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Armattan Japalura 4" Build Log
#1
Having decided that I needed another 4" quad in my fleet, I settled on the four inch version of the Japalura frame from Armattan quads. I've always liked Armattan's frames and this seemed a natural choice.

The parts list includes a Runcam Split, so I was faced with some interesting choices to get everything to fit inside this tiny little frame. Here's what I ended up with:

Frame: Armattan Japalura 4" silver
Motors: Brother Hobby Tornado T1 1407 3600kv
Flight Controller: Racerstar Star4S
VTX: Matek VTX-HV
FPV Cam: Runcam Split
RX: FrSky XSR

As I wanted to get this built before the winter comes, I used some of my VIP5 coupons at Banggood to make sure that everything arrived swiftly and sure enough, I had everything ready to start the build this Friday just gone.



Most of my Friday evening was spent dry fitting things to make sure I knew where everything would go. There was also a fair amount of hunting for screws! The frame only had two M2x8 screws instead of eight, the M2x6 screws that came with the motors were 1mm too long and needed swapping for M2x5 and the screws that Runcam provide to attach the mounting bracket to the Split's camera have heads that are too large to fit into the recesses in the bracket. This would have made the bracket too wide to fit in the Japalura's camera cage, but thankfully I had some small headed M2x3 bolts in my parts box.

The flight controller I'm using is a real all-in-one and has an F4 MCU, Invensense MPU6000 IMU, SPI connected OSD, 1A 5V BEC, current sensor and most importantly, four 30A BLHeli_S ESCs. Unfortunately, there's no dataflash chip for black box logging and neither are there any free UARTs to connect an external one. Hopefully I'll be able to do without black box.

There's so much crammed onto the flight controller, that there are only two UARTs that you can connect to. One is taken up by the S.BUS connection and the other UART is not inverted. I could see that if I wanted to use SmartPort telemetry on my XSR that I'd have to get the microscope out!

I stripped off the heatshrink from the XSR, removed the Picoblade socket, removed the current limiting resistor and smoothing capacitor for the CPPM output and wired the uninverted SmartPort signal to the now unused CPPM pin. Tricky work, but it allowed me to make the XSR thinner and connect four 30AWG silicone wires where the Picoblade socket used to be.



Pleased with my work so far, it was time to get the motor cables protected, get some blue thread lock dispensed and mount the motors to the frame.



You can see the modified XSR down at the bottom left of the picture.

I'm very impressed with the Brother Hobby motors! The strength of the magnets is very obvious when you turn the motor bell by hand. It's really notchy and requires a surprising amount of force to get the motor to turn. I'm starting to understand how these tiny little motors can deliver 750g of thrust on a 4045 propeller on 4S. Other nice things about these motors is the long silicone insulated phase leads and the really smart way that they exit the base of the motor. The overriding impression is one of quality.

Time to get the first layer connected up!



The motor wires go under the flight controller, as does the XSR receiver. Getting the wires connected from underneath was fiddly to put it mildly, but more than worth the effort. I've mounted the XSR antennas on zip ties from the rear arms in the now classic pattern.

So far, so good!

Now it's time to add a Schottky diode to the Runcam Split's power cable, get it connected to the Matek VTX and get the various wires connected to the flight controller.

More to come...
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#2
I shouldn't have wasted my time looking for replacement screws for the Split's camera mount. It doesn't fit the mounting pattern on the Japalura!

Currently waiting for my 3D printer to finish some mounts that will fit...

No chance of a maiden flight today. It's already pitch black here. Sad
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#3
Nice start. I said I will likely not do a build log, but I inspired and will document and post.
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#4
There's a bit of delay on finishing mine, mainly because I have a 39 degree fever and feel like a bag of ice, despite being fully clothed under thick blankets. I'm sure once the paracetamol I just took kicks in I'll feel like I'm sitting in a sauna! Sad
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#5
I hope that you're treating the source of the fever as well as the symptoms. Fever like that is pretty miserable....hope you feel better soon.
"Damn the torpedoes!!!  Full speed ahead!!!"
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#6
(19-Sep-2017, 10:10 PM)sirdude Wrote: I hope that you're treating the source of the fever as well as the symptoms.  Fever like that is pretty miserable....hope you feel better soon.

I wish I knew what the source of it was! All I have is moderate fever, exhaustion and painful joints. Normally I'd suspect I had the flu, but I'm not blocked up, coughing or anything like that.
If it gets really miserable, I have some very strong prescription pain killers. Then I just won't care! Smile
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#7
(19-Sep-2017, 10:43 PM)unseen Wrote: I wish I knew what the source of it was! All I have is moderate fever, exhaustion and painful joints. Normally I'd suspect I had the flu, but I'm not blocked up, coughing or anything like that.
If it gets really miserable, I have some very strong prescription pain killers. Then I just won't care! Smile

Better living through Chemistry!  Big Grin
"Damn the torpedoes!!!  Full speed ahead!!!"
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#8
Clean build, nice one!

How are you going to power the split?
I connected one to my Betaflight F3, functions fine untill suddenly the FPV image gets choppy.
It seems that the BFF3 5v power supply is not up for the job. -> They advertise 3A but everything points out to that not being realistic
Seeing your FC rated for 5V 1A output I'm hoping your will not have the same issues.
Check out my videos @ http://www.youtube.com/Marcelfint and let me know what you think!
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#9
(21-Sep-2017, 07:29 AM)Fint Wrote: Clean build, nice one!

How are you going to power the split?
I connected one to my Betaflight F3, functions fine untill suddenly the FPV image gets choppy.
It seems that the BFF3 5v power supply is not up for the job. -> They advertise 3A but everything points out to that not being realistic
Seeing your FC rated for 5V 1A output I'm hoping your will not have the same issues.

Thanks! I've finished the build now, so after I answer your question, I'll finish documenting it.

The 3A rating on the BFF3 is unrealistic. There's a diode in series with the output of the regulator that has a maximum forward current of 1A and that's what actually determines the limit of the regulator. If you're powering anything else off the BFF3's regulator, adding the Split will certainly overheat the diode and cause the effects you noticed.

Mine is powered off the 1A regulator on the Matek VTX-HV and it powers the Split just fine.
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#10
So, having recovered at least partly from whatever nasty virus knocked me off my feet earlier this week, I got back to the build!

Having got the flight controller and receiver installed and wired up, it was time to start fitting everything else. The first discovery was that the Split's camera mount didn't match the holes in the side plates on the Japalura. Thankfully, someone had been there before and had already published their solution on Thingiverse



With that problem solved, it was time to start getting things connected:



In the picture, you can see my modified power/video cable for the Split. I've added a 1N5819 Schottky diode in series on the +5V line to prevent the Split's control board from feeding power back when the USB is connected. The power input to the Split will be from the Matek VTX-HV as that has a 1A 5V regulator that will only be powering the Split.

I've also added a beeper and added a cable to connect from the LED strip output on the flight controller to the Matek VTX-HV's control input. (The blue/black pair going off to the top left.) As there is only one free UART on the flight controller and I'm using that for SmartPort, the idea is to re-map the LED strip pin as a software serial port. The white wire from the Split is the audio output that will go to the VTX.

Finally, everything is connected!



Sorry for the misleading photo - the camera should, of course, be on the left!

In the end, there's actually plenty of room inside the Japalura for all the parts. Here's a few more pictures of the finished result:



Black 4045 props to keep with the black and silver theme. (I know, I should have bought a Split with a black camera.)



The VTX is held in place with one zip tie just above the Split's PCB and has plenty of space around it for cooling.



I also made a last minute decision to swap the bulky XT60 power connector for an XT30. As the maximum current I expect on a punch out is no more than 60A, the XT30 is a much better match and is quite happy to pass 60A for a short time. I used a tie wrap to secure the power leads to the frame for strain relief in a crash and to make the flight controller's USB connector easily accessible.

Without battery, the build comes in at 215g.

All in all, it was a fairly easy build. The combined flight controller and 4-in-1 ESC really helped as it kept the combined stack with the Runcam Split the same size as a more conventional 4-in-1 ESC and flight controller. 

I think the finished result looks just great!

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#11
I agree!!  Thumbs Up
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#12
Great write-up Unseen. I'm interested to see how much the props show in the video. Is that the stock lens?
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#13
I just saw a video by Onigiri with the split on a 4" Japalura, I couldn't see any props in shot, not sure if it was the long or standard lens, but it does seem to fly very nicely. Cant wait to see how it goes for you unseen...
Windless fields and smokeless builds
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#14
(22-Sep-2017, 11:44 PM)RENOV8R Wrote: Great write-up Unseen.  I'm interested to see how much the props show in the video.  Is that the stock lens?

Thanks!

No, that's the RC25G 'long' lens.

I managed a quick test just after I'd finished and at the minimal camera angle that you can see in the pictures, the props are visible in the HD video. 

The 500mA/h 4S Turnigy Graphene battery that I tested with isn't really up to the job. I was supposed to be receiving some Tattu 850mA/h 4S 75C batteries yesterday, but was thwarted by the Swedish post. They managed to deliver the notification slip saying I had a parcel to collect, but failed to deliver the parcel itself to my local post agent. Rolleyes

The smaller batteries will do at a pinch and I have one older Turnigy Nanotech 850mA/h battery that might withstand a punch out a bit better, but I'm waiting on the weather before I can do any more testing. Right now it's decidedly grey, damp and misty outside and a rather chilly 13°C.
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#15
Looks awesome unseen! great build log too.

Sympathy for you for battery problems :p lol

I'd love to see video if you get a chance to share Smile
carl.vegas
Current Quads: Operational: Diatone GT2 200 In need of repair: Bumble Bee, tehStein,  Slightly modified Vortex 250 
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