SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 09, 2012, 05:56 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
11,766 Posts
As far as I can work out, the leaf blower sound comes from two main factors.
1. The fan RPM is lowish relative to the blade face area (Will explain more later)
2. The fan blade size, and even profile, and how it 'chops' through air

The higher blade count means far more SMALLER face area blades, and thus a different 'faster' chopping of the air. It probably has some effect of a higher fequency noise, versus a low blade count's lower freq - which gives the leaf blower sound, due to more low end freq (bass).
A lower blade count fan that runs at very high RPM sounds 'better'... so that shows the fact the blade, or tip(?), turbulence frequencies get higher and 'improve' the sound that X amount. But you still can't match a high blade count and the way that does far more 'smaller cuts' of the air. Maybe a 5 blade running double the RPM would match a 10 blade then. (??)

This fan aspect of sound is more to do with having a 'quieter' fan, than the jet/whoosh itself totally. So the high blade count fan removes the lower freq 'leaf blower' effect. Then you get to hear the airflow and its turbulences stronger than other 'annoying' noise.

The main jet/whoosh is from the high speed airflow travelling the entire ducting path. Like you hear with a vacuum cleaner hose when you close off part of it with your hand. Air under 'duress' being forced through smaller areas than it would 'like' to flow means the molecules are 'crashing' into edges (inlet lips), walls inside, through fan(s), etc etc. The more obstructions/restrictions that make a messy path, the more white noise there is - and that is what the jet/whoosh sound is.
A real jet has that exact same sound comonent, but it also has the 'roar' of combustion occuring. Which we lack of course.

Then when a plane is flying, the sound gets modulated by various aspects of the plane in motion, so the sound that was more cosnsitent on the ground - and a more 'plain whoosh' - becomes 'warbulated' (LOL)... too hard to put into words, but you know the wavering volume, bit of freq change, you hear as a 'jet' flies across the sky.... so we get that exact effect too, and that makes the white noise end up the pleasing 'almost a real jet' sound. (just missing the combustion road component).

So for creating the sound.... you really do nothing but use a CS10 etc (high blade count fan). And the higher the RPM, the higher the airflow, thus the higher the incidents of air molecules 'crashing around' through the ducting system.
If you MAKE impedances in the airflow, you can increase the noise too!! But impedances also reduce the fans ability to accelerate the air as well, so you will lose SOME thrust = which may or may not be worth it to you. Sound rise for thrust drop. But the thrust drop will also make the motor work less and current will drop too - so it doesn't waste much power at all. Just wastes potetntial of what amount more thrust you could have had.
PeterVRC is offline Find More Posts by PeterVRC
RCG Plus Member
Sign up now
to remove ads between posts
Old Oct 09, 2012, 07:31 PM
To drive or to fly......BOTH!!
FresnoJay's Avatar
USA, CA, Clovis
Joined Apr 2007
6,216 Posts
Peter, I would like to add just a little bit of experience. I have found by mistake that you can also mitigate the leaf blower sound by simply changing the housing with one that has a different number of stator vanes. Granted ducting does play a part. But so does the noise level that comes from the motor. Some motors are noisier than others even in a changesun.

Jason
FresnoJay is offline Find More Posts by FresnoJay
Reply With Quote
Old Oct 09, 2012, 08:26 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
11,766 Posts
Yeah, the stators are just a part of the 'airflow path'. Wrong angles will give more noise.
Depending on the angles, size etc... it could be more high freq, or low freq.

Motors, they give 'useless' sound... just a whine. Not jet sounding whine either.
You just hear them more notably if there is less other noise ("leaf blower" noise can drown anything), so in the quieter fan (more air whoosh heard) CS10, you also get to hear more motor noise.
Some motors add an acceptably nicer sound than others. Not jet whine/whoosh, but just a sound that you can accept as pleasing in the mix - but not really a jet-realistic sound addition.
PeterVRC is offline Find More Posts by PeterVRC
RCG Plus Member
Old Oct 09, 2012, 09:54 PM
To drive or to fly......BOTH!!
FresnoJay's Avatar
USA, CA, Clovis
Joined Apr 2007
6,216 Posts
The motor I found that gives a jet'ish sound in a CS10 is the Eflite 3200 that is normally in the PZ Habu. I balanced up a fan and mounted one in a CS10 for a friends F-18. The thing sounds just awesome. The motor whine is barely audible over the whoosh but just so it gives an almost turbine'ish sound. Need to get video its just awesome.

I have a CS10 that is waiting for a motor. I am trying to talk a friend out of a HET 2W23 to stick in it. Could be interesting.

Jason
FresnoJay is offline Find More Posts by FresnoJay
Reply With Quote
Old Oct 09, 2012, 11:54 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
11,766 Posts
The HET for 4S I guess.
I have 2W30's on 6S and they don't sound anything special - same sound as any others I have.
But they are great motors - made to do the job and LAST!

Hey!! On a side note.... everyone should own a Durafly Vampire!!!
It has the best jet/whoosh sound ever - due to the whole ducting layout - but also flies great. So it is an excellent EDF to have!
Its ducting even makes the stock 'leaf blower' fan sound good! But put in a CS10 and it becomes awesome!
Not as fast as a Meteor, but it is a better plane - even though the Meteor is a really good plane too! $125 approx - add more for CS10 if you do that. Say $just under $200 in total with a CS10, L2855, and better/surer ESC.

And/or... the Dynam Me-262.... another awesome plane. Big.... more costly - double cost of a Vampire, or a bit more, but it is another 10/10 great plane you would never be sorry to have bought. Approx $300 or so after useful upgrades - but well worth it.
PeterVRC is offline Find More Posts by PeterVRC
RCG Plus Member
Old Oct 10, 2012, 02:11 AM
To drive or to fly......BOTH!!
FresnoJay's Avatar
USA, CA, Clovis
Joined Apr 2007
6,216 Posts
Peter, Most of my planes that have been around a while run HET motors in various fans. So when I am sure a plane is sticking around its the brand they get for longevity. After the stock system starts to hiccup that is .

As for fans. I started digging around in my hobby room now that the 262 isn't occupying the space. I found 2 more fans that could be contenders for the Meteor. 1 is a well balanced and run in old Starmax fan I believe (looks like a Wemo clone) and a good ole HET unit. Plus I do still have the Meteor's stock rotor that is all balanced up. So I have a pretty wide range of fans to choose from. The whoosh sound is rather nice but the Meteor kinda gets treated like old reliable .

Jason

P.S. I have been watching the Vampire since it was announced. It was top of the list to get until the 262 came out. I have been praying for the 262 to come out in the Dynam size for quite some time. When it did the Vampire got bumped .
FresnoJay is offline Find More Posts by FresnoJay
Reply With Quote
Old Oct 10, 2012, 09:21 AM
Add your country to profile:)
CrashMaster39's Avatar
United States, CA, Crestline
Joined Oct 2006
309 Posts
Quote:
Originally Posted by Purple Pashin View Post
One of this morning's flights..
Tacon 2550KV, CS10 fan, Grayson 100A ESC, Sky Lipo 5S, 3300, 40C battery. Full throttle passes look to be close to 100mph..need a radar gun.
PurplePashin, how do you like the sound of your Tacon motor in the CS10? Its kind of hard to tell in the on-the-plane FPV video. Quiet or loud motor?
CrashMaster39 is offline Find More Posts by CrashMaster39
Reply With Quote
Old Oct 10, 2012, 07:29 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
11,766 Posts
At 2550kv it should sound very good. That is a fair amount more thrust/airflow than a 2300kv, which already sounds 'just good' (for a CS10 installation).
Airspeed itself gives more noise source (airflow over a plane) so even that will add a bit more - and audible, seeing the leaf-blower racket is gone too.
Any 5S 2500kv+ motor is going to just sound better and better.
PeterVRC is offline Find More Posts by PeterVRC
RCG Plus Member
Old Oct 10, 2012, 10:15 PM
Gotz tha Jet Feeva!!
Purple Pashin's Avatar
United States, GA, Kennesaw
Joined Dec 2011
147 Posts
Quote:
Originally Posted by CrashMaster39 View Post
PurplePashin, how do you like the sound of your Tacon motor in the CS10? Its kind of hard to tell in the on-the-plane FPV video. Quiet or loud motor?
Kinda loud..
I may try the cool 42, or the typhoon later. Might be more efficient then the Tacon, although the Tacon is decent for the money.
Purple Pashin is offline Find More Posts by Purple Pashin
Reply With Quote
Old Oct 10, 2012, 10:49 PM
To drive or to fly......BOTH!!
FresnoJay's Avatar
USA, CA, Clovis
Joined Apr 2007
6,216 Posts
Purple, For pretty close to the price of the 2550Kv you can grab a HET motor. Where I get them they have free shipping. So imho its worth it. http://shop.turbofanelectrics.com/

Gary At Efflux RC is an awesome guy too. So either way you can't really go wrong

Jason
FresnoJay is offline Find More Posts by FresnoJay
Reply With Quote
Old Oct 10, 2012, 11:26 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
11,766 Posts
You mean a 2W25? (2650kv). ($70 area)
Surely a better motor.. not a lot more cost.. BUT is then pushing the KV higher, and thus more power/current too. Too low for good 4S..... a bit high for efficient 5S.... in a CS10
As long as you WANT that costly (power) result, and can DRIVE that (Battery), then it would be a quite powerful 5S Meteor!

Better off heading to 6S on HET 2W30 2200kv ($77) when going for higher power - use more volts instead of Amps.
That would be the next step above 5S 2550kv - though not by a huge amount. A bit more power... but at less Amps.
PeterVRC is offline Find More Posts by PeterVRC
RCG Plus Member
Old Oct 11, 2012, 12:57 AM
To drive or to fly......BOTH!!
FresnoJay's Avatar
USA, CA, Clovis
Joined Apr 2007
6,216 Posts
I am still kicking around what to do in the Meteor and am weighing all the options. Its nice to hear someone that has experience with the Tacon motors actually, even if it didn't sound like it . I have another project that has been on the table for some time that may be a good candidate for the 36mm Tacon's. But that is for another thread .

I currently have 3 fan choices but its a matter of using what I have on hand. A 60A esc and 5S 3000 30C packs. Those I already have and know can be put back in the Meteor with no mods. So going with something like the 2855 might be the way to go in order to continue using them.

Jason
FresnoJay is offline Find More Posts by FresnoJay
Reply With Quote
Old Oct 15, 2012, 02:00 PM
RAVI KOTHARI
Joined Nov 2005
259 Posts
Have just installed a Leopard 2850 2670 KV Minifan running on a 6S 3700 Kv pack.
Simply amazing performance , i get about 6 Min flight and the power envelope is absolutely amazing, most of the flight is at half or less. Effortless. Measly amp draw at about 50A. Straight and level seems to me at about 120MPH. the vertical is astounding. The best motor out there? i think so..........................

The leopard motor is outstanding, i find it even better than the het 2w25 it replaced.
albeit heavier at 145Gms. and at 50$ its a screaming bargain.

Would do a superb job on a 4S CS fan.
But gotta love the minifan, the power just seems so much better than the CS.
ravikoth is offline Find More Posts by ravikoth
Reply With Quote
Old Oct 15, 2012, 05:43 PM
TakeOff=optional,Landing= Must
fg1972's Avatar
Australia, Melbourne
Joined Jul 2010
427 Posts
I've had approx 50 successful flights with fixed wheels and another 100 without wheels. Last weekend I fumbled my hand launch for the 1st time and drove it nose 1st into the ground. I've glued it together again but am going to buy another one to build up slowly and install retracts this time.
I know a few guys on here have installed retracts, if anyone has any detailed pics of the nose wheel configuration, could they please post them up or direct me to the link?
Thanks.
fg1972 is online now Find More Posts by fg1972
Reply With Quote
Old Oct 15, 2012, 05:54 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
11,766 Posts
Yeah, if you use Minfan, or any low blade count, you "get your power back". eg your 50A for better performance. And possibly a half way step to the great CS10 sound... still better than the stock leaf blower.

The 2670kv would not be overly good power on 4S in a CS10. Even 2800kv is not great.
But it would smoke on 5S !! LOL
That would take the motor into extremes and it might not like that or last. I am not sure, it would have to be tested... but a Tacon 2550kv is already heading near the 70Amps area on 5S in a CS10, so 2670kv has to be 'worse'/higher. My own thought on having that combo would be mid to high 60Amps really.
PeterVRC is offline Find More Posts by PeterVRC
RCG Plus Member
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold Larry Jolly "Meteor"-127" Kit NIB --Now $275 Shipped ldm1839 Aircraft - Sailplanes (FS/W) 5 Sep 29, 2010 06:34 PM
Discussion Meteor shower tonite, You goonna stay up for it? Bilbobaker Life, The Universe, and Politics 13 Aug 16, 2010 12:32 AM
Build Log Peter Rake's 30" General Western Meteor Prototype dz1sfb Scale Kit/Scratch Built 19 Aug 15, 2010 11:38 PM
Discussion Two Hours Outside and I only Saw One Perseid Meteor Chophop Life, The Universe, and Politics 12 Aug 12, 2010 08:28 PM
For Sale Russ Thompson Meteor fuse Bill L Aircraft - Sailplanes (FS/W) 0 Oct 15, 2009 10:18 PM