pierre smith
Well Known Member
...I got hold of Brian Wallis in Atlanta and he came by today and smoothed things out. First, he mounted a vibration sensor on the lifting eye of the engine, and a laser camera to the front left valve cover, as the picture shows. The laser bounces off a strip of reflective tape that he stuck on the face of the prop:
He then ran the wires to the control panel along the side of the airplane and we taped them down before running the engine:
Then, with him at the wingtip, I started the engine and ran it up to cruise...2400 RPM and the imbalance was 0.30 IPS or thereabouts. IPS, or Inches per Second, is a value that gets smaller as the engine/prop gets closer to being balanced, the smaller the number, the better.
We had to run it four times and got closer each time until it was in the 0.04 IPS range...much smoother than before.
His unit tells you where to add weight, as in 230 degrees from the top of the engine in the direction of prop rotation. A good balance will save your accessories from vibration damage, cracked baffling, etc.
In the end, we ended up adding 28 grams to the ring gear with an AD4 bolt, three fender washers and a nut, since the prop had a rock strike and the indentation at the tip lost some weight earlier in its life.
Best.
![DSCN0006.jpg](/community/proxy.php?image=http%3A%2F%2Fi663.photobucket.com%2Falbums%2Fuu353%2Fpierresmith%2FDSCN0006.jpg&hash=933242e1cf1db62641c14a55b652b74d)
He then ran the wires to the control panel along the side of the airplane and we taped them down before running the engine:
Then, with him at the wingtip, I started the engine and ran it up to cruise...2400 RPM and the imbalance was 0.30 IPS or thereabouts. IPS, or Inches per Second, is a value that gets smaller as the engine/prop gets closer to being balanced, the smaller the number, the better.
![DSCN0007.jpg](/community/proxy.php?image=http%3A%2F%2Fi663.photobucket.com%2Falbums%2Fuu353%2Fpierresmith%2FDSCN0007.jpg&hash=743b0cc17349925275db03521bf49262)
We had to run it four times and got closer each time until it was in the 0.04 IPS range...much smoother than before.
His unit tells you where to add weight, as in 230 degrees from the top of the engine in the direction of prop rotation. A good balance will save your accessories from vibration damage, cracked baffling, etc.
In the end, we ended up adding 28 grams to the ring gear with an AD4 bolt, three fender washers and a nut, since the prop had a rock strike and the indentation at the tip lost some weight earlier in its life.
Best.
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