Summer Adventure - FT Storch-D and Mr Tug

"The life of a floatplane pilot is pretty calm this time of year" he thought. "You wake up in the morning, check the plane, make a short flight to make sure everything is ok, and then just wait for the next task. Sometimes it's a quick delivery, sometimes is just lazy sightseeing; it's hard to keep yourself occupied in the calm, summer air". At first, he really enjoyed this life, and was already planning how to spend the "hard-earned" money. But two of the worst pilot's enemies - boredom and routine - were slowly creeping in; and were going to abruptly change his plans pretty soon.

That might be the beginning (or other part, I have no idea about that; I'm not a writer) of a nice short novel; but its actually pretty close to my last summer vacation. I was experimenting with version 2 of my floats, and I have to say I get pretty close to what I would like to call "the final version". Unfortunately I did not have access to materials and/or proper tools, so I could only do some tests and adjust the position in a range allowed by the design. That was actually done in a couple of days. After that, I could only "enjoy the flight". And I really did. But the routine did creep in; and one day, with a "help" from a tiny wind gust, I made a mistake on the final phase of the approach.

But I wasn't surprised nor worried. It wasn't the first time I ended up flipping the plane upside down on the water. I did a lot of that a year before, when testing previous version of the floats. At that time, It always meant I either need to swim, wait for a neighbour with a boat to come by, or just hope the wind will do the job. But not this time. This time I was prepared.

But first things first.

THE FLOATS

"The water is rough today. Thanks God those scrooges at the company got convinced." He was obviously thinking about new floats. Last year he was flying on "nobody-knew-where-they-came-from" logs (you couldn't use any other word to describe that pieces of junk) that were too small, poorly rigged and literally turning every take off and landing into panic struggle for survival. But this time... well, it's still nothing you could be proud of; but at least they handle much better. And they look like a genuine piece of aviation equipment, even though there still isn't any proof for that to be found.

The floats are based on my previous design, described in greater detail in this article. The difference in the construction isn't that big at all. I actually used the very same templates. What I did differently is that I set the tool (hot wire) at an angle, resulting in more volume (and thus more displacement) and more "scale looking" shape. As a result, new floats don't go nearly as deep into the water as the old one did, larger surface area makes them transit into planning at lower speeds, and the v-shaped bottom results in smoother toutch-downs.

But there are also two other changes: the floats are approx. an inch further apart, and the mounting brackets are much longer, with many more mounting holes and thus much wider range of adjustment. This last difference proved to be the most important one. After many flights I figured out the floats need to be moved forward significantly (again: about an inch) and the inclination angle needs to be increased a little. Now the upper surface of the float is parallel to the vertical stabiliser's "crest" rather than the fuselage itself. And this made the whole difference. Before the adjustment, the plane needed to go much faster than it was trimmed to fly to pull the floats off the water; which almost always resulted in sudden pop-off into the air, the airspeed loss and subsequently a struggle to avoid stalling back into the water. Now the plane can separate from the water smoothly with proper speed and angle, which makes the whole experience much more pleasant.

At this point I can conclude that the floats part of this project is completed. It may not seem so, the floats are roughly cut and with almost no finishiong touches. But that was one of the main goals: to build them quick and cheap, and prove that it actualy works! Thanks to that, everyone can see that you don't need to have any special skills or use any special materials to enjoy flying over the water. If anyone wants to make their folats "more complete", I'd suggest three improvements:

1) Use water resistant materials: wood is cheap, readily available, easy to work with and good enough for a couple of weeks; but using plastics or carbon is the easiest way to increase durability and longevity.

2) Use more stiff material for the floats cross-bracing and mout them more securely: I used thin stripes of plywood solely to keep the project cheap and simple, but it definitely played a part in the "crash" you saw on the video. I strongly advise to use "more proffesional" material (round carbon tube would be the best) and install it more securely (drill a hole in the float's side rather than glueing flat on the top).

3) Cover the floats with something slick and smooth: I did cover the front half of the floats with packing tape in the middle of flight trials. The change was barely noticeable, but it will help if your plane does not have tons of power.

I will definitely use all of the above in the final iteration of my floats; but I want to emphasize that those are not required and even not essential to have a success. The most important thing is: just go ahead and try. It's way easier than you think.

THE TUG

The plane hit the water just a couple of seconds ago, when the old Merlin engine hidden deep in the boat's guts woke up to live with a cacophony of spasmodic cough, rumble and a lot of other sounds that cannot be described in any human words. Another couple of seconds later the engine revved up, and the boat eagerly jumped forward. - OK folks, let's go rescue someone today! This is not a drill! Go, go, GO! - the captain shouted in the void. Nobody knows why he was doing that every single time he took his old, rusty tug "for a spin". After all, he was the only one on board. I fact, he was always the only one around "mr Tug", carrying for it as it would be a member of the family. Their relationship - just like their history - was always a bit of mystery, and everyone stopped asking soon after the two appeared. The most important thing was that they (both the captain and the boat) were always ready to help in any "situation".

"Thank goodness, this guy will not ask any questions" the pilot thought just after climbing out from the cockpit. "This day was pretty long, and is about to get way worse. Fortunately I still have a couple of minutes before "the old couple" will bring us back to the shore. It's time to pull "the fat guy" from the back seat. Maybe he will still pay me something for this unexpected attraction"

The tug boat from the video is in fact based on a pretty old design. I did not use any plans; just the overall shape based on many examples I found on the internet, like this or this. The shape is so simple that anyone can daw it by hand, there is no "magic" behind it - and that's exactly why I choose to use this one. The construction is also very simple:

All the vertical surfaces are 6mm thick, and the bottom of the hull (the only curved surface) is 3mm thick. Since this particular foam is very flexibe, I doubled it with 3mm balsa in three main locations: under the motor mount, around the shaft hole and at the very back, in the "steering area". Note that this particular hull shape provide a lot of buoyancy. I had to use four 600 size brushed motors to keep the prop screw under water. The weight itself is not a problem for the propulsion system I used (which is explained below), and as a "happy accident" it makes the boat extremely stable.

Interestingly enough, the tug is actually powered by a brushed motor designed for an airplane (400 size, geared). Even the plane type matches the "story", since this motor was in fact used in TWM P-51 Mustang (among others; I pulled it off from the Super Chipmunk). The plane was pretty underpowered (and limited to 2s voltage), but this motor/gear combo works perfectly fine on water. The gearbox converts relatively high motor rpm into a lot of torque, allowing for relatively large prop screw to be installed at the end of the shaft. This provided a massive static thrust as a trade-off for low speeds, but this boat is not meant to be extremely fast. All it needs is to push. And it sure can push a lot. I don't have much more photos of the "inner workings", but some of the details can be see on THIS VIDEO. By the way, this motor/gearbox combo is still available on the TWM site (and is relatively affordable), but there's also 3s capable, direct swap-in outrunner replacement that is cheaper (by half!), lighter, and provide significantly more power. But that's a story for another time.

As you can see on the video linked at the top of this article, the tug boat turned out to work perfectly when "rescuing" a plane that cannot pull itself back to the shore. Even with the plane flipped over, it still can easily be controlled in all directions. The only difficult part is to actually hit the plane, especially when it's drifting to the middle of the lake. Trust me, I know; I did that in the middle of the night. And since the Tug does not have any lights, I needed to put a cell phone (with a flashlight function) on it's back to see where I'm going. And it worked!

The whole point of building this boat was - similar to the floats - increase the safety of flying over the water with minimum cost and effort. And the final result turned out better than expected! But if you want to make it more "complete", here are some ideas for further improvements:

1) Lights: I didn't use any, and it back-fired when I had to rescue the plane (with a lot of lights, as you can see below) after the sunset. But even when you don't intent to fly at night, the lights would be very helpful in less than perfect lighting conditions, especially when the plane is stuck far away from the shore.

2) Reversing ESC: I did use one initially, but it burned out when the tug was flooded during the trial runs. It is not required to get the job done, but makes the fine maneuvers easier.

3) Some way to pull the plane rather than pushing it: this is definitely a suggestion for pro-builders. It never happened to me (yet?), but I can imagine a situation when you simply can't push the plane to safety (e.g. when the plane gets stuck in the high and dense weeds at the opposite, had to reach shore). This will certainly make the build more complex and expesive, but you may want to consider it as an upgrade when flying in places where you are not supposed to swim at all.

And for the boat-building purists/perfectionists: 

4) Install some device to pump the water out of the hull when it starts to flood (see #2). Not "if", but "when" - no matter how watertight your boat is, it will always leak. Be prepared.

Once again, those suggestions are not essential to have the Tug fully operational and meet it's main goal: to provide an additional margin of safety and thus a peace of mind when flying over the water. They will significantly improve the experience if you are willing to spend your time and effort, yet you can still have a great experience without any of them. I certainly did. The main goal of this part of the project was to show you how to easily make the floatplane flying less stressful and thus encourage more of us to try it; and to achieve this goal the boat described above is more than enough.

THE FUN

Flying the Storch is always fun, no questions about it. Fying it on the floats, over the small lake in the middle of nowhere elevates the fun factor even higher. And having the boat to bring the plane back "just in case" (it doesn't have to be a crash, even the died battery can be a problem for a floatplane) makes it calm and relaxing like never before. One pretty important thing worth mentioning: it's advisable to have both the plane and the boat binded to separate transmitters. And maybe some lights on the boat in case of flying at night. But the experience rewards all the trouble, especially since building both the floats and a boat like this is much easier than one can imagine; and certainly easier than building the plane itself. I hope this article would inspire more of us to try this side of our hobby, and help to overcome the fear of flying over the water for all of those who prefer to stay on the dry land. It's really worth it.

P.S. All the pictures above - and way more - can be found in my gallery.

Don't forget to waterproof your electronics; Good Luck, and Have Fun!