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Old May 06, 2007, 10:08 PM
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How to build a SERIOUSLY small R/C plane

Hi all, I'm Jaboi- I'm new here but semi-experienced with flying electric R/Cs, from park flyers to flying wings to (soon) sailplanes.

But for rainy, windy, or no-time-for-a-two-hour-flying-break days, I find myself bored at home and my Picco Z heli is only so fun (and kind of on the fritz). So I want to built a TINY 3D airplane for indoors. I looked at the Newbie guide, which was very helpful, but geared towards planes slightly larger than conventionally flyable in the home.

Here are what I envision this thing to be like:

Slow- really slow.
Durable enough to survive minor crashes.
Roughly 8 inch wingspan.
Rudder and elevator, both proportional (tiny servos?), and variable speed control
Very maneuverable- I am flying in a room 23' by 24' with a 16' ceiling.
Electric (lol, obviously)
Hopefully a decent flight time (7-10 min?)
Compatible with a JR 9303 transmitter

I know it will need a really big wing area and have to be really lightweight, but I don't know what kind of reciever could be that small or how to get servos cheap enough and small enough. I'm hoping I don't have to spend more than $60 or $80 bucks on it, but that may be unrealistic.

So, your opinions? Foam or balsa? Li-Poly batteries? What do you think is the most realistic way to approach this project? Biplane? High wing?

Thanks,

Jaboi

P.S. I don't care if it looks nothing like a real plane; it could be an 8" I.F.O. for all I care, as long as it flies nicely.

EDIT: Wow! I just discovered Keennon's Micro Micro Taxi in the Pager Plane thread- 7 in, 7.0 grams! Geez! Great job on all 3 Keennon!
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Old May 07, 2007, 03:38 PM
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SubNanoDreamer's Avatar
SF, CA
Joined May 2007
24 Posts
[pulls up a chair]

Your objectives are pretty in sync with mine. I'll be keeping an eye on the other replies to this thread!
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Old May 07, 2007, 07:32 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,426 Posts
Jaboi,
Welcome to the micro/indoor forum on RCGroups.

I would suggest a search in this forum on "living room 3D". That may give you an idea if others have thought of this before, and more importantly if anyone has succeeded. The $80 part is probably not realistic.

Gordon
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Old May 09, 2007, 11:49 AM
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Neil_J's Avatar
Florida
Joined Jan 2007
397 Posts
Reading around, I can't find much on Living Room 3D which makes me want to try it that much more I think I might start one this weekend....

I would take a good look at the Carbon Butterfly and try to make one yourself, which can be done for ~$80 if you know where to get your parts. It has a lot of dihedrial and is only 2channel but a 4-channel version with large control surfaces and zero dihedral could be fun. Mine has enough power with the 4mm motor to climb straight up on a full battery. I paid $300 for mine, but realized later I could have made a few of them for that price.

http://www.plantraco.com/hobbies/pro...butterfly.html

I would by the 2um clear mylar here: http://www.homefly.com/products.asp?id=31

and your carbon rod from the same place: http://www.homefly.com/products.asp?id=8

For the receiver, I would use Toichi Kanawa's infrared receiver (IR transmitter plugs into your 72mhz tx's trainer plug): http://translate.google.com/translat...language_tools

If you have some cash laying around the Plantraco 900mhz stuff is great, but expensive:http://www.bsdmicrorc.com/products.cfm?catID=10038

Depending on the size of your model the motor could be 4-7mm diameter, and you definately want a gearbox to keep it slow. The Didel GBxx are great and run about $13-15 for motor and gearbox.

Between BSD Micro, Homefly, and Koichi, you should be able to get everything you need. Let me know if you need any more info, I really think the Carbon Butterfly style (2um mylar, carbon rod, pager motor, electromagnetic hinge actuators) is what you want for indoor flying. Anything larger/heavier isn't as fun in such a small place.


Neil
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Old May 09, 2007, 07:21 PM
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SF, CA
Joined May 2007
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Seen this on hacking those Tomy bitcar micro RC cars for parts for a DIY plane?

http://members.aol.com/rchelicam/microszr/microszr.htm
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Old May 12, 2007, 10:40 AM
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yep. I've bought 2 of em for the purpose- and one of them had 2 motors (kind w/ wierd rotating head/front wheels). This got me thinking... I wonder how small you could built a living room heli. I have 2 Piccos already, but wouldn't it be cool to have one that launched off your thumb? I guess this is in the wrong forum... but oh well. Gonna see if I can make a 5 gram, 3-4 inch long heli
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Old May 14, 2007, 01:54 PM
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Joined May 2007
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Wow - that's frickin' amazing, because that's exactly the tangent I've been following too. When the BitCharG cars came out two thoughts crossed my mind: 1) "how cool is that?!", and 2) that's a really small Rx and servos in there... hmmm...

Now here I am years later, having just gutted the exact same make of RC car (at least, I think it is - it has a 2nd motor for the front, which is supposed to make it do some kind of flippy tricks or something I have yet to see it do). And the dream is to make a sub-micro or smaller Heli also. When I saw the articles here about modding bit-car chips to add an ESC and stuff like that, I knew I was in the right place!

Anyways...

While the indoor helicopter is the real dream, right now I'd like to start making small living room flyers of any sort. Glen's Foamie UFO (plans are free over at foamfly.com) looks pretty promising to scale down.



Quote:
Originally Posted by Jaboi
yep. I've bought 2 of em for the purpose- and one of them had 2 motors (kind w/ wierd rotating head/front wheels). This got me thinking... I wonder how small you could built a living room heli. I have 2 Piccos already, but wouldn't it be cool to have one that launched off your thumb? I guess this is in the wrong forum... but oh well. Gonna see if I can make a 5 gram, 3-4 inch long heli
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Old May 14, 2007, 02:40 PM
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Florida
Joined Jan 2007
397 Posts
Quote:
Originally Posted by SubNanoDreamer
Wow - that's frickin' amazing, because that's exactly the tangent I've been following too. When the BitCharG cars came out two thoughts crossed my mind: 1) "how cool is that?!", and 2) that's a really small Rx and servos in there... hmmm...

Now here I am years later, having just gutted the exact same make of RC car (at least, I think it is - it has a 2nd motor for the front, which is supposed to make it do some kind of flippy tricks or something I have yet to see it do). And the dream is to make a sub-micro or smaller Heli also. When I saw the articles here about modding bit-car chips to add an ESC and stuff like that, I knew I was in the right place!
I think you'll find it VERY hard to control a helicopter with a non-proportional Bit-charg rx/tx. Helicopters are very unstable and need constant adjusting. The bit-charg controllers are on or off (correct me if I'm wrong). I'm not saying it can't be done, but would require so much work that you might was well start from the ground up. There is a guy on this forum Andrewm1973 that is designing a micro receiver for the Picoo Z that would work for your project: http://www.rcgroups.com/forums/showthread.php?t=662454 They are still in the design phase but would do exactly what you're aiming to do.

Also take a look at the Pixelito (http://pixelito.reference.be/) and some of the other small nano/pico RC helis on the forum. You will find some 'rules of thumb' that you can use to get your design in the ballpark.

Also if you plan to use a motor you pulled from something, try to run the thrust calculations to see if it is suitable. Just about every motor to come out of an RC device has been documented on this forum, and some woudln't cut it for a small helicopter.

Please don't take this as pessimistic, I'm just trying to save you some time/money as I've been down this road before
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Old May 14, 2007, 04:15 PM
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Much appreciated Neil J! I know you're not being pessimistic at all, and it's nice to have references and not need to 'reinvent the wheel', as it were.

Yes, bit-cars' controls have on/off functionality and that's it. That was & is the first hurdle (which is also what led me to the aforementioned ESC mod) for a helicopter. Thank you kindly for the link to Andrewm1973's Rx thread too, that's good stuff!

Right now I'm just fiddling with DIY fixed-wing planes to get the hang of things - foamies, balsa, etc. - until I'm more comfortable with the electronic setup. I have experience with electronics, circuits, wiring, all that, but this is a bit different from anything else I've ever done given the weight & size constraints and the need to be more precise, relatively speaking.
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Old May 14, 2007, 05:10 PM
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Joined Aug 2006
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SubNanoDreamer,

If you are wanting to build a small heli then just jump in and make your own infrared RX/TX.

You can then decide exactly what you need functionality wise and for a small heli the IR range problem is a non issue.

If you need any help with the electonics just ask. I have a lot of people asking at the moment and there is only so much andrew to go around - but I will try fit you in somewhere
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