Feathered and fine props - can someone explain properly?
 

I've been searching Google for this one, but can't really find the proper explanation.

Can someone explain the terms fine and feathered pitch re. multi engine flight. I know that the fine setting is used during takeoff, rather like a low gear setting on a car. What I can't find the proper explaination on, is what exactly is 'feathering'?

Why is a propeller feathered if the engine fails?, how does that feathered propeller reduce the drag on the dead engine.

I've also been looking in the book Multi Engine Piston, but I can't find an explanation anywhere that I REALLY understand.

I'm hoping to do a MEP soon, so would really like a full understanding of the workings of the propeller beforehand.

Apologies if this post seems a bit daft

Ok a prop when driven by the engine produces thrust to propel the aircraft forward, when you have a problem and shut the engine down the prop will then as the blades of a windmill do turn in the airflow, this produces a lot of drag, also if the engine has suffered some damage the turning prop will be making that damage a whole lot worse as it is in effect turning the engine over........ but the worst thing is the drag on the side of the aircraft effected.

when you feather a prop you in effect turn the blades inline with the airflow, this stops the blades turning , reduces the drag and stops anymore damage being produced............

ok some useful links that will help you more understand the theory in an easy to follow style

http://www.auf.asn.au/groundschool/propeller.html

This prop is feathered.

http://img.photobucket.com/albums/v1...hered_prop.jpg

You can see, as NutLoose says, the blades of the prop are in line with the airflow.
In this position, it stops windmilling and, because of the streamlined shape, there is very little drag as it passes through the air.

FL

Send me a PM and I will send you the slides I wrote for teaching MEP and Constant speed prop.

Thanks for your imput. Flying Lawyer, the picture has made it clear, cheers

FD

Now, I can't resist asking, is that a Commanche?

These legal eagles sooooo clever.... It reminds me when I read of Einstein teaching the law of relativity, I think at Colorado, when he said "a wonderful thing happened at that blackboard .. suddenly I understood it!"
Seriously legal .. excellent picture and even I understand it!:D

Never seen a Twin Comanche with a 3-bladed prop.

Thank you for the compliment, but I don't deserve it.
The truth is I don't have any natural flair for mechanical/scientific matters so reduce anything I need to know to its simplest form so that even I can understand it. :)


I don't know the type shown in the photograph.
Any aircraft recognition enthusiasts able to identify it?


FL