Stretched Logo vibrations

[Griffo]

I've been pulling my hair out over this for about a week now and was hoping that someone might be able to shed some light on the possible source of vibration in my aerial footage.

I loaded up the stretched Logo 600 (690 blades) with Askman's 360 underslung mount yesterday and took it for a test run with an old NV-GS250 DV recorder onboard.

http://www.vimeo.com/882539

It's not the most scenic of locations but it was close by and out of harms way so my appologies for the ultra boring subject matter... and the sucky piloting. Disregarding the piss poor display of flying ability you might notice a vibration present at about 2min 25sec as the distant car passes by. THIS is the vibration I'm struggling with.

So far I've tried rebuilding the head, checking the blade balance, blade tracking, flybar level, tail blades balanced but the vibration still exists .

Perhaps I've missed something. Please HELP me!

[LITHIUMSTATIC]

boom struts?? i've heard of them vibrating.

[Griffo]

Thanks Jeremy, that's an interesting point.

What could I do to prevent vibrations in the boom supports and what do you think would cause them to vibrate in the first place?

I don't know if this helps diagnose the cause but the intensity of the vibrations seems to pulsate once a second.

[OICU812]

In regards to boom strusts make sure you pull back the boom support block tight so boom supports are evenly supporting on both sides.

[wlfk]

If it just happens occasionally, it might be a problem with resonance. In this case, you could try putting a small weight on the supports or changing the headspeed slightly.

K

[Griffo]

Thanks Shaun, I'll try that and see what happens.

wlfk, the vibration is always present . It's just the intensity of the vibe that pulses. I've tried bumping up the governor 15% but nothing changed. I'll try positioning a few weights on the mount.

Thanks for the ideas guys. Keep em coming if you think of any more :).

I'll post another vid later.

[LITHIUMSTATIC]

What could I do to prevent vibrations in the boom supports



Andy Rummer had this problem about 6 months ago. He used a piece of carbon fiber, zip ties and glue to fuse the two boom struts as one.

[OICU812]

Andy Rummer had this problem about 6 months ago. He used a piece of carbon fiber, zip ties and glue to fuse the two boom struts as one.


Or you can buy a made for it application, known as a support bridge, here ia an example of such item.

http://www.greathobbies.com/productinfo/?prod_id=CHP2266

[wlfk]

How about some rubber bands stretched between them. They might resonate themselves, but could also absorb some of the vibes due to dampening.

Weights... Should not be in the middle of the struts. Perhaps each weight on a slightly different position on each strut.

K

[OICU812]

Rubber bands, now that is a simple and good idea...:thumbup:

[Griffo]

This is all great stuff, thanks guys!

I would never have thought to reinforce the struts in this way. I'll start off with the rubber band method and if that improves things then I might try the great hobbies product :).

I'm pulling everthing apart again as we speak, just in case I missed something and should have it in the air again this afternoon... weather permitting.

I've got to dial in some expo on the cyclic too. I just went back and looked at the footage and sheez, I've really got to smooth out my stick work. Maybe I should cut back a bit on the coffee ;) .