Vibration analysis - Help with an Oxy 3 Qube

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Bladecrasher
Posts: 98
Joined: Wed 16. Mar 2016 15:58:50

I have an Oxy 3 Qube (3 blade head & 3 blade tail) with the uSpirit installed and have about 20 flights on it.

Once during a test rescue in flight, the heli drove downward, nice and flat ( just in the wrong direction) breaking the skids when it hit ground.

I believe this behavior is a sign of to much vibration.

All my pre-flight tests, and some in-flight test rescues , since this downward event have been flawless. Collective goes upward as expected. In checking the logs, I occasionally see warnings for high vibrations, even when I have had successful test rescues in flight. I now test much higher up so I can recover should the heli head toward the ground.

Today I removed the main and tail blades and held the Oxy to my workbench with tape. Then using the BT android app I checked the vibrations at 3 HS settings and found this info:

HS of 2950, 3175 and 3650

X-axis: 4%, 5%, 8%

Y-axis: 60%, 60%, 38%

Z-axis: 18%, 17%, 25%

Attached are 2 photos of the showing the vibration graph. The vibs are slightly different than what I noted during the testing, but close.

Do the graphs or values noted above mean something concrete that I should check on the Oxy?

Other than having concerns about rescue, the uSpirit has worked well on the Oxy.

Thanks for any input.
Attachments
Graph looks very similar at both 2950 and 3175 HS
Graph looks very similar at both 2950 and 3175 HS
Graph at 3650 HS
Graph at 3650 HS
xokia
Posts: 74
Joined: Sun 10. Feb 2019 7:10:27

Your questions would probably be better suited for an oxy forum. They build the tool not the heli. Vibration characteristics are going to be specific to a certain heli.

That said have you checked your belt tension?
Bladecrasher
Posts: 98
Joined: Wed 16. Mar 2016 15:58:50

Thanks, but since the tool (fbl unit) is creating the graph and data it seems like they would have some thoughts on how to interpret this information. Ultimately I will need to make changes like may be the belt tension. Maybe that is the only significant moving part along the Y axis.
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