# Washout (wing twist)

> What is washout and how much should a wing have?

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

- Washout twists the wing so the tip is at a lower incidence than the root; it keeps the root stalling first so ailerons keep working (Boldmethod) and lets tip and root reach their angle of attack together on swept wings (R/C Soaring Digest).
- Leishman gives typical washout between 0 and 10 deg nose-down, more being unusual; washin (tip nose-up) appears on the X-29's forward-swept wing (ERAU).
- Twist can also tune the span loading toward elliptical (Kitplanes).
- Used on: X-29 (washin).
- 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 |
|---|---|---|
| Typical washout | 0-10 deg nose-down | ERAU (Leishman) |
| Washin example | X-29 forward-swept wing | ERAU |
| Historic wing-warp turn trim (models) | about 1-3 deg tip washin | McCombs 1992 |
| Reference build | tapered 0.45 wing (twist parameter not in builder) | illustrative |

## Where the files are

- Embry-Riddle (Leishman), Introduction to Aerospace Flight Vehicles: [Wing Shapes and Nomenclature](https://eaglepubs.erau.edu/introductiontoaerospaceflightvehicles/chapter/wing-shapes-and-nomenclature/) — web — Publisher's page; dimensions are facts
- Boldmethod (pilot training): [How Stall Strips Keep Your Plane Under Control](https://www.boldmethod.com/learn-to-fly/aerodynamics/how-stall-strips-keep-your-plane-under-control/) — web — Publisher's page; dimensions are facts
- R/C Soaring Digest: [Twist Distributions for Swept Wings, Part 2 (June 2002)](https://new.rcsoaringdigest.com/2002/06/twist-distributions-for-swept-wings/[pdf].pdf) — web — Publisher's page; dimensions are facts
- Kitplanes (B. Wainfan): [Design Process: Planform Effects on Span Loading and Drag (2020)](https://www.kitplanes.com/design-process-planform-effects-on-span-loading-and-drag/) — web — Publisher's page; dimensions are facts
- Model Aviation (AMA), W.F. McCombs: [Vertical Tail Size for Models (Apr 1992)](https://library.modelaviation.com/article/vertical-tail-size-models-1) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/washout-wing-twist/index.json · license: https://xemstudio.com/files/hardware/washout-wing-twist/LICENSE.md

- washout-wing-twist-wing: [STEP](https://xemstudio.com/files/hardware/washout-wing-twist/washout-wing-twist-wing.step) · [STL](https://xemstudio.com/files/hardware/washout-wing-twist/washout-wing-twist-wing.stl) — tapered planform: span 1000, root 220, tip 99 mm, LE sweep 0°, dihedral 3°, NACA 2412

## Questions

**How much washout for an RC wing?**

Leishman gives 0-10 deg as the usual range; swept and tailless wings need more than straight ones (ERAU; R/C Soaring Digest).

## Fits with

- [Rectangular (constant-chord) wing](https://xemstudio.com/objects/rectangular-wing/)
- [Tapered wing (taper ratio for minimum induced drag)](https://xemstudio.com/objects/tapered-wing/)
- [Elliptical wing](https://xemstudio.com/objects/elliptical-wing/)
- [Swept-back wing](https://xemstudio.com/objects/swept-wing/)
- [Forward-swept wing](https://xemstudio.com/objects/forward-swept-wing/)
- [Delta wing](https://xemstudio.com/objects/delta-wing/)