Project Dualcopter – worklog #3

It's been exactly one year since my last update on Project Dualcopter. On 20th of October 2016 I've posted that there was a progress. Now, 12 months later, I once gain report, that there was a progress…. That was slow….

3d printed dualcopter aka flying bucket

servos for 3d printed dualcopter

  • I've finally installed control surfaces and servos
  • I've finally decided where LiPo will go: to the top of the whole stack. I want CoG as far from control surfaces as possible. They will not generate much force, so I need as much torque as possible. So, long lever FTW
  • My daughter called it Flying Bucket. Makes sense, right?
  • Plans for next week: battery mount

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Project “Dropship glider” – failure #1

I’ve described my Dropship Glider Project here. Previous weekend I finally tested its ability to glide when dropped from a drone 50m above the ground. And well… to be honest, I failed hard this time. Just see this short video from FPV camera:

Dropship survived two drops. After second one, AIO camera/transmitter combo got damaged. Continue reading “Project “Dropship glider” – failure #1” »

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Project “Dropship glider” – introduction

When I saw this video from rctestflight I knew I will build something like that for myself. A voila, few months later it is done. Here is Dropship Glider.

Dropship glider - depron FPV delta glider

It is 29cm long with 20cm wingspan. Weights 97g AUW and has 21g/dm^2 wing loading. So, in theory, should glide. Somehow… If I got center of gravity right. And did not made ailerons too big. Or…

Dropship glider - depron FPV delta glider

Delta 6mm Depron "wing" is attached to 6mm carbon fiber rod and has some quite big dihedral: 15 degrees.

Dropship glider - depron FPV delta glider

The biggest problem was radio link and mixer for ailerons. I could not use my Taranis: I need that for a carrier and only radio control link I had was EM-16 with PPM output only and no way to setup any kind of mixer. The radio just has no "features" like that…

So, took one Arduino Pro Mini and wrote short program that acts as PPM decoder and mixer for ailerons.

Dropship glider - depron FPV delta glider Arduino

  • power is supplied by 1S LiPo taken from my Tiny Whoop
  • FPV AIO Eachine TX02 also taken from my Tine Whoop
  • 5V is supplied from cheap, regulated, step-up converter
  • 3rd servo is to release tether

First flight, or rather drop, tomorrow. There will be a video from the event of course…

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How to read PPM signal with Arduino?

More than a year a published a post called Generate PPM signal with Arduino. Today it's time for part two: How to read PPM signal with Arduino?. Strange thing: internet does not gives very useful information on this topic. Strange, right? Some links to pages that does it either very very wrong or in not simple way.

There is a one almost good solution. It's an example code by Hasi123. Short, efficient and actaully works almost out of the box. But it has 2 problems:

  1. It is not a library. You have to copy paste code
  2. It alters Timer1 and that means, that many other things stops to work: PMW output, Servo library or anything else that uses Timer1. Crap…

So, I've invested some of my time and, based on that code, I've created Arduino library called PPMReader. Advantages?

  1. It is a library (!)
  2. It does not alters any timers (!)

Example code, that reads PPM signal connected to Pin 2 of Arduino Uno or Pro Mini (and other using ATmega328) and prints decoded channels over serial port would look like this:

#include "PPMReader.h"

// PPMReader(pin, interrupt)
PPMReader ppmReader(2, 0);

void setup()
{
  Serial.begin(115200);
}

void loop()
{
  static int count;
  while (ppmReader.get(count) != 0) { //print out the servo values
      Serial.print(ppmReader.get(count));
      Serial.print("  ");
      count++;
  }
  count = 0;
  delay(500);
}

The only required configuration is a decission of a pin and interrupt. Not all pins have hardware interrupts, so on many boards this is limited to:

  • Arduino Uno, Pro Mini and other based on ATmega328: pin 2 / interrupt 0 or pin 3 / interrupt 1
  • Arduino Pro Micro and other based on ATmega32u4: pin 3 / interrupt 0, pin 2 / interrupt 1, pin 0 / interrupt 1, pin 1 / interrupt 3, pin 7 / interrupt 4

PPMReader Arduino library can be downloaded from GitHub.

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AnyFC F7 and DIY buzzer for INAV

Because both original and Banggood clone of AnyFC F7 flight controller and missing buzzer support, its usefulness is somehow limited. There is no dedicated pin and driver. Next release of INAV (1.7.2) will finally solve this problem by reusing Motor #9 output as buzzer output.

But, some additional hardware will be required. To be precise, single n-channel signal MOSFET transistor like 2N7000. Connection diagram is shown below.

AnyFC F7 Buzzer driver with 2n7000 mosfet transistor

And this is how it can be soldered together.

AnyFC F7 Buzzer driver with 2n7000 mosfet transistor

AnyFC F7 with buzzer

That is all. Simple, right?

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DIY brushless motor kit – I give up, for now…

Latest update on the topic of DIY motor kit from Banggood (DIY Assemble 2204 2-3S Brushless Motor 0.42*2.8 Copper Wire with Motor Cap Banana Plug): I give up. For now, at least.

In total, I tried to wind this motor 6 times. In every single case it ended in the same way: one of the phases burned. So, it's either me, or this kit. I've verified winding directions and termination schema for at least few times, and if I didn't missed something extremely obvious, I did it in a right way. I even verified winding directions during "unwinding". So I start to suspect, that this motor is either no 12N14P DLRK (not very probable), or it should not be winded with 0.42mm wire. Next week I will order 0.20mm wire and try one more time…

This is a winding schema I used:

dlrk winding schema

Poles goes as follows: AabBCcaABbcC where capital letter is clockwise, while small letter is counter-clockwise.

Phases were connected like this:

  1. A1-C2
  2. B1-C1
  3. A2-B2

Sure, I could have done something wrong. But not 6 times in a row…

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DIY brushless motor kit – first failure

Just like it was expected, my first attempt to wind a brushless motor (12N14P) was a failure. Probable cause: short circuit between phases and my creation released magic smoke.

Then I tried for a second time, and failed again. This time less, no smoke, but motor overheats and does not want to start most of the time. I suspect this can be an ESC problem (Emax 30A) that is configured for DampedLight. Perhaps motor is rotation too fast (no load after all) and ESC tries to slow it down. Hard to tell. Tomorrow I will add a propeller and disable DampedLight. Maybe it will help. I will also try WYE configuration. Right now phases are connected in Delta setup.

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DIY brushless motor kit…

China is such a magical place… among all those affordable things you can buy there, there are those not so useful, but still affordable things that, for sure, you do not need. Just like DIY Assemble 2204 2-3S Brushless Motor 0.42*2.8 Copper Wire with Motor Cap Banana Plug.

DIY Assemble 2204 2-3S Brushless Motor 0.42*2.8 Copper Wire with Motor Cap Banana Plug

As you can see on a picture above, it is a motor that you have to assemble by yourself. Wind the coils, install bearings, learn the difference between Delta and Star configuration, and so on and so on… Oh, and there is absolutely no manual. So even number of wire turns is a mystery. I suspect something around 10, but who knows.

Tomorrow will be the first attempt to assemble it. I hope magic smoke will not appear…

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3D Printed Paddleboat

3D Printed Paddle Wheel Boat

It's not a secret, that me, and QuadMeUp, are not only about quadcopters. From time to time I like to do something completely different.

When I was a child (10-12 or something like that) I loved to build boats. Simple crude design: styrofoam or bark, simple sail or DC motor and tinwire propeller. No RC link. Just let it sail in "somewhere there".

When I got a 3D printer and learned that servos can be converted to continuous rotation simply by replacing potentiometer with a pair of resistors, the idea to build paddle wheel boat powered by servos was almost obvious.

So, here it is!

3d printed paddle wheel boat

  • Hull can be 3D printed, STL files are available on Thingiverse
  • Wheels are powered by 2 TowerPro 9g servos converted to continuous rotation
  • RC link by cheapest FrSky compatible D8 receiver
  • 2S LiPo gives enough "juice" and with power usage of about 300mA it can sail for hours

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