The last two times I posted, I stated that I would write again soon. That seems to have lead to my downfall every single time. Must. Not. Make. Promises. Time sucks.
So anyway, I have always had a preoccupation with boats. Not many know this, but I have been obsessed with them since the beginning of time. They seem to be an easy way to get started if you are interested in any hobby that involves motion. All you need is a thing that floats and you stick something that can push it on that floating thing. Piece of cake!
Well, not quite. There are many more intricacies involved but the basic concept is the same. So getting your feet wet, pun intended, is easy. But getting a whole lot more water than you bargained for is also easier.
Recently, I was able to realize this dream of making a relatively full function water craft and I thought I’ll share my train of thought about how it came to be in its final iteration.
This all started when I decided to bite the bullet and make a tricopter. A tricopter is a three bladed helicopter, with each propeller driven independently by a separate motor. Normally, people tend to make quadcopters since they are inherently easier to stabilize, but I was trying to go the cheap route. A tri means one less motor and associated circuitry and knick knacks than quad. Plus, a tri is easier to control from the pilot’s standpoint as it does not have the circular symmetry of most quads. So you know which way it is pointing at any given time, instead of relying on markers and trying to do trigonometry in your head (exaggeration much).
There is also one more important factor. The way in which a quadrotor yaws (rotates along its axis) is by changing the speed of a set of oppositely rotating propellers. It uses the difference in rotational torque to cause the yawing. But this is very ineffective and does not grant you enough yaw authority. A tri, on the other hand, pivots its entire tailrotor assembly giving much more yaw authority. So due to all these reasons I decided to go with a tricopter for my first attempt at flight.
So I did my research and ordered the parts off of Hobby King. Their service is excellent and prices are the best in the business. My only gripe is the astronomical shipping charges, but that is a necessary evil which cannot be escaped. The weight to shipping charges ratio wasn’t to my liking so I ended up purchasing the RC transmitter from a local supplier. And until now, haven’t had a problem with the one part (touch wood).
But this post isn’t about my tri-als and tri-bulations (couldn’t resist, I apologise for the inconvenience) with the tri. Long story short, it hopped, skipped and jumped the first and last time I flew it. The last hop proved to be a little too disruptive to its infant psyche and it decided to explode along one beam and commit hara kiri. My inferences about the mishap were that the tail rotor was too wiggly for the controller to compensate for the sudden movements. Screw this shit, I’m going home. Well, I did go home and decided to make a quad instead. To hell with circular symmetry. That would require more parts, so off to Hobby King we go. This is one profitable business model cause you are bound to crash sooner than later when you get into this hobby. Poor sods like me, with negative experience, fail badly. Epic fails, epic fails everywhere.
The parts would take quite a long time to get here so I decided to make something that has less unpredictability and lesser chances of failing. A boat! I had everything I needed: a powerful propulsion system, a controller, loads of flotation devices (also know as water bottles) and a fake Venice to test it in.
The first one I made was more of a test to see how fast I could make one. From start to finish, a complete working model took less that 2 hours, majority of which was spent in waiting for the super glue to dry. Pretty much no common sense was involved in the design, just intuition.
When I first took it out to test it, I noticed it didn’t behave very well and wanted to increase its interactions with water. Well, what better way to do it than by capsizing? One hard turn to the left and it looked like one of those autos, in the movies, which had a brief but intimate relationship with the road.
The dynamics actually, are remarkably similar. The auto has three points of contact with the tarmac. So did my boat. When there is forward motion and a sudden turn takes place, the body wants to continue moving forward but its being made to move left. So it tips over, with the imaginary line connecting the front wheel and one side wheel acting like the axis of rotation. The exact same thing happened with my ill fated wannabe Titanic, barring ice bergs.
What’s a guy to do when his sweat and saw dust of two hours takes a dive? He dives in, of course! I walked into the water, in jeans, and fetched it. It was in quite good shape for something that had just been dunked. Pretty much all the components worked fine after a little hairdryer action and TLC. All except the electronic speed control which decided it wanted to contribute towards environmental conservation by producing hydrogen.
To understand what happened here, you need a little more information about what previously unheard of intensities of electric current does to water.
In our college life, the maximum current value you would have encountered will be in the range of a hundred milli-amps at the most. Each of these electronic speed controls deliver a peak value of 20 Amps. Yes amps, not milli ,not nano. Powered by lithium polymer batteries, which have a tendency to spontaneously catch fire if treated unjustly, these are responsible for keeping the brushless motors happy enough to keep the quad/tri in the air. The fake river I was testing out my contraption is veeery unclean and full of who-knows-whats. The impurities make the water a prime candidate for electrolysis. So poof! Let there be hydrogen! This sudden decrease in resistance literally blew out the power MOSFETs used in the ESC due to the burst of current. There was actually a faint crater visible in the heat sink attached to it to keep it cool. (below image is very similar my case)
I lowered the motor/propellor assembly to lower the center of gravity and weighed down the bottles to aid in the anti tip-over coefficient (yes, I just made that up, if you’re wondering. Such is life. For inspiration look below).
And I added bracing to the front bottles so they don’t misbehave and point in random directions in motion. And I used the power of God, to increase control authority (wedding invitations have the best cardboard. Period.). And the great lizard approves! (for more information, look at previous posts).
After all that logical thinking, it performed flawlessly! Well mostly. Considering it is an airboat, ie. one that is propelled by air rather than water thrust, it behaves less admirably compared to a traditional boat. But as it’s made mostly out of trash, I’m pretty pleased with the way it turned out!
When I get my quad parts, the motor and ESC from this will be cannibalized to aid me in my quest for flight. But when that crashes to the ground, which it will with almost infinite certainty, conquer the water I will, once again.
Live long and prosper and continue tinkering, fellow makers!
Remember, making is baaasht when its done together.