Constant speed propellers – I know the basics, they hold engine speed by varying prop pitch for us, engine power permitting. I have been confused by a couple things. So, I started searching, and most of the info out there is pretty darned weak. I am after why we should do what is already the norm, if we should maybe do something different, and how the physics of the things is made to do what we want...
Being as an engine, prop, prop type, and accompanying governor is getting close, I feel I should be making a decision, not just following the crowd.
Conventional Singles – dropping oil pressure drives the prop to flat pitch.
How often do governors fail in flight as compared to how often engines quit making power in flight? And how severe is each of the failures? Seems a flat pitch prop will give us a shorter gliding range than a feathered prop...
Last is the counterweights. As I get it, counterweights are on feathering props to help them go to feather. Somebody please explain to me what is happening with counterweights and where they are applied to the blade. I am having trouble figuring out how such a thing would cause rotation of the blade towards feather. It looks like the change in radius from the prop centerline is pretty darned small as the prop blade rotates…
I suspect that the first answers will drive a bunch more discussion.
Billski
Being as an engine, prop, prop type, and accompanying governor is getting close, I feel I should be making a decision, not just following the crowd.
Conventional Singles – dropping oil pressure drives the prop to flat pitch.
- The only explanation I found for this is a governor failure with a running engine allows the airplane to be flown at the low end of its airspeed. The down side is that the prop is in the highest drag configuration when the engine quits.
- Is this all the explanation for the choice? Any more to it? I would love to know the rest of the story if there is more…
- I suspect that the governor for this prop is different from the governor for a feathering prop… Please correct me if wrong.
- The explanation I found for this is that rapid feathering after an engine failure reduces yaw and torque so that a twin can be controllable on one good engine and one dead engine.
- Is this all the explanation for the choice? Any more to it? I would love to know the rest of the story if there is more…
- I suspect that the governor for this prop is different from the governor for a conventional single… Please correct me if wrong.
- Why run an aerobatic bird differently from a conventional single?
- Different governor or same as one for a twin?
How often do governors fail in flight as compared to how often engines quit making power in flight? And how severe is each of the failures? Seems a flat pitch prop will give us a shorter gliding range than a feathered prop...
Last is the counterweights. As I get it, counterweights are on feathering props to help them go to feather. Somebody please explain to me what is happening with counterweights and where they are applied to the blade. I am having trouble figuring out how such a thing would cause rotation of the blade towards feather. It looks like the change in radius from the prop centerline is pretty darned small as the prop blade rotates…
I suspect that the first answers will drive a bunch more discussion.
Billski
