ROTO: The Indestructible Flyer

Model Airplane News, Jul 2004 by Bell, Rick

NORTHEAST SAILPLANE PRODUCTS

No other segment of the RC hobby has grown as explosively as electric indoor and outdoor 3D aerobatics-and it's likely to continue. Light, strong foam construction techniques; powerful, efficient brushless motors; radio equipment that weighs mere grams; and potent yet light lithium-polymer batteries have all contributed to this Dhenomenal growth.

To experience some of the thrill I had been hearing so much about, I decided to jump on the bandwagon and get an aerobatic foam airplane. I looked around for a model that would be 30-capable, durable and easy to build and repair and would not break the bank. Knowing that Northeast Sailplane Products has a wide variety of airplanes to choose from, I cruised its website, and the Roto really caught my eye. It had all of the attributes I desired and was a complete package that cost less than 95 bucks. The kit included everything except the radio system (servos, receiver and ESC) and flight battery. The kicker, though, was that the Roto is made of EPP foam and Coroplast-probably the most durable construction materials ever used for model airplanes! EPP stands for expanded polypropylene, and it differs significantly from the styrene foams we've been familiar with for years. The primary difference is its resilience; it's essentially a "rubber" foam that doesn't dent or break like regular styrene foam. And Coroplast is a plastic version of corrugated cardboard. It, too, is damage-resistant. EPP foam and Coroplast make the Roto almost indestructible!

ASSEMBLY HIGHLIGHTS

The Roto is simple to assemble, so I won't bore you with "I glued this part to that part" and so forth, but 1 will show you some of the changes I made to the model to suit me.

1 first built and flew the model in its stock configuration. In stock form, the Roto is a fun aerobat. The included Speed 300 motor is geared 7:1 and swings a fairly large prop. Its performance was good and could be described as refined. But I wanted the power to perform more aggressive 3D maneuvers, so I used a 16/7/7 brushless Mega Motor that's geared 2.8:1 and a Kokam 3S (3-cell) 150OmAh Li-poly battery. This setup gave me outstanding vertical performance and duration.

To fit the new motor, I had to modify the nose to accommodate the new motor mount. Some simple foam removal with a sharp knife took only a few minutes, and the motor was in place. Another area that had to be modified was the pocket for the battery in the underside of the wing; it was sized for the recommended NiMH pack, and the Li-poly pack I planned to use was a little wider. Again, a few minutes with a sharp knife, and I had trimmed the pocket to the required size. To securely hold the battery in place during wild aerobatics, I cut a couple of slots through the wing and slid Velcro straps all the way through the wing and around the battery. 1 assembled the rest of the Roto as instructed.

All DRESSED UP

Now that I had sorted out the power system, I wanted to dress up the plane without adding a ton of weight. The only drawback to EPP foam is that it doesn't look very pretty, and its texture, to me, is like alligator hide-rough and unattractive. The nice thing about EPP foam is that it takes well to paint and felt-tip markers. I wanted to try a different approach, however, and cover the model with an iron-on heat-shrink film. This way, the texture of the foam would be hidden, and the surfaces of the model would be nice and smooth. There are many coverings to choose from, and I decided to use SolarFilm SoLite that I purchased from Balsa Products. It comes in a variety of colors and weighs only 0.6 ounce per square yard. Its best feature, though, is that only very low heat is required to activate the adhesive and to shrink it. When working with foam, this is a huge plus! I also tried the SoLite on the Coroplast and, much to my surprise, it worked very well.

Working with the EPP foam proved to be very easy. I first needed to disassemble the model to its basic parts. The servos had been tightly press-fit into their pockets, and they came right out. Some careful cutting with a new no. 11 blade had the wing and tail feathers off in a few minutes. I then sanded all of the foam surfaces with a sanding pad and slightly rounded off all of the sharp edges.

Applying the SoLite film covering was pretty much like covering a model constructed of balsa. The only real difference was using a low heat setting so that the foam wouldn't melt. I found working with SoLite fairly easy; the material is superthin and adheres well to the foam. I covered the parts and then reassembled the Roto. When I had finished, I had a sharp-looking model that doesn't look as if it's made of foam. Very cool!

SUMMING UP

Would 1 rate this acrobatic park flyer a success? Most definitely! The Roto is a great-flying airplane as is. For really spectacular performance, add a brushless motor and combine it with a Li-poly battery. Want to dress the Roto up a little? Use foam-safe paint or felt-tip markers, and let your imagination run wild; you'll get great results. But if you want to take the Roto to the next level, try covering it as I did. 1 was very surprised with the results-as were my flying buddies. Have fun!