Build an Airboat from Model Airplane Floats - RC Groups

Build an Airboat from Model Airplane Floats

Check out this custom airboat made from model airplane floats and brushless motors.

Splash

This is Awesome!

RCGroups users are the best. We like having fun, being creative and enjoying this great hobby and this project is just one of many examples of that in action. I wrote an article earlier this week about a retrieval boat from Hacker Model and RCGroups user Bill Glover replied showing his homebuilt airboat made from a set of BushMule floats, some PVC and two brushless motors. You can see it in action in the video below. It is genius!

I remember building an airboat decades ago out of a weed eater engine and a boogie board, but this is so much better and looks super easy to drive around on the lake. I bet it's fun in its own right even if you didn't need a retrieval boat, and he has an FPV pod for it! If you have a pair of floats sitting around, you might consider this project. It's so fun to make something yourself and when it works this good, it really is a special feeling. I'll put Bill's build notes below along with some photos he posted. Great Job Bill!!!

Bill's Build Notes

"I keep meaning to do a build video when I get time, but here are some pics & details that should hopefully give enough info. I bought the airtight food box that holds all the electronics first, then designed the frame around it - this is from 'display grade' 1/2" PVC pipe, which is thicker-walled than normal overflow pipe and has a much wider range of connectors available (3-way, 4-way, 'T', 45 deg, etc.). The motors are 2216 900kV running on 3S (I've used from 2700 up to 8000 mAh), props are APC 10x7. But anything that provides thrust should be fine They use reversing ESCs and mixing on the TX to do the steering - there are no servos or control linkages required. I oversized the ESCs to avoid any risk of overheating inside the sealed box - the motors pull 15A each on full throttle, and the ESCs are 60A ones. There are small strakes (shallow fins) cut from styrene sheet under the back of the floats to help it track straight. The CG position is important if you're going to run at speed - it needs to be just in front of the step on the floats. The other dimensions were all just done by eye and aren't critical. You obviously want the props to be clear of the water and inside the width of the floats (so they don't hit things) - I use a little up thrust on the motors to stop them pushing the nose (bows ) down."

"Here's the FPV pod that goes on top (with Velcro) ... Runcam Split plus an 850 mAh 3S pack and a cooling fan to circulate the air I have a separate plain top for when I don't need the VTx. The clear 'window' on the front is cut from the cheapest action cam case I could find on eBay, stuck on with RTV silicone. I used watertight cable glands for the antenna (and the motor cables on the main box), but a blob of silicone would work:"

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Jun 28, 2018, 10:51 AM
Registered User
What a great idea!
Jun 28, 2018, 11:18 AM
Registered User
tghsmith's Avatar
WII RAF air sea rescue.. if you have some airplane parts about but need a shallow draft boat..(they even used an aircraft rudder)
Jun 28, 2018, 02:00 PM
Just Plane Nutts
AirDOGGe's Avatar
Nice! We had a discussion of these just a couple of years ago, and a few of the unique airboats (including real ones!) also used aircraft pontoons: https://www.rcgroups.com/forums/show...ype-of-airboat
Jun 28, 2018, 02:50 PM
Registered User
Bill Glover's Avatar
Well, in all my years on RC Groups I've never been in the Boats area before!

As a small boy I was given a high speed steam launch (designed to run tethered), custom built for someone in the 1930s. I ran it up a few times (good job my parents knew nothing about testing boilers etc.!) and still have it in the loft.

In my school days (1970s) I had a couple of airboats - first a free running balsa/ply one with an ED Bee 1cc diesel (a Mercury kit, I seem to remember), then a home-built one with 2 channel radio and an Enya 19 glow. That was quite a success, based on a bare fibreglass hull I bought cheap in a local model shop.
Latest blog entry: Eachine QX65 FPV quad review
Jun 28, 2018, 05:33 PM
Club Saito | Genesis 8:11
Bunnyshooter223's Avatar
Hmmm i wonder if this could handle glow engines...

Nice idea. All i thought of so far was Boogie Board or Soda Bottles. I really eant an airboat to run some thumper engines.

Lol, that RAF WWII sea rescue boat is my style
Latest blog entry: Saito Parts Note
Jun 28, 2018, 05:37 PM
Registered User
Wonder how effective it would be as a rescue boat for downed seaplanes?
Jun 28, 2018, 06:17 PM
Registered User
Jason, would you please post a parts list for the propulsion (with URL's if you have them)? I am motivated to try to make this as a seaplane rescue boat.

Thanks!
Jun 28, 2018, 06:17 PM
Steps? What steps?
zozer's Avatar
I've built several similar airboats, fun and potentially pretty fast (30+ mph pulling 50 amps). I used thrust vectoring on one (shown on PVC frame, not on floats) with a single motor on a swiveling mount. I preferred the water rudders, the twin motors with reverse may work even better.

https://www.rcgroups.com/forums/show...o#post24014987


.
Jun 28, 2018, 06:44 PM
RCG Admin
Jason Cole's Avatar
Quote:
Originally Posted by dgfinch
Jason, would you please post a parts list for the propulsion (with URL's if you have them)? I am motivated to try to make this as a seaplane rescue boat.

Thanks!
This is Bills project, so maybe he can post a more detailed list of what he used.
Jun 29, 2018, 06:18 AM
Registered User
Bill Glover's Avatar
In terms of propulsion it's pretty non-critical ... all depends on how big you want to make the boat, and how fast you want it to go. I did build mine specifically as a recovery craft for r/c floatplanes ... I just got a bit carried away on the speed side As mentioned above I'm using 2216 900 kV motors (I had a bunch of these spare after re-motoring a hexacopter) turning APC 10x7 props, running on 3S packs. These pull 15A at full power, so 30A in total. For the ESCs I used these 60A ones from Hobby King as my Tundra seaplane has the 40A version, which I knew worked well:

https://hobbyking.com/en_us/aerostar...html?wrh_pdp=3

These do use a separate input channel to switch from forward to reverse, which meant the mixing on the transmitter was quite complex. With hindsight car or boat ESCs might have been easier. I use the right stick ('aileron' & 'elevator') to operate the boat, with a safety switch to arm/disarm the motors. It uses 5 channels:

- Left throttle
- Left reverse switch
- Right Throttle
- Right reverse switch
- Strobe on/off

There's no 'right' setup for the yaw mixing - you just have decisions to make about the point where you reverse one motor, rather than solely using differential throttle. You can see this in my testing videos where sometimes one motor is stopped and the turning is being done purely with the other one.

The boat is fun to drive, the 'rudder' is responsive at low speed and when planing but at transitional speed (with the back of the floats low in the water) it needs a lot more input. It's fairly sensitive to CG if you want to go fast ... nose-heavy and it porpoises, tail-heavy and the nose rises and the props hit the water. There's also a high thrustline of course which tends to push the nose down, hence the slight up thrust on the motors. As mentioned I added small fins (skegs?) under the back of the floats to help directional stability at speed - it wandered slightly without them.

So far I've never needed to use it in anger (i.e. to rescue a downed plane), but it should manage this OK with gentle use of the throttle! I have a carbon rod bar that goes between the front float mounting points if necessary, to help catch anything that's low in the water.

I used BushMule floats (EPO foam) from Hobby King as they have threaded alloy mounting plates set into the top surface, so are easy to attach with M3 bolts (I just made up U brackets as shown in the picture). One float has a servo well but I filled that with foam and put white tape over it. The floats have a clear moulded plate covering the underside from the step forward, which is great for durability. The only thing to watch is that the floats are hollow, so if you use these ones check the join line between the top and bottom halves. I had a little water inside the floats after running it on rough water and found the seams were flexing apart slightly in a couple of places. Easily fixed with some foam glue. I used stainless steel bolts everywhere as these are easily available on eBay etc. and obviously don't rust!

It's been a really interesting project - happy to advise if anyone wants further details!
Latest blog entry: Eachine QX65 FPV quad review
Jun 29, 2018, 06:27 AM
Registered User
Bill Glover's Avatar
I should add the the whole point of the design was that it needs no air or water rudders, servos, control linkages etc. With everything being done by motor thrust all the r/c gear can be sealed inside the central watertight box, with just the motor cables coming out. Of course like any airboat there's nothing to snag on weeds etc. in the water, and it's pretty handy being able to reverse as well!
Latest blog entry: Eachine QX65 FPV quad review
Jun 29, 2018, 06:40 AM
the great GassifÔer
With some FPV gear it would be a brilliant rescue boat.

I have a stereoscopic set lying around, should be perfect for close range depth perception when picking up the object to be rescued.
Jun 29, 2018, 07:16 AM
Registered User
Bill Glover's Avatar
That would be excellent. I just used spare stuff I already had for the FPV pod, thinking it would potentially be handy for rescue work further out. I've only used it for HD recording so far, not to operate the boat.
Latest blog entry: Eachine QX65 FPV quad review
Jun 29, 2018, 07:55 AM
Registered User
Not exactly like the RAF version, but food for thought.

Regards Ian.


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