motor damper for x8 configuration

[aerialdroning]

Hi all,

We fly with an S900 and get flawless video results.

I am about to built an 450 size x8 craft and wanted to use motor dampers similar to my s900.

Have found something that will do the job from Tarot.
http://www.foxtechfpv.com/tarot-Φ16mm-suspended-motor-seatblack-p-1664.html

However, these will work for the top mounted motors, but for the bottom mounted motors I'm not sure what to do, here's why:

The damper system works because of the separation created between the motor and the arm when the blades create lift. However, this won't be the case with the bottom motors. Yes there will be rubber there but the motor lift won't cause any separation, but rather it will compress the dampers into the arms...

Has anyone else here built an X8 using motor dampers? Maybe you'd have a few ideas?

Other comments also welcome.

Cheers.

Aaron

 

[dazzab]

Very interesting. I bet it's fairly effective as well. But I really don't like the idea of my entire rig being held together by some rubber dampeners. There must be a lot of stress at that point. Then again, all of us are at the mercy of a tiny little C clip that holds our motor spindles in place (and the strength of the motor magnets). It's a wonder these things don't fall out of the sky more often than they do.
Back to your original question. I would think that the rubber dampeners would be just as effective being compressed as decompressed. But I'm no engineer. I'm sure others here will have more accurate info.

 

[aerialdroning]

Thanks for your reply. Well there is a screw that goes threw to hold it all together so thats ok. Yes, just the compression vs decompression thing that I'd like a more technical mind to shed some light on

 

[SleepyC]

I don't see the need for these at all. I have had several X8's swinging 15 - 16" props lifting GH4 - RED and there is no need for such a damper. I'd rather balance my props properly and hard mount the motors. Especially with an X8... there will be some kind of built up resonance because each motor will be pulling differently in the coax setup... I think that would be bad!

 

[eskil23]

I don't see the need for these at all. I have had several X8's swinging 15 - 16" props lifting GH4 - RED and there is no need for such a damper. I'd rather balance my props properly and hard mount the motors. Especially with an X8... there will be some kind of built up resonance because each motor will be pulling differently in the coax setup... I think that would be bad!

The need will probably be greater for smaller crafts with smaller cameras. A big rig with such heavy camera as the RED will have enough intertia in the gimbal (which will have it's own dampers anyway).

Edit: I intend to mount dampers on the motors for my F550. Photos will be published shortly.

 

[Bartman]

I'd rather balance my props properly and hard mount the motors.

i have to agree..spend the time balancing your props and damping shouldn't be necessary.

having said that, i'll be curious to see how it works if you try it.

 

[aerialdroning]

I don't see the need for these at all. I have had several X8's swinging 15 - 16" props lifting GH4 - RED and there is no need for such a damper. I'd rather balance my props properly and hard mount the motors. Especially with an X8... there will be some kind of built up resonance because each motor will be pulling differently in the coax setup... I think that would be bad!

Yes I saw the balloon video you posted with the new Arri, Ive not red flown anything with a cinema camera. Perhaps I'm just too hung up on replicating my s900 damping system. @eskil23 has a point? Maybe I should try both and see if there is a difference. I'll buy tiger props anyhow so should balance well.

 

[eskil23]

Well, the point is that you fight vibrations as close to the source as possible. First, balance the props and motors. Second, prevent vibrations to propagate from motors to frame. Third, prevent any remaining vibrations from affecting the photage.

The advantage of damping the motors is that motors rotating with high RPM have high frequency vibrations. If the vibrations propagate to the frame you'll get frame resonance vibrations instead, and those are lower frequency and need larger dampers.

Damping works well most of the time, but sometimes you can be unlucky and get free resonance instead, which only makes things worse.

 

[eskil23]

Edit: I intend to mount dampers on the motors for my F550. Photos will be published shortly.

The photos I promised. Note that I have not yet tried to fly with this, but you get the idea.
https://people.kth.se/~eskil/F550 build/motor mounts/