Let’s build 250 class quadcopter: mostly done

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.

ZMR250 quadcopter

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:

  1. It is heavy. With 1.3Ah 3S LiPo battery and RunCam HD it weights 530g. Have to make it lighter…
  2. 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.
  3. It is tough. Oh the crashes it has survived…

ZMR250 with RunCam HD

ZMR250 in air

Flips: rule number one

Rule number one when doing flips with multirotor (quadcopter) drone is to watch your altitude. Specially with bigger machines without big thrust to weight ratio. If you will not control altitude, it might end like that:

Quadcopter (built on Raptile 500 frame and Flip32+ FC) survived without a scratch. Camera (RunCam HD) survived as well. It “only” detached for quadcopter and traveled few meters by itself until landed in grass.

Dead Rat, wooden quadcopter, maiden flight

Last week I was, finally, able to perform a maiden flight of my DIY wooden quadcopter (here and here). I will not say it was huge success, but it was a success alright. What went like expected? Well, quite alot. First of all, it flies and has enough thrust to weight ratio to do flips and rolls. And is pretty stable in hover. What went not like expected? It is highly unstable on yaw. Really, really unstable. Probably rear propellers are too close to each other and I have to work on PID settings. As soon as I will have enough spare time…

In a mean time, here is a short video from DeadRat’s maiden flight:

Final configuration goes as follows:

  • Motor to motor diagonal: 500mm,
  • Motor to motor front arms: 370mm,
  • Motor to motor rear arms: 300mm,
  • Materials: 3mm plywood and 15mm wood spars
  • Motors: Suppo A2212/13 1000KV
  • ESC: XT-Xinte 30A
  • Flight Controller: OpenPilot CC3D (clone)
  • Battery: Turnigy 5000mAh 3S 25C
  • Propellers: Gemfan 1045
  • Start weight: 1212g
  • Hover time: 21 minutes

Next steps: tune it up and move battery to top. Somehow I do not want to construct a landing gear for it…

Drone crash: it happens

Crashes when flying any RC gear happens. And lower the entry level, more crashes we can see. Like, for example, those two “hard landings” I had few weeks ago.

First one is 100% pilot’s fault. I’ve got lost with FPV gear, lost sense of altitude and just hit that small tree trying to recover. Quad survived almost without a scratch.

Second one is a hardware fault and a proof that electronic components are sensitive to water. BEC got wet during rain and stopped to provide constant voltage. As a result, flight controller, OpenPilot CC3D in this case, was reseting itself on random basis. Result? Uncontrolled and rapid descend. This time quadcopter had taken some damage: broken landing gear. Good thing those things are pretty cheap, but still, it takes time to ship from China. In a meantime, steel wire 1.8mm has to work as landing gear replacement.