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CS Props/Eng Combos that are controllable eng OUT

W

wawrzynskivp

Well Known Member
Resultant Feedback:
1. Electrically controlled props
2. MT Three Blade MTV-12-B/183-59b, on YIO 390 down to 80 Kts
3. IO-360A1B6 with non-aerobatic Hartzell prop and MT Governor down to 80 Kts
4. 0 320 with a Hartzell prop with the MT gov

Looks like the common thread on a non-aero CS hydraulic prop is an MT governor. My understanding is that the governor is both a regulator and an oil pressure booster. So perhaps the MT governor has a higher oil pressure output at lower RPMs than other governors.

Would be nice to have a prop person like the folks at Catto weigh in.

Original question:


Hello All,

I would like to try to harvest some anecdotal information and repost a summary of which CS props and engine combinations yield control in engine out scenarios.

If you have done true no engine power testing (Not idle, but truly no power) and found that you can still control your prop to the course position please post your prop/governor/engine and lowest observed controllable airspeed in Knots.

Ideally a builder could consider this aspect of extended glide as worth one prop combo or another.
 
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wawrzynskivp said:
Hello All,

I would like to try to harvest some anecdotal information and repost a summary of which CS props and engine combinations yield control in engine out scenarios.

If you have done true no engine power testing (Not idle, but truly no power) and found that you can still control your prop to the course position please post your prop/governor/engine and lowest observed controllable airspeed in Knots.

Ideally a builder could consider this aspect of extended glide as worth one prop combo or another.
Click to expand...

... Aerobatic C/S propellers all automatically go to course pitch on engine stoppage. Thanks, Allan:D
 
Aerobatic Props

PerfTech said:
... Aerobatic C/S propellers all automatically go to course pitch on engine stoppage. Thanks, Allan:D
Click to expand...

This is not exactly true. The "counterweighted" aerobatic props are designed to go to coarse pitch upon loss of oil pressure, but if the engine stops producing thrust while maintaining oil pressure the prop will continue to "govern"...

With that said, my IO-360A1B6 with non-aerobatic Hartzell prop and MT Governor (circa 2006) is fully controllable in a true engine-out glide. I have tested this down to ~ 80 KIAS. At 100 KIAS, the difference between prop lever forward and prop lever aft is ~1500 RPM/~600 RPM.

Skylor
 
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skylor said:
This is not exactly true. The "counterweighted" aerobatic props are designed to go to coarse pitch upon loss of oil pressure, but if the engine stops producing thrust while maintaining oil pressure the prop will continue to "govern"...

With that said, my IO-360A1B6 with non-aerobatic Hartzell prop and MT Governor (circa 2006) is fully controllable in a true engine-out glide. I have tested this down to ~ 80 KIAS. At 100 KIAS, the difference between prop lever forward and prop lever aft is ~1500 RPM/~600 RPM.

Skylor
Click to expand...

How did you test that?
 
skylor said:
This is not exactly true. The "counterweighted" aerobatic props are designed to go to coarse pitch upon loss of oil pressure, but if the engine stops producing thrust while maintaining oil pressure the prop will continue to "govern"...

With that said, my IO-360A1B6 with non-aerobatic Hartzell prop and MT Governor (circa 2006) is fully controllable in a true engine-out glide. I have tested this down to ~ 80 KIAS. At 100 KIAS, the difference between prop lever forward and prop lever aft is ~1500 RPM/~600 RPM.

Skylor
Click to expand...

....I was referring to prop stopped, and the hub with the spring reversed. You have zero RPM prop stopped.
 
swjohnsey said:
How did you test that?
Click to expand...

While well above an airport, I established a glide at idle, then pulled the mixture to ICO. When finished with the test point, advancing the mixture then throttle results in immediate power.

Skylor
 
So the engine was still turning and producing oil pressure? I have similar setup, IO-360 with Hartzell CS.
 
As long as the engine is turning, the oil pump and governor will be able to control a hydraulically actuated prop. This goes for windmilling too as the pumps and accessories don't know what the source of engine rotation.
 
David Z said:
As long as the engine is turning, the oil pump and governor will be able to control a hydraulically actuated prop. This goes for windmilling too as the pumps and accessories don't know what the source of engine rotation.
Click to expand...

This is not universally true.

We have done engine off glide testing in the RV-10 and RV-14 demonstrators and I can say for certain (I was pilot for the tests on the RV-10) that on our RV-10, prop control position made zero difference on decent rate or RPM. I think that was the case for the RV-14A as well.

I have read reports that I consider reliable, of tests that did indicate that pulling the blue knob increase glide performance, so I don't know what factors are in play when it doesn't. My guess would be that it is related to what the minimum RPM is that you can control the propeller while the engine is running. If the wind milling RPM is below this value, pulling the blue knob on a wind milling engine will have no effect.

So I suggest not assuming that it will help, but I know of no down side to doing it, in case it will.
 
I have tested both the Hartzell and MT governors on my 0 320 with a Hartzell prop. Engine out (mixture at idle cutoff) the MT will govern a windmilling prop but the Hartzell governor will not.

Fin 9A
 
Finley Atherton said:
I have tested both the Hartzell and MT governors on my 0 320 with a Hartzell prop. Engine out (mixture at idle cutoff) the MT will govern a windmilling prop but the Hartzell governor will not.

Fin 9A
Click to expand...

... If you are trying to extend the glide as far as possible, you need to feather
the prop, pull the nose up and stop the prop. If this extended glide is a point
of concern for you, and you are building, you need to decide on the prop hub
that will address this, and allow you to feather or at least keep the prop in
course pitch when engine is stopped. There are advantages and disadvantages
to each configuration, but for extended glide you want prop stopped, and as
course a pitch as possible. Thanks, Allan--:D
 
PerfTech said:
... If you are trying to extend the glide as far as possible, you need to feather
the prop, pull the nose up and stop the prop. If this extended glide is a point
of concern for you, and you are building, you need to decide on the prop hub
that will address this, and allow you to feather or at least keep the prop in
course pitch when engine is stopped. There are advantages and disadvantages
to each configuration, but for extended glide you want prop stopped, and as
course a pitch as possible. Thanks, Allan--:D
Click to expand...

You can't have full course pitch and prop. stopped with a conventional propeller.

Course pitch wind milling is the next best thing.
Prop fully stopped may be the best but in an emergency, slowing to a speed that causes that to happen is not always an option.
 
rvbuilder2002 said:
This is not universally true.

We have done engine off glide testing in the RV-10 and RV-14 demonstrators and I can say for certain (I was pilot for the tests on the RV-10) that on our RV-10, prop control position made zero difference on decent rate or RPM. I think that was the case for the RV-14A as well.

I have read reports that I consider reliable, of tests that did indicate that pulling the blue knob increase glide performance, so I don't know what factors are in play when it doesn't. My guess would be that it is related to what the minimum RPM is that you can control the propeller while the engine is running. If the wind milling RPM is below this value, pulling the blue knob on a wind milling engine will have no effect.

So I suggest not assuming that it will help, but I know of no down side to doing it, in case it will.
Click to expand...

Suppose I should have continued my statement. The governor will be able to control the prop with engine rotation WITHIN the governing range of the system. Can't go more coarse than the coarse pitch stops or more fine than the fine pitch stops. Can't govern at RPM below the minimum governing RPM or above the max governing RPM.

With the engine rotating, the prop will still function as it had regardless of what is causing the engine to turn.

A feathering prop on an RV would be interesting. Has anybody tried that? I suppose it's quite reasonable to take the whole engine/prop combo off a Piper Seminole or Twin Comanche and put it on an RV.
 
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David Z said:
Suppose I should have continued my statement. The governor will be able to control the prop with engine rotation WITHIN the governing range of the system. Can't go more coarse than the coarse pitch stops or more fine than the fine pitch stops. Can't govern at RPM below the minimum governing RPM or above the max governing RPM.

With the engine rotating, the prop will still function as it had regardless of what is causing the engine to turn.
Click to expand...

I agree with that statement as long as it is meant that on some airplanes the wind milling RPM may be lower than the minimum RPM that the gov. can control the prop.
In those cases, moving the prop control will have zero effect.
 
Prop

The Twin Commanche has a special extended shaft prop and requires the type 2?? engine mount angle so it would be a major project not even considering the CG issues. Feathering props are used on single engine turboprops but I have never heard of on e on a piston single.
 
jrs14855 said:
The Twin Commanche has a special extended shaft prop and requires the type 2?? engine mount angle so it would be a major project not even considering the CG issues. Feathering props are used on single engine turboprops but I have never heard of on e on a piston single.
Click to expand...

I actually heard of a story of an experimental race plane (years ago) that had a feathering prop installed in spite of warnings to the owner from some folks. The plane was involved in a non-fatal accident that was the result of the prop inadvertently going full-feather in flight resulting in 0 thrust. This is probably not a good idea on a single engine piston where you only have 1 prop.

Skylor
 
David Z said:
Suppose I should have continued my statement. The governor will be able to control the prop with engine rotation WITHIN the governing range of the system. Can't go more coarse than the coarse pitch stops or more fine than the fine pitch stops. Can't govern at RPM below the minimum governing RPM or above the max governing RPM.

With the engine rotating, the prop will still function as it had regardless of what is causing the engine to turn.

A feathering prop on an RV would be interesting. Has anybody tried that? I suppose it's quite reasonable to take the whole engine/prop combo off a Piper Seminole or Twin Comanche and put it on an RV.
Click to expand...

... A couple of points that we have done a considerable amount of experimenting with and could possibly help in an engine out situation. if you put the prop in course pitch with engine rotating, then go idle cut off, then to full throttle, the engine is required to do more work as a compressor and will come to an abrupt stop, thus facilitating the best glide. I actually reworked the internal stops in my prop to allow far more course travel. Not quite a full feather, but close, and at that configuration my 9-A feels like a sailplane.
Thanks, Allan--:D
 
skylor said:
I actually heard of a story of an experimental race plane (years ago) that had a feathering prop installed in spite of warnings to the owner from some folks. The plane was involved in a non-fatal accident that was the result of the prop inadvertently going full-feather in flight resulting in 0 thrust. This is probably not a good idea on a single engine piston where you only have 1 prop.

Skylor
Click to expand...

Every plane I've flown with feathering props had a pretty obvious gate or detent to overcome before feathering occurred. If rigged properly, this prevents inadvertent feathering. I've never heard of a prop inadvertently feathering outside of a mechanic rigging the prop controls. I mostly see feathering capability as unnecessary complexity, cost and weight for our planes. In a twin, it's a life saving capability, but that's a different cup of tea.

Now a reversing propeller, I'd LOVE to be able to back up into a parking spot. :D Let's just ignore the added complexity, cost, weight and cooling issues for a useless party trick.
 
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