudio.com/files/hardware/aileron/aileron-wing-segment.stl) — aileron: wing segment 200 mm chord × 300 mm, 20 % chord surface deflected 20°

## Questions

**How much aileron throw?**

Sadraey suggests keeping deflection under about 25 deg to avoid aileron stall.

## Fits with

- [Frise aileron](https://xemstudio.com/objects/frise-aileron/)
- [Differential ailerons](https://xemstudio.com/objects/differential-ailerons/)
- [Elevon](https://xemstudio.com/objects/elevon/)
- [Flaperon](https://xemstudio.com/objects/flaperon/)
- [Spoiler](https://xemstudio.com/objects/spoiler/)
- [Trim tab and antiservo tab](https://xemstudio.com/objects/trim-tab/)