You can build a bit-plane! - Step by step instructions - RC Groups
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May 28, 2005, 05:36 PM
Down with ARFS!
indoorff's Avatar

You can build a bit-plane! - Step by step instructions

Hi Everyone,

This forum and the people on it have been a big help to me, and I feel I should give something back. I have spent a bit (no pun intended) of time putting together this step by step instruction set for converting a bit car for aircraft use. I found when I started building bit car aircraft that there was a lot of good info in this forum, but wading through tens of pages of posts wastes a lot of time to try to find what you want. That is why I created this thread. It will provide a step by step approach that anyone should be able to follow and cover everything you need to get a car system working in your aircraft.
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May 28, 2005, 05:37 PM
Down with ARFS!
indoorff's Avatar

Step #1

Lets start with a material list. Some is required, some is optional (denoted with a *).

1) Soldering Iron, low watt, fine tip (I like the Antex 12watt iron with the 0.012 needle tip) (
2) Solder, as fine as you can get it, rosin cored, 60/40
3) Mosfets, digikey part number SI4410DY-ND (
4) Fine magnet wire (I use .0095 for everything except .005 for extending the actuator to the receiver outputs – more on this later) I get this from old motor armatures
5) Wire clippers
6) Sharp knife
7) A bitcar, of course!
8) Reverse Tweezers* (squeeze to open them)
9) Eye magnification*
May 28, 2005, 05:38 PM
Down with ARFS!
indoorff's Avatar

Step #2

Take apart your bitcar, and desolder everything from the board to get it out of the car. You should just be left with the board with the antenna attached.
May 28, 2005, 05:39 PM
Flying on Flux Capacitors
Flipper_118's Avatar
Sounds like a good idea, I have found a few occasions where a person went right from the bitcar to airplane, but not many, and not very indepth.
Can't wait to see what plane you made.
May 28, 2005, 05:39 PM
Down with ARFS!
indoorff's Avatar

Step #3

Now, it is time to prepare the mosfet. Be careful! This are static sensitive, so make sure to touch something grounded first before handling, and as long as your not dragging your woolen socks across the carpet while you are soldering, you should be OK.

The first thing I do is pre-tin the legs. Flip the fet on its back so you are working on the underside. Because my solder isn’t very fine, I cut off very small pieces with the sharp knife and get them on the tip of the iron and transfer them to each leg of the fet. Remember those reverse tweezers? They make it very easy to hold the mosfet in place while you are soldering.
May 28, 2005, 05:40 PM
Down with ARFS!
indoorff's Avatar

Step #4

Time to add the necessary wire to the mosfet. Take 3 pieces of the thicker magnet wire, and scrape some of the enamel off both ends to make it easier to solder, about 3/16 off one, an 1/8 off the other, and just the very tip on the last one.

Tin these now. See the picture for my leg numbering. Solder the piece of wire with the 3/16” bare across all legs 1-4. Now with the wire with just the bare tip, solder this to the leg 8 only. Now take the last wire and solder it across all the remaining legs 5-7. Now the mosfet is ready to go! (yes, I know my soldering isn’t that pretty!)
May 28, 2005, 05:41 PM
Down with ARFS!
indoorff's Avatar

Step #5

Ok back to the receiver. For the mosfet to function as is should, there are two transistors that need to be removed. See the picture. To remove these, I get the sharp knife and try to jam it under them a little and apply some pressure, then with the soldering iron, re melt the solder on the leg that is all by itself on one side. If you have enough pressure on the knife when the solder melts, the transistor should bend upwards and the leg is free. Simply bend it back and forth now until the other two legs break off.
May 28, 2005, 05:43 PM
Down with ARFS!
indoorff's Avatar

Step #6

Now the time has come to solder the appropriate wires from the mosfet on to the receiver. Most receivers have the outputs marked, but I will re-lable them in the picture incase yours doesn’t. Solder the wire that is connected to the 3 legs on the mosfet to the ground pad on the receiver. Now solder the wire that is connected to only one leg on the mosfet to the location labled ‘gate’ in the photograph. This is rather hard if you don’t have the finest of soldering irons.
May 28, 2005, 05:44 PM
Down with ARFS!
indoorff's Avatar

Step #7

So now it is time to hook everything up. Lets start with the motor. The last wire that is hanging off the mosfet that should be connected to all four legs on one side if you have done everything right, needs to be soldered onto one terminal of the motor that you have chosen to use. These fets are good for around 10 amps if I remember correctly, so you should be able to use a large variety of motors. The other terminal goes to the ‘+’ location on the receiver in the photograph. Now solder on your choice of battery connector to the receiver, to the ‘+’ and ‘gnd’ pads respectively. Solder a longer antenna on, I use roughly double the original length. The gauge of the wire doesn’t matter, so I use the finer of the two magnet wires.
May 28, 2005, 05:45 PM
Down with ARFS!
indoorff's Avatar

Step #8

So that is pretty much it now. Now if everything is correct, and you plug in your 1 cell lithium polymer battery, the right steering button on the transmitter should turn on the motor. If it doesn’t, double check all your connections, and if all else fails, try a new mosfet, you may have fried it with too much heat or static electricity.
May 28, 2005, 05:46 PM
Down with ARFS!
indoorff's Avatar

Step #9

You need to have some way of steering your model. I like to use a coil type actuator. I will not go into the details of making one here, because there is plenty of good information on this forum on that, and it is very straight forward. If you don’t like working with very fine wire, then I have seen some people just use a motor with a control horn on it to actuate the rudder. You have to have some stops so the motor does not keep spinning around, but instead binds with something so your rudder has equal travel in both directions. I have not used this method before, so I cannot comment on its effectiveness. A magnetic actuator is lighter, and will draw less current than another motor.

In both cases, solder your choice of actuator to the ‘F’ and ‘B’ pads on the receiver. You will operate the rudder then with the forward and back buttons on your transmitter. It helps if your turn your transmitter on its side to do this so as not to get confused.
May 28, 2005, 05:47 PM
Down with ARFS!
indoorff's Avatar

Step #10

If your are going to be wanting to fly outdoors, take apart your transmitter and solder a 3-4 cell battery box in place of the old one to improve the range. This is very straight forward and obvious, so I will not bother with any pictures. Also solder a longer antenna in place.

Well that should be everything anybody would need to know to get the bitcar system working for aircraft use. As for a model to put it in, I recommend the Greg's Flamingo,
There are plans you can download off that thread. It flies very well indoors and out, even in your living room!

Lastly, I have made this tutorial available to download as pdf file. It is too large to upload here (311k) so you can download it from:

Last edited by indoorff; May 28, 2005 at 06:04 PM.
Jun 04, 2005, 11:51 PM
raythomas's Avatar
Did you not get the wiring backwards?? Wouldn't you want the forward button to turn the motor on and use the left right buttons for the rudder? Just curious. Please continue.

Thanks Ray
Last edited by raythomas; Jun 05, 2005 at 01:10 AM.
Jun 05, 2005, 12:06 AM
Micro Flyer, Big Poster
Pete P's Avatar
Somebody? Finally? Step-By-Step? It's been done, in part and full, many times!

Thanks for doing it again. Everybody does it a little bit different. Feel free to scream at some of the questions you will now be asked.
Also, I like your choice in FETs. It's a bit easier to solder, I'm past them and onto the drop-in replacement type most use, but not all of us are, and this type is for the most of those who are not :-)
Jun 05, 2005, 02:23 AM
Down with ARFS!
indoorff's Avatar
Ray - The reason it is set up like this is because of the way the bitcar steering and motor works. The motor is reversing, but you dont need a reverse running motor for an aircraft. In many bitcars, the steering is performed by energizing one coil to turn left, and then energizing another coil to turn right, two seperate circuits. This is of little use with a conventional actuator. You could wind an actuator using two wires instead of the usual one, but I find this more difficult and heavier.

Pete - you are right, everyone does it different. This is as far as I can tell, probably one of the easiest ways. It is also very versatile, with the mosfet being able to handle 10 amps.


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