# Vortex generators

> How do you size and place vortex generators?

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

- Vortex generators are small vanes that stir high-energy air into the boundary layer to delay separation; full-span VGs reduce stall speed, outboard-only VGs mainly improve stall behaviour and aileron control (Kitplanes, Wainfan).
- First-try height is about 1.2x local boundary-layer thickness (roughly 1-2% of distance from the leading edge), at 15-20 deg to the flow, slightly upstream of the natural separation point (Kitplanes).
- Drag can be significant on laminar wings (Kitplanes); on the S1223 airfoil VGs caused an abrupt stall with hysteresis between 16 and 20 deg (Selig & Guglielmo).
- Used on: Beech Baron (retrofit), Rutan Voyager, Beech Starship, Boeing 727 fin.
- 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 |
|---|---|---|
| Height | ~1.2 x boundary-layer thickness | Kitplanes (Wainfan) |
| Boundary layer thickness | ~1-2% of distance from LE | Kitplanes |
| Angle to flow | 15-20 deg | Kitplanes |
| Co-rotating: root chord / spacing | ~4h / 5-6h | Kitplanes |
| Counter-rotating: root chord / pair spacing | ~2.5h / ~10h between pairs | Kitplanes |
| Reference build | chord 100, VG at 20 deg | Kitplanes |

## Where the files are

- Kitplanes (B. Wainfan): [Wind Tunnel: Vortex Generators and STOL Performance (2012)](https://www.kitplanes.com/wind-tunnel-14/) — web — Publisher's page; dimensions are facts
- University of Illinois (Selig & Guglielmo), Journal of Aircraft 1997: [High-Lift Low Reynolds Number Airfoil Design (S1223)](https://m-selig.web.engr.illinois.edu/pubs/GuglielmoSelig-1997-JofAC-S1223.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/vortex-generators/index.json · license: https://xemstudio.com/files/hardware/vortex-generators/LICENSE.md

- vortex-generators-wing-segment: [STEP](https://xemstudio.com/files/hardware/vortex-generators/vortex-generators-wing-segment.step) · [STL](https://xemstudio.com/files/hardware/vortex-generators/vortex-generators-wing-segment.stl) — Wing segment, NACA 2412 100 mm chord, with a row of vortex generators at 25 % chord (illustrative size)

## Questions

**Where do VGs go on the chord?**

Just ahead of where the flow would naturally separate (Kitplanes).

## Fits with

- [Plain flap](https://xemstudio.com/objects/plain-flap/)
- [Split flap](https://xemstudio.com/objects/split-flap/)
- [Slotted flap](https://xemstudio.com/objects/slotted-flap/)
- [Fowler flap](https://xemstudio.com/objects/fowler-flap/)
- [Leading-edge slat and fixed slot](https://xemstudio.com/objects/leading-edge-slat-slot/)
- [Gurney flap](https://xemstudio.com/objects/gurney-flap/)