Large electric motors and scale-like sound

[Forest Flyer]

Which large (1500 - 2000 watt) electric motor yields the most scale-like sound? I have no particular plane in mind, but I am looking for an option that comes close to the sound of a piston motor or a turboprop. I would also like that sort of scale-like sound to extend down to about half-throttle as well.

Perhaps I am asking for something that does not exist, but any thoughts on this would be appreciated.

FF

[Greg Smith]

My experience has been that 'scale sound' on larger electrics comes mainly from prop roar, so what you want is IMO a quite motor which means an outrunner.

You can add sound packages. Check out John Ranson's work at http://www.rcscalebuilder.com/forum/default.asp,
Brian Taylor Plans section. He has built a Spitfire, Me109E, and is working on a Corsair all electric and all with sound.

He's quite a helpful fellow and will answer questions.

You have to register at that site and it has lots of rules but it is worth it to see some of the models.

[Ron101]

Hey FF
I must say for the turbo prop sound you can't beat a geared Neu motor

I have a 1521 geared neu in my 30% extra and it sounds wicked
guys at the feild really dig it..very much like a turbo prop

it's also putting out 4100 watts on a 24x12 prop :eek:

fun stuff

Ron

[Wingman26]

I've noticed the same prop noise in the big electrics, its quite similar to full size aircraft prop noise, mainly when the prop tips go supersonic, I kind of like it! :D

[E-Challenged]

I keep hoping that some genius comes up with a sound system that stays on the ground but the model carries a light weight device which commands the sound system to give volume , pitch and doppler effects. The same device could reproduce a variety of authentic engine/prop sounds such as 4 and 6 cylinder opposed, radials, V-12's, jet and turboprop, etc. Planes using it would need to carry the command device. Any genii out there????

[61ahs]

Check out the Benedini sound system -

http://www.aerosoundrc.com/

[Dorme]

I've found that folding props on small aircraft do sound rather well. Even a folder on a direct drive 400 size motor has a nice rumble to it.

[E-Challenged]

The Benedini system has the heavy sound system with speaker etc in the plane, my concept has the sound system on the ground and lightweight command system in the plane telling the ground sound system the volume and pitch and doppler effect to make.





Check out the Benedini sound system -

http://www.aerosoundrc.com/

[AmpAce]

FF,

I think your best bet for realistic sound is going to be from prop noise, as stated above.

While it is a much smaller than the motor you seek, I just bench-tested an Atlas 4030-16 brushless outrunner from Hobby Lobby. It was run up to about 900 watts, and was very quiet in it's operation. I used an old Top-Flite 20X6 wood prop, and it made a very nice, scale-like sound, that should resonate wonderfully in the light airframe, (not yet constructed), that I plan to use it in.

Atlas makes larger outrunner motors, up to well over 2000 watts, that might be worth a look. The 4030-16 that I purchased seems to be of excellant quality, and the prices aren't bad, for a quality motor. I see that Hobby Lobby now states that they are discontinued, so don't know whether they still have any in stock, but they are still listed and priced on their website.

I've also read that large belt-drive power systems often make scale-like sounds, but I don't know of any now available in that size, so you would probably have to put your own together.

AmpAce

[Forest Flyer]

Thanks for the responses and the useful info. I agree that many strong outrunners can sound pretty scale-like when at full throttle, especially with a big prop. I also did not know that about those sound systems.

But that leaves the low-throttle higher-pitched "whining" of many large outrunners. Is that just a characteristic of such motors?

FF

[Lynxman]

the best way to eliminate the low rpm whine is to rubber mount the motor. This means that the plane will be extremely quiet though at low rpm. I do this with all my planes.

[Wildman777]

Hopefully someone can correct me if I'm wrong but I believe the Reaper motors sound similar to a turboprop engine. I think it has something to do with the design of the motor that's a little different from the others.

[AmpAce]

Thanks for the responses and the useful info. I agree that many strong outrunners can sound pretty scale-like when at full throttle, especially with a big prop. I also did not know that about those sound systems.

But that leaves the low-throttle higher-pitched "whining" of many large outrunners. Is that just a characteristic of such motors?

FF

Some outrunners have a much worse whine than others. Axis are notoriously "whiney", while the example of the Atlas motor that I have is very quiet, even at low rpm. It just makes a little "chirp" at startup. I'm sure there are other brands that are quiet too. I also have a Cyclon 110 outrunner that is supposed to be quiet, but I haven't tested it yet.

Any one else have any experience with large quiet outrunners?

AmpAce

[warhead_71]

Just want to throw an idea out there...

When we were kids, we used to clothes-pin playing cards to the forks of our bikes so it would hit the spokes and sound like a motorcycle... this is the same concept:

I had a small outrunner that sounded a lot like a "real" plane when the plastic label on the bell started to peel off and slap against the inside of the cowl. The cowl acted like a sound-box, making the "tic, tic, tic, tic" into a "tunk, tunk, tunk, tunk"... a much deeper tone.

Next, I thougt "hmmm... how can I do this on purpose?" so I rigged a different plane with a plastic "tine" that was mounted to the firewall and protruded out to the hit the back-plate of the spinner, which had reinforced radial webbing on the back. This produced a phenomenal sound, as the tine vibrated the firewall and the whole fuselage acted as a sound-box "bup, bup bup, bup", plus the spinner itself produced a higher-pitched "tak, tak, tak, tak"... it really sounded like exhaust tones mixed with machine gun fire. That lasted about 3 flights until the tine shattered due to stress.

So, for the third version I made a tine from 3/16" piano wire. Instead of the tine hitting the backplate, I replaced the prop adapter grub bolts with a couple of small phillips-heads bolts... so the tine is now screwed to the face of the firewall and extends out past the front of the motor bell and bends around so it hits the two screws. Net result... too springy. I was getting an intermittent "clackitty-clack" at the tine bounced off the screws. Different RPMs yielded a varying cacophony... but it never sounded good, and I worried about the wire getting caught or ejected... it didn't seem safe.

Here was my final solution. I mounted a reinforcing block of hardwood to the firewall, through which I drilled a 1/4" hole. In the hole I epoxied a length of hardwood dowel, the dowel extending to the length of the prop adapter. At the end of the dowel I cut a notch that could hold a durable yet flexible piece of plastic. The plastic was positioned to hit the prop adapter screws. Much like a guitar pick, the plastic was "plucking" the screws as they came around. The energy still transferred through the wood dowel to the firewall and made a pleasant woody "tup, tup, tup, tup". (I'll make an illustration).

So, the next logical step would be to go back to the machine-gun sound and make it servo-operated for a realistic "guns-ablaze".

*edit* This all with a small 120W motor... and it didn't seem to affect the performance of the motor. I'd think with a bigger motor (rather, a bigger firewall to work with) you could build an actual sound-box on the face of the firewall to get the exact tone you want. Or you could build two "pickers" with different volume sound-boxes to get offset, harmonized tones.

[Forest Flyer]

... Or you could build two "pickers" with different volume sound-boxes to get offset, harmonized tones.
Wow, I wasn't thinking about music from an outrunner, but I suppose that is possible! Your wheel-and-spoke idea is very interesting indeed. What exactly does it sound like, as compared to something in the mechanical world?

[Forest Flyer]

..... Axis are notoriously "whiney"...At low throttle, the large AXIs certainly are! But at higher throttle, the scale-like sound is not bad.

I too would like more info on large outrunners that are pretty quiet at low throttle.

FF

[The Reaper]

hey dman

yes the reapers have a whine to them , motors with a whine tend to have a tighter airgaping , the space between the magnets and the stator the tighter the tolerance the higher pitched whine you get and we run some pretty tight airgapping to get the most power out of our motors.

scott

Hopefully someone can correct me if I'm wrong but I believe the Reaper motors sound similar to a turboprop engine. I think it has something to do with the design of the motor that's a little different from the others.

[wellington53]

http://www.youtube.com/watch?v=S1zWH_UTb0c&feature=channel_page
Forest Flyer, As far as I know this is the only you tube video of an electric plane that the motor and prop can be heard as loud as this. My setup is an E Flite power 60 and a Phoenix 45 amp High Voltage which means I can shove 40 odd volts through the motor, I'm using a 12x8 prop and at wot it's got 2010+ watts of power! I also had no clue that this plane would make so much noise. Love it!!!

[Forest Flyer]

... I also had no clue that this plane would make so much noise. Love it!!!
That is indeed a unique sound. I thought that maybe you had one of those gizmos described by warhead (post 14) in the mustang.

Nice video, BTW.

FF

[wellington53]

Thanks FF, I originally had a 6s2p battery configuration wired in parallel with a 80a Phoenix esc with a 16x10 prop but wanted more speed. That's when I decided to go with a Phoenix 45 High Voltage esc and 6s1p. Obviously I down propped to 12x8, also did do some tests though to make sure the motor could take the heat and after a 4min wot flight the motor was hardly warm.

[The Reaper]

hey wellinton

how did you come up with 2000+ watts 45 amp esc 6s pack 25v thats only 1134 watts ?

scott

http://www.youtube.com/watch?v=S1zWH_UTb0c&feature=channel_page
Forest Flyer, As far as I know this is the only you tube video of an electric plane that the motor and prop can be heard as loud as this. My setup is an E Flite power 60 and a Phoenix 45 amp High Voltage which means I can shove 40 odd volts through the motor, I'm using a 12x8 prop and at wot it's got 2010+ watts of power! I also had no clue that this plane would make so much noise. Love it!!!

[wellington53]

Hey Scott, I must apologize for the mistake, what I meant to say was 6s 2p wired in series, 44volts or so, Sorry.

[The Reaper]

hey wellinton

no problem i was just wondering. honest mistake.

scott

Hey Scott, I must apologize for the mistake, what I meant to say was 6s 2p wired in series, 44volts or so, Sorry.

[Tipover]

I have one of the original Hacker A50 L motors and there is zero whine, all you hear is the prop beating the air, very nice sounding.

The newer versions with the internal fan have a bit of a turbin sound at slower speeds. I personally wish they would have left the original design alone. Mine has been working great for 3 years.

Kevin

[eye4wings]

Hi guys

Here's a throw-away idea I never tried, but someone might get fired up and give it a shot.
Gazing aimlessly into a river one day I noticed a reed swaying in the current. It was growing edge-on to the flow and was swaying to one side swivelling slightly and getting taken back the other way. It just kept going and I thought if I mounted a thin strip of plastic in an airflow, say upside down in the belly radiator of a Hurricane with a flat plate for the tip to resonate against, could I get a half decent machine gun sound? A small servo could either divert the airflow to stop it or slide a deadening loop down towards the tip, which could have a weight attached to accentuate the hit. A heavier weight would slow the vibration time and make a louder sound.

My experience of motor sounds has convinced me that the larger wooden propeller is the cheapest way to get a good sound. With a lightly built airframe to act as a sounding box it can be really nice.
Have any of you tried notching the tips? I noticed once when flying with a damaged prop (ground strike on take-off from tarmac) that the sound improved, but that may have been because it was then slightly out of balance.

Turboprop sounds well reproduced on my Aviocar by 4:1 geared Astro neodym motors.

[Tyler P]

Kind of an interesting thread! In my Multiplex AcroMaster I find that it sounds like a gas plane. I'm using a Turnigy C3536 and a Master Airscrew 12x6. I think it's mainly the hollow Elapor nose that ends up making that much noise, but it really sounds cool when I start tossing it around at higher throttle!

I'm in the middle of a 78" 10s electric Extra 330L project where I'll be propped with a 20x12. I'm kind of anxious to hear what that'll sound like! Should be very cool!

That P-51 had a crazy sound! Sounded almost like a lower pitched F1 car! That was very neat.