Pitch-to-diameter ratio — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/pitch-diameter-ratio/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Catalog version: 2026-10-20

Sizes: see table below
- Pitch ratio (pitch divided by diameter) sets what the prop is good at. APC recommends a near-square ratio such as 9x9 for high-speed use and a low ratio such as 13x4 for aerobatics and hovering (Model Aviation, APC Q&A).
- Low-pitch props let the engine reach high rpm and maximum thrust at low speed, the same reason full-size constant-speed props use low blade angle for takeoff and higher pitch for cruise (FAA Powerplant Handbook).
- 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.

parameter  value or range  source
Speed example  9x9 (P/D = 1.0)  Model Aviation (APC)
Aerobatics / hover example  13x4 (P/D = 0.31)  Model Aviation (APC)
Full-size takeoff vs cruise  low blade angle takeoff; higher pitch cruise  FAA Powerplant Handbook
Reference build  13 x 4, 2 blades  APC example

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Model Aviation (AMA), J. Smith with APC Propellers: Common Questions with APC Propellers (Mar 2021) — web — Publisher's page; dimensions are facts — https://www.modelaviation.com/node/2115
- FAA: Aviation Maintenance Technician Handbook - Powerplant, Ch. 7 Propellers — web — Publisher's page; dimensions are facts — https://www.faa.gov/sites/faa.gov/files/09_amtp_ch7.pdf

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/pitch-diameter-ratio/index.json
API: https://xemstudio.com/api/geometry?object=pitch-diameter-ratio