Propeller helix angle and blade twist — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/propeller-helix-angle-blade-twist/  (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
- Blade angle is the angle between a blade section's chord and the plane of rotation; the tip moves much faster than the root, so the blade is twisted (pitch distribution) to keep each section at a useful angle of attack (FAA Powerplant Handbook).
- The FAA defines geometric pitch from the blade angle at the 75% station: GP = 2 x pi x R x tan(blade angle). Rearranged, a constant-pitch blade needs angle = atan(P / (2 pi r)) at every radius r, i.e. the angle falls toward the tip (helix-angle rule, derived from the FAA formula).
- Slip is the difference between geometric and effective pitch, and propeller efficiency varies from 50% to 87% depending on slip (FAA).
- 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
Geometric pitch  GP = 2 pi R tan(beta) at 75% station  FAA Powerplant Handbook
Blade angle for constant pitch  beta(r) = atan(P / (2 pi r))  derived from FAA formula
Example (derived), 10x6 prop  beta at 75% radius (3.75 in) = atan(6/(2 pi 3.75)) = 14.3 deg  computed
Propeller efficiency  50-87%  FAA Powerplant Handbook
Reference build  10 x 6, 2 blades  computed example

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- 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/propeller-helix-angle-blade-twist/index.json
API: https://xemstudio.com/api/geometry?object=propeller-helix-angle-blade-twist