Constant speed prop

I have a question for which someone might have a answer. Why isn't it possible to feather the prop on a RV during a engine failure which would increase the glide range since the drag created by a windmilling prop would be non existent .

Dear bob the normal cs props are are configurated to go fine pitch if it lost oil pressure the other case is the aerobatics props that goes tu max pitch when lost oil press. I dont know if the aerobatics props goes to full feather.

Bob,
This is my understanding.

Normal hydraulic GA props are set up for the prop control failure mode to send the prop to fine pitch (ability for engine to produce full power assuming prop control failure). Since the prop control is based on engine oil, when the engine gives up the ghost, the prop control fails by default and the prop goes to fine pitch. Unfortunate consequence of the failure mode philosophy.
In addition, I believe counterweights are needed in order to provide the forces required to feather prop blades. As a result, the non-feathering GA props are lighter.

It is my understanding that for aerobatic craft, the desired prop control failure mode is course pitch in order to prevent overspeeding an engine if the control fails on a downhill maneuver. Therefore, counterweights on those props and different internal construction in the hub. Since I am not a aerobatic pilot, others should speak up to correct or add.

Beta

Why stop at a feathering propeller? Get one that goes into Beta.

Yeah but how do you back into a parking spot with a castering tailwheel or nosewheel??

Full feathering props are heavy and expensive.

Pulling the prop to coarse pitch will reduce the drag somewhat.

If you have plenty of altitude, stopping the prop will help even more.

The latter is recommended ONLY when you KNOW that there is no hope for a re-start.

rzbill said:

Yeah but how do you back into a parking spot with a castering tailwheel or nosewheel??

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VERY CAREFULLY!

rzbill said:

Yeah but how do you back into a parking spot with a castering tailwheel or nosewheel??

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Differential brakes.
I know a pilot who can parallel park a turbine Otter on wheels. Although he's cheating because that airplane has electric power steering on the tailwheel.

I had briefly thought about putting a reversing prop on my plane. Biggest concern is the engine cooling while in reverse. It would also be extremely expensive and a novelty feature that has very limited practical value.

Feathering

As Mel said, feathering props are heavy and expensive. They are generally used when there is a benefit to being able to feather - such as on twins. Feathering a failed engine allows you to continue flight (much more efficiently and with much less rudder- and most light piston twins won't maintain altitude at all without feathering the dead engine no matter if your leg gets tired of holding rudder or not) when you have an engine on the other side. With one engine, the outcome is the same with or without your heavy expensive prop - forced landing.

One of the Mooney conversions, I think the 262 "Missile" one, used a feathering prop because the glide ratio with the big engine up front wasn't good enough without it. Just stopping the prop has similar effects. As mentioned, probably not worth the weight penalty.

BobCollins(AA) said:

I have a question for which someone might have a answer. Why isn't it possible to feather the prop on a RV during a engine failure which would increase the glide range since the drag created by a windmilling prop would be non existent .

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Safety.

If your prop governor fails in flight, you can still fly the airplane.

If a full-feathering prop fails in flight, you cannot fly with it feathered.

If your engine fails, you are going down anyway. Fine pitch reduces your glide, but not so much that under ordinary circumstances you cannot pick a place to land. It could even be a benefit, helping you slow.

I've never heard that full-feathering, or even Beta-capable, props are heavier. They might be, but I don't believe it has anything to do with why single engine planes are generally equipped with props that fail to fine pitch.

Twin engine airplanes often have props that fail to feather for the same reason - safety. If one engine or one prop fails, you can still fly the airplane.

breister said:

Safety.

If your prop governor fails in flight, you can still fly the airplane.

If a full-feathering prop fails in flight, you cannot fly with it feathered.

If your engine fails, you are going down anyway. Fine pitch reduces your glide, but not so much that under ordinary circumstances you cannot pick a place to land. It could even be a benefit, helping you slow.

I've never heard that full-feathering, or even Beta-capable, props are heavier. They might be, but I don't believe it has anything to do with why single engine planes are generally equipped with props that fail to fine pitch.

Twin engine airplanes often have props that fail to feather for the same reason - safety. If one engine or one prop fails, you can still fly the airplane.

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Feathering props usually have counter weights and an unfeathering accumulator.

I have a three blade MT with counter weights and acro governor on my -7. When I idle the engine and pull the prop to low pitch, you can feel the acceleration. Practicing engine outs over my home field, I found myself pushing the prop back in on final most of the time as it was obvious I would overshoot by a lot when flying my normal close pattern. It's a significant difference. Maybe one of these days I will try to figure out what the glide ratio increase is, but for now I have pulling the prop to low pitch as part of my engine out checklist.