Part 2 of my quest to build a boat out of RC airplane parts sees most of the seacraft come together! Check it out.
As with the challenge of flight, the challenge of getting something to go very quickly across the water is technical, demanding and pretty darn difficult. I'm currently building a small speedboat, or hydroplane, to learn what I can about this mission. It uses two quad motors, balsa wood and some other aircraft parts. If you haven't already, make sure you read part 1 of this article series which outlines the boat's design. This video update shows you where I was at just before I got cracking in earnest.
Build
Starting with the plan drawn up in part 1, I cut out the sides of the fuselage along with the main 'floor' that everything else was built around. You can see it as a horizontal line in the middle of the drawing.
Unfortunately, I didn't hit my deadline to get the boat finished in a mere three days. As mentioned in the update video, I had wanted to take it on a planned trip to some a region of England with some large lakes to test it on which was the week after Flite Fest. As I was getting ready to jump on a plane and head over to the United States, nothing much got done and I had to travel to the lakes without the boat.
Skipping forward to a few weeks later, however, progress was getting going again. Basswood, balsa wood and carbon fiber tubes were the main ingredients used the make the hull of the boat. The tubes were left over from an old drone project. I decided they would make for some nice sponson supports as well as a good motor mount pylon.
The bow of the hydroplane was curved upwards. This will hopefully displace any water as well as helping to lift the craft out of the water. I used many pins to hold each section of wood in place. Not many of these components were planned out in advance - instead, a gap was measured, a template was drawn on paper and a chunk of balsa was cut out. It was rather off-the-cuff.
After feeling a little like the build wasn't going all that well, I decided to attach the newly assembled sponsons to the carbon supports to see how it was all looking. To my pleasant surprise, it looked like a speed boat!
To secure the carbon parts, I decided to go with a two-part epoxy. All you had to do was mix the two parts, apply the thick substance, and slide the carbon into place. You have a working time of five minutes, but it's best to let the glue dry completely for a rock-solid result. This takes about 24 hours.
Sometimes I had to go back and apply another few blobs of epoxy to fully seal the joint between balsa and carbon.
Cladding the underside and top deck of the main hull took a while, but it all came together relatively quickly in the grand scheme of things.
Again, pins were used to hold setting pieces in place. After the glue had set, each part was given a light sand to remove balsa 'fluff' and level out any joint seems. The edges of the square shapes were curved to make a pleasingly smooth finish.
With most of the hull complete, I decided to have a go at setting up the motor mount and fin. Moving onto the electronics side of things was a nice change to wrestling with balsa wood, although it came with a whole new set of challenges. The mount itself is made from two modified mounts found on an old multirotor kit. Together they make up a nice solid unit to mount these motors to. There's quite a lot of extra room to mount some bigger props (the current ones are just 5"), although I think that I could do with shortening the carbon pylon to get the mount a bit lower. As I don't really fancy cutting the carbon, I might simply modify the mount so it can slide down and be fixed into place.
Where we are right now
There's still a lot to do, but the thing really does look like some kind of boat! An odd looking one, maybe, but still a boat.
I'm pleased with how the balsa hull turned out, on the whole. There are some imperfections, but it still looks the part. The carbon parts are rock solid, the balsa is smooth and the lines look spot on. 
What with the two contra-rotating quad motors atop this machine, this thing should rip along the water.
I'm a little concerned that the center of gravity may be a little high up, making the roll axis of the craft unstable, but we shall see. I still need to move these downwards and attach a metal keel to the boat, so that might help. We shall see!
Next Steps
The very next things to do on this build are as follows:
Hull
- Sanding
- Adding a water rudder and hardware for steering
- Staining with waterproof wood sealer
- Epoxy sealing to seal all of the wood permanently
- Painting various parts
Electronics
- Extending ESC wires
- Waterproofing ESCs with waterproof epoxy
- Creating a receiver waterproof box
- Installing a servo for the rudder
Links
Make sure you check back soon for Part 3 - Speed Testing. There's quite a bit to do, but when it gets done, it will be awesome!
Article by James Whomsley
Editor of FliteTest.com
Contact: james@flitetest.com
YouTube Channel: www.youtube.com/projectairaviation
Log In to reply
Log In to reply