Ultra cheap RC quadcopter (preferably using brushed motors)


Hey everyone.... :)
I'm organising a camp to encourage high school students to take up STEM courses..... and I'd like to have them build their own RC quadcopters. I want the course to have a minimal fee.... so the quad should be INSANELY CHEAP.
The quad should be able to do just one thing:FLY.
Also, durability is not an issue.... just one or two flights should be sufficient.

1)Can someone please suggest a design using brushed instead of brushless motors? (Simply because they're cheaper)
2)If there's any way I can build a flight controller using off-the-shelf components.... please share your ideas..
3)I have no idea about how to make the remote control/ RF transmitter....... is it the same as that of an RC toy car remote control?
4)I've come across some lovely designs where the frame is made out of paper or cardboard.... so that's not an issue. 

Help in any form is welcome.... I'd love to hear from y'all.... 
Thanks in advance...:)

sort by: active | newest | oldest
JohnL392 years ago

I have a trantula x6 and I has brushed motors and I would really like to put brushless motors on it and by the ESC Freeman but how would I am out then to the original cheap flight controller can I can I wire the ESC to the existing motor control I'm just not sure I just need some more information to see if it's even possible

jduffy543 years ago

I really, really doubt that something like this could be done even by someone with lot of experiece with quadrocopters, simply due to the small ammount of such copters avaliable commercially. Not being such an experienced person myself, I really cannot attest to how hard or difficult it really is, except note that

1) there is a reason they use brushless motors, they're WAY more efficient and lighter. It's difficult to make something that can even fly if constructed perfectly with brushed motors (I've tried a few times and failed).

2) the contorls involved have to compensate for yaw, pitch and roll all at once, as well as any commands given. That means PID loops, IMUs, and four independent motor controllers. PID loops means tuning, which means many test flights to get anything that does more than fall over and destroy itself.

I'm not saying it's impossible, as I'm not nearly experienced enough to say it can or cannot be done nearly that easily and cheaply. I was recently part of running a camp for virtually the same reason (though with younger kids), and that seems like an awfully complicated project to undertake as a starting project. A single rotor, teathered helicopter (like that old game with a helicopter on a stick) would probably have a higher degree of success, or, retrofit some of the rubber band powered balsa wood gluiders with motors. I have done this before with some degree of success. Something like this http://www.dx.com/p/mpx06-strong-magnetic-motor-silver-161327 could work fairly well at, at very least extending the range of the plane, especially if paired with a good battery.

Good luck finding what you wanted, and that someone with a little more knowledge on the subject can help out.

afshaanmaz (author)  jduffy543 years ago

Thanks a lot for the detailed reply :)

I get the point... brushless motors make the mechanics simpler, and give better torque..so it doesn't make sense to substitute them.

I did some looking, and found a few things.
http://hackaday.com/2011/04/29/mini-quadrocopter-is-crazy-awesome/
is a TINY quadrocopter, though it requires fabbing a PCB and connecting to a computer.
You could also (MUCH easier and cheaper) make some RC blimps. These could be RC'd by just the reciever from an RC car and some cheap propellers,as done here: http://hackaday.com/2013/11/16/13-homemade-rc-blimp/
I have made an rc blimp before, and it's almost as cool as a quadrocopter, but way, way, way easier to fly on the first try. I crashed a COTS quadrocopter a few dozen times before it could stay in the air more than a few seconds.

If you're good with ~$100, you MIGHT be able to get something usable without having to reinvent the wheel. http://www.dx.com/s/brushless?PriceSort=up about 3/4 of the way down has some controllers and motors around the $10 mark each, and around $20 for a pair of pre-matched motors and controllers (which is probably better). The propellers are cheap, and using an arduino mini, cheap battery and props from the same site, you MIGHT be able two squeeze in under a hundred with all the code and design already done. Anything less, and I don't know.
I know at the camp we did, for some of the more expensive things we had several people work together on it, though they didn't get to keep them at the end. I'm not sure if you meant for them to keep the copters when done, but if not, that could work.

Again, good luck and have fun.
partly, my main point is that you would really need someone who knows a LOT about quadcopters, most importantly, making them, not just flying them. I've done some work with IMUs before, and it took a few weeks of FRC build season just to get the basics of working with an IMU, much less get accurate readings and measurements. The controls have to account for both pitch and roll, and therefore run a different value for each rotor (so you cannot just use the transmitter from an RC car or something). You need two different types of rotors, one to go clockwise and one counterclockwise, AND counter the rotation caused by those with the other rotors, while balancing the craft.

The point is, while not impossible, unless you find someone who has actually built their own controls and stuff before, it seems unlikely that you'll be able to get something really cheap (I'm assuming you're aiming for <$30) to fly by itself. And even then it sounds difficult at the very least.
Good luck with whatever you do try, though.
Pazzerz3 years ago

Places like American Science and Surplus sell things like cell phone vibrator motors that can easily be used in a project like this. You just have to remove the weight on the shaft. This is a surplus site, so not every item listed will be available all the time.

Pazzerz Pazzerz3 years ago

Oh, and the remote can be scavenged from the really cheap RC cars that are only good for running on a carpeted or bare wood floor. I bought a couple online for less than $25 for two. Had to keep one, though, my granddaughter likes to play with it and chase the cats around with it.