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06-06-2021, 04:17 PM
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Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,856
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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
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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06-06-2021, 04:28 PM
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Join Date: Jul 2017
Location: Piedmont, SC
Posts: 445
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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%.
__________________
Bob Y - builder 12iS E-LSA
N569TT first flight 2/9/2020
#121047
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06-06-2021, 04:50 PM
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Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,856
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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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06-06-2021, 05:23 PM
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Join Date: Jul 2017
Location: Piedmont, SC
Posts: 445
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As a reference, I used 36.8 g on the spinner perimeter - 46 g on the 8” diameter.
__________________
Bob Y - builder 12iS E-LSA
N569TT first flight 2/9/2020
#121047
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06-06-2021, 05:35 PM
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Join Date: Dec 2019
Location: Highland, CA
Posts: 558
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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.
__________________
Live as if you were to die tomorrow. Learn as if you were to live forever.
visit my blog - http://waltsrv12.com
-- Walt --
Last edited by seagull : 06-06-2021 at 05:38 PM.
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06-06-2021, 06:19 PM
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Join Date: Dec 2008
Location: Lacey, WA
Posts: 1,469
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RV-12 Sensenich - DynaVibe
Mine was 19.4 grams at the 9" diameter, for 0.08 ips final.
__________________
Tony
E-LSA RV-12 ULS
Last edited by Tony_T : 06-07-2021 at 12:07 PM.
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06-06-2021, 11:59 PM
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Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 3,350
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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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06-07-2021, 12:02 PM
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Join Date: Jul 2012
Location: North Brunswick, NJ
Posts: 406
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my buddy ended up adding just 1 washer under an existing spinner #8 screw. His readings were fairly good to begin with.
On mine, I started with 0.30-0.34 IPS and ended up adding 13g at a hole that was appox 3/4" from the spinner backplate edge. End result was about 0.04 IPS
Incidentally, I rent out my DynaVibe for $100 to any builder that needs it (up to a maximum of $1400.. as I'm looking only to recoup costs and not make money off it)
__________________
Rob Carsey, Winfield Park, NJ
RV-12iS (N713) / Completed 12/2020 / 350hrs and counting
ASEL, Glider, AGI/IGI, LSRM-I, FCC GROL
APRS Track or ADSBExchange Track
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06-07-2021, 01:33 PM
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Join Date: Nov 2018
Location: Peachtree City, GA
Posts: 278
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Mine was .50 after adding 27 grams it came down to .05 I used a 1/4" NAS bolt and 2 OD washers and lock nut to mid span of spinner bulkhead 180 degrees opposite of heavy spot...piece of cake.
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06-16-2021, 04:19 PM
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Join Date: Jan 2006
Location: Omaha, NE.
Posts: 7
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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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