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.

Quadcopter made from wood

After building my last quadcopter drone, I was lest with a lot of spare parts, I’ve decided to invest some time (and money, of course) and build wooden multirotor drone. Od course, not everything would be made from wood. That is kind of impossible. Only frame. Quick research on the internet proven that is fully possible. A lot of people are using wood to build drone frames. If they can, so do I.

Since this project was supposed to be as cheap as possible, I’ve decided to use the same propeller size as my main setup: 10×4.5″, the same radio: Turnigy TGY-i6 and batteries Turnigy 3S 5000mAh 25C. Full planned configuration is as follows:

  • ~400mm wooden frame (plywood and slats) in Dead Cat configuration,
  • 10×4.5″ propellers,
  • Suppo 2212/13 1000KV motors,
  • 30A Xt-Xinte ESC,
  • Thunder QQ Super Flight Controller, since seller has sent me a new one,
  • Turnigy TGY-i6 radio,
  • Turnigy 5000mAh 3S 25C battery

Today was the first day of actual building. After one day I have central plate and front arms.

Cutting plywood for quadcopter frame

Fron arms with Suppo 2212/13 1000KV motor

Front arms attached to central plate

Fron arms with Suppo 2212/13 1000KV motor

3mm plywood was too flexible, so I reinforced central plate on edges with additional wooden slates. That gave some extra rigidness on longer axis. Arms are secured using M4 bolts.

I must say, that this frame might be way better than I expected in the beginning. I was surprised how rigid front arms are. And lighter than anticipated. It’s not done yet, but I expect frame’s weight will be around 400g. I’m only affraid if it will survive first crash…

Testing quadcopter drones at home

I think everyone who owns a drone would like to be able to test it at home. No wind, no rain, close to computer and all required tool. But… If you do not have a very very big room that might not be a best idea ever. Limited space makes everything extremely dangerous. Specially in case of untested aircraft. Human body is fragile, quadcopter is a delicate device and propellers can spin quite fast. Luckilly there is a way to test at least some aspects of multirotor flight at home. You just need some kind of harness that will prevent drone from getting out of control and smashing into anything.

To create simple harness you will need 4 pieces of rope and something to attach them to. Like chairs. Or table. Or any other furniture. It only has to be heavy enough to support weight of your drone.

Quadcopter harness

In more advanced version, like I did, you can attach to 2 wooden board to a basement/garage walls or bookstand. Just like on a picture above.

Will it work? Of course! Like that, for example:

Brushed or brushless – RC motor dilemma

You want to fly, you need a motor. Electric, internal combustion, jet, ion, gravity. It does not matter. And since gravity engines are not invented yet, ion has no place in atmosphere and jet or internal combustion are kind of non-practical for multirotors usage, we have to stick with electric motors.

Brushed DC motors

In RC world there are two types of DC motors we can choose from: brushed and brushless. The brushed ones are wth us for decades. Cheap and proven, but with a few downsides. First of all, they have brushes and brushes wears off because of friction. After time, they stop to conduict electricity and has to be replaced. Plus, they cause sparks, lowers efficiency, make noise, are sensitive to dust and so on… This is why, we do not use brushed DC motors any more.

Brushless BLDC motors and ESC

 

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Turnigy MT2213-935KV MultiStar Motor & Propeller Combo 10-4.5 Review

Good motor-propeller combo is a key for building stable and reliable multirotor platform. Since many amateur RC builders does not feel qualified enough for choosing motor and propeller separately, many producers offer brushless motors and matching propellers as sets. One of them is Turnigy with their budget, entry level set of 935KV motor and matching 10×45 CW and CCW propellers.

MT2213-935KV motor propeller set

It contains:

  • one MT2213 935KV brushless motor with dual mount for both standard and DJI style sloted propellers with male 3mm “gold” connectors,
  • one CW 10×45 DJI style sloted prop,
  • one CCW 10×45 DJI style sloted prop,
  • 3 female 3mm “gold” connectors,
  • screws

First, the motors. They are rated at 935KV and are suited for both 3S and 4S batteries. Unfortunately, not too high power limit (200W in surge) does not allow to use 10″ props with 4 cell batteries. Manufacturer suggests 10″ prop with 3S and 8″ props with 4S. Too bad, since from my experience, their effective lift limit is around 250g per motor. Going above that value causes multicopter to behave little sluggish due to not enough power on more aggresive maneuvers. One the other hand, my current bulid uses four of those motors and weights 1400g with camera, FPV set and 5000mAh 3S battery. And it flies like a charm. I would not mind to have more power, but it’s fast and agile enough to have a lot of fun. Of course, one can forget about aggressive acrobations, but flips and rolls are doable as long and one remembers about alitude loss.

Very nice feature of those motors is possibility to use both DJI props and standard, not-sloted propellers. Short M6 shaft helps to eliminate extensive vibrations for running propellers. And a drop of anaerobic glue secures shaft’s nut tight enough not to let it unscrew in midflight.

Turnigy MT2213-935KV

Second, the propellers. To be frank, those props are crap. Sorry guys, but that is true. They are not rigid and reliable enough. At about 60% throttle they were going into audible oscillation that even my neighbor that had never any experince with RC recognized as something strange. And he was right, since one of those props actually broke during flip. And I think everybody knows what happens to a quadcopter when one of propellers stops to exists then machine is in the air. Crash. And although it fell into high grass grass that softened the fell, all four propellers were broken after that. So I replaced them with APC 10×4.5MR without any regrets.

To sum things up: motors yes, propellers absolutely not! If you are looking for a good 900~1000KV motor then consider Turnigy MT2213-935KV bought separately. And match them with, for example,  APC 10×4.5MR like I have.

All photos are from HobbyKing.com website

Thunder QQ Super Multicopter Flight Controller

Originally, this post was supposed to be very positive review of Thunder QQ Super Multicopter Flight Controller unit. But, unfortunately, it will not. Why? I received my unit damaged. Only M1 and M2 ESC outputs were working. Other 4 ESC outputs were damaged and ECS were unable to arm. So, instead of a review it will be a description of a product… Too bad.

Thunder QQ Super Flight Controller

Thunder QQ Super is a simple entry level multicopter flight control unit. It supports quad and hexa-copter configuration and requires at least 4 channel Rx system. Additionaly QQ Supper supports auto-level feature and this is more less all about it.
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