# Anhedral on ground-effect wings

> Why do ground-effect craft wings droop?

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

- Lippisch craft used inverse dihedral so the tips or sponsons touch the water while the hull stays above it, forming a high-pressure 'air tunnel' under the wing (Rozhdestvensky; Frontiers 2022).
- On a reverse-delta wing tested at 8-45 deg anhedral, 15 deg was selected; at h/c near 0 the anhedral configuration gave lift increases of 270% (8 deg) and 150% (45 deg) over free flight (Frontiers 2022 review).
- Used on: Lippisch X-113.
- 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 |
|---|---|---|
| Anhedral tested / selected | 8-45 deg / 15 deg | Frontiers 2022 |
| Lift increase at h/c ~ 0 | 270% (8 deg), 150% (45 deg) | Frontiers 2022 |
| Reference build | span 700, root 400, anhedral 15 | Frontiers 2022 |

## Where the files are

- Progress in Aerospace Sciences (K.V. Rozhdestvensky, 2006): [Wing-in-ground effect vehicles (review)](https://www.hassanhameed.com/wp-content/uploads/2016/01/wingingroundeffectvehicles-130120003005-phpapp01.pdf) — web — Publisher's page; dimensions are facts
- Frontiers in Aerospace Engineering (2022): [Review of ground-effect experiments on rectangular, reverse-delta and delta wings](https://www.frontiersin.org/journals/aerospace-engineering/articles/10.3389/fpace.2022.975158/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/wig-anhedral/index.json · license: https://xemstudio.com/files/hardware/wig-anhedral/LICENSE.md

- wig-anhedral-wing: [STEP](https://xemstudio.com/files/hardware/wig-anhedral/wig-anhedral-wing.step) · [STL](https://xemstudio.com/files/hardware/wig-anhedral/wig-anhedral-wing.stl) — Lippisch reverse delta: straight leading edge, trailing edge swept forward to the tips, span 700, root 400 mm, anhedral 15° (scale to your craft)

## Questions

**How much anhedral for a WIG model?**

One reverse-delta study chose 15 deg (Frontiers 2022).

## Fits with

- [Ground effect: height/span ratio and induced-drag reduction](https://xemstudio.com/objects/ground-effect-height-span-ratio/)
- [Ground effect: height/chord ratio (ram / chord-dominated regime)](https://xemstudio.com/objects/ground-effect-height-chord-ratio/)
- [Lippisch reverse-delta ground-effect craft](https://xemstudio.com/objects/lippisch-reverse-delta-wig/)
- [Ekranoplan layout (low wing + high tailplane out of ground effect)](https://xemstudio.com/objects/ekranoplan-wing-tail-layout/)
- [Tandem-wing ground-effect craft (Jorg type)](https://xemstudio.com/objects/tandem-wig-configuration/)
- [Power-augmented ram (PAR)](https://xemstudio.com/objects/power-augmented-ram-par/)