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A silly question about constant speed props

tedka

I'm New Here
Hello,
This is my very first post on this Web site :)!
I wonder why a mechanism similar to a collective pitch control found in helicopter swash plates
https://en.wikipedia.org/wiki/Swashplate_(aeronautics)#Collective_blade_control
(and in automotive and other clutch (dis)engagement mechanisms as well) is not used in constant speed propellers (at least, I was unable to google anything like that). From the common sense point of view, such a mechanism would be simpler, cheaper and more reliable than a typical hydraulic pitch control mechanism found in piston engines. Plus, it could be used on any engine (even those not provisioned for hydraulic constant speed propellers),and could be driven by a hydraulic cylinder, an electric motor or even purely mechanically (by a cable or a control rod). It could be used together with any kind of an RPM control unit - a mechanical or electronic one. I am just curious.
Thanks in advance!
 
The pitch change mechanism in a C/S prop is very much like a collective in a rotor hub. Very simple, robust, and reliable. But you still need the "brains" to control it, and that's found in the prop governor - also a fairly simple, robust, and reliable piece.
 
Here’s the maintenance manual for legacy Hartzell props that were used on old Navions/Bonanzas with the “E” series engines. The cut away drawings start on page 2-8. These things have An external operating mechanism like the collective on most helicopters. It has a diaphragm, external drag links and a huge bearing similar to a throw out bearing. I can attest that things get really messy if that bearing fails. Any way here’s the link. The newer arrangements like Vans sells make a much cleaner robust installation.

https://hartzellprop.com/wp-content/uploads/140-0000-R03-AW.pdf#page73

YMMV

BOB
 
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