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  #1  
Old 12-30-2020, 04:30 AM
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kjelle69 kjelle69 is offline
 
Join Date: Aug 2011
Location: Sweden, 67?07′N 20?45′E
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Default Holes on the back of Propeller hub

See attached file, I have a Pacesetter propeller which have two holes on the back of the hub, anyone who knows what the purpose of these holes is? Balancing?

One is filled with resin and the otther one partly filled with a grey-ish glue.
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  #2  
Old 12-30-2020, 06:01 PM
Aerodon Aerodon is offline
 
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I have an aluminum prop with a spacer. There are two locating dowels, on opposite sides, but not exactly between the adjacent holes.

Aerodon
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  #3  
Old 12-30-2020, 06:22 PM
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Its for balancing. A few wood prop manufacturers do it this way.
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  #4  
Old 12-30-2020, 06:34 PM
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PaulvS PaulvS is offline
 
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If the holes are for balancing then I wonder why are they not symetrically opposite each other? Wouldn't it be more efficient for the prop manufacturer to sand off a teeny bit from the blade rather than drill a hole that is so close to the hub.
I don't know the answer and probably it doesn't really matter other than for curiosity, but I thought that perhaps the holes are tooling holes from the manufacturing process.
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  #5  
Old 12-30-2020, 06:55 PM
BoydBirchler BoydBirchler is online now
 
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Pacesetter is a great performing prop, the best fixed pitch I have ever flown behind!
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  #6  
Old 12-30-2020, 08:05 PM
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Mel Mel is offline
 
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Quote:
Originally Posted by PaulvS View Post
If the holes are for balancing then I wonder why are they not symetrically opposite each other? Wouldn't it be more efficient for the prop manufacturer to sand off a teeny bit from the blade rather than drill a hole that is so close to the hub.
I don't know the answer and probably it doesn't really matter other than for curiosity, but I thought that perhaps the holes are tooling holes from the manufacturing process.
You cannot balance the prop until it is complete, including the finish. If you sand after finish, then you have to refinish. Now you have to balance again.

See the vicious circle that has started?
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  #7  
Old 12-30-2020, 08:06 PM
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Mel Mel is offline
 
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Quote:
Originally Posted by BoydBirchler View Post
Pacesetter is a great performing prop, the best fixed pitch I have ever flown behind!
Ever flown behind a Catto?
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EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
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  #8  
Old 12-31-2020, 01:26 PM
theduff theduff is offline
 
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Default Wood Props

Quote:
Originally Posted by Mel View Post
Ever flown behind a Catto?
I have and flown behind a metal FP as well as a variety of wood props. Warnke’s both Bernie and Margy, Pacesetter, Sterba and Performance Propellers both Clark and Frank’s versions. I can say that they all have there +’s and -‘s but a properly built wood prop has a special feel to them, hands down smoother than all of the others. Don’t knockem till you try’em !😁
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  #9  
Old 12-31-2020, 02:06 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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I think Catto props are made using a wood core(?) so they probably fall into the same category, but I agree with your comment.

I was the first RV-6(A) builder to put one of Clark's Performance Propellers 3 blade props on my 6A in the early 90's. Every other RV owner that ever flew in it with me always mentioned how it felt turbine smooth (and we didn't even know what dynamic balancing was back then)
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  #10  
Old 12-31-2020, 02:29 PM
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Quote:
Originally Posted by PaulvS View Post
If the holes are for balancing then I wonder why are they not symetrically opposite each other?
Because they are balanced laterally as well as on the longitudinal axis of the propeller.
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N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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