# Gull wing

> What is a gull wing and why was it used?

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

- A gull wing rises steeply from the root, then flattens outboard. On the PBM Mariner flying boat the gull wing 'kept the vulnerable engines out of the salt spray' and avoided the external bracing a parasol wing like the Catalina's needed (Smithsonian NASM).
- Wainfan notes changes at the wingtips matter more for lateral stability than changes near the root, and part-span dihedral needs slightly more outer-panel dihedral to match a constant-dihedral wing (Kitplanes).
- Used on: Martin PBM Mariner.
- 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 |
|---|---|---|
| PBM Mariner wing | gull wing on deep hull; engines above spray | Smithsonian NASM |
| Part-span dihedral rule | outer panels need slightly more dihedral | Kitplanes (Wainfan) |
| Reference build angles | illustrative (no published angle fetched) | illustrative |

## Where the files are

- Smithsonian National Air and Space Museum: [Martin PBM-5A Mariner](https://si.edu/object/martin-pbm-5a-mariner:nasm_A19730270000) — 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/gull-wing/index.json · license: https://xemstudio.com/files/hardware/gull-wing/LICENSE.md

- gull-wing-wing: [STEP](https://xemstudio.com/files/hardware/gull-wing/gull-wing-wing.step) · [STL](https://xemstudio.com/files/hardware/gull-wing/gull-wing-wing.stl) — gull planform: span 1000, root 200, tip 120 mm, LE sweep 0°, dihedral 5°, NACA 2412

## Questions

**Why did flying boats use gull wings?**

To raise engines above the spray without parasol bracing (Smithsonian NASM, PBM Mariner).

## 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/)