# Leading-edge cuff (drooped leading edge)

> What does a leading-edge cuff do?

- Category: Aircraft design › Wing features
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/leading-edge-cuff/ · JSON: https://xemstudio.com/api/geometry?object=leading-edge-cuff · Plain text: https://xemstudio.com/objects/leading-edge-cuff/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 cuff extends the leading edge down and forward, lowering stall speed at a cruise-speed penalty (FAA PHAK ch.6).
- On NASA's canard GA model an outboard droop of about 6% chord extension and 3% camber over the outer 25% of span stopped premature tip stall, increased roll damping and eliminated wing rock; without it roll damping went unstable near 16 deg (NASA TP-2623).
- The reported cruise drag penalty was 0.0040 (NASA TP-2623, citing reference data).
- Used on: NASA canard GA model (TP-2623).
- 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 |
|---|---|---|
| Outboard droop geometry | ~6% chord extension, ~3% camber, outer 25% span | NASA TP-2623 |
| Roll damping without droop | unstable at ~16 deg AoA | NASA TP-2623 |
| Cruise drag penalty | 0.0040 | NASA TP-2623 |
| Reference build | chord 100, 6% extension on 25% of a 1200 span | NASA TP-2623 |

## Where the files are

- FAA: [Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), Ch. 6 Flight Controls](https://www.faa.gov/sites/faa.gov/files/08_phak_ch6.pdf) — 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/leading-edge-cuff/index.json · license: https://xemstudio.com/files/hardware/leading-edge-cuff/LICENSE.md

- leading-edge-cuff-wing-segment: [STEP](https://xemstudio.com/files/hardware/leading-edge-cuff/leading-edge-cuff-wing-segment.step) · [STL](https://xemstudio.com/files/hardware/leading-edge-cuff/leading-edge-cuff-wing-segment.stl) — Wing segment with a drooped/extended leading-edge cuff on the outer half (illustrative)

## Questions

**Where should a cuff go?**

Outboard: NASA used the outer 25% of span to keep the tips flying (TP-2623).

## Fits with

- [Plain flap](https://xemstudio.com/objects/plain-flap/)
- [Split flap](https://xemstudio.com/objects/split-flap/)
- [Slotted flap](https://xemstudio.com/objects/slotted-flap/)
- [Fowler flap](https://xemstudio.com/objects/fowler-flap/)
- [Leading-edge slat and fixed slot](https://xemstudio.com/objects/leading-edge-slat-slot/)
- [Gurney flap](https://xemstudio.com/objects/gurney-flap/)