VIBRATION in Ctr Hub=O-Rings
11-17-2007, 11:06 PM
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VIBRATION in Ctr Hub=O-Rings
FYI,
If you've been flying your AXE CP for awhile, and it has survived a mutitude of crashes, BG replacements, main shafts, etc.
Don't forget about those tiny O-Rings hidden behind the shims on the blade-grips (with the center-hub, 2 on each side), they support & dampen the feathering spindle. Crashes can cause FLAT-SPOTS with the ID of the o-rings, they can also become stiff & brittle with age & tempurature.
I learn this the hard way, spending 3 days chasing a major vibration issue, after checking EVERTHING, but the O-rings. I couldn't get the NEW blades to track, (HD plastic trainer blades). After talking with an old'timer at the LHS, he told me to "check the condition of the dampners in the hub." He was right, the O-rings on one side had a "flat-spot" that was causing some additional play in the feathering spindle.
I found replacement O-rings for the AXE CP at the local hardware store, they were cheap. Other heli's use a piece of cylindrical tubing instead of 2 o-rings, per side. They also get choices in the softness/stiffness (durometer), depending upon what the intended use is.
Rick
If you've been flying your AXE CP for awhile, and it has survived a mutitude of crashes, BG replacements, main shafts, etc.
Don't forget about those tiny O-Rings hidden behind the shims on the blade-grips (with the center-hub, 2 on each side), they support & dampen the feathering spindle. Crashes can cause FLAT-SPOTS with the ID of the o-rings, they can also become stiff & brittle with age & tempurature.
I learn this the hard way, spending 3 days chasing a major vibration issue, after checking EVERTHING, but the O-rings. I couldn't get the NEW blades to track, (HD plastic trainer blades). After talking with an old'timer at the LHS, he told me to "check the condition of the dampners in the hub." He was right, the O-rings on one side had a "flat-spot" that was causing some additional play in the feathering spindle.
I found replacement O-rings for the AXE CP at the local hardware store, they were cheap. Other heli's use a piece of cylindrical tubing instead of 2 o-rings, per side. They also get choices in the softness/stiffness (durometer), depending upon what the intended use is.
Rick
11-18-2007, 12:59 AM
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RE: VIBRATION in Ctr Hub=O-Rings
Something else I just found was to balance your flybar. Disconnect the Flybar connect rods going to the stabalizer. Also, disconnect the pushrods from the blade grips. This allows the flybar to balance freely. Loosen the screws from the slide block if necessary. Once the flybar moves freely, move it either direction to make it balance by loosening the wheel collars and sliding it left or right.
Balance the blades and it should be nearly perfectly free from vibration.
See image for disconnect locations as terminology might be a little off.
Balance the blades and it should be nearly perfectly free from vibration.
See image for disconnect locations as terminology might be a little off.
