OK, so lockdown ain't allowing for much full size rippage so I have been working on some micro builds.    I've always liked the frames by GnarlyFPV as the canopy design into the frame is pretty unique and of a high quality.   The small builds can be tricky to tune but now I'm using 4.2.x with no issues.  A lot of micro builds would still favor BF 3.5.7 due to its flight performance for this size class.   BF 4.0 was a nightmare to tune on micros but now it's a lot better.

Here's the end result before I get into the build...   It's a sweet, tight build...  




Starting the the parts list...

• JHEMCU F4 FC - JHEMCU SH50A F4 OSD 2-3S AIO FC - This is a new version of the old school purple whoop FC they make.  Unlike the beefy whoop/toothpick FCs this one is light.
  
• RCINPOWER - 1204 5000kV motors
  
• TBS Unify32 Nano VTX
  
• R-XSR receiver.
  
• CADDX ANT FPV camera, 16:9 PAL version.
  
• No-name micro AXII vtx antenna
  
• Gnarly FPV PRIMO frame - https://gnarlyfpv.com/collections/best-s...ucts/primo
  
• 65mm HPPROPS t-mount
  

With whoop FCs and toothpick style quads, you need to get the motor wiring right the first time.  Mounting the wires is not only tricky but thought needs to be given to the layout to ensure they are stable, not in the way of getting caught on anything mid flight and not under any stress of force.

I wire the motor cables facing inwards and them loop them back out.  I force the bend in the wire manually with pressure so the solder joints aren't pulled on when doing this.   The length of the motor wires is checked beforehand.  In this case the motors were coming from another micro build that had seen better days and one of the cable sets was too short.  You can see the extension of wires in the pic below.



Now the next part comes together with a few other items at the same time.  The filtering cap is placed on the FC board direct to the power solder pads.  I've done this for two reasons. 1) I don't want the cap on the end of the xt30 connector, at such a small size of a quad I reckon that the cap on the xt30 would influence the quads flying characteristics as it is a rather large in comparison to the small quad.   2) there is talk around the net that on high-S builds for toothpick style quads the cap has a greater effect when placed directly at the power solder pads.

Fitting the FC to the frame is easy with two m2 screws and some whoop gummies.  At the same time the motor wires are twisted to make them neat and take up any extra slack in the length.   The battery strap is inserted too as this time as it can't be moved once the FC has been secured to the frame.

Starting to look the part....



At this point it is time to plug power in and test the motors in BF.   Flash BF to 4.2.2 and flash the BL_HELI_S esc to 16.73 of the JM firmware for RPM filtering.  DSHOT set to 300 and magnet pole set to 12 (smaller motors are usually 12 magnets).  Tested motors for RPM errors and all good.  I like to run props-out so I setup BF with prop direction reversed and review the motor direction in BLHELI configurator to ensure they are all spinning in the correct direction.

The battery cable is secured to the rear left arm and power cap.  Just to make sure!  There is very little clearance between the top of the battery cable and propeller. 



Next is the receiver and VTX.  The R-XSR has the JST connector removed for space and heatshrinked for electrical isolation.  I cut out some heatshrink for the bind button.  The R-XSR is from another build and missing an antenna.  No biggie, this quad ain't even a park flyer so range is not really an issue.   The Unify nano vtx is also heatshrinked for safety with the U.FL connector exposed to allow a connection to the vtx antenna once the canopy goes on.

In micros like these, hot glue is your friend.  It provides a solid yet non-permanent fastening to the FC.  It also holds things in place, raised above the electronics to help from accidental shorts.    I've stopped using double sided tape in these builds.  The glue also withstands bumps and crashes pretty well, keep things in place!

Here you can see the layout of the vtx and receiver.  The goal is to fit them in the diamond profile of the FC.  Keeping them to the centre line for canopy protection yet low enough that the camera can have a good range of angle movement.   Note the location of the U.FL connector for the vtx antenna.  



At this point I would connect the camera and spare vtx antenna to configure BF and test that everything is working OK.  Don't forget your vtx tables!

Now onto the vtx antenna.  Using a lighter to heat up the coax I can bend it to shape to a) fit the canopy profile b) have the U.FL connector rest in place as to where it will connect to the unify nano vtx.  This minimizes any stresses on the cable pushing/pulling against the U.FL connection.

Here' is a pic showing the path the vtx antenna coax takes to sit where the U.FL connection is located.



Now the canopy is installed.  The antenna cable is fed through the access hole in the canopy and antenna tube placed over it.  I've installed both antenna tubes for looks. :  CADDX Ant camera is also connected.




Comes in at a dry weight of 59grams, not too bad.



I'll post some video of ripping around the house soon!

Cheers,

ph2t.

Nice build man! I'm working on a micro myself and its also from Gnarleyfpv. I'm building the Guppy v3. I was looking at this frame as well. I like how you ran the wires. Smart man. Very clean build!

Here's a rip around the homestead. Was fun playing with the blackbox overlay graphics.

Nice build. Seems like a lot of motor for a 5amp esc.....let us know how it holds up. I'd like to use that board on a 85mm whoop / 2" prop build but am thinking it's a bit too close to the amp draw limit.

Nice toothpick! Good job on the dry weight. I am currently working on a toothpick myself but I don’t think I’ll manage to keep the dry weight under 60 grams. How
much is the AUW?

How many uF is that capacitor? I have a 200 uF capacitor that came with the fc but I’m thinking I maybe should get a larger one.

(17-Sep-2020, 07:29 AM)ph2t Wrote: Here's a rip around the homestead. Was fun playing with the blackbox overlay graphics.

Nice little ripper....neat tight build. How do you add the Blackbox overlay to your video?

Nice build and great detail with the build log.

Deal

Thanks everyone!    Appreciate the comments.

Jasper I used Oscar's tutorial to get the sticks graphic on the video: https://oscarliang.com/overlay-blackbox-...fpv-video/ . I used premiere pro to overlay it onto the DVR video, move it around and crop other stuff out.   I like the animated throttle on punchouts, lol, looks cool.

The current sensor isn't 100% accurate but most flights I max out at 14-15A drain.  Given the FC is apparently rated for 20A(4x5A) and 28A peak I'm hoping it will survive the long run.  The motors are slightly warm.  I agree they are beefy for this class but I just find going out (12xx) versus going up (11xx) on motor stators these micro fellas perform better..

3S 300mAh GNB stick pack is what I'm running, all up weight of 84 grams.

The cap is 470uF 10V.  Yes it's underrated on the voltage but was the smallest capacity versus size cap I had on hand.  The quality of the vtx helps - I'm really happy with the video quality.  Noise is non existent.  Being so close to a telemetry receiver like the R-XSR I expected some lines/banding in the video feed.  Happy to not have anything like that.

Cheers,

ph2t.

(18-Sep-2020, 03:42 AM)ph2t Wrote: The current sensor isn't 100% accurate but most flights I max out at 14-15A drain.  Given the FC is apparently rated for 20A(4x5A) and 28A peak I'm hoping it will survive the long run.  The motors are slightly warm.  I agree they are beefy for this class but I just find going out (12xx) versus going up (11xx) on motor stators these micro fellas perform better..

I run the same motors on my 4s build with 3 inch 3-blade props and a 25A 4-in-1 ESC and never had any problems. I think you'll be fine.

Happy flying!

Thanks for the tip on the video.

I have a Primo too but on 2S with the puny 1102 motors and HM AIO Camera 25mw VTX. It buzzes like a bee with the flexible biblade. You managed to cramp a lot goodies into the small space and neat too. Skills.

Thanks guys. Jasper I found that 2s needs a fairly high kv. Also the batts are pretty heavy even at 450mah 2s packs. I’m also building a GnarlyFPV meemo which is a 2inch only quad and I have some 6000kv 1202 motors on that. I think the 8900kv or even 10000kv in that 1202 size will be the sweet spot for 2s on two inch props.

Just found this thread.  

NICE BUILD.