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Go Back   VAF Forums > Model Specific > RV-12/RV-12iS
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  #1  
Old 06-06-2021, 04:17 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Default Prop Balance - How Much Weight to Add?

We are balancing a RV-12 prop with DynaVibe. It's our first experience doing this. The unit is telling us 0.4IPS x 50 grams starting point = 20 grams weight.

Does that sound reasonable?
How much weight have folks added for balancing?

Thanks in advance...
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
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Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 830

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  #2  
Old 06-06-2021, 04:28 PM
Bob Y Bob Y is offline
 
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See page 32 of the attached I received from the manufacturer. Mine was pretty close to this guide.

https://www.dropbox.com/s/8vhcmufjxc...eller.pdf?dl=0

Remember you’ll be increasing the weight when you move it to the spinner backplate. Since the spinner is ~10” diameter, mounting at 8” gives a nice round increase of 25%.
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  #3  
Old 06-06-2021, 04:50 PM
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Piper J3 Piper J3 is offline
 
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Right... what I'm wondering is how much weight folks have used to balance the Sensenich ground adjustable prop on RV-12. I'd like to see if we are in ballpark...
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 830

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H
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  #4  
Old 06-06-2021, 05:23 PM
Bob Y Bob Y is offline
 
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As a reference, I used 36.8 g on the spinner perimeter - 46 g on the 8” diameter.
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  #5  
Old 06-06-2021, 05:35 PM
seagull seagull is offline
 
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Jim,

I ended up with about 19g on the back plate of my -12, drilled at a 9" diameter to get .03ips

Friday I did a Lycoming 320 with a Hartzell 2 blade. With no weight is was .43ips. The finished solution was 17.8g on a 10" diameter to get .04ips.
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Last edited by seagull : 06-06-2021 at 05:38 PM.
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  #6  
Old 06-06-2021, 06:19 PM
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Tony_T Tony_T is offline
 
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Default RV-12 Sensenich - DynaVibe

Mine was 19.4 grams at the 9" diameter, for 0.08 ips final.
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Last edited by Tony_T : 06-07-2021 at 12:07 PM.
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  #7  
Old 06-06-2021, 11:59 PM
RFSchaller RFSchaller is offline
 
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The guy who did mine added one #6 machine screw to the spinner bulkhead. Hardly seemed worth the effort.
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  #8  
Old 08-07-2021, 03:22 PM
431HG 431HG is offline
 
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Location: Southbury, CT
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Getting ready to balance prop, my mechanic uses Chadwick Helmuth equipment and has no RV-12 prop balance experience. Can anyone share photo of equipment mounting and Chadwick experience I can share with him prior to work?
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  #9  
Old 06-16-2021, 04:19 PM
Mike Howard Mike Howard is offline
 
Join Date: Jan 2006
Location: Omaha, NE.
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Cool gram scale

I just finished balancing the Sensenich prop on my RV12. before the balance it registered .17 in/sec after balance we got it down to .05 in/sec.
Now the rub! I added one #8 x 1/2" screw with a nylon lock nut at 4.5" from the center of the shaft. My gram scale said that the screw and nut only weighed 3.8 grams. Everyone else seems to be coming up with much higher weights to do the balance.
I hope the scale is not wrong because it is the same one I use to weigh the carburetor floats and they came in at 6.7 grams for each pair.
Any thoughts?
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  #10  
Old 06-16-2021, 06:23 PM
Bob Y Bob Y is offline
 
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The weight added will depend upon your starting vibration level. Yours was already relatively low to start with, thus not requiring as much counter weight.
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