Speed 400 Powered "Microflight" R/C Planes

Three planes all based on the dirt cheap "speed 400" motor. Starting nearest to the viewer is the original version of the Modelairtech Elipstik, then the "Wingo" (I say it like Wing-oh, but who am I?), then the Zagi 400. All use three channel control and fly very differently from each other.

My first attempt at venturing into "micro" r/c was a bit early. There were modelers who were having success and there was some light weight gear available, but it was difficult to pin down exactly what combination of equipment a person could purchase that would insure success. Specifically, I wanted to fly a Herr 35" J-3 as an r/c plane. I had built the rubber powered version (as it was intended to be) and really loved watching it fly. Now of course there are several geared drive units but at the time I was faced with units that were small and light, but expensive and probably not powerful enough, or units that would have done that job--if I was willing to watch my J-3 fly at scale speeds best suited for a P-51.

Rather than make a mistake in purchasing equipment I held off. I read everything I could about micro r/c flight, both electric and CO2 powered. There is a free flight genius named Don Srull who published plans for a plane called the "Skipper" in Flying Models and also for a Farman Moustique in Model Airplane News. The articles both came as close as I had seen (at that time) to "Hey this is the exact equipment I chose, here's what I did with it and what you should expect if you duplicate my efforts". Sadly, the little DC5-2.4 motor was out of my price range.

Enter another genius, this one by the name of Pat Tritle. I found his plan for a 1913 Eastbourne Monoplane in RCM. This plane was larger than the Moustique and while it still used the smallest commonly available r/c gear, it used a geared "speed 400" motor for power. In case you've never heard of the speed 400 type motors, while they are available from many different sources there are only two manufacturers. It's most common name is the Mabuchi 380, with the other unit being manufactured by "Johnson". The reason they are so cheap and readily available is because they are very common motors used in toys and battery powered hand held devices. The only thing you as an end user need to keep track of is what voltage the motor is rated to run at. I'll quickly demonstrated that we don't bother running it at it's rated voltage, but it is a primary consideration in what kind of performance we expect out of a given motor.

Pat's designs used the speed 400 with a gear drive unit. In case the job if a gearbox hasn't clicked in your head yet, it allows a given motor to turn a larger prop more slowly. The effect is the same as driving your car around in low gear. It will climb readily and the load on the motor is low when you are cruising. The downside is that your speed will be seriously limited, so they are not at all suitable for planes with a high wing loading (i.e. anything fast).

So I got Pat's plans from RCM just about the same time that Hobby Lobby came out with kits for the Eastbourne, a Super Cub and a Farman 400. I ended up with both the Super Cub and the Eastbourne, and started construction of the Super Cub immediately. After getting it all framed up (it is very much like building a free flight plane) I was proud of what I had done, but then chickened out on setting up the radio and power system.

If you have already been flying conventional r/c planes you will find that there is something just plain wrong about using tape to hold in servos, or removing the case from your reciever (warranty, what warranty?) and gluing it to some stringers. I had never charged up a power pack, let alone wired one up. My soldering skills were non-existant, and I really didn't want to total a potentially great model because I was too dim to carry it out fully.

The ARF's are all far to expensive considering what you get, but they do offer the advantage of giving you a reasonable chance of success. I chose a Nora, a geared 280 powered plane. It served it's purpose and I eventually sold it in fair condition to reclaim more than half the purchase price.

Next I purchased a Modelairtech Dimwatt, which used a direct drive speed 400 motor and the commonly found Gunther 5x4 prop (a silly looking thing you would think belongs on a toy, but turns out to be a great match for the speed 400). The Dimwatt was built entirely of 1/4 x 1/8 balsa sticks and covered in lightweight iron on covering. The plane was a hot rod and it was a very cute size, but I'm sad to say that I wrecked it an embarrasing number of times for a number of reasons (a bad reciever contributing at to at least two crashes, and an accelerated stall doing me no favors on another). To be fair, I did get some great flights on more than one occasion. It was a quick, manueverable plane with great power to weight. As bad as my luck was, I still think of it as a great airplane in terms of it's size, shape and mission purpose.

I also built a Modelairtech Elipstik, which now gives me an excuse to explain the voltage ratings of the speed 400 series and how they are applied to model airplanes. There are three voltage ratings that I have in my planes: 6, 7.2 and 9.6 volts. With the nominal voltage of a NiCad battery cell at 1.2 volts then you might reach the conclusion that they are intended for use with 5, 6 and 8 cells. Well, sort of. In actual use 6 volt motors are often pushed as high as 10 cells (I haven't done it), and getting back to the Elipstik, it uses a 9.6 volt motor with 7 cells (calling out for 6 on the plan).

So what gives? Easy. First understand that motors are commonly pushed a cell or two past their limit to get more power out of them. Next, understand that for a given pack (say 8 cells for example), a 6 volt motor will fly with more enthusiasm than a 7.2 and will flat blow away a 9.6 volt motor. The down side is that the 6 volt motor will use up it's battery pack sooner, giving you a shorter flight. That could lead you to the correct conclusion that the Elipstik is intended to give lazy, low rpm flights with it's high voltage pack running a low cell count battery pack.

Two other planes pictured above were actually built by my father who made a brief foray back into r/c. The Wingo is a fun airplane made of foam. It flies at a slow jog which makes you snicker during a high speed pass. It would be a great trainer plane if it weren't for the nasty "tuck" thing that early Wingos were known for when they picked up too much speed (which I understand is something they have fixed). If the plane hadn't predated the highly impact resistant EPP foam then it would have been a great choice for the Wingo. As it stands, you pay good money for a well designed plane made of cheap beer cooler foam. For the record, the Wingo uses a 6 volt motor on 7 or 8 cells and has one of the Gunther props turned around to work as a "pusher".

Speaking of 6 volt motors and the Gunther prop, the Zagi 400 uses the same set up, and it is made of EPP foam. First glance is dissapointing, because the wing is covered in strapping tape for strength and 2" packing tape for color. Top that off with tip plates made of that plastic version of cardboard crap and you have a real looker. Cough. But any doubts dissapear when you give the plane a chuck. The Zagi is a fast, manueverable plane with good roll rate, and it is very tough. I have taken the Zagi to altitude, shut it down and used a thermal or two until I was sick of them and then dived into a very high speed pass without particularly worrying about bad results. Bottom line is that it is a fun airplane.