Is prop/engine feathering physically possible to see? Like when the Lady Be Good crashed and they could tell.

Question

I'm reading a book on the WWII bomber Lady Be Good, which crashed in the Libyan desert. The inspectors found that 3 of her engines were feathered, or stopped I guess, before she crashed. How could they tell?

Answer 1

Prop feathering is the changing of the pitch angle of the propeller blade and is very noticeable.  When an engine ceases in flight if the propeller is left at its normal pitch angle it creates drag.  By feathing the propeller its pitch angle is increased (i.e. the propeller blades are rotated) and the drag is diminished as the back of the blade is no longer facing into the forward but now the edge of the blade is.

Answer 2

a picture is worth a thousand words...see:

http://images.google.com/imgres?imgurl=h...

Answer 3

Yes, there are a number of ways to tell. When a prop is feathered, its angle towards the wind is changed to a neutral position to avoid resistance. This is done whenever the engine is shut down to avoid drag and increase range. For instance, if I ran out of fuel and the engine died, I'd feather the prop so it would move through the air more easily and not slow the plane down. This would let me glide farther. Pilots do all of this with controls in the cockpit, so the first thing you'd want to investigate in a crash is the cockpit. Unless they're changed afterward, the gauges and controls will still be in the position they were in when the plane crashed. Unless the cockpit is destroyed, they'll tell you everything you need to know about the plane's operation right before the crash. If the pilots stopped the planes and feathered the props, the controls will show it. If the instruments and controls are damaged, the most obvious indication after the fact is that when a prop is rotating and it strikes the ground, one or more prop tips will be bent slightly in opposite direction from the rotation because the propeller blades are moving sideways against the ground when they hit. If the engine was stopped, the tips would only be bent backwards by the impact with the ground.