Merica 3

By WISCAL on Mar 13, 2018

16  737  6

My First Build
FPV caught my eye in November of 2017 and while I've had a few quads this is my first build.

Frame: Catalyst Machine Works - Merica 3"
Already having a 2.5" Torrent 110 and a 5" RMR Stretch Reaper I decided I wanted to build something to complement my developing quiver. I have yet to race but am planning to do so down the road so I wanted something that would hold its own at the track. I also wanted something durable with replaceable, affordable, arms as I'm rather new and crashing usually means damage. The Catalyst Machine Works Merica 3" seemed to have what I wanted along with a solid reputation for great products. Sold!

ESC/FC/Motors/Props
The time I spent reading reviews and watching flights for frames paled in comparison to what time I dedicated to shopping for the right ESC, FC, motors and props. While it's very exciting to be involved with such a new and growing hobby the downside is that there's a lot out there and not enough time has passed to weed out the mediocre from the exceptional. As a result every pilot has their own experience and own opinions with lots and lots of different products. Beyond discussions of actual product quality and fitment I regularly encountered political slants towards software developers and companies as a whole. Eventually I just picked someone I hoped I could trust and let them guide me. I'm sure many options would have sufficed and possibly for a lot cheaper when considering my novice level and general inability to note any real differences. This setup sure seems to rip so I'm happy.

Camera/VTX
While I was considering the RunCam Micro Eagle I ended up going with the more affordable RunCam Micro Swift 2. There is a huge following for the Micro Swift 2 and it seems that I really couldn't go wrong with that choice while saving a couple bucks. For the VTX I found a lot of positive reviews on the Eachine VTX03 and for the price it seemed like a great choice. One thing I did want was audio fed to my earbuds but only realized too late that while ordering the ATX03 (VTX03 plus audio) was the right move I needed to have a camera with mic or a separate mic altogether to get that perk. Oh well - not replacing my camera and not looking to add a mic.

RX
My original drone, the Torrent 110 bnf, was purchased with a Spektrum DX6E. A few months in and I wish I had a Taranis but I'm not about to change just yet. Eventually when I get into long range, which I hope to sooner than later, I'll get something that can easily hook up with TBS Crossfire. So I'm dealing with Spektrum for now. They have a rx with telemetry and one without. I went with the cheaper as the FC will feed data to my OSD and I don't really need the telemetry.

Other
Got some great LEDs from TinyTys that wire directly to the battery pads which is very straight forward.
Weighs in at 177g w/out battery, 266g auw.

Merica Lessons Learned

  • You can assemble this frame with the rear arms at the same height as the front arms or offset above depending on placement of spacers. I went with the raised rear arms.
  • I specifically chose this frame for the removable arms as I'm new to the hobby and crash rather often. While that's a perk down the road it definitely made for a challenging build. This frame is rather intricate with so many parts that don't like to stay in place. The assembly guide has numerous steps placing and removing screws along the way just to keep things somewhat in order.
  • Everything fits but it's rather snug. That was to be expected but it still made for some work in tiny spaces.
  • Use a 4-in-1 ESC
  • It's likely not a very big deal but the canopy has two antenna mounts that point at each other. That doesn't seem to be too beneficial for my diversity rx so I heated the straws and bent them out from each other closer to 90degrees.

General Lessons Learned

  • Spektrum makes two receivers for quads that operate on different voltages. I removed the telemetry rx when it refused to bind and installed a new rx sans telemetry (cheaper). Unfortunately the former runs off 4.8-7.4V and the latter off 3.3V. Well when the 3.3V rx was hooked up to the pads I was using for the other rx I got to experience my first smoke show. Dead rx.
  • It's a good idea to have someone check your plans prior to soldering. Fortunately due to my novice status I wanted eyes on my wiring diagram and received some helpful feedback. Had I gone the original route I would not have been able to get OSD data to my VTX.
  • Standard ESCs are not happening on this 3"! My original parts order included 4x Spedix ESCs for the arms but upon assembly I realized there was no room. This build is intended for a 4-in-1 but I guess I missed that somewhere along the way.
  • I chose the ATX03 opposed to the VTX03 because I wanted audio. I only found out later when I was getting my wiring diagram reviewed that the camera I have does not have a mic. I'd need a separate mic if I wanted sound. I opted out but now I know for next time.
  • Don't leave a part behind on the bench! When I was finally done with assembly and began to admire my work I noticed the buzzer sitting all alone on the bench. My joy faded immediately as I realized I was going to have to fully take it apart to access the appropriate pads on the FC.
  • u.fl connectors are as delicate as I've been warned. While consciously being very careful popping off the stock antenna I pulled the connector off the ATX03 along with one of the pads.
  • Don't expect all advice to be good! I was told to put a bloop of solder on the u.fl connector on my vtx to stabilize the connection. When I went to swap antennas I wet the solder and it seeped into the connection killing the vtx. While that may actually be good advice and I just executed it poorly I'm going to stick with hot glue going forward.
  • Apparently the Spektrum Telemetry RX is mislabeled on its plastic wrapping. The part states on it that it uses 4-8.4V. I learned from TinyTY that the true voltage is 4.8-7.4V. Good to know for future builds.

Casualties

  • dys 4-in-1 30A ESC: There is a vertical black pin connector on the top of the board that was interfering with the way the layers of the Merica frame stack. I was told the piece will pop right off and then the pins can be cut. Yes it popped off, but the pins came off with a few of the pads. When I was configuring the build later on I was only getting 3 of the 4 motors to show up in BLHeli. Whether that was a pre-existing issue or a result of my mod I'm not sure but either way there is no warranty on the board now.
  • Two Eachine ATX03s: Ripped the connector and pad off number one. Seeped solder into the connection of number 2.
  • 4 Spedx ESCs: Well not really a casualty but money spent that didn't need to be. I'll get use out of them eventually.

Photos

Part List

Frame

Merica (3 to 3.5 inch) - no canopy (4 builds)
Catalystmachineworks.com
$45.99

Flight Controller

DYS F4 Pro V2 Flight Controller (11 builds)
Fpvheadquarters.com
$38.20

ESCs

DYS F30 4 in 1 ESC - 30amp (2 builds)
Fpvheadquarters.com
$44.99

Motors

4 x BrotherHobby T1 1407 3600kv Brushless Motor (162 builds)
Fpvheadquarters.com
$63.96

Propellers

HQProp 3x4x3 V1S Propellers
Fpvheadquarters.com
$2.99

FPV Camera

Runcam Micro Swift 2 Camera 2.1mm or 2.3mm Lens - Orange (229 builds)
Racedayquads.com
$26.99

FPV Transmitter

Eachine ATX 03 Video Transmitter - 25/50/200mw (VTX03 with Audio) (21 builds)
Racedayquads.com
$13.99

Antenna

RDQ U.FL Dipole Antenna - U.FL to Dipole (24 builds)
Racedayquads.com
$2.99

Receiver

Spektrum DSMX Quad Race Receiver with Diversity (116 builds)
Amazon.com
$24.99

Batteries

CNHL 850mAh 3S 70C MiniStar 11.1V Li-Po Battery - XT60
Racedayquads.com
$13.39

Misc Parts

Spare Arm 3.5mm (Merica 3 Inch)
Catalystmachineworks.com
$3.50

Misc Parts

3-6s Tiny LEDs (13 builds)
Tinysleds.com
$2.00

Misc Parts

Merica Canopy (Mayday FPV - TPU) (4 builds)
Catalystmachineworks.com
$16.99
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Discussion

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leigerreign   Mar 14, 2018  
1

Hey! I'm building this exact quad right now! Your example came out very nice. I definitely recommend picking up a 4S battery for this beast!

WISCAL   Mar 14, 2018 

I think you have the right idea! The 3S is actually feeling a bit overburdened.

leigerreign   Mar 14, 2018 
1

I run the Lumenier 850mah high voltage 4S on mine. Though I admit it's a little heavy for a 3 inch. I've been tempted to try the Tattu 650mah 4S. You need really good batteries for demanding props on high performance 1407 motors.

Oh, and just looking at your build a little closer, I can't tell if your XT30 is strain relieved. I really recommend zip tying it to an arm.

I'd also recommend adding a capacitor to your build. A 470uf would be fine.

My Merica 3" isn't posted yet but I'll take some pics this weekend and get it up here.

All the best!

WISCAL   Mar 15, 2018 

Good eye. No strain relief in these pics. On there now. I'm holding off on the cap for now to see how much this setup will need it. Avoiding it if possible.
Looking forward to your post!

The Van   Mar 15, 2018  
1

Excellent writeup, and very nice first build! Way to go man.

7uvoK   Mar 13, 2018  
1

Nice build and nice discussion about your process!

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