# Propeller slip and efficiency

> What is propeller slip?

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

- Geometric pitch is how far a prop should advance per revolution with no slip; effective pitch is how far it actually advances. Slip is the difference (FAA Powerplant Handbook).
- Efficiency, thrust horsepower over brake horsepower, ranges from 50% to 87% depending on slip (FAA). APC publishes performance data from vortex-theory simulations by rpm and airspeed for comparing props (Model Aviation, APC Q&A).
- 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 |
|---|---|---|
| Slip | geometric pitch - effective pitch | FAA Powerplant Handbook |
| Efficiency range | 50-87% | FAA Powerplant Handbook |
| APC data basis | vortex theory, by rpm and airspeed | Model Aviation (APC) |

## Where the files are

- FAA: [Aviation Maintenance Technician Handbook - Powerplant, Ch. 7 Propellers](https://www.faa.gov/sites/faa.gov/files/09_amtp_ch7.pdf) — web — Publisher's page; dimensions are facts
- Model Aviation (AMA), J. Smith with APC Propellers: [Common Questions with APC Propellers (Mar 2021)](https://www.modelaviation.com/node/2115) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/propeller-slip-efficiency/index.json · license: https://xemstudio.com/files/hardware/propeller-slip-efficiency/LICENSE.md

- propeller-slip-efficiency-propeller: [STEP](https://xemstudio.com/files/hardware/propeller-slip-efficiency/propeller-slip-efficiency-propeller.step) · [STL](https://xemstudio.com/files/hardware/propeller-slip-efficiency/propeller-slip-efficiency-propeller.stl) — 10×6 in propeller, 2 blades: each section set at the geometric pitch angle atan(P / 2πr); chord and section illustrative

## Questions

**How efficient is a propeller?**

Between 50% and 87% depending on slip (FAA Powerplant Handbook).

## Fits with

- [Propeller diameter vs pitch](https://xemstudio.com/objects/propeller-diameter-vs-pitch/)
- [Pitch-to-diameter ratio](https://xemstudio.com/objects/pitch-diameter-ratio/)
- [Propeller blade count (2, 3 and 4 blades)](https://xemstudio.com/objects/propeller-blade-count/)
- [Propeller helix angle and blade twist](https://xemstudio.com/objects/propeller-helix-angle-blade-twist/)
- [APC propeller RPM limits](https://xemstudio.com/objects/apc-propeller-rpm-limits/)
- [Propeller naming suffixes (E, SF, MR, P, W, N, C)](https://xemstudio.com/objects/apc-propeller-naming/)