MtnMac
Heliman
Location: Roseville, CA, USA
My Posts This: Topic Forum | The Beam is my first 450. Still sorting out setup issues. Tonight I removed the main blades and spun it up. Starts smoothly, passes through a rough patch, then smooths out at about 40% headspeed and stays smooth — barely any vibration, just a faint buzz in the tail.
As it spins down, it passes again through the rough patch where it gets growly sounding, I'd guess around the main gear. In that range, the tail gets funky, too, kind of wagging (I have it sitting on a turntable to observe this). Below the growly zone, it smooths out and comes to a stop.
What parts cause vibration, and how much is acceptable? My guess is that the growl is from a harmonic resonance where several different vibes get together, then separate as the headspeed changes, which changes the frequencies. But what's vibrating? All my shafts and tail are straight, everything's oiled, all the parts move freely including the belt spindles. And you know the vibes aren't because of cheap parts.
Where should I be looking?
Thanks!
Skids |
