Horrible vibration; Trex 450 in a heliartist 500D

[Ian_R]

I've been trying to eliminate vibration in my 450 based Heliartist 500D, even though it was flying OK. Mainshaft was straight, blades balanced, tail seemed OK, head dampers replaced and bearings, tightness etc checked.

Then it shook itself to pieces on the ground when I switched to idle-up on Saturday (with the TX stick at zero pitch). Upper, lower frame, bottom plate, mainshaft, main gear, tail drive gear, one servo case and a few screws all knackered!

I have not fully assessed the damage to the fuselage yet (it was a repaired second hand one), but I suspect the support/base board inside is going to be torn apart. I'll try to repair it (am I wasting my time?). I've got a new, unused fuselage (bought from the for sale section on this forum), but I'd realy like to sort any source of vibration before I build that one.

The rebuild is going to be with a KDE direct alloy bottom plate rather than the very flexible plastic one, and high strength Align mainshaft to try to keep it all together.

Any suggestions? Anyone experience any unusual sources of vibration (e.g. could it be the motor at high speed)? Or should I stay away from idle-up...LoL?

[rapidgaz]

Horrible vibration; Trex 450 in a heliartist 500D

It will be resonance, you have to achieve a spot on head speed, not sure what this is, I just did it by trial and error. To high is bad thou that is for sure. A good esc with gov function would help to maintain this. However I did it with just curves.

[Ian_R]

Thanks for that; obvious now I think about it! I've considered mounting the 450 base to the 500D support/base board with some little (M3 thread, 8mm diameter, 8mm high) bobbin style model boat engine mounts, and fixing the top of the fuselage to the top of the 450 frame with long screws and spacers in an attempt to reeuce the vibration/resonance damp things down. Good idea, or bad idea?

[Jonp]

I played with one of these for weeks. One moment it would be OK, the next it would vibrate and the magnets holding the front on would let go and half the cockpit would fall off. In fairness my heli was half clone half Align parts. I think the source of my vibration was from the tail. I eneded up packing foam between the boom and the inside of the fusealge to try and dampen the vibration. I also paid a lot of attention to how the heli was mounted to the floor of the fuselage - as you know it is very tight in there.
Despite this experience I am thinking about having another go - possibly using my 600ESP.
Stick with it, I am sure you'll get it smoothed out.