The 'Mayfly V2.0' Long Range sub 250g 4" Li-Ion 3S

By jeffcd on Sep 08, 2022

23  1,759  6

4" Long range sub 250g quadcopter with 1404 3800 KV motors.
This is version 2.0 of my first build.

My goal with the the frame was to make it as light as possible but also to improve the resonance issues I had with my V1 frame by adding some triangulation on the rear arms with the hope of making them stiffer. I also made some larger cutouts under the AOI to try and keep the weight down. Did it work? No. LOL. This frame still has some resonance peaks at 70 Hz on roll and 50 Hz on pitch, which made it really difficult to tune.
The bottom plate is 2.5mm thick and top plate is 1.5mm thick. With 20mm standoffs and screws it weighs in at 19.6g.

After experimenting with 2S and 3S on my V1 design, I realized that 3S is the way to go for longrange. So I designed for 3S 18650 Li-Ion battery specifically.
I also wanted to try INAV instead of Betaflight this time. I wanted to try the INAV waypoints mission feature so that I could program the quad to fly consistent laps around a park for battery testing. Unfortunately, this didn't go too well, because the frame osciallations were throwing the quad off course when navigating turns. But, I absolutely love INAV's true Return to Home function and Position Hold feature. The only catch is, you need to make sure you use a compass and you select a FC that is supported by INAV. Of course you also need the usual components for long distance missions, so it has a lost model buzzer/light, GPS & barometer.
To save additional weight I switched from the IRC Ghost Atto Duo RX to a regular Atto RX with reduced the number of antenna's.
I also switched from the IRC Tramp Nano VTX to a TBS Unify 5G8 V3 VTX which up'd my power output from 500mW to 800mW. TBH, that Tramp Nano is a really good VTX and it easily got me out to 11.1 km with my previous build.

I also used titanium screws throughout the frame for weight savings.

I made my own 3S pack with a small spot welder and nickel strips.
Credit goes to Roteron on the IntoFPV forum for the awesome idea to eliminate the balance lead to save weight and instead use a magnetically attached balance lead during charging.

I designed the frame using Fusion 360 and had it cut by CNC Madness.
Full build log here on intoFPV forum:

Here's a video from my longest ever flight (maybe a sub250g quadcopter record??). 15.1 km out (30+ km total distance) and 34 min flight time.



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ferocious_r   23 days ago  

Another source of vibrations will be that long antenna. I do realize it's probably necessary for such distances, just wanted to point it out. The battery mounting rubber has been mentioned by someone else. The third thing I'm sceptical of is the way you're trying to soft-mount the AIO. I'm sure you already know Chris Rosser's videos on that subject, but if not, you'll find them to be a very useful resource indeed!

Tibor   May 22, 2024  

Good day. Admirable. I would like to kindly ask you for the file for your frame.
Inav 7.1 has already solved frame removal and non-standard handling of the drone such as max. throttle in navigation modes. I also had problems with withdrawals. Try inav 7.1 and see for yourself that it works. Thank you very much in advance.

yingjiegao   Oct 21, 2022  

suggest 1207 motor 5000kv about the same weight ; but it flys better; a little more responsive

airrage   Sep 10, 2022  

max flight time and distance?

glock   Sep 09, 2022  

Очень интересно следить за вами. Вы маньяк по облегчение коптера). Попробуй перевернуть моторы, это должно прибавить до 5-10% экономии. Жду новых сборок.

Jodie Froster   Sep 08, 2022  

I love that magnetic balance lead connector system!!!!!
Some of your vibrations could be from that heavy battery/wimpy rubber band combo

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