Propeller blade twist is to provide somewhat of a constant aerodynamic pitch
(alpha) along as much of the blade as practical.
Propeller blade twist is a function of desired RPM and desired aircraft
speed, typically described as climb or cruise or race.
A propeller for an ultralight is nearly twistless.
A propeller for fast planes have quite a bit of twist.
Some of this twist at the root can be for improved ground cooling.
Controllable pitch propeller blades can have twist for climb or cruise.
In an installation w/ low power, blades w/ twist for climb is 'better'.
Then advancing the pitch at speed will get you some extra performance.
In a high power to airframe type ratio installation, the extra performance
is the improved launch and climb w/ finer pitch settings allowing the engine
to rev up and provide power.
Check out the twist of the popular choices.
I am currently researching these factors and might have a spreadsheet soon.
Nic - xs145
:)
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