Radio Controlled Watermelon
Created on: 17 December 2012
Updated on: 3 January 2013
A radio controlled watermelon built out of parts taken from a radio controlled aeroplane (RC airplane) and a hollowed out watermelon.
The video below shows the RC melon being tested in a small pool. Steering the melon using the remote control requires some learning before the melon can be controlled properly.
A skeg under the melon in the middle and another at the back were necessary to increase the overall stability and also improve control of the melon.
Can't see the video? View on YouTube →
Unfortunately the watermelon tipped over shortly after filming it, burning out the electronics.
The RC watermelon is built from a hollowed out watermelon and the parts from a kit RC airplane shown here:
The Electronics and Parts
Motor and Propeller
The watermelon is propelled by the air propeller from the RC airplane. The direction of thrust of the brushless motor was reversed by swapping two of the three wires of the motor – any two of the three wires can be swapped to reverse the direction of the motor; any two of the three wires can be swapped again so that the motor rotates in the original direction.
The propeller is mounted on a threaded rod that rotates in a wooden base block. The threaded rod is rotated about the base block by a RC servo which points the propeller in a different direction enabling the melon to be steered.
Two fixed rudders were needed to gain proper control of the melon. Without the rudders, it is not possible to steer the melon – the melon just skids around without proper control when there are no rudders.
The rudders are shown detached in the above photo. The rudder to the left was attached in the middle of the melon and the rudder shown on the right was attached at the rear of the melon. Both were attached using sticky putty (Blu-Tack). The rudders were cut out of the lid of a plastic ice-cream container.
The Radio Controlled Parts
The radio controller handset sends signals to the receiver which then controls the speed of rotation of the propeller and the RC servo position.
A speed control unit connected to the receiver provides the correct voltage for controlling the brushless DC motor.
The Assembled Melon
Wood blocks are used for the base of the electronic parts. This photo shows the parts mounted in the melon.
As already mentioned, the RC melon met with an untimely death after tipping over. The water in the electronics managed to destroy the battery and speed controller (which just burned out). Please help us by making a donation to help pay for the damaged parts and to fund new and exciting projects. Any amount will be much appreciated. :)
See below for a video and photos of the burned out electronics.
Burned Out Electronics
The battery and motor speed controller were destroyed, but amazingly enough the receiver and servo survived. The video below shows the burned out electronics, the receiver and server operating from a 5V power supply and the battery that swelled up after the boat tipped over.
Can't see the video? View on YouTube →
RC Motor Speed Controller Photos
The motor speed controller board got so hot that the solder melted and some of the components slid off their PCB pads.
The bottom of the speed controller board showing the heatsink.
The bottom view of the speed controller with the heatsink removed shows the ICs that burned out and emitted smoke after the watermelon boat tipped over.
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