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Old Feb 07, 2013, 08:02 PM
Ochroma Lagopus Tekton
Fly Wheel's Avatar
Blackstock, South Carolina
Joined Sep 2007
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Question
Gearbox with the best sound.

Next aircraft kit scheduled to occupy my build table is going to be a 1913 Eastbourne. This bird is designed to be equipped with a Ni-Cd pack, Speed 400 motor and a gearbox. I plan on using Lithium instead of nickel and a brushless inrunner in place of the can, but stick with the gearbox; partly to help maintain balance, but also because I heard that gearboxes can actually make an electric bird sound more "scale like". Seeing as this is a model of an actual plane I figured keeping something that would at least add to it's aesthetic appeal would be better than adding a bunch of lead to bring it back into balance (I may also use a wooden prop if the gearbox alone isn't enough).

So my question is this: In your opinion, what good quality, long wearing gearbox would sound the most like a 3-cylinder Anzani radial engine that's been seriously shrunken down?
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Old Feb 07, 2013, 10:03 PM
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Albuquerque, NM USA
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LOL

The sound of a gearbox or belt drive has two parts. The sound itself, and how the airplane changes that sound. The second is more important than the first.

Sheeted fuselages/nacelles work best in my experience. It seems the balsa sheeting acts like a reverb chamber/speaker.

I liked the MPJet gearbox for the sp400. They also made a brushless inrunner that fit the same gearbox (I have one in my P-47). Mainly because it was totally enclosed. A bit less noisy than most. The Maxx gearbox was very noisy but was exposed and needed fairly frequently lube. The Olympus was another one a lot of folks liked.

You might also try one of the inline boxes to keep the scale look.

charlie
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Old Feb 08, 2013, 04:30 AM
An itch?. Scratch build.
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Go for a belt drive, they have a nice rumble. Gearboxes can make an awful whine.
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Old Feb 08, 2013, 05:33 AM
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Norfolk, England
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Not sure which Eastbourne Monoplane model this is, but if it's similar in size to my 48" model getting a belt drive within the dummy engine could pose a problem. An extended shaft will put the motor a long way back and complicate balancing. Unfortunately, with the possible exception of the MP Jet one, an off-set gearbox suffers the same problem.
Although much easier to get within the space, most in-line gearboxes run quite quietly and sound absolutely nothing like an Anzani.

With care it may just be possible to get a Mini Olympus gearbox to fit and that does have a nice rattle/rumble to it - especially if you distort the pinion gear by over tightening the grub screw. Whether or not you'll be able to fit a BL motor to it is another matter.

Pete
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Old Feb 08, 2013, 09:53 AM
An itch?. Scratch build.
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South Wales U.K.
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There a quite a few Eastbourne threads on the forums if you want to see what others have done, or used.
A search found around 30 threads with Eastbourne in their titles.
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Old Feb 08, 2013, 11:05 AM
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My models with Mini Olympus gearboxes sounded like they had a full scale 4-banger. Flying buddies would worry that the noise would get us kicked out of the schoolyard. If you can find an old but usable one, do not over-tighten grub screw on pinion gear, it may strip threads in the hard nylon. I use the common 6 volt brushed "Speed 400" motor. Never tried a brushless inrunner in the Mini-Oly.
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Old Feb 08, 2013, 12:03 PM
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Ugh, I can't stand the sound of a gearbox on an electric plane. I just barely tolerate it on a couple of my PZ micros. Silent flight is OK by me.
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Old Feb 08, 2013, 07:11 PM
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I might not have put that quite right. That wasn't an instruction to tighten the grub screw, just a warning about what can happen if you do. Apart from the risk of stripping the threads, it starts to sound vaguely like a steam engine. The Eastbourne may be quite old, but it's definitely not steam powered.

Silent has its' place, but not when you actually want an engine-like sound. That's why people go to great expense to install sound systems. A totally silent Spitfire is just wrong somehow. It should at least sound something like a Merlin - even if most don't sound very much like one.

Pete
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Old Feb 08, 2013, 11:41 PM
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USA, FL, Orlando
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The one that comes to mind and which I have used very extensively "and" which is still available at:

http://www3.towerhobbies.com/cgi-bin...P?I=LXSL79&P=8




It has other Gear Ratios by purchasing the other Pinion Gears so, the sky is the limit and you are not stuck using just a few propellers!!!

This Metal Pinion Gear -to- Plastic Spur Gear (Very robust) makes the best sound for Electric in my opinion.

Here is my Great Planes Super Sportster EP with the gearbox flying right at 74+ MPH Ground Speed (Measured using a GARMIN Geko 201 GPS).



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Old Feb 09, 2013, 03:46 AM
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Norfolk, England
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Isn't that a 600 size gearbox? Even if it were 400 size, it's likely to be too bulky to fit the model.
Athough I still don't know the precise model we're talking about, my 48" model has a crankcase less than 2" diameter. For an off-set gearbox to fit that it would need to be less than 1" from the shaft c/l to the outside of the gearbox at the motor - so the shaft could exit centrally. Given that a 400 size brushed motor is around 1" diameter it's umlikely that an off-set gearbox of any make will fit. That was why I showed an in-line gearbox on my drawings - but actually ended up fitting an outrunner.

Pete
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Old Feb 09, 2013, 07:51 AM
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United States, NJ, Browns Mills
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I have to chime in with the Olympus gearbox, too, although I also only used it with a ferrite S400. I had one in a Sopwith Pup that made it sound very much like the rotaries we heard at Rhinebeck, only quieter.

CD
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Old Feb 09, 2013, 12:57 PM
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Quote:
Originally Posted by PETERRAKE View Post
Silent has its' place, but not when you actually want an engine-like sound. That's why people go to great expense to install sound systems. A totally silent Spitfire is just wrong somehow. It should at least sound something like a Merlin - even if most don't sound very much like one.

Pete
Now that you mention it... My Andreasson BA-4b makes a God-awful racket, with its 3530 (3.5 oz) motor and 10x5 prop. Its first motor fried mysteriously, and the second one isn't sounding any better. I'm beginning to wonder if the firewall that it's mounted to is somehow acting as a resonator. Maybe it needs to be reinforced with crossbeams or something. Beautiful plane, but it's been plagued by power-plant problems.
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Old Feb 09, 2013, 07:01 PM
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Quote:
Originally Posted by PETERRAKE View Post
Not sure which Eastbourne Monoplane model this is, but if it's similar in size to my 48" model getting a belt drive within the dummy engine could pose a problem. An extended shaft will put the motor a long way back and complicate balancing. Unfortunately, with the possible exception of the MP Jet one, an off-set gearbox suffers the same problem.
Although much easier to get within the space, most in-line gearboxes run quite quietly and sound absolutely nothing like an Anzani.

With care it may just be possible to get a Mini Olympus gearbox to fit and that does have a nice rattle/rumble to it - especially if you distort the pinion gear by over tightening the grub screw. Whether or not you'll be able to fit a BL motor to it is another matter.

Pete
There is a way Peter: build the gearbox BEHIND the motor and use a long output shaft

Since all you need for a belt drive is a pair of formers equipped with ball races, a shaft and a couple of pulleys a collett and a belt, and a slotted mount for the motor, its all relatively hand craftable.
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Old Feb 09, 2013, 07:04 PM
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Quote:
Originally Posted by rafe_b View Post
Ugh, I can't stand the sound of a gearbox on an electric plane. I just barely tolerate it on a couple of my PZ micros. Silent flight is OK by me.
belt drive is fine

this is a speed 600 and a belt drive

http://www.shaman.co.uk/models/black...lack-magic.wmv

plenty of commutator whine, but the rest is prop noise.
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Old Feb 09, 2013, 08:56 PM
Ochroma Lagopus Tekton
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Blackstock, South Carolina
Joined Sep 2007
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Sorry, I should have been a little more specific; The Eastbourne I will be building is the 43" WS kit built by AeroCraft for Hobby Lobby, which has a nice ""soundbox" in the front end. As far as the noise is concerned, I belong to a club which has it's own field way out in the boondocks. Seeing as no one has complained about the 60" gassers that most members seem to prefer flying I doubt a 20 ounce gearboxed electric will cause any dismay.

I've done searches both here and on Wattflyer, but the only build threads I've seen that mention gearbox sound are years old.
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