Part 4 of the Hydroplane project sees a couple of modifications going a long way.
Sometimes, all that lies between success and failure is the smallest of tweaks. It can be moving the battery just an inch forward on your FT Scout or dialing some expo into your RC transmitter. This hydroplane project showed a lot of promise in the previous installment of this series, but more was to be done. Here's what happened when I upgraded the boat to 4s power.
Previous Parts
If you're not familiar with this project, here are the previous parts. Essentially, this is an ongoing mini-series to see how far a bunch of quad racing electronics can be pushed when fitted to something entirely unrelated to drone racing. Hopefully it inspires you, as one of our awesome community members, to have a go at building something different yourself.
Stepping Up The Speed
Since the last installment in the article series, the hydroplane (then powered by just a 2 cell battery) proved it could handle slightly faster speeds. I wanted to see what the thing would do with a seriously limited power setup to make sure that it wouldn't explode when I switched to a 4 cell. The tests showed it would 'plane'. This means that the boat uses lift to bring its hull out of the water to reduce surface resistance.
After a few of these trial runs, it was time to open the throttle wide open. Impressively (on just a tiny 7.4v battery remember) the craft really showed it was capable of some speedy performance. Imagine what would happen if this power is doubled! You won't have to for long.
Power Upgrade
The battery to be used in the upgraded boat was a 1300mAh 4s Hyperion battery. You can pick up these things from the Flite Test Store. They're very handy for lots of different aircraft, quads and - of course - hydroplanes like this one!
A quick power test indicated that the thrust had nearly doubled from around 1kg (2.2lbs) to just under 2kg (4.4lbs). If this craft had wings, it would be able to fly vertically no problem!
In addition to the upgraded battery voltage, the boat also needed some waterproofing upgrades. Unfortunately, on the previous tests, it had taken on some water which had resulted in the wood warping and splitting around the glue seams. These were pinned back together and coated with 5-minute epoxy. This stuff is great for waterproofing electronics too.
How It Should Work
The way this particular hydroplane works is a little difficult to get your head round at first, but it's actually super simple. There's a reason the motors are mounted high up like they are, and it's not just because you can't swing big props lower down (although that is kind of true). You see, by having the center of thrust placed high up and rearwards of the center of gravity, it creates a moment of force that's beneficial for keeping the boat's nose firmly pressed down the faster and faster you go. It helps keep the boat stable.
You see, like with an airplane, you've got several things to think about when it comes to keeping a hydroplane in a straight line without it somersaulting or nosediving. A balance of the forces is essential, but it's pretty troublesome to get right straight away. Again, this is why I found it necessary to carry out a few low-speed tests.
Once you've got the rudder creating a rearward center of pressure like the feathers of an arrow, the motor producing thrust that keeps the nose down, the lift of the floats keeping as little of the boat in the water as possible - then you've got yourself a sweet performing hydroplane.
Almost Full Throttle
With the modifications in place, it was time to unleash the hydroplane. Even though the rain was coming down, the craft performed flawlessly in a straight line.
Another run saw the speedboat power across the lake in style. Side on, it's easier to see how fast the thing is going. You can also clearly see the hull lift out of the water as it gets up to speed. Unfortunately, after this go, I haphazardly steered it into some vegetation growing at the side of the water. What a fail. Oh well, next time out will be fun!
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Article by James Whomsley
Editor of FliteTest.com
Contact: james@flitetest.com
YouTube Channel: www.youtube.com/projectairaviation
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I think it'd help a lot if you could configure a way to reverse at low speeds...
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