Hands on: DALprop T5046 propellers

Last weekend I had an opportunity to spend some time in the air with new DALprop T5046 propellers from Surveilzone.
They are "funny" propellers. On one hand they have some nice features, on the other, they have few flaws that almost disqualifies them in my eyes…

  • Pros
    • Good air "grip"
    • Good efficiency
    • Smooth flight
    • Nice speed
  • Cons
    • Oh man, they are fragile. Each crash equals at least one broken propeller. If you got used to "tough" props from DAL, you will be shocked
    • They are very, very sharp at edges. I've cut my fingers when I was unscrewing shaft nut. You either have to hold them very carefully or wear gloves?
    • Too flimsy. I was afraid that they will bend in flight and cut ESC. I've already lost 2 ESC because of flimsy/bendy propellers and I started to pay attention to "flimsiness"

DALprop T5046

Final conclusion: while they might be an interesting option in terms of performance, they are not prepared for everyday use!

Photo from Surveilzone

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Tip: how to secure XT60 plugs

I had a problem with my SkyZone goggles: I was constantly breaking battery cable near XT-60 plug. One not careful enough grip and cable was ripped away. I've decided to fix it and permanently secure the cable with epoxy glue.

Sure, I could use hot glue (that looks ugly) or Sugru (that is expensive), but since few weeks ago I've bought HobbyKing Mid-Cure Epoxy glue, I've decided to use it instead. It worked fantastically!

HobbyKing Mid-Cure Epoxy glue

Solder cables to XT-60 plug pretty close to external coating as possible.

XT60 plug

Now, prepare a "mold" using electrical tape. Just wrap it around plug and cable leaving empty space inside. Prepare epoxy glue and pour it into "the mold".

puring epoxy into mold

After and hour or so, epoxy glue will be hard enough, that electrical tape can be removed. There is no chance I could ever rip this cable from the plug by accident!

protected XT60 plug

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INAV is learning to do mini-quad racing too

Let's be honest: in terms of mini-quad racing there is Betaflight (probably also Raceflight but I've never flew it yet, so will not comment on its flight performance), long long gap, and then it's everything else including Cleanflight, LibrePilot, INAV etc.

Originally INAV concentrated on "big" UAVs with GPS capabilities. After all NAV in name stands for Navigation. Mini-quads and acro performance were left alone, and once again, let's be honest: comparing to Betaflight, it sucked. It was possible, I've even written a short tutorial how to set it up, but it sucked.

Luckily, it is changing. INAV 1.2 had brought some improvements like Iterm limiting and acceleration limiting, and Acro flying in INAV became very nice. Small revolution, or maybe bigger catch up, is planned for INAV 1.3: asynchronous gyroscope, accelerometer and attitude processing. I've been working on it for last few months and results are very promising: INAV can drive a mini-quad with Betaflight comparable performance. Like this (please remember I'm not the best pilot!)

Setup:

  • PID task frequency: 1kHz
  • Gyro task frequency: 2kHz
  • Accelerometer task frequency: 120Hz
  • Attitude task frequency: 100Hz
  • Frame: Reptile X4R 220
  • Motors: EMAX RS2205 2300KV
  • Propellers: DALprop TJ5045
  • Flight controller: SPracingF3
  • Firmware: INAV 1.2 with custom changes

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marabou depron KFm-2 airplane

Marabou Stork: fixed wing FPV platform

Marabou Stork, my Depron/Carbon/3D Printed FPV airplane is officially done. Although it had first flight a week ago, some technical problems postponed full feature trials until yesterday. I would not call it a "huge success", but it was fine.

Here is a video from some FPV flying:

After around 1 hour in the air, here are some conclusions:

  • Wing is closing to it's limits. Originally it was designed for an airplane that weights around 500g. Marabou Stork weights 900g. Do not get me wrong, it still flies good, I really love KFm-2 profile on it, but you have to start to remember about things like air speed, specially during turns: too much yaw, not enough speed and bam, you have stall. It's easy to recover, no problems there, but last years model (the same wing, less weight) was free of it
  • Neo-6m GPS is, hmm.., crap… I have to update to Ublox Neo-M8 as soon as possible
  • INAV is unable to process GPS altitude and barometer altitude simultaneously: altitude jumps up and down like crazy. For now, the only solution is to disable either baro or GPS altitude component from computations. It's simple and I will try to write few words about it next week
  • Did not tested fixed wing navigation features of INAV yet. Reasons: two points from above
  • Boscam TS-351 200mW 5.8GHz transmitter with crappy clover-leaf antenna behaves much better than expected. I had excellent reception on my Skyzone Sky-01 at 1km and had to return due to RC link RSSI warnings
  • I'm disappointed with FrSky X4R range. Looks like 1km is a safe side limit here. RSSI was dropping to 40 and did not wanted to push it further. Probably it's because crappy antennas. They are equipped with simple whips, not dipoles like X8R for example. Next week I will try connecting 2.4GHz dipole to X4R and will give it another try

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Hand on: DAL (DALprop) TJ5045 propellers

After moving to new, 4S powered, mini-quad based on Reptile X4R 220, EMAX RS2205 2300KV and FVT Littlebee 20A, I’ve discovered that I’m missing some power. DALprop 5040 and DALprop T5040 I’ve been using on 3S did not delivered enough power. So, I’ve gave DALprop TJ5045 a try.

According to specs, they should be most efficient from all DAL 5045 family. Well, efficiency will be determined, one thing is sure: they surely give much more thrust and pitch speed comparing to T5040.

Dalprop TJ5045 top

Dalprop TJ5045

Thrust and speed improved a lot. ATM, hover is at about 32% of throttle and climb rate is impressive. I love it! They also seem to be little quieter that T5040.

Dalprop TJ5045 on Reptile X4R 220

They are also durable. Maybe I’m not crashing as often as before, but when I do, it’s much more spectacular. Today I had two of those spectacular crashes and all propellers survived. Nice.

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Marabou Stork: FPV airplane maiden flight

For the last few week I’ve been little busy building my next fixed wing UAV: “Marabou Stork” Depron/Carbon/3D Printed airplane with pusher prop build for FPV. It’s improved version of “Red Cruiser” model from last year.

marabou stork depron airplane

marabou stork depron airplane 2

It’s equipped with KFm-2 wing, Turnigy D2826-6 2200KV motor, APC-E 7×4″ propeller, 2700mAh Lipo battery, FPV setup with MinimOSD and RunCam PZ0420H camera. And Flip32 running INAV for stabilization and navigation (no GPS yet).

As you can see on a video above, it flies. Even pretty well. It needs some tuning, but have big potential. Unfortunately elevator malfunction grounded it after few minutes in the air.

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How to install and configure Betaflight 3

Latest Betaflight 3.0 is a new quality for flight controller software. It brings many new, cool, features comparing to previous versions. If you fly mini-quad or micro-quad, you have to check what Betaflight 3 has to offer.

This tutorial will show how to install Betaflight 3 and how to configure it so mini-quad can go into the air in under 20 minutes.

To play with Betaflight 3.0 you will need latest Betaflight Configurator! Install or update to latest version.

Flashing

Open Betaflight Configurator

Betaflight Configurator

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Micro MinimOSD stops overlaying in flight: solution

Both MinimOSD and Micro MinimOSD suffers from irritating technical problem. In some setups, they stops overlaying data during hard maneuvers or even right after arming. Problem is very simple: chip MAX7456 is extremely sensitive in terms of supply voltage quality. Working motors and/or servos, can introduce enough power supply noise to occasionally force MAX7456 to reset.

Luckily, solution is simple: separate LC power filter or big enough capacitor connected in parallel to 5V pads of MinimOSD.

Almost any big enough electrolytic capacitor will do (> 100uF, the bigger the better) but best results can be archived with low ESR > 500uF capacitor.

In my case symptoms were not very strong, usually only very fast flips caused MAX7456 to reset, but I’ve decided to go big: 1000uF low ESR capacitor.

Low ESR 1000uF Capacitor

Micro MinimOSD has 5V pads on a side and they are the best place to attach capacitor.

Micro MinimOSD

As you can see below, capacitor is bigger than MinimOSD itself and I had to think a little how to place it inside my Reptile X4R 220 frame.

Micro MinimOSD with capacitor attached

Results are great: no more MinimOSD problems. OSD stays on all the time, no matter how hard I use the stics.

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Preview: cheap APM Power Module for Cleanflight

Recently I’ve got my hands on a pair of cheap APM Power Modules from eBay with integrated 5V BEC and current meter (90A max). Although they are APM designed and will not work stright away with STM32 flight controllers like Naze/CC3D/SPRacingF3 (or rather would work only once since they are 5V scaled and those flight controllers require max 3.3V input) I have an intention to make them work!

So far, I’ve concluded that:

  • current measurement is done with Texas Instruments INA169 and 0.5Ohm shunt resistor
  • analog current out is 5V scaled, so probably 90A current flow results in 5V on meter output
  • voltage sensor output has 1/2 voltage divider. We can ignore it, most SMT32 flight controllers have voltage dividers (CC3D does not, but 1/2 is not enough in this case)
  • It more less works with a 1/2 voltage divider between current sensor and flight controller. Requires some tweaking, but something is measured. Will require scaling!
  • Integrated BEC works, and this is all I can tell about it I’m affraid

cheap apm power module for cleanflight

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blackbox_header

How to measure gyro noise frequency with Blackbox

Cleanflight / Betaflight / INAV lowpass filter tuning can be a hard thing to do if you have not idea what is noise frequency you want to cancel. Sure, you can blind test or read tutorials. But what if I tell you, you can measure it quite precisely using only Blackbox logs? Or measure rotation speed of motors? That would be nice, isn’t it? The only requirement are few seconds of Blackbox log with visible gyro (it can be also motor output or Pterm or even ACC reading) noise.

blackbox measure frequency 1

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