Evolution into Simple-X 2.5" 2s full featured micro-quad.

By saahbs on Sep 30, 2020

5  286  0

I've been flying RC-everything for 25 years. Six years ago, after flying 450-size (3s2200) LOS quads and DW-Tricopter, I decided to try FPV micro-quads. I got a cheap Eachine Aurora100. The bottom plate was weak, Vtx antenna was crap and the stock tune was garbage - I hated working on it, as everything was tiny and not readily accessible. I put it on a shelf three years ago, but during the lockdown started flying it again. This is the story of evolving it into an awesome micro quad.

I'm thrifty, so I got an Eachine Lizard95 true-X frame and moved all electronics into it. Switching to Hulky 2040 3-blades also helped a lot, as 1104 motors were over-propped by the four-blade RacerStars. It flew much better, but with no longer supported F3 controller, I was unsuccessful in curing it of FOD (flip of death).

Next upgrade was swapping the FC to Lumenier Micro Lux V2 (20mm) - a quality F4 board with onboard blackbox flash. Tuning was easy and I got it flying like on rails, super stable and smooth at WOT and fun to freestyle. With micro lipo buzzer and RDQ 2s650 the weight was 118g and 5min of fast acro flight. It wasn't perfect, the Eachine non-diversity D8 receiver had limited range and 25mW Vtx wasn't ideal, while the camera was crap.

Lizard95 video: http://www.saahbs.net/videos/lizard95-proximity.html

As soon as I was enjoying the Lizard95, Eachine 4-in-1 ESC blew up! That was it - out with Eachine! - what a waste of time! I bought a blheli32 iFlight SucceedX 4-in-1 ESC (still 20mm), QAV PIKO3" frame, RunCam Racer Nano2, Eachine (I know) Nano Vtx V2 and Jumper R1F receiver. The Piko frame came with horrible "top-hat" (the topmost stack component holding the camera). I ended up designing a minimalist, wiring outside (for ease of servicing), high strength interlocking (camera body is load carrying) replacement 20mm stack top-hat. It has a functional shark-fin, provides protection and cooling to Vtx, protects camera, while holding Rx and Lipo-buzzer securely. It also has mouting lugs for zip-tie antenna masts and due to lug location prevents antenna pinching in crashes. It weights 2g less than the QAV top-hat and is highly functional - in a Mad-Max post-apocalyptic style :) Since this is a 20x20 build and I wanted to use 3mm nylon bolts, I couldn't find spacers that would work. I ended up designing and 3d printing my own asymetrical 3mm, 4mm and 5mm high spacers.

I wired in camera-control, IRC Tramp Vtx control, have telemetry, have in flight mic (awesome to detect impending failures), finally good Rx range and more Vtx range than I know what to do with :) The Piko3 build came out to 128g with the same RDQ 2s650. It flew very well, but I really felt those extra 8g and lost 30sec of flight time. Around that time I discovered RotorBuilds and started searching for a lighter base plate. Simple-X 110mm @2.5mm thick was it. I got the weight down to 120g!!

Hint: for a very lightweight battery mounting, choose frames with integrated rubber band lugs, use two small pieces of ummagrip and four "rainbow looms" rubber bands - this has less than half the weight of light rubberized velcro loop and is just as secure.

That frame is big enough for 2.5" props, but as I'm still running Eachine 1104 motors (7500kv). The only 2.5" props that work well are 2-bladers, giving me 6min of fast acro flight. I tested a few more 2" props, but Hulky 2040 3-blade continued to be the best all-around prop for speed, freestyle, handling in turns and enough efficiency for 5min flights. I run my batteries to 3.7V cell resting voltage.

I think I'm done with this quad - I'll now fly the snot out of it, while using lessons learned on it to build a 3" 25mm whoop-style AIO board successor with onboard HD recording. I'm using the same RDQ 2s650 packs (they are tanks, no sag and very inexpensive) as a fixed design constraint for comparing performance and tradeoffs. For me a 2-3" 2s is a sweet spot for safe flying in nearby parks, using cheap batteries with very good performance if components are selected and tuned correctly.


  • empty weight: 78g
  • RDQ 2s650 ($7.25 battery) AUW: 120g
    • 5min with Hulky 2040 3-blade
    • 6min with HQprops 2.5x1.5 2-blade
  • Crazypony 2s650 HV ($11 battery) AUW: 104g
    • 4min with Hulky 2040 3-blade
  • 400mW Vtx with PIT mode
  • D16 diversity Rx
  • Lipo Buzzer (saved the quad twice after crash lipo ejections)

Thanks! saahbs


Part List


Simple X-110 FPV Drone Frame (4 builds)

Flight Controller

Lumenier MICRO LUX V2 - F4 Flight Controller + OSD (20 builds)


iFlight SucceX Mini 40A 2-6s ESC 32bit BLHeli_32 4-in-1 ESC with Telemetry Pad Built in Current Sensor DSHOT1200 for FPV Racing (3 builds)


4 x Eachine 1104 7500KV 2S Brushless Motor For Eachine Aurora 90 100 RC Drone FPV Racing Multi Rotor (2 builds)


Gemfan Hulkie Clear 2040 Durable 3 Blade - Set of 8 (4CW, 4CCW) (5 builds)

FPV Camera

RunCam Racer Nano 2 1000TVL 16:9/4:3 NTSC/PAL CMOS FPV Camera (1.8 or 2.1mm) - Orange (20 builds)

FPV Transmitter

Eachine NANO V2 VTX 5.8GHz 25/100/200/400mW Switchable


Lumenier Micro AXII 5.8GHz U.FL FPV Antenna - Choose Your PolarizationLHCP (59 builds)


Jumper R1F F-Port Receiver


RDQ Series 7.4V 2S 650mAh 70C LiPo Micro Battery - XT30 (2 builds)


Jumper T16 Pro V2 Hall Gimbal OpenTX Type-C Charge Multi-Protocol RadioTransmitter (15 builds)


EV800D 5.8GHz 40CH Diversity FPV Goggles with DVRDefault Title (20 builds)

Misc Parts

FullSpeed Lucky Box Beeper Buzzer 90dB 5V Built-in Battery for RC Drone FPV Racing (24 builds)

Battery Charger

2 x ToolkitRC M8S 400W 18A Charger, Cell Checker, Servo Tester, Signal Tester (8 builds)
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