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Old Nov 08, 2010, 03:27 PM
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Minimizing multi-copter noise

Hi, long time lurker, first-time poster.

I've been considering a multi-copter build for a while, but the biggest turn-off for me is the amount of noise that they put out.

What can be done to minimize the noise?

Do you have any links to builds that did a good job of this? (preferably with vids with unedited audio)

Thanks in advance!
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Old Nov 08, 2010, 04:06 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
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Hmmm...most multicopters are relatively quiet compared to helis that can lift the same weight. I suppose using the largest props you can and turning them the slowest you can to hover your AUW would get the quietest multicopter. What do you want use it for? Aerobatics? AVP?
Her are some links related to all things multicopter for you to read:Quadrocopter and Tricopter Mega Link Index
Cheers,
Jim
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Old Nov 08, 2010, 05:20 PM
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Navarre, FL
Joined Mar 2002
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Building a very quiet quad has always interested me as well, but so far, I haven't attempted it.

All the noise is from the props, so that's where you'd have to do the most work. First, keep the weight (disc loading) as low as possible, since there's that much less air to move.

In general (as Jim mentioned) larger props turning slower would be best. The most efficient, and quietest prop would likely not be something we typically use.

It would be important to minimize turbulence above, and particularly below the prop. Airfoil shaped arms would be the way to go, and probably with the props as far below the arms as possible.

One of these days, I'm going to get around to working on this...

Rusty
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Old Nov 08, 2010, 07:04 PM
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and ballance the props too
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Old Nov 08, 2010, 09:11 PM
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Joined Jun 2008
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Quote:
Originally Posted by immacoolguy View Post
Hi, long time lurker, first-time poster.

I've been considering a multi-copter build for a while, but the biggest turn-off for me is the amount of noise that they put out.

What can be done to minimize the noise?

Do you have any links to builds that did a good job of this? (preferably with vids with unedited audio)

Thanks in advance!
Have you heard an Octo in person or just in videos? I ask because my octo is so quiet for what it is doing, no one has ever said it was load.
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Old Nov 09, 2010, 09:55 AM
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Originally Posted by jesolins View Post
Hmmm...most multicopters are relatively quiet compared to helis that can lift the same weight. I suppose using the largest props you can and turning them the slowest you can to hover your AUW would get the quietest multicopter. What do you want use it for? Aerobatics? AVP?
Her are some links related to all things multicopter for you to read:Quadrocopter and Tricopter Mega Link Index
Cheers,
Jim
I'd like to use it mostly for logistics.

On-board video, stability/position hold and a larger carrying capacity to experiment with other components (thermal camera, radio-based triangulation, sonar/etc. for tight space navigation, spotlight)

But first I'd just like to get something off the ground But ideally the build would be able to support future experimentation without having to upgrade too many components.

Quote:
Originally Posted by Tarro View Post
Have you heard an Octo in person or just in videos? I ask because my octo is so quiet for what it is doing, no one has ever said it was load.
I haven't heard or seen any multi-copter outside of videos. Any idea what kind of dB your copter puts out with a reasonable load?
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Old Nov 09, 2010, 10:07 AM
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Quote:
Originally Posted by immacoolguy View Post
I'd like to use it mostly for logistics.

On-board video, stability/position hold and a larger carrying capacity to experiment with other components (thermal camera, radio-based triangulation, sonar/etc. for tight space navigation, spotlight)

But first I'd just like to get something off the ground But ideally the build would be able to support future experimentation without having to upgrade too many components.


I haven't heard or seen any multi-copter outside of videos. Any idea what kind of dB your copter puts out with a reasonable load?
To give you an idea, with my quad 12x3.8 props on it and 4 meters, i could speak to and hear what two people 5 meters from me were saying.
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Old Nov 09, 2010, 10:32 AM
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Quote:
Originally Posted by immacoolguy View Post
I'd like to use it mostly for logistics.

On-board video, stability/position hold and a larger carrying capacity to experiment with other components (thermal camera, radio-based triangulation, sonar/etc. for tight space navigation, spotlight)

But first I'd just like to get something off the ground But ideally the build would be able to support future experimentation without having to upgrade too many components.


I haven't heard or seen any multi-copter outside of videos. Any idea what kind of dB your copter puts out with a reasonable load?
They sound loud in the inflight videos because the mic is on the camera. I videoed an out doors wedding ceremony and did not bother anyone there.
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Last edited by Tarro; Nov 09, 2010 at 10:53 AM.
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Old Nov 09, 2010, 10:49 AM
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Originally Posted by Tarro View Post
They sound load in the inflight videos because the mic is on the camera. I videoed an out doors wedding ceremony and did not bother anyone there.
Wow! That's really impressive. I guess it's time to start ordering parts then

(just kidding, there's a whole lot of planning that comes before that)
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Old Nov 09, 2010, 10:54 AM
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(just kidding, there's a whole lot of planning that comes before that)
Do you really think so?
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Old Nov 09, 2010, 12:00 PM
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Do you really think so?
You mean this isn't a one-weekend project?

Nevermind
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Old Feb 11, 2014, 02:59 PM
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Palm Harbor, FL, USA
Joined Mar 2001
575 Posts
Minimizing multi-copter noise

Stiff props are also quieter. My Gemfan 10x4.5's are significantly louder than my APC 10x4.5MR's and HQ Prop carbon composite 10x5E's.

The flexy props deform under load and sound...flappy.
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Old Feb 11, 2014, 04:51 PM
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United States, NH, Fitzwilliam
Joined Jan 2014
95 Posts
lunacy

i was trying to think up a method of active noise cancelation being broadcast from the quad to completely cancel constant prop sound.?!. who knows. mike it and pipe it at the source? not going to rip appart a 300$ set of seinhausers to figure it out though.
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Old Feb 12, 2014, 09:04 AM
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Palm Harbor, FL, USA
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You could do a lot of good before going to that length.

Precision balancing your props will reduce noise

Stiff props reduce noise

Good motors with quality bearings reduce noise

Lower PID values reduce noise

Stiff frames with no long unsupported areas resonating are quieter.
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Old Feb 12, 2014, 09:18 AM
gyro, simonk n call it a day
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United States, NJ, Hamilton Township
Joined Jan 2013
196 Posts
I once built a 450 clone with 800kv 2212's 10/4.5 SF APC's I meticulously balanced the motors and props and measured CG, well lubed bearings. Ran a Naza no GPS. It was completely silent at about 8' away, 6-8' high. It was an efficient machine and to describe it here really does no justice. Haven't been able to replicate it with any other setup. Got about 13 min from a 2200-20c bat I think it was 1100g AUW , ill post exact setup here in a little
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