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11-28-2007 07:39 AM  10 years agoPost 101
MPA

rrElite Veteran

Australia

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monterey

Wood is good.
Glue and screw a bit of wood across a large vibrating metal panel stops the thrumming sound off the panel.

Note many vans have foam sanwiched down the inner walls to stop panel vibration noise.
It is a similar concept.

The bungy test is a fairly simple test to do.
And at that rate, I would suggest everyone with a Heli cam mount give it a try and see if they get any result.

Even on a mount that is seemingly free of vibe.

If there is some change, it would be safe to assume that there is something going on with the frame itself aside from the heli.

But if doing it provides no result or change then it would be fair to assume that the mount frame itself is all good and suffers no odd vibrations.

It may be that some have a mount that gives a bit of vibe only at certain tiems.
Like during descent, or flying sideways etc that in the past they always put down to factors beyond control.

Wind it up with a thick bungy and try it.
You might find the odd vibration you occasionaly get is gone.

It is not the answer to a fix.
But it seems to be able to clearly show if a mount is, or is not, prone to vibrating itself.

That at least leaves you with a choice of things to look at.
If the bungy gives some effect, then fix the mount becuase there is a fault there.
If the bungy has no effect, that mount is ok, find the vibe inthe heli.

You may find a fault in the mount and heli, you try the bungy then fix the mount till you get no effect uisng the bungy, any remaning vibe must be the heli, right ?

Give it a whirl.

As to solutions in the case you do find the mount is a bit "live" with the bungy test.

Well you cant leave the bungy on, pity.
So something a bit more technical is needed to fit the thing, look ok and have the same effect of quieting the mount.

It was this point I went back to ground up approaches and built the mount from a material shape that is least prone to be "live"

But if you have a mount already you have to work with what you have.
It may be as simple as bonding some wood slats to any parts of the mount frame that are large in area or span like flat alloy or large sheet CF.
That might deaden the section.

One way to find out, bungy it and test it to see if the mount is still "live" or not.
If it is less "live" then whatever you stuck on must be contributing in some way.
Keep at it till there is no effect with the bungy test.

Others might have some snappier ideas on what you could bond or glue on in places to do the job.

Cheers
Dave

rvv.com.au

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11-28-2007 03:02 PM  10 years agoPost 102
monterey_tip

rrVeteran

Monterey, Ca - USA

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Hey Dave,
I haven't tried it yet, but I'm not sure I follow you as to not leaving the bungee on because it is "live"? If the bungee gets rid of the vibe why wouldn't you leave it on? Is there an adverse effect? (live)

Also, do you guys find any difference between a front and underslung mount for stability and vibration? I'm currently using an underslung, but I see a lot of front mounts for video.

Thanks,
Tip

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11-28-2007 07:15 PM  10 years agoPost 103
MPA

rrElite Veteran

Australia

My Posts: All  Forum  Topic

No, wehn I refer to "Live" I am talking about the mount tendency to vibrate itself.

The bungy is to deaden that vibration.

Make the mount dead to vibration.

But where you fit the bungy cord probably wont allow the tilt to operate and will probably get caught up in the works if you go opewrating the mount with it wrapped around..

When I say warp it around the mount, I mean right around the entire pan and tilt.
From one side to the other.
Trying to avoid the camera itself because it is the mount you want to deaden.

Ill see if I can find the video of me wrapping it around my mount so you can see what I mean.

As to vibe that front mounts or underslung.
Front mount is harder to sort out for vibe becuase it is futher away from the centre of the rotors and as such would get more vibe off the rotor head.

Underslung is directly under the mast which results in less rotor vibe to the unit, and less rotor downwash.
But that is all relative to rotor vibe.

The bungy tests is to "see" any vibe by effectively removing any from the mount itself so you can focus on the mount, or the remainder
No matter where the source of vibe is..

rvv.com.au

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