Hi.
I am working on a little hobby project where I want to make a remotely controlled paper airplane.
I control it with a smartphone using a Bluetooth module and have got the throttle up an running. I use a small dc motor salvaged from a quad-copter.
The idea is that the throttle will be used to keep the airplane elevated and at a constant speed.
Now I have the problem of figuring out how to be able to steer it.
Light weight is essential. I thought about using mini servos but the one I have (9 gram mini servo) is the smallest one I could find and still is bulky and heavy.
Does someone have any ideas how I could be able to steer it with something very small. I do not need precision. I only need to be able to be in three states. Turning left, turning right, and going forward.
Riva, I looked into those before. There are a few problems with those that make them pretty impractical with my application.
They have a high hysteresis that will make the airplane kinda uncontrollable.
They require high currents which adds a resistor / mosfet to each one.
If I do not find any other solution I will probably buy some just to try it though.
BH72, could you elaborate a bit more on that?
I think you are suggesting I make my own. If it can be made pretty small then it might work for me.
Fulliautomatix, about the 4.4g servo. It is more the shape of the servos that are hindering. Since the gears and potentiometer need to be inside the casing it makes it bulky.
That guy from the forum has a bit different setup and goal than me. I intend to fly a normal paper airplane. Thus I can't really make the same setup as that guy. But his setup is impressive and it gave me a bunch of ideas for if I make a second version
Thanks for all the suggestions though. I hope more suggestions will come.
simmisj:
BH72, could you elaborate a bit more on that?
I think you are suggesting I make my own. If it can be made pretty small then it might work for me.
You can indeed make your own with some time and patients, although these can be purchased as well. They are commonly called magnetic actuators or coil actuators. If you google "magnetic actuator rc" or "coil actuator rc" you get back a pretty good collection of results from rcgroups.com that makes for good reading. Or if you are more interested in purchasing one there are ones out there under a gram from pretty reasonable cost...
You could likely shop around for better price or exactly what you want, that is just an example of what is out there.
The basic idea of this is you have a coil of wire that acts as an electromagnet and a fixed magnet that is in proximity to the coil, energizing the coil causes movement in the magnet, reverse polarity motion is opposite direction. Some of these have a "centering magnet" that will pull it back to center if the coil is de-energized, otherwise they are this way or that way. A bit of research will lead you to the conclusion that if you make a coil that has a resistance of around 200 Ohm you can actually drive it directly from Arduino pins with no additional components, although the additional components required to drive a purchased version (you usually see them in the neighborhood of 50 Ohm) would be pretty minimal.
You get no real proportional control with these types of actuators, basically is is either turn or not turn sort of thing (not like a servo where you can turn a little or a lot or anywhere between), but as far as weight I doubt you will find anything smaller than a magnetic actuator.
Now I have the problem of figuring out how to be able to steer it.
The very small RC cars have little coils with a magnet in the middle that swings the front wheels. You might check out this setup. You might look at the very small RC planes and possibly cannibalize one for parts.
There is already a product that you put in a paper dart airplane and fly controlled by how you tilt and swoop your phone, it's on Youtube but I forget the name.
BH72:
You get no real proportional control with these types of actuators, basically is is either turn or not turn sort of thing (not like a servo where you can turn a little or a lot or anywhere between), but as far as weight I doubt you will find anything smaller than a magnetic actuator.
Maybe you could go old-school and do something like the "Galloping Ghost" - basically PWM the actuator - the longer it is "on" the steeper the turn...?
Why not use two motors and "differential steer" the airplane? Make it so that the plane, when under power, tends to fly "up", but when not, noses down a bit. Left and right turns would be done in the logical manner...
This kind of setup is actually used on a variety of low-cost RTF foam kits...
Maybe you could go old-school and do something like the "Galloping Ghost" - basically PWM the actuator - the longer it is "on" the steeper the turn...?
Back when I was a kid the RC tx/rx were one tube kits (like $15.95 and that was way out of range) and the rx pulsed a windup rubber band escapement for the rudder. I got curious the other night and started looking on ebay for the old equipment to see if it was still around.
zoomkat:
Back when I was a kid the RC tx/rx were one tube kits (like $15.95 and that was way out of range) and the rx pulsed a windup rubber band escapement for the rudder. I got curious the other night and started looking on ebay for the old equipment to see if it was still around.
I still have one of the latter.
O.S. Pixie single channel, a couple of different types of escapements and a hand written code for up to seven controls.
cr0sh:
Maybe you could go old-school and do something like the "Galloping Ghost" - basically PWM the actuator - the longer it is "on" the steeper the turn...?
I actually thought about whether you could PWM a magnetic actuator to get some sort of proportional control, but honestly could not get my around how to translate that idea into actual use.
UKHeliBob, that looks very promising. I will take a good look at that one. Thanks for the link.
BH72, making my own would be challenging. Maybe a bit more challenging than I care for. But those from the link you posted look nice. Thanks for the link.
zoomkat:
The very small RC cars have little coils with a magnet in the middle that swings the front wheels. You might check out this setup. You might look at the very small RC planes and possibly cannibalize one for parts.
Buying a whole RC plane and scavenging a part from it feels like beating the purpose. But I might end up doing just that since part of this is just the fun of making something
GoForSmoke:
There is already a product that you put in a paper dart airplane and fly controlled by how you tilt and swoop your phone, it's on Youtube but I forget the name.
Yes I know. That is where I got my inspiration from. I saw it and said to myself: "hmm, I could probably build something like that myself". Of course I can just buy it but part of the fun is to make the thing.
cr0sh:
Why not use two motors and "differential steer" the airplane? Make it so that the plane, when under power, tends to fly "up", but when not, noses down a bit. Left and right turns would be done in the logical manner...
This kind of setup is actually used on a variety of low-cost RTF foam kits...
Do you mean two motors to power it forward and then vary the speed of them to make it change direction or? I didn't even think about doing that since I thought that it was simply not doable because I have never seen airplanes like that.
simmisj:
Do you mean two motors to power it forward and then vary the speed of them to make it change direction or? I didn't even think about doing that since I thought that it was simply not doable because I have never seen airplanes like that.
That is the idea exactly, two motors running about the same speed and plane goes straight, slow one motor down and the result is an induced yaw toward the slower motor side.
I see.
That is going to be hard to do on a paper airplane though.
The idea was to put the motor in the front of the paper airplane to pull the paper airplane since it would be stable there. Putting motors on the wings of a paper airplane is going to be challenging.
I asked you to see that to see what they do since it works with paper airplanes.
Most RC planes I know of, the parts are way outsized and heavy for regular paper airplanes.
Put a sheet of paper flat on a table and push the ends inward about 1mm and see how high the sheet arches. With very little displacement or power you can steer the plane, a tiny solenoid is all you need.
Also if you put the prop up front then you have to deal with spiral propwash.
GoForSmoke:
I asked you to see that to see what they do since it works with paper airplanes.
Most RC planes I know of, the parts are way outsized and heavy for regular paper airplanes.
Yeah. I think so too.
GoForSmoke:
Put a sheet of paper flat on a table and push the ends inward about 1mm and see how high the sheet arches. With very little displacement or power you can steer the plane, a tiny solenoid is all you need.
That is a nice idea. Just bend the whole airplane (or parts of it)?
GoForSmoke:
Also if you put the prop up front then you have to deal with spiral propwash.
I did not think that would be a problem but I see how it might.
I have all the electronics ready on a breadboard for a test run without being able to steer it. So I think I might put everything in as small a form factor as possible now and set up a test flight just to see if it actually flies and can handle the weight of the electronics. No reason to try to steer it if it does not fly in the first place.
