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May 21, 2019, 02:25 PM
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biomecanoid's Avatar
Thread OP
Discussion

WL912 RC boat mod to pusher airboat


Hello,

I could not find a more suitable place to post my thread i didn't find a category specific to airboats.

I got the WLTOYS WL912 RC Boat from Gearbest. The boat looks pretty good and works on 2.4ghz with a 390 brushed motor and 7.2v Li-Pe battery.

What is unusual about the boat is that it is using a gear system to provide power to the prop shaft. The motor pinion is made out of brass but sadly the gear attached to the prop shaft is plastic.

The plastic gear lasted 3 2000mah packs and it stripped. I have the boat "dead" for a long time now and i am researching of ways to revive it.

I think the easier way to make the boat operational again is to just stick a brushless outrunner motor at the back where the wing is, maybe with a volantex 757-4 motor and motor mount. So i would like to convert the WL912 to airboat keeping the existing water rudder.

I would like some suggestions on what motor to user size, kv, prop etc. How do you choose what power system you need ?

I already have several 3s batteries, boat esc i just need motor, mount and prop.


Running videos:


WLTOYS WL912 RC Boat Maiden and crash (1 min 47 sec)



WLTOYS WL912 RC Boat 2nd try with new prop (9 min 2 sec)




Thank you
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May 22, 2019, 05:36 PM
If it flies - I want one!
Petem's Avatar
Might be worth looking at one of the compact drone motors - they are light, powerful, fairly high KV (typically around 2500 or more) and drive multi-blade small diameter props CW or CCW (suits your pusher requirement).
The mount you will have to build yourself, unless you have contacts with good 3D printing design and print skills. Otherwise, make one up from ply and balsa, just tall enough to clear the deck.
Sounds like a fun restore and mod project.
Cheers,
PeteM
May 23, 2019, 06:24 AM
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biomecanoid's Avatar
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Well i have been looking for motors and props but i don't know what size and KV motor i should be looking for ?

I have found some likely candidates:

https://www.banggood.com/Racerstar-R...warehouse=GWTR

https://hobbyking.com/en_us/vspec-mo...minations.html

https://www.banggood.com/EaglePower-...r_warehouse=CN


But these don't come with a cross mount so i can screw them on a stick on a pylon like people do with gliders


The boat is about 46cm long and weights 350gr without battery so what are the specs of the power system i would need ?

They only thing i know for sure is that i wanna use 3s batteries since i think it will provide enough power and i already have a lot
May 23, 2019, 06:48 AM
If it flies - I want one!
Petem's Avatar
I'm out of my knowledge area in boats, but I have one of the 1808-2400 HobbyKing motors on your list in a flying wing that weighs around 350gm.
Have run it on 2S and 3S and a 5x3 prop and it is very lively.
A 12 minute flight on a 1000mAh 3S pack used only half the capacity an ran very cool, so I think it would be happy with a 6x4 prop or a 5x4 three-blader.
The CCW variant has the left-hand threaded shaft which suits running standard prop as a pusher. If you use drone props you could use either variant.
You can make your own flat mount from ply - drilled through from the rear for the 2mm screws, bigger than the motor diameter, drilled from the front for your mounting screws. I had a friend print a couple of 3D printed PLA mounts for mine that work nicely, but have used ply on similar motors with no probs.
Cheers,
PeteM
May 23, 2019, 01:19 PM
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biomecanoid's Avatar
Thread OP
Thanks for your help.

I will do a quick research into what i need and post back my findings
May 23, 2019, 01:40 PM
Just Plane Nutts
AirDOGGe's Avatar
Airboats are often flat bottom or nearly so to deal with the stability issues of a high-mounted motor turning a large diameter prop, and to reduce chance of capsize.

I'm not sure one of these budget self-righters with roly-poly hulls would do well for such a task. Good luck.
May 23, 2019, 01:46 PM
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biomecanoid's Avatar
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Yes airboats are mostly flat. Any ideas on how to make this boat work ?

The stock drivetrain was awful but the hull and rudder is good
May 23, 2019, 02:06 PM
Just Plane Nutts
AirDOGGe's Avatar
You could try fitting the flex drivetrain for a Volantex in there. You'll need these 2 parts:

Shaft, stuffing tube, liner, prop
https://www.banggood.com/Volantex-V7...r_warehouse=CN

Prop strut (required for above)
https://www.banggood.com/Volantex-V7...r_warehouse=CN
Last edited by AirDOGGe; May 23, 2019 at 02:25 PM.
May 23, 2019, 02:23 PM
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biomecanoid's Avatar
Thread OP
Thanks for the links i will also need a motor mount and a way to attach the motor to the shaft.

The WL912 with its small brushed motor is slow and not much fun so since i will mod it i may as well upgrade it.

I think i will use the electronics from the volantex atomic i have the atomic and its fast and reliable so i guess its safe to buy the same power system for the WL912.

Can you recomend a motor mount and and adapter to secure the shaft on the motor ?
May 23, 2019, 02:35 PM
Just Plane Nutts
AirDOGGe's Avatar
Plenty of mounts around, but you will have to custom install it somehow. I doubt you'll find anything that would bolt right in.

I had to make a floor for my mount and a support for the stuffing tube from hobby plywood for my modded boat: https://static.rcgroups.net/forums/a...00kvmount2.jpg

The motor mount I used is this one: https://www.atomikrc.com/collections...e-xl-rc-boat-1

Optionally there's this when it's in stock: https://hobbyking.com/en_us/quanum-w...2-version.html


If you use an inrunner motor with a water jacket, then you will not need a cooled motor mount and can use a basic one.
May 23, 2019, 03:15 PM
Registered User
biomecanoid's Avatar
Thread OP
Yes thats looks doable. One thing missing though, how do i attach the motor to the shaft ?
May 23, 2019, 03:24 PM
Just Plane Nutts
AirDOGGe's Avatar
Using a flex shaft means you can use any rigid coupler. WHICH coupler to buy depends on flex shaft and motor shaft diameter. Samples:

https://www.ebay.com/sch/i.html?_fro...ler&_sacat=220
May 24, 2019, 06:08 AM
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biomecanoid's Avatar
Thread OP
Well i think i found a cheap big can motor with enough KV:

https://www.gearbest.com/motor/pp_00...ml?wid=1433363

Looks a bit unusual though. I don't see a flat spot on the axle unless its where the "colar2 is.
If that is so i guess i just need to cut of the rest of the axle. Also i don't know the thickness of the axle
May 24, 2019, 07:06 AM
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biomecanoid's Avatar
Thread OP
OK i think i found a proper setup, which is a copy of Feilun FT012 :

Motor US$15:

https://www.ebay.co.uk/itm/New-Brush...f7ad08a85f4f6c

Transmission Parts US$5.77:

https://www.banggood.com/FT012-2_4G-...r_warehouse=CN

Motor Mount US$3.00:

https://www.banggood.com/FT012-RC-Ra...r_warehouse=CN

Fins US$3.48:

https://www.banggood.com/FT012-RC-Ra...l?rmmds=search

Inner Hatch US$4.32:

https://www.banggood.com/FT012-2_4G-...r_warehouse=CN

ESC 60A US$13:

https://www.ebay.co.uk/itm/1X-60A-Br...4AAOSwyQVczCrB


That's about 45US for everything or 37US without the Fins and inner hatch


So with all this hardware the WL912 will be a clone of the FT012

https://www.banggood.com/FT012-Upgra...r_warehouse=CN
Last edited by biomecanoid; May 24, 2019 at 11:02 AM.
May 25, 2019, 12:38 PM
Just Plane Nutts
AirDOGGe's Avatar
Don't forget shipping cost. By the time you get it all done and added up, you may as well have bought an FT012. you can get one as low as $71 (price +shipping):

https://www.ebay.com/itm/FeiLun-FT01...MAAOSwtGlZIszH



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