40 min+ Mini Quad Flight Time! - Build

My name is Vaidotas, I am originally from Lithuania but I am currently living in Norway. I was hooked on RC hobby 1,5 years ago and I like it very much. 

I love mini quadcopters - they are very mobile and portable, you can take them when you hiking or climbing mountains, they can go through tight spots and if you race in a forest it feels like you are in one of the Star Wars movies, BUT the battery does not last a long time… That was quite annoying for me for a while so half a year ago I started THE project. Project goal was to have long flight time but still use robust frame and not think much about crashes, use shelf products and make it from reasonably priced parts.

So I started with a balsa frame and a couple of 1806 2280KV motors from Ebay, 12A Emax ESC and ncr18650b batteries. It did fly but it was more or less ground effect and it was quite a disappointment. It did fly well on 3000mah 2s RC battery (did 20min) but balsa is not for quadcopters.

Previous Attempts

For the second attempt I made a frame from 8x6 carbon fiber square tubes and used rctimer 1806 1450kv motors. It did fly quite well on ncr18650b’s but it handled crashes quite badly. After one flip on the ground I destroyed it, but the search still continued.

For my third attempt I bought a frame from Ebay and switched to even better batteries – ncr18650GA

(Thanks Panasonic!) 

My Eventual Solution

And finally this setup did the job very well. I had enough power for reasonable speed and climb rate and of course long long flight times on robust mini frame. 

For this build the parts and right combo are THE key. Final setup and links to where I bought it:

RCTimer 1806 1450kv Motor 

Carbon fiber 7024 T-Style Propeller 

Favourite Sky 3 Quattro 4 x 6A Brushless Quadcopter ESC  

N32+ Flight Controller

Frame  

Battery 

TX/RC 

Without battery, the quadcopter weighs ~175g (3s 3450mah battery - additional 165g).
I used a battery box to protect my batteries but it weighs like 23g!!! 

So I will get rid of it in future. As a build goes it is very easy. All you need to do is use one bottom plate of a frame and screw two bolts per leg. I also kept the metal bolt on from the original frame set instead of a plastic one per leg so if a crash happens (oh it will happen) it will bend and absorb more of the impact.

Next is to get rid of plastic boxes, just get rid of those! and glue everyhing on the frame: ESC on top, FC in the middle and receiver on lower part. Keep wires short by cutting them and soldering. I still used a receiver socket since I plan to use this receiver for different purposes. 

 Also I had to use some spacers to fit 7” propellers that obviously cost some minutes on efficiency.

Few things to keep in mind when repeating this type of project:
1) Spend time on planning and calculations. Robust long time flying quadcopter require juggling between weight and power. Test your motors and batteries on load because 18650 batteries have quite huge voltage drop. In general try to keep your frame 70-100g. range and make sure you can support 7 inch props and use components above and you will also be flying 40min.

2) Use quality parts and materials. If I would start this again I would skip balsa and ebay motors, that was a huge mistake that I regret now. Use carbon fiber propellers, they are more expensive but not as much but they cut air very nicely and are very light.

3) Never give up! Not always things go as planned, to achieve wanted result sometimes you might need to build more than one prototype but at the end you will be happy and smiling. Biggest smiles require biggest effort.

I am quite happy with the results and I wish to inspire you to do it better and have better flight times and more fun! 

My 40+min hover test: