# Tandem wing

> What is a tandem-wing aircraft and how does it stay stable?

- Category: Aircraft design › Tail configurations
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/tandem-wing/ · JSON: https://xemstudio.com/api/geometry?object=tandem-wing · Plain text: https://xemstudio.com/objects/tandem-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 tandem wing uses two lifting wings in line. The front wing gives pitch control and should stall first, which naturally limits angle of attack, comparable to a Rutan canard (Kitplanes, Flying Flea analysis).
- The Mignet HM.14 Flying Flea suffered fatal tuck-under dives; Baynes argued c.g. positions 'farther aft than 40% chord of the forward wing' made it unstable, and the vertical c.g. position added nonlinearity (Kitplanes).
- Once the c.g. was moved forward the rear wing carried little load; the Abbott-Baynes Cantilever Pou had a front wing almost twice the rear's area and was better seen as 'a monoplane with a large tail' (Kitplanes).
- Used on: Mignet HM.14 Pou-du-Ciel (Flying Flea), Abbott-Baynes Cantilever Pou, Mignet HM.293.
- 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 |
|---|---|---|
| C.g. limit cited for the Flea | not aft of 40% chord of the forward wing | Kitplanes (Baynes) |
| Cantilever Pou front/rear wing area | front almost 2x rear | Kitplanes |
| Fatal Flea accidents | at least 7 (possibly 11) | Kitplanes |
| Reference build | rear surface 300 x 60 mm at 500 mm (front wing is main wing) | illustrative |

## Where the files are

- Kitplanes (B. Wainfan): [Wind Tunnel: More Flying Fleas (2017)](https://www.kitplanes.com/wind-tunnel-65/) — web — Publisher's page; dimensions are facts
- NASA Langley (D. Satran): [Wind-Tunnel Investigation of the Flight Characteristics of a Canard General-Aviation Airplane Configuration, NASA TP-2623 (1986)](https://ntrs.nasa.gov/api/citations/19870000606/downloads/19870000606.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/tandem-wing/index.json · license: https://xemstudio.com/files/hardware/tandem-wing/LICENSE.md

- tandem-wing-tail: [STEP](https://xemstudio.com/files/hardware/tandem-wing/tandem-wing-tail.step) · [STL](https://xemstudio.com/files/hardware/tandem-wing/tandem-wing-tail.stl) — canard layout: horizontal span 600 × chord 100, vertical 120 × 90 mm on a 500 mm boom, NACA 0009 surfaces

## Questions

**Where should the c.g. be on a tandem wing?**

Forward enough that the front wing stalls first; Baynes put the Flea's limit at 40% of the front wing chord (Kitplanes).

## Fits with

- [Tail volume coefficient (horizontal and vertical tail sizing)](https://xemstudio.com/objects/tail-volume-coefficient/)
- [Tail moment arm (tail lever arm ratios)](https://xemstudio.com/objects/tail-moment-arm/)
- [Conventional tail (low-mounted stabiliser and single fin)](https://xemstudio.com/objects/conventional-tail/)
- [T-tail (stabiliser on top of the fin)](https://xemstudio.com/objects/t-tail/)
- [Cruciform tail (stabiliser part-way up the fin)](https://xemstudio.com/objects/cruciform-tail/)
- [V-tail (butterfly tail with ruddervators)](https://xemstudio.com/objects/v-tail/)