Dynamic prop balance

Hi All,
I'm looking for a shop in the southeast Wisconsin/northern Illinois area that can do quality dynamic prop balancing, preferably with Rotax experience. Any/all suggestions appreciated.
Barry

bernsbm said:

Hi All,
I'm looking for a shop in the southeast Wisconsin/northern Illinois area that can do quality dynamic prop balancing, preferably with Rotax experience. Any/all suggestions appreciated.
Barry

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Not SE WI but at the Cumberland Airport, WI the Cirrus dealer does it. I have not used them.

http://www.aviationvibes.com/vibration-analysis-and-mitigation/

I'm curious... why do you feel the need to balance your prop? I set the pitch on my blades with Van's sheetmetal gage and I'm very pleased with the flight performance and engine/prop smoothness especially at cruise RPM.

I have balanced quite a few 12's and every one benefited significantly. It is also a recommended procedure by both Rotax and Sensenich.

Just finished balancing mine this weekend. Started out at 0.21 ips, was very happy with the final result after adding 11 grams of weight.


John Salak
RV-12 N896HS

Prop balance

Where and how did you attach the weight?

Slane said:

Where and how did you attach the weight?

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x2 . . . . . .

Call Poplar Grove Airport, IL they have a guy that balances props. About $250. Mark C.

Slane said:

Where and how did you attach the weight?

Click to expand...

I started out by adding weights (washers) under the spinner attachment screws at the clocking angle indicated by the DynaVibe display. Took four runs to get the ips down to 0.01-0.02. I used a precision scale to weigh the washers and converted the inch/gram value based on the spinner screw hole location to the spinner plate location I drilled (radius decrease by 1/2" so weight value increased). I added a #8 screw with two nuts and a spacer weight at the new hole in the spinner backing plate. The total weight of the screw, nuts, washers, and spacer weight were 11g. I was fortunate that the clocking angle was almost exactly on a spinner attachment screw.

The factory listed weight difference between the two Sensenich blades is 6 grams (1204g and 1198g), so the weight location is actually near the root of the lighter blade. Not sure how that compares with other RV-12s, but it may be an indicator of the improvement you can expect from dynamic balancing.

John Salak
RV-12 N896HS

Make sure the Dynavibe cables are well removed from any ignition wires. It's very susceptible to interference creating what you describe. We had this issue and the reading appeared random from average to average. Our soulution was to tape some empty oil bottles horizontally along the top of the engine & taping the wires on top. YMMV. This worked great for us. Bob