With a sheet of inexpensive foam, glue, tape and a power system, you can build this electric powered radio controlled airboat. This is a lot of fun because you can drive it everywhere! Asphalt, sand, water, grass or even gravle, and with a powerful power system the airboat can reach very high speeds. The total cost of this project is estimated to be approximately 150$.
Step 1: Material and Components
Here's a list of all the necessary materials and electronics you will need for this build.
- Sheet of foam (styrofoam, bluecore, pink foam, etc.)
- Wood of different shapes.
- Hot glue
- Bolts and screws
- Metal rod (1-2mm)
- Brushless motor (http://www.hobbyking.com/hobbyking/store/__14342__...)
- Electric speed cotnroller (http://www.hobbyking.com/hobbyking/store/__8993__H...)
- Transmitter and receiver (http://www.hobbyking.com/hobbyking/store/__23165__...)
- Servo (http://www.hobbyking.com/hobbyking/store/__16265__...)
- Propeller (http://www.hobbyking.com/hobbyking/store/__22427__...)
- Battery (http://www.hobbyking.com/hobbyking/store/__56840__...)
- Charger (http://www.hobbyking.com/hobbyking/store/__58285__...)
- Soldering iron
- Knife (optional: hot wire cutter)
- Screwdriver and allen keys
Step 2: Airboat Body Dimensions
Once you have gathered all the necessary electronics, such as a motor, electric speed controller, batteries etc. Your first step is to cut out the body of the airboat. Use a marker and a ruler to draw the body onto the sheet of foam, and make sure you leave strong visible lines.
I made my airboat 1000mm long and 430mm wide based on my power system. Since I was building an airboat with a super powerful motor and high voltage batteries, the larger size increases stability of the airboat. What dimensions should you choose? Like I said, it's all based on your power system, but if you have the electronics linked in this Instructable you can use the same dimension I did.
Step 3: Cut, Sand and Form
For ease of use I decided to cut my foam with my DIY hot wire cutter, found here: https://www.instructables.com/id/DIY-Hot-Wire-Cutte...
Obviously you can use a simple knife, but depending on the thickness of your foam it may require a longer knife than usual. After the body has been cut out you will probably feel the urge to sand the edges, since the cutting process may have left ugly scratches and marks.
In order for the airboat to smoothly run over obstacles and more easily "get out of the water", you need to lift the front of the airboat. You can do this by placing a square piece of foam underneath the airboat body, stack a bunch of heavy bottles on one end, and push with your arm on the other. While doing this you will have apply heat, I perfer using a heating gun.
Step 4: Motor Mount
Now, don't go too crazy with reinforcing the motor mount, since the rudder will be the the designed weaked point. Meaning, if the airboat were to flip over, the rudder will hit the ground, not the motor mount.
Begin with a square piece of wood and tightly screw on the motor. Some of the motors have shafts in both directions, make sure the wooden mount is deep enough for the shaft not to go all the way through. Then take another rectangular shaped piece of wood and attach it to the square motor mount using glue or screws. Use hot glue to secure the motor mount to the foam body, and reinforce it with a wooden dowel or something of that nature. Place the reinforcement along the pushing axis, this will make the mount very strong along that axis, but weak from the sides. Follow the pictures if unclear.
Step 5: Vertical Stabilizer and Steering
To make the vertical stabilizer, or the rudder, you can use the same material as the body of the airboat. However, I recommend you use something stronger, like 3 layers of 6mm depron foam. Use the dimensions shown in the pictures.
With 3 layers of foam (+ 2 glue layers) the rudder is very bendable and strong enough to withstand most impacts. You may want to reinforce it even more with barbecue skewers along the sides. 1 layer of depron is sufficient for the moving rudder part. Use tape on both sides of the rudder to make the hinge, and glue the rodern horn (wooden piece in picture number 4) securely into the foam.
When the rudder is complete you may contuine to glue it to the body, remember to reinforce it with toothpicks att the very bottom. Use a good amount of hot glue when attaching the rudder. Once the rudder is secure, take your servo with the metal rod make z-bends in each end. One end will be attached to the rudder horn and the other one to the servo arm.
When glueing the servo, remember to power it up. This will ensure the servo is centred and installation will be easier.
Step 6: Finishing Touches
You basically have a working airboat, good job! Now it's time to clean it up. Make canals for the wires to go in, and rooms for the electronics. Make sure the receiver and ESC is fully waterproofed by either using hot glue or create a waterproof room.
Tie all the cables down with zip ties and glue the switch in case you have one. Do not dig holes in the foam for the batteries, you will need to find the proper centre of gravity for your specific airboat. I used velcro to semi-secure my batteries. When using a 2x 1400mAh 4S batteries in parallel I placed them 700mm from the leading edge of the airboat. Obviously your battery placement will differ from mine.
Step 7: Drive Like Crazy!
It's made out of foam! As long as you make the elctronics waterproof this thing will not break. The rudder might bend, but it will never break (depending on material of course). It will drive on asphalt, sand, water, grass, snow, ice and dirt. If you are thinking of driving on gravle you may want to add duct tape on the underside of the airboat.
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