mandevil's blog - RC Groups
mandevil's blog View Details
Posted by mandevil | Yesterday @ 05:26 AM | 1,198 Views
Quick and short edit of my recent flight.

Nakléřov, a flight with DJI F550 (2 min 29 sec)

Posted by mandevil | Dec 30, 2017 @ 02:12 PM | 1,325 Views
Posted by mandevil | Dec 03, 2017 @ 02:49 PM | 1,687 Views
After one abortive attempt (motors rotating in the opposite directions because the translation of the DJI manual for F550 states wrong direction of rotation) I re-maidened my rebuilt F550 with the iOSD Mark II incorporated. This allowed me to rid of the extra battery that I used to power the VTX/FPV cam for some minor weight saving. Funny enough, the balance that this extra battery provided made the main battery to move forward to the limit. I also soldered XT90 connector for battery connection (my Gens Ace Tattu batteries have these) and the joint was fairly hard to solder for me, so I pray to patron saint of model aviation that the joints are good and won't come apart in mid-flight. Another mod was finishing the proper attachment of the Z1 Tiny gimbal using four M4 screws and proper attachment of the RunCam – these were held by duct tape before. I hoped to reduce the vibrations that creep into the GoPro image when it's windy or at high speeds. Doesn't seem to have helped, so I guess it wasn't fault of the attachment to begin with.

Following short video shows the iOSD in action. The flight was made in freezing temperatures and quite windy weather, so you can notice significant pitch/roll of the FPV cam picture compared to the GoPro image.

The iOSD works nicely, there was no issue connecting it. I decided not to use the video switching feature and use my SmartFPV switch instead, because the way video is switched with the iOSD is rather awkward. The navigational data show look pretty great, the "direction to home marker" seems to be spot on. What surprised me that the persistent "red blinking LED" problem I encounter very often is not loss of GPS lock, because I've got it with 10 satellites locked.

F550 with iOSD Mark II (2 min 41 sec)

Posted by mandevil | Nov 25, 2017 @ 02:34 PM | 1,610 Views
Three weeks ago I had an out-of-LoS landing with my DJI F550 hexacopter. I lost orientation in fog and GPS hold somehow wasn't holding location and wind blew me few hundred meters away. The craft landed softly, but after few seconds it flipped over for unknown reasons. My explanation is that loss of control signal triggered fail safe that tried to take off. Anyway, the copter survived mostly intact (or so it seems), but all props were ruined and they also sprayed soil all over.

I took the hexacopter apart to clean it and also started to think about improving it. To my surprise, DJI iOSD mkII price went drastically down -- to about third of what it used to cost when I last checked. So I ordered it and started to work on putting it all together. After lot of research I decided not to use the video switching feature to switch between FPV camera and GoPro and use my trusty SmartFPV video switch. I mix OSD only to FPV cam while leaving GoPro picture without OSD. After few days of work all is finished and ready for the re-maiden.
Posted by mandevil | Jul 01, 2017 @ 11:05 AM | 2,909 Views
I have bought my F550 hexacopter new batteries -- Gens Ace Tattu 4S 6750 mAh. The difference this makes! Now I seem to be easily reach 15 minutes in the air where before I did not dare to stay past 8 minutes (with aged Turnigy 4S 5000 mAh).
Posted by mandevil | Apr 16, 2017 @ 05:45 AM | 3,777 Views
Yesterday, when I was fixing gimbal mode selection not work (turned out to be a loose pin in the JR connector) I decided to investigate different gimbal version. So I loaded 1.11p version into it. Well, it seems to work, but now I cannot perform any more upgrades. When I try the gimbal apparently stops responding and goes completely slack. So it seems that I'm stuck with what I loaded in.

The new software is the 'p' version, which is the PWM input directly commands the position as opposed to the 's' software that commands speed and sense of change. There are some advantages to the position version -- you can adjust your transmitter so that the slider detent is neutral position and the maximum deflection is some other position like 90 degrees downwards for the pitch axis. The downsides are that you can't easily do the very slow movement. I have added a delay for the pitch axis and see how it works. Also, the movement is limited in this version, so the 90 degrees down is the limit and you can't pitch upwards as well.

Also, the Zhiyun Tech website no longer lists the gimbal, so it looks like they discontinued and no new version of the control SW are coming. Sigh.
Posted by mandevil | Apr 01, 2017 @ 03:34 PM | 4,118 Views
Today I have installed video switch from SmartFPV (this one), so that I can switch between RunCam and GoPro cams. This will allow me to use gimbal controls in flight. Everything worked pretty much out of the box. The last thing I need to do is to affix the gimbal to the aircraft frame properly -- the duct tape is a shame. New videos can be seen here.
Posted by mandevil | Feb 25, 2017 @ 04:07 AM | 4,651 Views
This is video from my vacation in November, but it is still my distance record.

FPV flight to 1.3 km (2 min 25 sec)

Posted by mandevil | Feb 18, 2017 @ 02:18 AM | 4,496 Views
Finally, I have replaced broken landing gear on my F550. I also soldered gimbal power supply to the main power bus, so now only the cam and the video transmitter are powered off a separate battery. Below is short video from the first session with the repaired hex:

Winter with DJI F550 (2 min 1 sec)

Posted by mandevil | Nov 04, 2016 @ 01:33 PM | 4,562 Views
Yesterday, I dodged not one, but two bullets while flying my F550 hexacopter.

The first close call happened as I was flying near Vimperk. I flew to about 100 m AGL to gain a view of the town. After short while filming I decided to return. And guess what, I couldn't find my starting place no matter what I tried. Video link got quite spotty and I thought I am above myself, but in fact I was behind some trees and not very close. I tried to recognize the terrain (meadows with groves) but I couldn't no matter how hard I tried. Eventually, I decided that it's better to land at unknown place than to fall while searching fruitlessly. Fortunately, the craft did not lose the control link (that would trigger RTH which I don't think would work as I suspect that GPS fix was lost). After about 15-30 minutes I found the copter intact in the middle of a meadow. Video from the camera eventually showed, that the landing was fairly smooth, if bit fast.

The second close call happened on different place, where I decided to finish off the same battery from the previous flight. It was showing 14.75 V (4S battery) or so, so I thought I can eke out a minute or two. Bad decision. After I reached my target some 300 m away I noticed that my main voltage is 9 V! Before I could do anything, the copter started to descend rapidly. Fortunately, I was just a few metres above the ground, but even then the impact was more violent then in my previous screw up. The landing gear legs snapped on one side, but apparently gimbal did not hit the ground. So it seems nothing but the landing gear broke. Of course, now I need to order new one, before I fly again.

Lessons learned:
  • on unfamiliar location don't just fly away, but look back and find some orientation landmarks that will help you find your way back
  • make sure you're receiving GPS coordinates in telemetry; make sure your transmitter is displaying all pertinent navigational data: AGL height, ground range, distance!
  • have alarm for low voltage that triggers at about 13 V

Edit: Video of the above is available.
Posted by mandevil | Oct 31, 2016 @ 05:21 PM | 4,463 Views
Third session with my DJI F550 hexacopter with new Zhiyun Tech Z1 Tiny 2 gimbal. Very roughly edited because I'm on vacation and don't have real editing software here.

Aerial from Šumava (quick edit) (5 min 39 sec)

The occasional vibrations occured again. They never happen when low, sometimes just turning into opposite direction will make the flight smooth again. I am more and more conviced it's the prop downwash impinging on the gimbal platform. I tried to move the gimbal back a bit, but no discernible improvement. But it definitely needs to be resolved, since it seems to be able to ruin otherwise good shot.
Posted by mandevil | Oct 28, 2016 @ 03:51 PM | 4,475 Views
So, as promised, today I took the Zhiyun Tech Z1 Tiny 2 brushless gimbal to flight. I compiled a video from today's footage (total of about 24 minutes cut down to some 6 minutes). I couldn't do much processing since I'm on vacation and my video editing workstation is not with me.

Overall, good impression -- it just works. Horizon is level, heading stays put, stabilization looks mostly pretty good. There were some periods where there were considerable vibrations visible. Not sure about that, but either there was some wind up there or something is not quite right with the copter.

I don't have video switching in the copter yet, so I couldn't try remote control of the gimbal.

Zhiyun Tech Z1 Tiny 2 gimbal maiden flight (7 min 0 sec)

Posted by mandevil | Oct 27, 2016 @ 02:07 PM | 4,179 Views
I completed equipping my F550 hexacopter with Zhiyun Tech Z1 Tiny 2 gimbal. Since I am on a vacation, it's not the final solution yet, but it should be airworthy enough for a few flights.
  • Had to extend gimbal control wires; spent entire evening making JR connectors agonizing without proper tools
  • The hang frame supplied with the gimbal does not fit my landing gear's rail I decided that I will just affix the gimbal's top plate to the rail platform but I don't have the screws/nuts for that; temporary solution: duct tape! Much professional, much strong, much wow!
  • Mode selection doesn't work on the completed rig. Not sure what went wrong, I checked both the cable and the mode setting before installing. I don't want to take everything apart again, so default mode will have to do.
  • Takeoff weight is 2 kg. DJI spec says it should fly.

See you tomorrow.
Posted by mandevil | Oct 26, 2016 @ 06:31 AM | 4,354 Views
I ordered Zhiyun Tech Z1 Tiny 2 gimbal after reading positive reviews and good experience with it. Also, Banggood had it in their European warehouse and for a good price (about 30 EUR lower than in their China warehouse!) It arrived in about 10 days -- just few days before my vacation.

So now I am in the process of adapting the F550 so that I can install the gimbal. I installed the "tall legs" landing gear that include a rail for installing the gimbal. Unfortunately, the rails spacing cannot be adjusted and of course, it doesn't match the Z1 Tiny's hang-mount frame. So I will just screw it in the gimbal mount plate supplied with the landing gear (being on vacation, I don't have the screws...). BTW, I don't feel too good about the landing gear as it seems that both plates extend will into the down-wash of four out of six props.
Posted by mandevil | Oct 03, 2016 @ 03:34 PM | 4,832 Views
Had the third flight with my DJI F550 hexacopter. The first thing I did was to fly to the edge of the forest in distance... turned out to be at 700 m range. The video link was flawless. I'm very satisfied with my VTX/VRX performance so far. I get bit nervous when flying beyond LoS (which really is anything beyond in excess of 200 m), but hopefully I'll soon try to reach 1 km, weather cooperating.

Here is the video of the "long range" trip:

FPV flight #3: 700 m range reached (DJI F550 hexacopter) (3 min 13 sec)

Unfortunately, the Eachine DVR that's integrated with their LCD8502D diversity receiver is really crappy and barely usable. It records video at some non standard framerate (worked out as 16.9234 fps for me), which makes it difficult to match with the primary video. What a shame. Below is an example of what it records (taken on my FPV session #2). It took me the whole evening to be able to match the video with the GoPro footage and even then it's not perfect. Also there's noticeable tearing in the picture.

Second DJI F550 FPV Flight, with DVR recording this time (repost) (4 min 35 sec)
...Continue Reading
Posted by mandevil | Sep 26, 2016 @ 02:56 AM | 8,319 Views
Finally, after all that time procrastinating, I had my first FPV flight. I thought my Sky Surfer will be the first to fly, but equipping the F550 turned to be much easier with some velcro and binding wire. Currently I use extra battery to power VTX/camera, which adds about 140 g of weight.

Everything worked out beautifully. The video link was absolutely clear with no static whatsoever. I only dared to max 280 m away from myself. I will put together short video later today.

Can't wait to fly again.

Update: Here's the video. No sound, just a quick edit.

My First FPV Flight (DJI F550) (6 min 54 sec)

Posted by mandevil | Aug 22, 2016 @ 08:15 AM | 5,666 Views
After some waiting, my FPV kit is mostly complete:
  • Eachine LCD5802D as LCD display with integrated 5.8 GHz diversity receiver and DVR
  • Eachine ET600R 600 mW 5.8 GHz video transmitter
  • pair of Aomway cloverleaf antennas
I forgot to order the camera, though, so there's some more wait. Meanwhile, I range tested with my GoPro (thanks to Eachine to supplying two cables with their VTX, so that I could use one for the testing). I range tested by walking away from the transmitter with the receiver. The picture was perfect to about 300 m, then it started to exhibit some minor graininess. By 500 m mark the picture degraded quite a lot. I would be still able to control the aircraft, but it wasn't pleasant. I don't have much experience with this, but given how low both the transmitter and receiver were above the ground, I can only assume lot of the quality loss could be attributed by the Fresnel zone 1 getting big enough to be blocked by the ground.
Posted by mandevil | Aug 02, 2016 @ 08:07 AM | 5,289 Views
For ages I had selected several clips that didn't fit anywhere else and I wanted to give them some kind of home. That is, to compile them into a video. Finally got around to complete the job. It's nothing special really, just some random bits and pieces.

Anyway, as I was editing this, I got bit tired with Sony Vegas and decided to try DaVinci Resolve as NLE. I think it worked well enough that I want to repeat the experience. Few words about my Resolve impressions are below the video embed.

Compilation of unused aerial footage (5 min 25 sec)

Totally Green Video Editor's Impression of DaVinci Resolve

I was fairly conversant with Sony Vegas and I liked the way basic timeline editing was implemented in it. There were some problems, though. The UI wasn't properly supporting high DPI displays; when using Lagarith VfW codec, audio playback lagged terribly; crashes were a thing. Then I have found out that Resolve 12.5 is free to download and use. Free as in free. Wow. Let's give it a go! I edited two little videos and I think I have switched for good.
  • UI works beautifully on 4K HiDPI display; no more broken menus; no more microscopic type; letters are properly scaled, everyhing looks gorgeous
  • VfW is not supported at all; good bye Lagarith. Looking for an intermediate format, I converged on using Apple ProRes -- the format is supported by Resolve for reading and ffmpeg supports encoding it. What's better, I can write Deshaker output directly into ffmpeg ProRes
...Continue Reading
Posted by mandevil | Apr 10, 2016 @ 01:44 PM | 5,744 Views
After not much happening during the winter, I have ordered and received some new gear. The first one is FrSky Taranis X9D+ TX with X8R RX module. This means I have RX for each F550 hex and Super Sky Surfer. I also ordered Zaggometry, so I can receive telemetry from Naza M V2 flight controller. And the last order were two more 5 Ah LiPos, so I can finally get more training time.

Now if weather would cooperate...