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  #1  
Old 11-24-2009, 02:11 AM
Doug Rodrigues Doug Rodrigues is offline
 
Join Date: Aug 2005
Location: Lockwood (8 miles east of Reno), Nevada
Posts: 85
Default Pros or Cons: Full feathering Hartzell hc92zk-2B 8447-12a

Does anyone have any comments about mounting a full feathering Hartzell prop from a Twin Beech Travel Air to a O-360A1D on an RV-8? The Travel Air cruise speed is about the same as an RV-8....I think? Don't know about the prop governer though?
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  #2  
Old 11-24-2009, 11:54 PM
Dragonfly Dragonfly is offline
 
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Is there a particular reason your thinking of full feathering? have you got a deal on it?
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  #3  
Old 11-25-2009, 03:47 AM
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Kevin Horton Kevin Horton is offline
 
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Location: Ottawa, Canada
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Quote:
Originally Posted by Doug Rodrigues View Post
Does anyone have any comments about mounting a full feathering Hartzell prop from a Twin Beech Travel Air to a O-360A1D on an RV-8? The Travel Air cruise speed is about the same as an RV-8....I think? Don't know about the prop governer though?
Having a full feathering prop would buy you a small amount of glide performance improvement, but adds a new failure mode. If the prop governor fails, the prop will feather. Personally, I would prefer to not have a feathering prop, unless I had a multi-engine aircraft.
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  #4  
Old 11-25-2009, 05:08 PM
Doug Rodrigues Doug Rodrigues is offline
 
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Default It's a good deal.....but....

I've been talked out of it. Too many unknowns and maybes, plus no aid in slowing down with the power pulled way back. It was just a consideration of getting a prop cheap and into the air faster.
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  #5  
Old 11-25-2009, 05:56 PM
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n5lp n5lp is offline
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Location: Carlsbad, NM
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Quote:
Originally Posted by Doug Rodrigues View Post
I've been talked out of it. Too many unknowns and maybes, plus no aid in slowing down with the power pulled way back...
It would still have the braking effect of any other CS prop.
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  #6  
Old 11-25-2009, 07:27 PM
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Kevin Horton Kevin Horton is offline
 
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Quote:
Originally Posted by Doug Rodrigues View Post
... plus no aid in slowing down with the power pulled way back.
As long as the engine is developing oil pressure, and the prop governor, oil line to prop, etc are serviceable, it will work like any other constant speed prop. I.e. the prop governor will control the blade pitch to attempt to keep the rpm at the selected value. So, if you pull the power back, the rpm will fall, and the prop will go to fine pitch. Exactly the same as any other constant speed prop.
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  #7  
Old 12-01-2009, 09:19 PM
Doug Rodrigues Doug Rodrigues is offline
 
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Location: Lockwood (8 miles east of Reno), Nevada
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Default Just got information from a Hartzell engineer....

**He said that the feathering prop is 20 lbs heavier that the Hartzell compact hub with the 7666 blades. Didn't know that.
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  #8  
Old 12-01-2009, 10:16 PM
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TCONROY TCONROY is offline
 
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You'll get a surprise when you accidently run out of gas on the right side and it feathers before you can switch. Just hypotheticals but I really don't think its a good idea to have a fully-feathering prop on a single-engine piston.
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  #9  
Old 12-02-2009, 12:24 AM
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John Clark John Clark is offline
 
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Location: Santa Barbara, CA
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Default Won't feather by itself

Quote:
Originally Posted by TCONROY View Post
You'll get a surprise when you accidently run out of gas on the right side and it feathers before you can switch. Just hypotheticals but I really don't think its a good idea to have a fully-feathering prop on a single-engine piston.
Doesn't work that way, you would have to pull prop control all the way back to feather even if the engine is just windmilling. Otherwise, the prop would feather every time you shut the engine down.

John Clark ATP, CFI
RV8 N18U "Sunshine"
KSBA
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