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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INAV 1.8 is just around the corner

Next release of INAV, navigation enabled flight controller software, is almost here. INAV 1.8 RC1 has been released just 2 days ago. List of changes is rather long, so here is shortened version with the most important things:

  • STM32F1 boards like Naze and CC3D are no longer supported. INAV 1.7.3 is the last version that can used on those boards. All F1 users are encouraged to migrate to F3 or F4 boards
  • INAV is now able to get current time from GPS. Time is saved in blackbox logs and can be displayed on OSD
  • SmartAudio (TBS Unify Pro video transmitters) and TrampHV video transmitter support. When connected over free UART (TX pin only) and properly configured, band, channel and output power can be changed using OSD and CMS subsystem. Changing this over MSP and SmartPort on a OpenTX radio (Taranis, Taranis Q X7) with Betaflight LUA script is not tested yet and probably does not work (yet)
  • Receiver type is no longer selected using feature command. There is receiver_type CLI variable instead. Configurator handles this in transparent way
  • Multiple OSD changed. And by multiple, I really mean multiple. Not only is has better update rate but also takes less memory and less CPU time. On top of that, new OSD elements has been added as well:
    • Combined "On time"/"Fly time"
    • System messaged indicator showing additional modes information, arm failure reasons, navigation stages
    • Average cell voltage
    • New throttle indicator showing also throttle requested by navigation subsystem, not only by user
    • Time indicator
    • Heading graph indicator
    • VTX band and channel, required SmartAudio or TrampHV
    • Distance alarm
    • Negative altitude alarm
  • AUX channels have been remapped to RC channels. AUX 1 is now CH 5, AUX 2 is CH 6 and so on. Be careful when restoring rc map from dump!
  • Navigation modes override MOTOR_STOP. This solves the problem of motors shutting down in rare cases when Navigation modes were enebled
  • Several other changes and bugfixes

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E45-TTL-100 Configuration Tool for Linux

This will be fairly short entry. Do you know what E45-TTL-100 LoRa wireless serial modules were missing? They were missing configuration tool for other platforms than Windows. And even on Windows it had some minor problems. Luckily, this has changed only a few hours ago.

E45-TTL-100 configuration tool for Linux

Stronnag, the man behind mwptools mission planner and tools for iNav and multiwii-nav, has released E45-TTL-100 configuration tool for Linux. Kudos!

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Toy Stirling engine = best toy ever and best Christmas gift?

How is it until Christmas? 2 months and something. Pretty close. And like every year there will be problem: what to buy someone who has everything? Tough one, right? Sweater? Socks? Toy Stirling engine? I vote for Stirling engine for sure. There is only one precondition: recipient has to like mechanics 🙂

I’ve tested the cheapest toy Stirling engine from china you can get. For less that $20 you get a functional engine model that, surprise, surprise, works. Amazing, right? Here is my video review of it:

Oh, by the way, for me, this is the best toy ever!

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And the most popular flight controller for INAV is… (August 2017 edition)

More than 2 months after previous “What it the most popular flight controller for INAV“, welcome to second edition.

I mportant, this is not the number of boards flashed with INAV, but rather number of times a board was connected to Configurator!

This counts TARGET software name, not retail name. For example, all clones of Naze32 will be counted as Naze32

Data was taken in August 2017, multiple connections during single user session are stored as single entry.

  1. SP Racing F3 – 25% of all boards, lost 4 percent points
  2. Omnibus F4 Pro (aka v2 aka SD) – 15% of all boards, gained 5 percent points
  3. Naze32 rev. 5 and 6 – 13% of all boards, lost 6 percent points
  4. Omnibus F3 – 12%, lost 1 percent point
  5. Naze32 older than rev. 5 – 7%, gained 2 percent points
  6. Omnibus F4 v1 – 4%, gained 1 pp.
  7. Omnibus F4 v3 and v4 – 3%, first time in TOP 10
  8. SP Racing F3 EVO – 3%, lost 2 pp.
  9. CC3D – 3%, lost 1 pp.
  10. AnyFC F7 – 1%, first time in TOP 10

Other targets have 14% in total.

This data also says something about CPU generations distribution:

  1. STM32 F1 – 27%
  2. STM32 F3 – 47%
  3. STM32 F4 – 25%
  4. STM32 F7 – 1%

What changed comparing to June?

  1. First F7 board appeared in TOP 10!
  2. F1 and F3 targets are loosing market share, while F4 and F7 are more and more popular
  3. Naze32 is no longer second most popular board
  4. OpenPilot Revolution and Airbot F4 (more less the same) are out of the TOP 10
  5. Boards with integrated OSD are more and more popular. They already have 47% of market share

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RunCam Split very late pseudo review: it’s not good

Yes, I know it’s few months too late. And it’s not really a review but rather, since I was never able to use it or I describe my friends experience with RunCam Split.

I own RunCam Split. I own it for like 2 months now, and it’s still in a box. Never connected, never really used. And in the meantime, I’ve build 2 mini quads are rebuild third. Why is that? Is there something wrong with RunCam Split that I’m not using it anywhere? And not planning to? Let’s be quick about it:

RunCam Split camera module and PCB

Continue reading “RunCam Split very late pseudo review: it’s not good” »

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Testing 868MHz LoRa range, part 3: round trip

After determining that range of 868MHz LoRa wireless modules E45-TTL-100 have, at least, quite impressive range (5,7km and I was out of line-of-sight to test further) I’ve decided to test something else.

In the beginning I was planning to use those radio modules for telemetry only, but then another thought crossed my mind: why not to build DIY TBS Crossfire for the poor? After all, TBS Crossfire also uses 868MHz LoRa (SX1272 vs SX1276), so it should be possible to build DIY radio link for medium range (up to 5km) for RC planes, right?

First of all, I will need to know how fast data can be transferred and how much delay can I expect in real life. So I’ve modified Arduino code and E45-TTL-100 configuration:

  • UART speed bumped from 9600bps to 57600bps
  • air speed bumped from 2400bps to 19200bps
  • output power lowered from 100mW to 50mW (17dBm)
  • transmitter sends 5 bytes of data (current microseconds and prefix)
  • relay receives packet and resends it to transmitter
  • current received number is deducted from current microseconds and round trip time is showed on OLED display

LoRa E45-TTL-100 round trip test


  • Round trip time is 82ms on average and it does not changes with distance
  • at lower output power (50mW vs 100mW) reception at 2.8km is worse. 100% of packets are received only then antenna alignment is not worse than 45 degrees
  • with slightly bigger payload size (up to 7 bytes) it should be possible to archive at least 20Hz update rate

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Quick note on SEMTECH SX1276 100mW output mode

Few facts about SEMTECH SX1276 LoRa modem and 20dBm (100mW) mode:

  1. +20dBm (100mW) is possible only on PA_BOOST pin
  2. Pins RFO_LF and RFO_HF allows only up to +17dBm (50mW)
  3. Maximum allowed duty cycle while using +20dBm mode is 1%
  4. Maximum allowed VSWR while using +20dBm mode is 3:1

The biggest problem with +20dBm on PA_BOOST is allowed 1% duty cycle. On the other hand, +17dBm mode (50mW) does not have such a limitation and maximum range should be only 1.42 times shorter than in 100mW mode.

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Hands on: Tiny Frsky 8CH Receiver from Banggood

I have a nasty habit of buying things and then forgetting about them. Something like that happened to Tiny Frsky 8CH Receiver (Wolfbox F802 software compatible) from Banggood I’ve purchased last year. For some time I used it in JJPro P175 quadcopter, but then it landed in a box and I forgot about until last week.

Tiny FrSky 8CH DIY Receiver Pinout

So, let’s do overdue “hands on” on Tiny Frsky 8CH Receiver from Banggood… Continue reading “Hands on: Tiny Frsky 8CH Receiver from Banggood” »

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