This Instructable details the construction of a remote-controlled airboat made from cardboard, designed for skimming across grass. The project utilizes readily available materials and electronic components, offering an engaging DIY experience.
The build requires an RC Transmitter and Receiver, specifically a FLYSKY FS-i6 with the FS-iA6B Receiver. A cost-effective Amazon kit provides the motor and ESC, while a Tower MG90s servo and an 11.1V Lipo battery complete the electronics. Safety is emphasized, particularly when using a craft knife, with a preference for scissors where possible.
A video demonstrating the airboat can be found at: https://youtu.be/e0AFj-AIQz4
Supplies:
- FLYSKY FS-i6 or FS-i6X Transmitter (Amazon UK)
- FLYSKY USB Data cable (Amazon UK)
- Stiff Cardboard (Creality Glass build plate box recommended)
- MG90s Servo
- 1mm Steel rod
- Hot Glue
- CA Glue
- Craft Knife
- Scissors
- Gaffer tape
- Wax
- Velcro
- Piece of 8mm dowel
Step 1: The Starting Point, Sides and Bottom of the Boat
The primary material for this project is a sturdy Creality CR-10 Glass Build Plate Box. The construction began without a detailed plan, by cutting out the two side pieces of the airboat. The bottom piece was then cut and attached to one side using hot glue, ensuring straightness with a 90-degree angle gauge. The bottom piece was scored where it met the front angle of the boat and secured with hot glue. An additional piece was added to the bottom for length and strength, also secured with hot glue. The exterior of the box, which is black and smooth, was used for the bottom surface, ideal for grass skimming.
Additional cardboard bracing pieces were cut and glued into three positions internally: center and rear. These braces were set a few millimeters down from the top, serving as supports for the seat and motor deck. Angled notches were cut in the rear corners to accommodate the internal hot glue seams. The next phase involves creating the seat component, which will also house the motor.
Step 2: The Airboat Seat
The height of the airboat seat was determined by holding the propeller in its approximate final position and measuring the required height. An L-shaped seat design was marked out on cardboard, copied, and mirrored onto another piece. A separate piece of cardboard was cut for the rear of the seat, with the top part braced for additional strength to support the motor. Another cardboard piece was cut for the front of the seat and secured with hot glue. The remaining sections were left open until the motor and ESC installation. The next step involves cutting the cardboard piece that will serve as the airboat's deck.
Step 3: Airboat Deck, Seat Positioning and Motor Fitment
The airboat's deck was marked and cut from cardboard, with notches in the back corners to accommodate the hot glue seams. After positioning adjustments, the seat was placed on top of the deck, and a square opening was marked and cut for the motor cables. The seat was then hot glued into position.
For motor installation, the metal crucifix mount was centrally positioned, and its holes were marked with a pencil. A 3mm drill bit was used to create the holes. The motor was attached to the crucifix using the four countersunk screws provided with the motor. The entire motor assembly was then secured in place with four 3mm x 20mm Allen head bolts, washers, and locknuts to prevent loosening from vibrations. A small notch was also cut for the motor cables. The next step focuses on developing the rudder arrangement.
Step 4: The Rudder Arrangement
A two-rudder arrangement was chosen for the airboat. A framework for the rudders was constructed from two pieces of cardboard glued back-to-back, with the bottom parts splayed out and hot glued onto the rear of the deck in two positions. A brace was added along the top, and gussets were included on the inner sides for additional strength. A wooden spar provided further bracing.
Brass tubing and wooden dowels were used for the rudder hinges to ensure robustness, especially given the pressure from the propeller wash when skimming grass. Two 30mm long, 10mm deep wood slats were hot glued to each side of the cardboard framework. Two lengths of 6mm dowel were cut and hot glued vertically to these slats. Two cardboard pieces for the rudders were then offered up to the dowels, and the positions for hot gluing the brass tubing were marked. This hinge mechanism proved effective. The next task is to fit the servo for steering the airboat.
Step 5: Steering
Initially, the steering servo was planned for one side of the boat, but this proved impractical for full range of motion. A central position between the two rudders was chosen instead. Two 3mm MDF slats were cut, hot glued together, and then hot glued to the rear of the deck board, extending approximately 20mm. The servo was then hot glued onto this board. Small wooden blocks were made, each with a 1mm hole drilled through the center, and CA glued into position at the same height as the servo horn on each rudder.
Two control arms were fashioned from 1mm wire. Small lengths of heat shrink tubing were applied to the protruding ends and shrunk with a blow torch to prevent the control arms from detaching from the wooden blocks. The next step involves fitting the ESC and wiring it along with the servo.
Step 6: Electrics, Testing and Summary
The ESC (Electronic Speed Controller) was connected, and the three motor wires were attached. If the motor spins in the wrong direction, swapping any two wires will correct it. The ESC is plugged into channel 3 on the receiver, which controls motor throttle vertically. The steering servo is connected to channel 1, controlling left and right movement. An 11.1V Lipo battery powers the system, providing 5V to the receiver, motor, and servo.
Initial testing began with steering, which functioned well. Pushing the left joystick up spun the motor, but in the wrong direction. Swapping two motor wires resolved this, preparing the airboat for its first test run.
Before testing, a piece of gaffer tape was applied to the front of the decking, acting as a hinge between the front support and decking. Velcro fasteners were added to the back of the decking, along with small knobs to assist in opening them. During the first motor spin-up, the decking lifted, demonstrating the effectiveness of the hinge and fasteners.
Initial grass tests were not optimal, even after cutting the grass shorter. The boat tended to lift its rear and flip over. This issue was resolved by repositioning the propeller further along the shaft. This adjustment significantly improved performance, though the boat remained somewhat flighty and prone to quick turns and overturning. Trimming the rudder servo movements by 50% improved control, especially on grass. Gaffer tape was also applied to the crease on the underside of the boat for protection.
A prop guard was considered for safety but a suitable design could not be found for this test. The airboat is expected to perform well on water, but waterproofing cardboard is not feasible for this project. Despite this, it provided good fun on grass and offered insights for future builds. This project marks the builder's second radio-controlled endeavor, and the process of building without a strict plan and seeing it work was highly rewarding. The builder looks forward to the next RC project.
Yours for the making
