Measuring and avoiding vibration effects on quads 2

Following my previous post, I've also tried a new frame design, with my original round tubes cut in half and attached together with 2 MikroKopter.de carbon fibre central plates.

I wonder if these central plates have a vibration reduction role too, beyond just making it easier to mount.

Here is my initial design :

You can see the 2 extra graphs and the results / conclusion at the end of the original blog.

Now I'm really wondering if the ROUND tubes are more "vibration prone" than the "standard" square ones that almost everybody seems to be using ???

Also, what if, the vibrations I'm seeing, while quite important, are normal and people manage to fly their quads in spite of them !? I'm thinking maybe my ESCs (which are really the cheapest I could find on giantcod.co.uk) have a too low update frequency ?

As you can see, any feedback / idea would be welcome.

I've gone far beyond my expectations in testing/re-building the quad, without flying it for even 1 minute... which as you can imagine is quite frustrating ! :)

thanks,

dan

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Comments

dan March 27, 2011 at 5:32am

@Ramon

- thanks, I do indeed have some issues with mounting the propellers as none of their adapters fits my 3mm motors' shafts...

@Darren

- could you point me to some article / post doing this comparison ? It sounds both frustrating for having spent so much time on a suboptimal solution AND encouraging, as maybe by changing the tubes I'll get better results...
Darren March 26, 2011 at 10:39pm

I believe there was alot of work done to conclude the arducopter had better sucess with square vs round for vibration resistance.
Sebastian Gralla March 26, 2011 at 3:31pm

dan: i don't have one here now, i will record my next flight
Ramon L March 26, 2011 at 12:39pm

verify your props are correctly balanced. unbalanced props can cause vibration at many range of RPMs ... thats where i would go in the first place. use a prop balancer for a more precise result... also be very carefull when mounting the props.. in some cases the prop hole is larger compared to the motor prop mount... this also will result in vibrations due to uncentered position.
dan March 26, 2011 at 10:34am

Thanks Sebastian, that's great !

Would it be possible to have the same graph with better resolution (shorter period of time) and without oscillations ? It's quite hard to discriminate between "actual movement" and vibrations in the previous image...
Sebastian Gralla March 26, 2011 at 10:18am

in flight

this was with very hard oscilations on my quad (so what you see is the actual movement, not the vibrations)
dan March 26, 2011 at 10:09am

I have already tried some standard foam tape (about 2millimeters thick) but there were not noticeable effects...

I was wondering, has anybody else measured their vibrations ? Are they comparable to what I see ? (not in absolute value, but just compared to no motor or motor spinning without a propeller ) ??

thanks,

dan
Sebastian Gralla March 26, 2011 at 4:43am

put some foeam under your APM to reduce vibrations, it should do the trick

This reply was deleted.