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  #51  
Old 09-08-2021, 07:47 AM
WingsOnWheels WingsOnWheels is offline
 
Join Date: Mar 2009
Location: Plano, TX
Posts: 2,232
Default

Quote:
Originally Posted by Snowflake View Post
Pull into a vertical climb, and your prop is lifting your entire gross weight, half on each blade (for a two-bladed prop). I doubt you're pulling with that much force when you move it on the ramp.
What he is talking about is that the spinning of the prop and resulting centrifugal force changes the force vector on the blade so it is closer to parallel to the blade vs perpendicular. So that actual thrust load is low compared to the total load on the prop. Think of the tightrope example from physics class. The load of the person walking the rope is transferred to the tension of the rope. In this case, the centrifugal force replaces the anchor point at one end of the rope.

That said, unless someone is nuts, they pull from right up against the spinner near the root of the blade. The nickel is well outboard of that area so there is no bending load being applied to that part of the blade. I don't think it is a contributing factor to the cracking.
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RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
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  #52  
Old 09-08-2021, 08:15 AM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 1,727
Default I agree

Quote:
Originally Posted by WingsOnWheels View Post
What he is talking about is that the spinning of the prop and resulting centrifugal force changes the force vector on the blade so it is closer to parallel to the blade vs perpendicular. So that actual thrust load is low compared to the total load on the prop. Think of the tightrope example from physics class. The load of the person walking the rope is transferred to the tension of the rope. In this case, the centrifugal force replaces the anchor point at one end of the rope.

That said, unless someone is nuts, they pull from right up against the spinner near the root of the blade. The nickel is well outboard of that area so there is no bending load being applied to that part of the blade. I don't think it is a contributing factor to the cracking.
I agree it is highly unlikely, but just threw it out there. The real data needed is that is this cracking only on one blade, or do all blades suffer cracking on a given prop?
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2021, worth every penny

RV9A- Status:
95% done, 15% left to go
Electrical/Panel 95% done
Firewall Forward 5% in work
Fiberglass 0%, thought i was building in metal?
www.pilotjohnsrv9.blogspot.com
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  #53  
Old 09-08-2021, 11:51 AM
WingsOnWheels WingsOnWheels is offline
 
Join Date: Mar 2009
Location: Plano, TX
Posts: 2,232
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Originally Posted by PilotjohnS View Post
I agree it is highly unlikely, but just threw it out there. The real data needed is that is this cracking only on one blade, or do all blades suffer cracking on a given prop?
Mine cracked on both in nearly the same location, which suggests a lot of flex at about mid-span. The repaired pro has a shorter NLE with prop tape on the inboard portion.
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Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
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  #54  
Old 09-08-2021, 10:45 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 1,727
Default Before after

Quote:
Originally Posted by WingsOnWheels View Post
Mine cracked on both in nearly the same location, which suggests a lot of flex at about mid-span. The repaired pro has a shorter NLE with prop tape on the inboard portion.
If you look at the before and after pictures in post 26, it appears they have changed the NLE. And with the just announced change in warrenty period, I am confident the problem is resolved and they will stand behind their product. I cant wait to get my hands on mine I have just ordered.
__________________
John S

WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2021, worth every penny

RV9A- Status:
95% done, 15% left to go
Electrical/Panel 95% done
Firewall Forward 5% in work
Fiberglass 0%, thought i was building in metal?
www.pilotjohnsrv9.blogspot.com
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