#131 | dr03 – Update on the quadcopter (hardware side)

Hi guys!

I really need to think about something else aside of the final project. So today, let’s talk about the drone because the hell it is fun too and we need quite a work to optimize our little beast. If you don’t remember this, just go there:
– #03 – Making a quadcopter drone with Raspberry and Navio2
– #04 – Getting started on the software side of your drone build with the Navio2 & Raspberry Pi
– #08 – Update on the quadcopter (software side)
Bach and I need to calibrate the overall stuff once again: the last time, the drone hasn’t flight because of a thrust propeller issue due to the motors. It didn’t take off from the ground but rather slide on it with one handicapped arm.
Here was the list of the hardware and software parts of the drone:

  • Battery charger 12V with adaptor 
  • Battery Lipo 2200 mAh 25-35C 
  • Rotor CW and CCW 2204-2300
  • Electronic Speed Controler (ESC) 12A
  • Power distribution board (PdB)
  • Frame Fpv 250mm
  • Propeller CW-CCW 5300
  • 32Gb SD card
  • Raspberry Pi Camera Module V2
  • Raspberry Pi 3
  • Fr-Sky Radio Receptor DBR-XP X8R-ACCST
  • Fr-Sky Radio transmitter – Taranis Q-X7
  • Navio 2 with GPS-satellite module and power module

Yesterday night, I’ve observed a bigger issue on the overall hardware calibration: our motor was a 2204-2300kw. The real issue was to know the real thrust to lift the drone. You need to remember one thing though: all the motors need to be able to lift two times and more the weight of the drone (it means one motor need to lift the normal weight of the hardware and structure if it is a quadcopter). Why? To be more flexible in the control of the drone.

In reality, the real deal was also the issue due to the battery. The volts going through the wires give the juice and the power to lift the drone, and it means more rpm (rotation per minutes). In fact, if our motor was good calculated, the last experiment gives us a good estimation of the real “thrust” needed. The rotors used a Lipo 2S-3S (a bit less than 11,3 volts), it also means that the maximum juice is at 3S, it is why it was a big mistake to make the drone lift with outdated hardware: it would mean at full power (3S), it can only lift the normal weight of the drone and not three times what we needed.

So to solve the issue we need:
– To change the motor that can get more power from the battery, and that means bigger motors, plus changing the ESCs that regulate the voltage through the wires. But it also means to change the power distribution board (Pdb) because the ESCs would be too big… And that also means that the drone will be really heavy with all that stuff… And that will lower down the flight time of the drone, draining out the big battery. The solution could be to use larger propellers to lift the drone off at less rpm… But it would means to change the structure of our drone and that’s a lot of hardware update and it is not what we want.

Or,

– We can change the battery to upgrade to a 4S cells, it means more voltage going through the wires to the motors. It also means we can reduce the motor weight and ESCs size (and keep the Pdb if the ESCs are of the same size as the female jacks of the board). In fact, this solution is the best because:

1) The weight of the drone will drop thanks to the reduction of the hardware size.
2) The battery size will also be smaller and give more power to the motors.
3) The motors will be more powerful and could lift more than two times the weight of our drone.
4) We can know the thrust from online data on the web.

Btw, our outdated hardware has a weight around 650 grams. It means we need an overall thrust power to be able to lift a minimum of 1300 g and 325g per motors but we want to be large and get good motors that can lift 1950 grams and 487,5 g per motors (and for the Lipo, we have taken the 3S because we were afraid of the quick discharge of the battery).

See you guys soon and thanks for the reading!

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