Feathered propellers...?

Question

What does it mean when propellers are feathered?

Answer 1

Feathering is accomplished by releasing the governor oil pressure, allowing the counterweights and feathering spring to feather the blades. This is done by pulling the governor pitch control back to the limit of its travel, which opens up a port in the governor allowing the oil from the propeller to drain back into the engine. The time necessary to feather depends upon the size of the oil passage from the propeller to the engine, and the force exerted by the spring and counterweights. The larger the passages through the governor and the heavier the spring, the quicker is the feathering action. Elapsed time for feathering, between three and ten seconds, is usual with this system.

The ability to unfeather the blades, or re-establish normal pitch, within the same elapsed time is not considered important for the light twin-engine airplane. The possibility of feathering the wrong propeller in an emergency is remote, as the wrong action will become apparent in ample time to be corrected. Furthermore, the requirement to restart the dead engine for landing does not exist, as the light twin can easily be landed with only one engine. About the only requirement for unfeathering is for demonstration purposes.

What all of the above means is a propeller is set to a pitch or bite to pull the aircraft thru the air. When the propeller is feathered the pitch goes to zero of no bite and the air passes over the propeller blades without creating drag.

You can read more on this in AC 65-12 just type it into a search engine or go the FAA.gov web site and search from there.

Answer 2

It means the blades are lined up with the airflow. This prevents the prop from being turned by the air when an engine is shut down, reducing drag.

The method of feathering and un-feathering a propeller varies greatly between different propeller models.

Answer 3

Here's the LEAST technical explanation:

There are two ways to control thrust in a prop driven plane... one is the adjust the engine throttle. Usually then a fixed-pitch propeller is in used. The other way is to adjust the propeller pitch, while the engine itself remains at constant speed.

Only "variable pitch" prop can be "feathered". Variable pitch means the blade "angle" can be adjusted for maximum "bite" into the air, or MINIMAL bite into the air (feathered).

Why feather a propeller? An unfeathered propeller creates drag, which is bad for air speed. And in a multi-engine plane, asymmetrical thrust (different amount of thrust from different engines) is bad for control. (EDIT: Imagine one engine is pulling, and the other is actually pushing!) While it is possible to keep the plane level, you would have applied so much rudder that the plane is actually sideslipping through the air, and airspeed is way down, and it could go down far enough that you can no longer maintain altitude.

By feathering the propeller, you reduce drag and the thrust is no longer (edit: add VERY) asymmetrical, just a little bit off center, and that doesn't affect the plane nearly as much. Now the plane can keep flying without losing altitude, and find a safe place to land.

EDIT: Here's a MORE detailed explanation

http://selair.selkirk.bc.ca/aerodynamics1/Multi/Page2.html

Answer 4

When the propeller is feathered the blades are rotated to the high pitch stop (88 degrees blade angle) by the feathering pump. This puts the blades in an aerodynamic lock which prevents and further rotation of the prop and the engine. The prop can be feathered by various means depending on the aircraft type. Please feel free to ask if you want more info on this.
If the prop has been feathered because of fire or engine failure then it remains feathered for the duration of the flight. If it is feathered for training purposes or test flight then it can quite easily be UN-feathered and the engine restarted. Again depends on aircraft type.
On the P3 it was normal to shut down No1 engine for "loiter shutdown". This was done to conserve fuel.

Kasey C - you may be a top contributer to computer stuff - so please stick to that and leave Aviation to those who know what they are talking about.
Enjoy your two points, but you contributed nothing to this subject.

Answer 5

When the pitch is taken out of the propeller to eliminate any thrust or drag comming from the pitched propeller.

on a twin engine airplane, if one engine quits you feather it and make less drag.

Answer 6

The blades are rotated so that they point into the slipstream, so there is no momentum transferred between the propeller and the airstream. This reduces the drag if an engine fails.