# Forward-swept wing

> What are the pros and cons of a forward-swept wing?

- 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/forward-swept-wing/ · JSON: https://xemstudio.com/api/geometry?object=forward-swept-wing · Plain text: https://xemstudio.com/objects/forward-swept-wing/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

- Leishman describes forward sweep as aeroelastically unstable and rarely used, because aerodynamic load twists the tips to higher incidence (ERAU).
- NASA's X-29 used composite aeroelastic tailoring, letting the wing bend but limiting twist to prevent divergence; reversed spanwise flow kept the tips and ailerons from stalling at high angle of attack, with good control to 45 deg (NASA FS-008).
- Forward sweep gives an unstable dihedral effect, so it needs more geometric dihedral than straight or swept-back wings (Kitplanes, Wainfan). The X-29 did not show the drag reduction earlier studies predicted (NASA).
- Used on: Grumman X-29.
- 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 |
|---|---|---|
| X-29 span / length | 27.2 ft / 48.1 ft | NASA FS-008 |
| X-29 controllable AoA | excellent to 45 deg; limited at 67 deg | NASA FS-008 |
| X-29 wash | washin toward tip (forward-swept) | ERAU (Leishman) |
| Reference build sweep | -30 deg LE (illustrative; no published angle fetched) | 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
- NASA Armstrong: [X-29 Fact Sheet FS-008](https://www.nasa.gov/wp-content/uploads/2021/09/fs-008-afrc.pdf) — web — Publisher's page; dimensions are facts
- Kitplanes (B. Wainfan): [Wind Tunnel: Roll's role in lateral stability (2008)](https://www.kitplanes.com/wind-tunnel-135/) — web — Publisher's page; dimensions are facts

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

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

- forward-swept-wing-wing: [STEP](https://xemstudio.com/files/hardware/forward-swept-wing/forward-swept-wing-wing.step) · [STL](https://xemstudio.com/files/hardware/forward-swept-wing/forward-swept-wing-wing.stl) — swept planform: span 1000, root 250, tip 120 mm, LE sweep -30°, dihedral 0°, NACA 2412

## Questions

**Why aren't forward-swept wings common?**

They tend toward structural divergence and need stiff, tailored structure (ERAU; NASA X-29).

## 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/)
- [Delta wing](https://xemstudio.com/objects/delta-wing/)
- [Cranked arrow / double delta wing](https://xemstudio.com/objects/cranked-double-delta-wing/)