Foamboard Air Boat on the Snow

by eagle4 | December 7, 2014 | (14) Posted in How To

Hey gang, with the winter now upon us I wanted to build an airboat from parts i had laying around. This is what I came up with. and It can be built from only 1 sheet of foamboard. I am running this off a 24g hextronic motor, Same one that FliteTest uses for most of their earlier planes, like the FT Flyer, Nutball, BloodyWonder etc. I'm using a 10amp esc, as thats what I had laying around, anything will do. a 2200mah 3s, but you could use a smaller battery. not sure how a 2s would go, but a 3s definately wasnt too heavy and it had a lot of punch. I was using an 8x4 prop. This also works with a smaller prop of course, i just had some 8 inch props laying around.

I started off modeling it roughly in 3D, to get the rough shape i was after, then i tweaked my design so that I could use 1 sheet of foamboard!!

Firstly start off by downloading the plans and transfering them to your foamboard.

AirBoat Plans

 

 

Start out by cutting out your Hull and your Cross Braces. Tape the underside of your Hull first, I used duct tape along where my corners were going to be and a strip down the middle (I was rnning low or i would have used more) I then covered the entire bottom in packing tape for slipperyness over the snoe. Then cut along the score lines on the Hull and do a slight bevel cut. (I just mashed it in with a bbq skewer, but it would have been much easier to do a 45 degree bevel cut) Then glue in the Cross Braces into place.Line them up so that they are both on the rear side of the reference line. you could have it infront of the line, just make sure both are the same.

 

Now by adding a lot of hot glue, fold up the sides of the Hull to meet the Cross Braces, once they are in place glue the front, corners and sides together. You want these to be strong so dont skimp on the hot glue.

Now cut out the motor mount sides and test fit them to make sure they fit. I forgot to add this in the photos, but glue on the motor mount and the motor mount brace  to the top to help it stay square. Then glue it in place centered across your Hull. Lots of hot glue again. we dont want this coming loose.

Cut out your Top Deck and cut 45 degree bevels  at the front of the hatch and at the rear fold down pannel as indicated on the plans. 

Tape up the whole upper deck I used Caution tape as its bright and easy to see it racing across the white landscape.

 

Now you want to glue the Top Deck to the Hull. Once its in glue down the rear fold down part into the fuselage, this is to help the air flow get from the prop to the rudders in case you're using an 8 inch prop

 

This is what it looks like from the back once you've glued on the Rear Wall. Tape up everything!!!

For the rudders I planned on having it driven by 1 servo with a connection between them. This didnt work well at all as when you pushed the rudder the linkage in the middle would shift and you wouldnt get a good push. You'll notice 2 braces between the rudders, these were placed with the smallest amount of glue possible, just to keep the spacing even between them and to keep them both square. the glue easily came off with a bit of pulling once they were installed

I eneded up using a y harnis between my two servos. if you choose to use 1 servo you can just plug it straight into your receiver.Glue on the rear tail assembly. Pretty close should be good enough. 

And here it is finally built. I planed on putting the battery up front with the receiver, but the CG for an airboat needs to be 30% from the transem. (aka the back of the boat) So I had to stand the battery up next to the motor. it hasnt gone anywhere in any crash of mine and its only been held on by velcro. For extra strength I've 

After a small sideswipe with a tree the rear tail assembly came loose. as hot glue, tape and cold weather dont mix. I fixed this by putting some bbq skewers down the leading edge of the rudders and the tail assembly and embedding them through the top deck and partially into the hull underneth. added a bunch of hot glue and this tail is super strong, its not going anywhere.

COMMENTS

TapeGlueSolder on December 7, 2014
Nicely done! Well put together article and video! Kids will love playing with.
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Grearson on December 8, 2014
Cool, was designing one by myself when i saw the video of MesaArc FoamFighters. This is about what i had in my Mind =) saves a lot of work, so thx a Bunch just need the snow now.
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eagle4 on December 8, 2014
I actually saw their video. It came out after I had built this one, but before I got a chance to test it out. Their video made me think this was going to be a bit under powered... boy was I wrong :)
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rcflyer729 on December 8, 2014
I would like to build one with spare electronics that I have doing nothing. Just encase it snows here in NC but the plans you have are not tiled could you make a tiled version?
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Bellows on December 8, 2014
I am building this right now and am wondering if it might also work in the water.
LooseBruce
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eagle4 on December 8, 2014
Hey, Thats awesome you've started building it! I think it should work on water, but just make sure you waterproof it a lot. It might also be good to keep the CG as low as possible. a smaller battery than my 2200 might be in order to stop it from rolling on tight turns.
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alibopo on December 9, 2014
Hi - nice simple build, and loads of fun too. You must have known I was about to comment on the battery height :) I doubt there's anything wrong with that size of battery - in fact it's probably the only thing stopping it flipping over at speed! There must be some way to get it down closer to the hull. Maybe open-up that cross member in front of the prop and let the battery project into the prop 'bay' within a little protective box?
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Bellows on December 11, 2014
Hi, I built it and maidened it today. WOW, it is a blast and a little easier to navigate than my planes (I disabled a couple of planes scrounging for parts). I have a lot to learn about being an airboat captain. It is fun to slide around in the turns.It seems to turn well when going slow but not so much when going fast but I have only run it a little.I think a nice mod would be to add a brake because I have met the road a few times already.I was thinking about a servo that would lower a couple of pieces of BBQ skewer into the snow. Maybe a left and right skewer could make some wild turns.I was thinking of controlling them like elevons (Left, right or both for brake) I haven't tried the 8" prop yet but I will. I did get away with using only 1 servo for the rudders. I linked the 2 rudders with a couple of zip ties and it is working well.
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eagle4 on December 11, 2014
That's fantastic that you built one and are having a blast. I'd love to see it. I think you get better steering with the smaller prop, but try the 8 and see. I find i get good steering at high speed, but i completely lose steering if i kill the throttle, as there is no longer air getting blasted past the rudders. I find turning before you need to is the trick to driving the airboat. I'm truly glad you're having a ton of fun driving this little guy around.
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Bellows on December 11, 2014
I think you may be able to see it here:

https://www.youtube.com/watch?v=k6qUO979BR8

Worth a try at lease
LooseBruce
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eagle4 on December 11, 2014
Hey mate. Awesome work on the build, it looks fantastic. Where is your cg? Do you have it at about 30% from the rear? It should roughly be where the motor mount is. Also try adding some more throw on your control surfaces. You may also find cruising at a medium speed is easier to control it. Keep up with it mate.
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Bellows on December 12, 2014
Hi thanks for the compliment. I did add more throw and it helped a little. COG is about 30% by eyeball. I should play with that.Still, starting from a dead stop I can do donuts in either direction but if I am moving along fast it is hard to turn. I did add a brake that has been helpful. I think what I really need is reverse :)


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Bellows on December 12, 2014
You were correct....my eyeball was off. I measured for COG and it was far too forward. Much better now and I extended the steerable brake. It works well. My batteries are almost at the transom!I think I am ready to race with my friend now, Thanks

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Mostly Harmless on December 8, 2014
Got the plans printed, cut out, and taped together. Construction begins soon. Seems strange to be hoping for some snow... all summer long, I've been hoping for good weather to fly. (Thanks for a cool winter project!)

One mod I think I'll try: It looks like it could use a little lateral stability (seems like it likes to slide sideways more than I would be comfortable with). I might add a 1" strip of foamboard lengthwise along the sides on the bottom to act as runners. That should help keep if from sliding, but hopefully won't keep it from steering. Laying the battery flat on the bottom might also keep it from tipping quite so easily. So many cool things to try out with this design! (Thanks, again!)

I've also thought about doing Peter's water-proofing treatment and trying it on the water. Some great possibilities there, too.

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eagle4 on December 8, 2014
the sliding sideways as i was driving straight was me fishtailing on purpose. i found if i drove it straight it tracked like an arrow. I personally liked how it slid in corners. thats why I angled up the sides. I'm super pumped that you're building one and I really look forward to seeing your mods and how they work out. Good luck mate.
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Mostly Harmless on December 8, 2014
My planes fly like that even if I'm aiming for straight and level... ;) I'll try it without the runners first and see what it's like (if we get some snow, at least).

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Bellows on December 15, 2014
Hi Flyers, I started a thread in the forum based on this design. I hope folks will share their pics and videos of similar builds. I realize these are not aircraft but they have come about because of the Flite Test community. Here is the link

http://forum.flitetest.com/showthread.php?14372-FT-article-inspired-Foamboard-Air-Boat-on-SNow&p=153853&posted=1#post153853
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stereodreieck on December 26, 2014
One of best articles all time. Two big thumbs up
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JohnVH on December 30, 2014
struggling on how to print it with a small printer.. want to make an fpv boat
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eagle4 on January 3, 2015
Hey John, there is an option to print it as a tiled poster in Adobe Acrobat reader. It will then print out all the pages, just stick them together and go from there. I look forward to seeing it when you're done :)
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kabturek on February 2, 2015
Great article! I've build one and its a blast! ive used turnigy 2204-14t motor that i had on hand (swinging a 7x5 prop) but i had to use full throttle most of the time. i've updated the motor to a turnigy d2826 still with a 7x5 and its a monster!
I've sealed all the open areas and hidden all stuff there - on the next version i plan to hide the servos too.
I have a camera mount on the motor mount to for some FPV but when i drive FPV im very cautious ;)

I've added a led strip inside around the edge and its a blast to run at night.

Here is a video of some rides: http://youtu.be/l6Iu8_2csWU
The night shots are out of focus :/ my camera didn't cooperate.



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Rich60 on May 4, 2015
Hi ! This construction is soo awesome, I'm gonna do the same airboat from the plans but I've one question: what are the dimensions of the sheet of foamboard ?
Thanks !!
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eagle4 on December 30, 2015
It's a 20x30" piece of foamboard. The stuff here in Canada is from Elmers, but Adams ReadiBoard will work fine too. just make sure you waterproof it with tape properly
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MarkPrima on November 13, 2015
Great set of instructions!!!
I would like to know more details on how you fastened the two rudders so they move.
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eagle4 on December 30, 2015
I set up the rudders to work exactly like it is in a plane. i cut a 45 degree bevel on the hinge line and added a servo and a pushrod to push on a control horn attached to the rudder.
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MarkPrima on December 11, 2015
Well, I came up with my prototype, tested it on water and runs good so I came up with a set of plans - http://flyingblog.primaveraphoto.com/snow-water-bug-prototype-and-plans
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konkilr on January 30, 2016
https://youtu.be/fRoiTpamYK8 Mine will do a back flip if you go to fast! I might need some nose weight.
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Travos on November 11, 2016
Just made this for use on water, a major problem is the motor is mounted too close to the cg, which means you can't really add adequate thrust angle to counteract the rotational force of the motor being mounted up high. The problem is the rotational force causes the bow to dig in, this isn't noticeable as much on land but it does have negative effects making the thing grab and flip. On water id means it can't plane, and just plows water and grabs the sides. I'm working on a solution and i think it's to mount the motor as far back as possible and add adequate thrust angle, ideally you want the motor to be pointing at the cg to get zero rotational force, but that might be pretty tricky with the cg being so far back and the motor so close to it.
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eagle4 on November 29, 2016
That's good to hear your feedback from having it on water. I only designed this to work on snow. water was never planned for me, as i dont have any water nearby to drive it on, but i get a few months of snow lol. if you get it sorted for the water I'd love to see your modifications that you came up with.
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Menus666 on January 2, 2020
distance between the 2 rudder???

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Foamboard Air Boat on the Snow