Getting started with 18650 Li-Ion batteries

18650 Lithium-Ion batteries are the workhorse of modern consumer (and not only consumer) technology. If you have anything that is battery operated and there is a "Li-Ion" mark anywhere on it, probably it is powered by 18650 Li-Ion battery. Laptop batteries, cordless drills, cordless tools, e-cigarettes. All of them (probably) have 18650 cells inside.

In this video, I will just go with the basics of 18650 cells. Dimensions, protected / not protected difference, weight and so on. Expect more in the future!

My Reptile S800 Sky Shadow flying wing

I am fully aware that Reptile S800 Sky Shadow EPP flying wing is not a fresh topic. It is on the market for much more than a year and the internet is full of reviews. So it will not be a review. I will only say that I like S800 very much. Much much, much better than ZOHD Nano Talon 😉


  • Flight controller: Matek F405 Wing, the best INAV compatible flight controller for fixed-wing airplanes. Period
  • Motor: T-Motor F80 1900KV – it' an oversized mini quad motor. With 2408 it's slightly too big for drone racers but provides a shitload of trust and torque for small airplanes. Oh yeah, it's rated for 1000W 😉
  • Propeller: APC 6×4 clone. Combined with the T-Motor F80 1900KV it's enough for 120km/h flight. Too bad one has to cut foam on S800 to fit 7-inch props
  • ESC: Racestar 35A Tattoo – just works
  • Video transmitter: TBS Unify Pro HV
  • FPV camera: RunCam PZ0420M
  • Radio system: FrSky R9 Slim receiver with EU LBT firmware and FrSky R9M TX module. With the latest firmware, this thing finally works, but it's kind of far from perfect…
  • Power is provided by 4S mini quad LiPo battery. I had to replace the main compartment cover with 3D printed one and cut some foam to fit it. I like to keep my batteries unified so I can swap them between airplanes and drones

iFlight XL7 v2 7-inch endurance quadcopter

7-inch drones are "special". They are not as smooth as 5 inchers but they shine in terms of range. Cruising speed of 50km/h, 8 minutes of flight and it easily can fly a distance of 5 kilometers before the battery runs dry. I never really flew it that far, but it should be doable with the equipment I have over there.

What I'm showing over here is based on iFlight XL7 v2 carbon drone frame with some "special" motors. But everything else is almost like in a normal racing FPV drone.

How to use INAV Autotune

Autotune (or Auto Tune) that is present in INAV for quite a long time is a working solution for tuning PID (or rather PIFF) controller used by INAV on fixed wings (all airplanes, flying wings). Not like all the attempts designed for multirotors, this one actually works.

INAV Autotune can be used on any airplane and is fairly simple to use as long as you follow a few simple steps:

What is Betaflight 3.5 Feedforward and how to use it

Betaflight 3.5 is just around a corner and it brings new cool things. There is no more Dterm setpoint weight and Dterm setpoint transition (relaxation ratio). They all were replaced by easier to understand Derivative and Feedforward (Feed Forward when you refer to the control theory tho).

Betaflight Derivative and Feedforward parameters are the new way of controlling "damping force" of the Dterm and responsiveness of a drone. The more Derivative gain you set, the more "damped", "delicate" and "swooshy" drone will be. The more Feedforward gain you apply, the more responsible to the sticks it will be. It's almost the same as with Dterm setpoint weight, but in my opinion, made simpler and can be set separately for each axis.

ZOHD Nano Talon V-tail airplane review

Let's cut to the chase: my final review of ZOHD Nano Talon is: this airplane is crap. Just like that. Period. It might be good looking, it might be spacious inside and quite well thought through but it lacks one thing: it does not want to fly well. As simple as that.

As long as air is calm and there is no wind it's kind of OK. You can even have some fun with it. Yaw still sucks, a roll is strange but it's OK. But as soon as wind appears and Nano Talon has to fly through the disturbed air, it is over. This thing just does not wants to fly straight. Always tipped to one side, unresponsible and wobbly. Nope nope nope…

How to connect HC-SR04 to any flight controller (INAV, Betaflight, Pixhawk too)

I’ve been asked to cover this topic multiple times. So, welcome to part one: how to connect HC-SR04 sonar rangefinder to INAV and any flight controller? The answer is simple: don’t. HC-SR04 sonar is absolutely not suited to work on a drone! It picks noise instead of ground echo and above a certain altitude (low altitude by the way) reports rubbish! From time to time it kind of work over concrete but immediately loose measurement capabilities over grass.