When I was building my 250 class quadcopter I wanted to make that cheap. So, I’ve bought cheap ESC: Turnigy Multistar V2 10A ESC for S2-3 with 2A LBEC. And yes, they are cheap: slightly less than 8EUR per piece. With preloaded BLHeli software. Cool, isn’t it? Well, not so cool after all, but first things first.
Preloaded BLHeli software (version 13.1 in the ones I’ve ordered in late June 2015) simplifies a lot. No need experiment to upload BLHeli and 1-wire interface is available from the start. Also update to BLHeli 14 was pretty simple without any glitches. Unfortunately, there is a reason those ESC are so cheap…
After 2 months of using them in my 250 quadcopter I can state the following:
They are cheap all right,
None of them burned yet so it’s a good sign,
Preinstalled BLHeli and easy to upgrade
10A is not much for a quadcopter needs, slightly higher max current would be welcomed . But this is my fault, not those ESC,
they do not support Damping Light, so no active breaking on those ESC (booo),
OneShot125 on those ESC behaves strange when throttle is below lower limit. They screech. Fortunately nothing bad happens in flight,
2A LBEC regulator is in fact double LM7805. And it heat a lot.
Asymmetrical frames like Dead Cat or Spider type have many advantages. Big central plate to put all the electronics, front view not obscured by arms and motors. And they look cool. Way cooler than traditional X frames. But there is a price. Because they are asymmetrical, flight controller has to put much more effort into stabilizing them. Motors are not in equal distance from center of weight, and because of this require different force applied when performing stabilization. Quad will fly even when standard X configuration is programmed into flight controller, but will not archive best performance. For example, when FC wants to roll, different motor distance from COG might induce also pitch rotation. Of curse FC will compensate in next cycle for that unwanted pitch movement, but what if it would have to do that? Less corrections, lower power usage, higher stability, better control.
This is why most flight controller software allows to program almost any motor configuration and tell it how far any motor from rotation axis is to match applied force for each motor separately. General rule: motors closer to rotation axis require more force than those further away (torque and stuff). This is called custom mixing. Continue reading Cleanflight custom mixing for Reptile 500 frame
It’s been few weeks since my last post about 250 class quadcopter based on carbon fiber ZMR250 frame. Machine is mostly finished by now. At least in LOS configuration. FPV gear has only arrived last week and I still had no time to put it in.
Anyway, it flies and crashes a lot. But this is 250. It’s supposed to do so. After little more than 2 hours in air I can say that:
It is heavy. With 1.3Ah 3S LiPo battery and RunCam HD it weights 530g. Have to make it lighter…
Turnigy Multistar V2 2206 2150KV “Baby Beast” with Gemfan 5030 propellers does not provide enough thrust. Do not get me wrong, it is fast, but I was kind of hoping for higher level craziness.
While playing with newly arrived Micro MinimOSD and attempting to flash it with latest MW OSD software, I’ve discovered that offical tutorial, as well as many other are missing one tiny detail that makes whole process much harder than expected. In theory, MinimOSD just Arduino Pro Mini with additional hardware. So, in theory, you plug in your FTDI USB adapter and upload a sketch. But if you never worked with Arduino Pro Mini (like me, it was always Uno, Pro Micro, or barebone Atmega328) you might not know one detail. Yesterday it took me more than 30 minutes to figure out firmware upload is not working, while it should. So, another tutorial will be written.
To flash MW OSD to Micro MinimOSD we will need:
Micro MinimOSD with soldered pins, but isn’t this obvious?
Buying cheap from China is like a lottery. Sometimes everything is fine, sometimes is not. For example, I will never again buy super motors and pellers. This just does not work. With electronics it is slightly better. Usually it works. But sometimes, well, it does not. And this might be a case for Flip32+ multirotor flight controllers from around June 2015 (give or take few weeks) v2.3_OEM RTF. In those FC, buzzer is not working when connected to designated pins.
Reason? Instead of 100Ohm SMD resistor in buzzer circuit, there is a capacitor. Solution is quite simple: replace capacitor with a resistor and fix manufacturing error.
What you will need, is a 0603 size 100R (100Ohm) SMD resistor and a (good) soldering iron. Position of faulty element is shown on a picture below.
Today I’ve fixed two of mine Flip32 flight controllers and succeeded on both. 0603 size SMD are small, but big enough to do it at home. If your soldering iron has temperature setting, set it to 280-300C. If not, use one with about 20-25W. And sharp, good soldering tip of course. To remove old SMD element just heat it up about 1 second and push away with a tip of soldering iron. Apply some new solder to pads. Place new element on pads, push it carefully with a needle when needed. Heat it for a second and that is all. New SMD element should be soldered to pads and buzzer should be working like expected.
My 250 class quadcopter project is slowly coming to a successful (hopefully) end. Finally had some time to assemble motors and ESC.
Since I wanted to have rather standard setup with 5×3 propellers, I had no super high demand on ESC, I’ve decided to use Turnigy Multistar 10A V2 ESC preflashed with BLHeli software available at Hobby King. Why them? Cheap, already flashed with BLHeli so no need to to flash at home and 10A is enough to drive 5×3 props. And it’s also enough for 6×3. Just in case.
Motors are also Turnigy bought at Hobby King with 50% discount few months ago: Turnigy Multistar V2 2206 2150KV “Baby Beast”. After discount they were super cheap: $7.5 apiece. And they are green, what goes nicely with carbon fiber ZMR250 frame.
Right now motors are not soldered directly to ESC, I’ve only removed 2mm bullet connectors from both motors and ESC. Waster on space. I’m still thinking about where to put those ESC, so for first few weeks there will be some extra cable between them. Later we will see.
Yesterday I finaly had some time to work on my 250 class quadcopter based on ZMR250 carbon fiber frame. There was a plan to finish it before weekend, but looks like plan will have to be changed. I’m missing motor screws. They were not with frame nor motors. Too bad…
After one evening of work I’ve been able to assemble bottom plate with motor arms and attach Flip32+ flight controller to it. As you can see, Flip32 is rotated 90 degrees clockwise. USB port points left, not back. This allows much simpler access to USB port. On the other hand, it requires additional configuration entry that allows fllight controller software to compensate for that. But all in time.
One last remark: the frame, even without top plate is super stiff. Very good since it will take serious beating in next weeks. I’m finally learning to fly in Rate mode without auto-leveling. Boy, it’s hard. After two 20 minutes sessions I’m able to make a turn…
Flip32 and Flip32+ (10 DOF version of Flip32 with built-in barometer and magnetometer) are nice little flight controllers. And cheap. Some call them clones of Naze32, but this is not completely true. Yes, they are very similar, share the same hardware, but they are not identical. I would say they are better than Naze32 since have more features and are easier to extend. But that is not the topic.
One of coolest features of every drone is GPS support. This allows for both Position Hold and even navigation support. I will not explain how to configure Position Hold and navigation on Flip32+ and Cleanfligh today. The reason is simple: I’m still trying to fully understand PID controllers used in those modes: Pos, PosR and NavR. And it is not going very well I must say. Position Hold in low wind is OK, but navigation and PH in wind conditions is unreliable and I’m still unable to configure it to work well. But GPS even without Position Hold has some use. For example, Home marker on OSD when flying FPV.
In this tutorial I will use Ublox Neo-6M GPS module, Flip32+ 10DOF and Cleanflight 1.9.0.
Many say that small 250 class quadcopter are super fun. Small, fast, agile, tough and crash resistant. I’ve decided to check it out and build 250 quadcopter drone by myself. And next few posts will be tightly connected with this topic. Let’s call it a build log.
The most important part of every multirotor is a frame. It decides about everything. For my quad I’ve decided to use ZMR250 clone frame made from carbon fiber.
There is also glass-fiber version of this frame, and it’s half a price (below $20 while carbon is around $35). So, what do we get for additional $15? We get 2 good things, and one bad. But let’s begin with good things:
carbon fiber is lighter than glass fiber. My frame weights 145g while glass-fiber equivalent weights 181g. 36g might not seem much, but it is a difference after all. In my oppinion a difference worth $15,
carbon fiber is more durable than glass fiber. At least in theory. So, in theory carbon fiber quadcopter frame should be harder to break during crashes. We will see.
An the bad thing? Well, carbon conducts electricity and can block radio waves. This means, that you have to be extra careful with all the cables and antenna placement. Insulate everything, never leave any cables touching the frame and antennas has to be placed as far from frame as possible. Some kind of mast would be recommended.
How hard it is to build a RC plane without plans and starter kits? To do it in “Trust me, I’m an engineer” style. In mid June I’ve decided to give it a try and right now I can tell: it’s hard, but not that hard as one might imagine. All the problems I’ve faced were faced previously by someone else. I only had to ask right questions, read a lot, and use engineering sens to make plane work.
And well, it works. Way better than I expected it might work. Look for yourself.