Why Do We Love the Little Red Motor (Emax CF2812)?
There are plenty of decent motors in the 370 class. As I browse the forums (mostly the CrashTestHobby forums on RC Groups) I think it's funny to observe the love/hate relationship that people have with this little motor. The purpose of this article is to give some info on why CrashTestHobby recommends this motor for all of their small wings and small and midsize trainers. I've seen posts that claim the little red motor is a decent six dollar motor, but a crappy ten dollar motor. I really wonder where these comments come from. In my experience these motors work great across a wide variety of applications.
Price point
At the time of this writing, these motors can be had for six bucks and some change. A lot of new flyers will try to get into the hobby as cheaply as possible. At around six dollars these guys are almost disposable. This is probably one of the main reasons these motors are our favorite for our combat planes.
Availabilty
Hobbyking sells this motor as the fc 28-12 and it's available in the US warehouse. If you are in the states and don't like ordering from across the ocean, it can also be had from many suppliers in the US. Prices vary, they can be found on ebay, PlaneInsaneRC, HeadsUpRC and Value Hobby just to name a few.
Weaknesses
There are some gotchas with this motor. Once you are aware of it's shortcomings and take a little time and effort to work around them you can have a motor that will work great and last a long time.
- Mounting plate- the base of the motor is held into the mounting plate by two little grub screws. These motors are often delivered with the screws loose. Blue locktite is your friend here. Pull the two little grub screws, a generous drop of locktite in each hole. Put the screws back in tight, but careful not to overtighten. If you lose one (or both) of the screws you can replace them easily with a 3mm socket head screw. Be careful not to overtighten, it is possible to crank down on the screws so hard that the bearing gets squished.
- Bearings- the bearings are cheap, they can be replaced if needed. A drop of bearing oil on the front and rear bearing every now and then and they will last for a long time.
- Thin motor leads- the wires that exit the windings are very thin and are also fragile. The first thing to do to prevent them from breaking is to make sure the motor is mounted securely (see above). What we see very often is that the motor will try to spin in the mount causing stress in the wires. Another thing that can help with this is stress relief. I like to wrap a very small zip tie around where the leads exit the windings, I also like to secure the leads to the plane either with hot glue (or goop) or another small zip tie.
- Naked motor leads- Most places that sell the little red motor don't supply or put on the little 3.5mm bullet connectors that we all know and love. You are going to need to source them from the web or your local hobby shop. Soldering them is a little bit more difficult but still easily accomplished. If you want to try a different option you could check out the CrashTestHobby site and use a modified Deans mini connctor like Lee does.
Rewinding and experimentation
This is where this little motor really shines and truly shows it's value. The design of this motor makes it really easy to rewind. I know of people who will actually take a brand new motor, strip the windings and then rewind them. This is one of the few places in this hobby where you get something for almost nothing. A little time and the right wire and you can take a burned out motor and end up with one that works better and is more reliable. I have one motor that has been rewound several times before I figured out the right kind of wire to use. I gave up on the cheap wire from radio shack and use only wire that has a high (200c) temperature rating. It looks like the sweet spot for this motor is nine turns of 23 or 24 gauge wire. I've seen other winds succeed and work well with this motor. Experiment and have fun.
Check out this thread on RC Groups if you are intested:
http://www.rcgroups.com/forums/showthread.php?t=1456812
I've seen these motors work well on so many different planes. Just some that I know of off the top of my head... Brushless conversion Hobbyzone Supercub. Scythe and Assassin Combat plane. Roswell foam delta. Coroplast and dollar tree F22 planes. CTH Pelican and Albatross trainers.
Address the items in the weaknesses section and for about six bucks you've got what I think is a great motor. It works well across a wide variety of planes and for pilots with a broad range of skill levels. Please also feel free to comment. I'm sure there are other great motors out there, maybe I just haven't found the one that I like better- yet.
Rewound sporting a zip tie
Chopped shaft, riding pusher on an F22. I usually don't shorten the shaft anymore unless it's going on a front mounted setup
Coroplast F22 with a happy little red motor
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