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lazer

Need help building a super small quadcopter

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I want to build a really small quadcopter. Something like the think geek micro 4 channel ufo: http://www.thinkgeek.com/geektoys/rc/a5b0/

According to superdave42 on rcgroups I needthe following:

1. PWM to PPM converter to convert PWM outputs of Spektrum RX into a single PPM stream that the Saucer or / JJ can understand.

2. 4 single PPM to PWM converters ( to drive the Brushless ESC's from the brush motor outputs

3. 4 Brushless ESC's

4. 4 Brushless motors

5. 4 Prop adapters

6. 2 CW rotating props

7. 2 CCW rotating props

8. higher power battery.

9. Custom Carbon Frame from DC Concepts ( to mount the BL motors )

Does anyone know where I can get parts like these? Im considering building my own form scratch. How would I do that?

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What experiance do you have?

I don't think you can do better than buy a snelflight jump jet and convert it to radio.

Adding convertors for brushless and spektrum will just make it bigger but you said you want it realy small.

Terry

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I dont have much experience unfourtunetly. I can fly helicopters but I have never build a quadcopter. I like the way the flying saucer looks so I still want to use that one. Do you know of any really small brsushless converts brushless motors and ppm to pwm converters? Im hoping I can cram everything onto it. I think I may have to add a second deck to fit everything.

Edited by lazer

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If you want to use that as a base - forget about brushless. Keep the original motors, and either replace the controller board or hack it for R/C operation like has been done for the Jump Jet (seems the jumpjet and saucer actually use the same gear except for the "shell").

1. PWM to PPM converter to convert PWM outputs of Spektrum RX into a single PPM stream that the Saucer or / JJ can understand.

2. 4 single PPM to PWM converters ( to drive the Brushless ESC's from the brush motor outputs

3. 4 Brushless ESC's

- That alone with the Spektrum RX would make a pack of gear that is already way bigger than the whole saucer frame.

- Small brushless motors are hard to find, common smallest ones (12x30mm) are about 5x heavier than the stock brushed ones.

- To have good performance, brushless quads usually use specially designed / modified ESCs that can operate at a much higher update rate (about 10x more).

But what was the goal in the first place?

Edited by Kilrah

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Well I wanted to build a really small quadcopter the size of a cd case just for fun and because I thought it would be cool. I imagined it being almost like a large bug. However that seem impossible :( now. What would be the smallest I could build it? Maybe say 6 inches? Is that more reasonable?

I found some brushless motors: http://www.superfastrc.com/feigao-1208436l-12x30mm-brus.html $100 for all 4

Edited by lazer

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Well, just buy that saucer / jumpjet and you'll have one that works ;) No need for brushless etc...

Those motors are heavy, 17 grams each, plus prop etc let's say 80gr total for the motors, plus frame, electronics and wiring (a small brushless ESC is about 7gr), you'll end at about 150gr without battery... the jumpjet weighs 25gr with battery... So you'll need a lot of current to lift that, so a big battery with room for it, and especially big props that will force you to make the frame bigger...

6 inches is about the size of the jumpjet, so I would say you'd need something substantially bigger.

Otherwise HC has some 2gr and 5gr motors and 1gr brushless ESCs, I'd look there and calculate carefully to stay within the low thrust they provide. But again if you need a bunch of converter boards you'll be out of room quickly as they were sized for full size quads. That's not at all an impossible project, but typically one where you'd need to really start from scratch and design the adequate electronics too :)

Edited by Kilrah

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Ill probably buy that saucer anyways but I dont like the ir control because you cant fly outside and you have to aim the tx at it inorder to stay in control.

Ill use 4 5gr motors form hc totaling 20gr with 200gr of thrust all together: http://www.hobbycity.com/hobbycity/store/u...utrunner_1850Kv

4 props at 5gr each totaling 20gr: http://www.hobbycity.com/hobbycity/store/u...?idProduct=4254

spectrum 2.4ghz reciever at 2gr

3 BA Nano Gyros at 2.3gr each totaling 6.9gr:http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4320

I cant find the speed controller you mentioned though? What battery would I use? The motors require a 3 cell lipo but I dont know how much current they need?

Edited by lazer

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Ill probably buy that saucer anyways but I dont like the ir control because you cant fly outside and you have to aim the tx at it inorder to stay in control.

As said above, the JJ is easy to convert for conventional R/C operation. At least a lot easier than trying to build a quad from scratch...

The motor you linked is a bigger 13gr one. But I see what 5gr one you mean, they only have one AFAIK.

The ESC is this one: http://www.hobbycity.com/hobbycity/store/u...peed_Controller

But it only matches the 2gr motor, not the 5gr one (because of cell count). For the 5gr one you need this: http://www.hobbycity.com/hobbycity/store/u...peed_Controller

If you intend to use just standard heli gyros, I wish you luck. Not that it's impossible, but you'll have a hard time getting that to fly, and it will be a lottery whether your gear combo works or not. BTW, some mixers are needed too in this case.

For a quad with good performance you should aim for a flying weight not exceeding half the total maximum thrust.

Edited by Kilrah

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There are several ongoing open quad projects, see for example MikroKopter or UAVP. But those electronics are targeted towards "standard"-sized frames, so you might have to do some "porting" of the hardware to a smaller size. Or just start everything from scratch and redesign from the ground up. AFAIK there isn't aynthing readily available for micro quads, the best you could go with is again - the jumpjet and its board.

Edited by Kilrah

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I found a guy who is going to start selling very small microcontrollers that can control anything up to 6 motors.

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Very impressed !

Looks like he will make it plug and play.

Terry

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He said he will try to make it affordable. I can't wait! It could be an alternative to the microkopter controller.

Edited by lazer

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I thought I read he said it could output standard r/c pulse or 12c too.

Terry

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Yes, but again going with a servo signal and common ESC limits you to 50Hz updates, not 400-1000Hz commonly used for quads for better regulation performance. Which is why all the other BL projects use I2C to talk with the ESCs, which in turn need to be made for that.

Yes I know he said he'd add that too but it's not there yet, and so far the matching I2C ESCs are each the same size than the board as they're made to handle 10A per motor, so smaller ones need to be made, which all means that there's still a long way to go to catch up, so don't expect it for tomorrow, it will maybe be there at the end of the year ;)

The other quad projects have nearly 3 years of development behind them now...

If I really wanted a tiny BL quad now and had some time to dedicate to it, I'd take the proven MK project, which has all the source and hardware schematics published, just miniaturize the hardware (both flight controller and ESCs) and go with that.

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