Foam Park FliersHere are some pictures of foam RC planes that I've made. They are electric powered, and made of either Depron or Fan-fold. Depron is like what a restaurant to-go box is made of, or perhaps a meat tray. Fan-fold foam is made for house insulation, and is folded in big sheets and available at your neighborhood rubber-stamped home improvement store. Foam has several advantages as a building material, since it is fairly cheap, light, and strong. While other people have made much more exotic designs (some that you would not believe are even foam), I've stuck to the basic two-dimensional profile designs. Since most of the expense is in radio gear, motors, and batteries, the airframes are essentially expendable, which makes for some interesting flying. When you can genuinely fly it as though you don't care if you ball it up, a whole new set of manuvers becomes available. My only rule is that I have to recover the wreckage- having it fly away, sink in a pond, get stuck in a tree, or eaten by a bear are not acceptable methods of crashing, since the expensive equipment is unrecoverable.
Here are a few tales, essentially in chronological order:
Here was my first adventure in Fan-Fold foam: it is a copy of an F-22. When I made the first one, I didn't have immediate access to the original, so as you can see, the copy isn't quite right. That may have explained why it didn't fly quite right. Or really fly much at all, short of a little bit.
It has two e-hobby 4.9 gram servos, a GWS direct-drive motor, and the stock prop that comes with it. At that point, all that I had was an etec 700 mAh lipoly, so it was heavy and underpowered. Gross weight was a little over 4 ounces.
So I figured I'd try my Go Brushless 14 turn CDROM motor. This 14 turn was the first motor that I made, so the 14 turns were just to keep it easy. But, it didn't have very much power either, so the F-22 project reached its end.
Then, having much better access to the original (which may very well be copyrighted), I made a second copy. This time I used an almost identical setup to the original, so I was convinced it would fly well. Thus, I spent a little bit of time on a nifty tiger paint job, which is testor's spray paint for the base orange, misted with testor's yellow, and then striped with the brush-on black. All of these paints are available at your local neighborhood rubber-stamped wal-mart, which you should find pretty close to the store where you find the foam.
It turned out not to fly so well at all. I attribute this problem to several factors. First, I still used the etec 700 battery pack. I had a 250 mAh pack to use, but I couldn't get the cg close enough with it. Short of moving the servos up to the very front, (which isn't worth it on this particular airframe, but rather an idea for the next one) the only option was to use the heavier pack. This left the flying weight a little bit high still, and it was still underpowered with the CDROM motors. I tried another GWS direct-drive, this time with the much steeper 4.25x4.25 prop. This time it had more power, but I lost sight of it in the sun and crashed it. Perhaps I'll build another later.
So then begins my quest for an IPS-powered 3D plane. I already have an IPS powered Mini IFO, which is certainly a 3d airplane, but it has no rudder. This rules out all sorts of manuvers, like spins, knife-edge flight, etc. While people have added rudders to the IFO, I figured I'd be better off with a more conventional plane. My first attempt came from the plans so artfully crafted by "stringfly" from ezone. His plans are available free online, and they are very well-made and easy to print on a normal printer. It is a scaled-down shock flier, specifically the super-star. I used a 23-turn CDROM motor to start with, and it went well. The plane flew like a very good sport plane, with responsive control on all axes. I especially liked how the CDROM motor was essentially silent. Unfortunately though, it didn't fly like a shock flyer. In fact, on a subsequent flight, I decided to try a high speed knife edge, and since I had no spanwise carbon spars, the wing folded. For some reason, inflight structural failures are always fascinating, and it spiraled down from 50 feet or so and made a splat. On to the next design, hopefully something with more wing area.
As you can see, part of my fascination with these types of planes is that I can take them on the road with me. Since I practially live in hotel rooms, where time is often an abundance, it is a good hobby for what I do. Here is a picture of the work area, which I'm sure scares the maids. They probably think I'm a terrorist conjuring up small anthrax-delivery platforms. Also pictured is a highly experimental Air Tractor for CDROM power. It is no more complete now as it is in this picture, but maybe one day I'll finish it.
So next, I tried the 3DX plans that are scaled down and available on ezone. As you can see, they are just as easy to print and put together, and here is the template process in action. This one used the same radio gear and battery as the smaller plane, with the new Feigao 1208436 Brushless IPS Replacement motor available from Balsa Products. The airplane came in at a little more than 7 ounces, and the motor in a B gearbox with a 9x7 GWS prop put out just about that much thrust. This one flew pretty well, until the motor spun itself off of the mount, gearbox and all. The lesson that I learned here was that I should be much more careful to make a more secure mount! Anyway, the result was that the three leads going into the back of the motor were cut off clean at the edge of the endbell, rendering it useless. I took the motor apart, hoping to find enough wire inside to solder to, but had no luck. But here are some pictures of the inside of the Feigao 1208436, in case you ever wondered what it would be like in there.
Here is a case of where I did something I almost never do; I bought an airplane ready to fly. It was kind of a special case, being as how I didn't have any onboard components in the appropriate size range, and a local hobbyist was getting out of it completely.
It is a Don Helms 39" Sukhoi with a Himax brushless motor, GWS D gearbox, GWS 12x6 prop, CC Phoenix 25 ESC, 1425 mAh 3S1P Lipoly battery, Hitec HS 55s, and the GWS Rx. With the package also came Don Helms 39" Edge 540 kit. Since these were essentially the components that I would have bought, at a lower price than retail even without the airplanes considered, I jumped on it. I have flown the Sukhoi, and while it is certainly a fantastic flier, there is lots of room for improvement. So far I have reprogrammed the ESC, and my next project is to re-attach the aileron that came off during a high speed dive the other day. The plane seems to have some strange harmonics at high power settings and high speeds. It starts as a definite hum, and then develops into all-out shake stuff off flutter. Another priority is to replace the gearbox, as the mesh isn't so great. I've been thinking about the Himax gearbox, because it is priced very fairly, and apparently a bit more rugged. The heat sink also sounds quite appealing. I'm not too happy with the amount of flexing in the tail either, since in flight I can see it twisting back and forth. Perhaps I'll put together something like the foamy3d Extra, that includes a horizontal fuselage component. That would allow for more bracing.
See part 2 here