Welcome to our S800 Group Build, Project Rosetta Stone. A project from the INAV Fixed Wing Group. You will be building a plane in conjunction with other members in the group at a controlled pace. You are free to ask questions as we go in the Facebook group. We will be building an S800, but you are welcome to substitute the S800 for a plane of your liking. A couple of months ago we published an agenda and suggested parts for you to order. Hopefully by now you have most/all your parts. If not, the first two weeks will focus on the flight controller build. Flight controllers can usually be found locally or from somewhere close by to get shipped to you fairly quickly.

Please note: In this first week of the S800 group build, we pack a lot of information about setting up your flight controller. We won’t be flying for another six weeks. So, take your time. You will not be securing your flight controller in our plane for a number of weeks. So please do not solder on any wires to your flight controller right now; it will change as you build your plane. For now, you’ll simply need to start understanding how the flight controller is wired.

Step 1: Find documentation

If you bought a Matek board there should be some documentation on their web site about the flight controller. For example, here’s the layout for the Matek F405-WSE. Here’s the layout for the Matek F405-Wing. It’s not important at this time that you understand everything that you are seeing. For now, just get yourself acquainted the board. The wire color coding is important. Though this looks a tad bit overwhelming now, you’ll soon be able to quickly browse these types of layouts and figure out, roughly, how to wire up the board. In the meantime. You will need to know what target to use for INAV. On Matek’s write up there is a term INAV Target. Matek is very detailed in their layouts and descriptions so finding documentation is important.

The flight controller with the least documentation is the Omnibus. Here’s what you can find for the F4 Pro V3.

IF you get stuck, you can ask questions in the group or find information online. And yet, this is the reason you’ll want good documentation for your first board because this can be a bit overwhelming.

Step 2: Download INAV Configurator

Please download a copy of the INAV Configurator from GitHub. They have it for Mac, Windows, and Linux. Make sure to download the right version for the computer system you’re using. But, if you experience any problems downloading or opening INAV Configurator please contact Leslie Yagin in the group. You will want the latest version of INAV Configurator. At the time of writing this 2.6.1 was out. But, INAV 3.0 was on the way. You should download the full program, not the Chrome extension.

Step 3: Attaching the flight controller to the computer

Flight controllers rarely arrive dead. Before you want to solder the flight controller let’s see if it’s working. Attach your flight controller to your computer using the appropriate USB cable. We highly suggest you do the following:

  1. Cold reboot your computer
  2. You’ll want to use the USB port on the back of your computer instead of a USB hub.

Caution: many cell phones cone with charging cables and not data cables. They look identical to each other and though your flight controller may light up, if it’s a charging cable it won’t be able to send or receive data.

Steps for attaching to your computer:

  1. Plug your cable into the flight controller in first
  2. Plug the other end of the cable into the computer.

If you hear a connecting sound, you’re off to a good start. This means your computers recognizes the flight controller

In the Configurator, the flight controller port should say anything but USB 1. Give it around 30 seconds find the flight controller. You should see the flight controller light up. But, you may have to use the pull-down menu if you don’t see the USB 1 change. Don’t be surprised if you don’t see it. We’ll help you sort this out next.

Problems you may experience

Problem 1. No lights at all

This is the worst sign of all, it means that your flight controller isn’t getting power from the USB port and could mean that your cable is bad or your flight controller is dead. Flight controllers rarely arrive dead. Try a different USB cable.

Problem 2. No USB connection sound, but you see lights

This may be a sign you’re using a charging cable. If you don’t own a USB data cable you may need place an order for one on Amazon, or somewhere that can ship to you quickly. It’s also worth getting a decent quality cable. Some cheaper cables don’t last long. Also, think about your fight controller and what it will be like inside the plane. Sometimes a 90 degree USB cable is really handy.

If you need to order a data cable, the vast majority are Micro USB. Up until a few years ago this was the most popular connector for Android phones and tablets. This has a D connector so orientation is important. Also treat it like it’s made out of fragile glass. These USB ports rip off of the flight controller fairly easily and the flight controller cannot be flashed again once the connector is missing.

USB Type C connectors are what are most commonly found on new devices. It’s an oval shape to the connector which means it can be plugged in with little regard to orientation. So far, these connectors are only found the very latest Matek boards.

When ordering a cable you want one that is fairly long, at least 6 feet (two meters). You will be plugging it into your plane and you may want some space between the plane and the computer.

Problem 3. You see lights, you hear sounds ,but the USB stays at USB 1

This is a fairly common problem, especially with Windows 10. You need some extra drivers. Oscar Laing did a pretty good write up how to fix this. The Impulse Driver Fixer he suggests is excellent. Please keep your eyes on what is going on in the group as others many have problems with this as well. We’ll get through this phase.

Flashing INAV onto your flight controller

If you really don’t want to have massive problems later on you will need to really double check your selection right now. If you’re using one of Matek’s boards go to their website and look for the term INAV Target. It will be on the page for the specific flight controller you’re using. Also, with some matek flight controllers, it’s even printed on them. So check underneath.

We get people who just assume they can figure out the right one and they instead pick the wrong one. When things don’t work later on they have start all over again. Don’t assume anything about which target to use, verify it on their website. The five minutes you spend looking for the answer now will save you untold hours of frustration.

If you can’t find the target

Click on the Connect button in the top right of the Configurator screen. Depending on the firmware on the flight controller, you may just be presented with a black page with a text box at the bottom. Don’t worry, this is exactly what we need. If you don’t have this. Look in the menu on the left, and right at the bottom you’ll see a CLI tab. Click that. Once you’re on the CLI page, type version in the text box and press enter. It will show something like:

# version # INAV/MATEKF405 2.6.1 Jan 21 2021 / 13:25:29 (03a5c1922) 

The MATEKF405 that you can see above is the target. Please note that if it says something other than INAV/ before the target, the INAV target may be called something slightly different.

Flashing INAV

Typically your flight controller has a boot button on it. You depress it while plugging in the flight controller into the computer and the USB port will change to the term “DFU.” If you buy a flight controller with INAV installed you can go into the configurator and go to the CLI tab and type DFU and sometimes that works. If it has BetaFlight on it and you’re familiar with BetaFlight you can try the same thing with the BetaFlight Configurator. If all else fails try the Impulse RC Driver Fixer. It’s excellent for sorting out problems.

You will need to select your flight controller’s target, then the version of INAV you wish to use; the most current stable one is what is suggested. If you are uncertain which one is the right one, try posting a message about it in our Facebook Group. You then select Load Firmware [Online]. Once loaded, click Flash Firmware and everything should start rolling. When it has finished successfully you will be notified. If you don’t finish successfully you perhaps selected the wrong firmware? Try again.

You may need to unplug your flight controller and close and reopen INAV configurator right after you flash your flight controller. Then select the correct port and connected.

After the firmware is on the flight controller, go into INAV configurator and look around. I go to the CLI tab first and type “Defaults.” This performs a complete wipe of any settings that may be still on the flight controller. Feel free to look around but we won’t be getting on to setting up the flight controller for a couple of weeks.

Step 4: Soldering your flight controller.

Soldering is a skill that you will need to develop. The one very crucial point is that the things we solder are getting smaller and smaller. The new Matek boards have resistors right up against the part where you solder on pins to the board. It’s very easy to splash solder onto crucial electronics and ruin your flight controller. You essentially have two directions you can go when soldering up a flight controller.

Using pins

The advantage to pins is that you can add and remove hardware when flight controller is in the plane. If the thought of soldering your flight controller inside your plane scares you a bit, this is the route to go. Often, the flight controller will come with pins. Matek sends the color coded ones

  • Red for Power
  • Black for Ground
  • White for Signal

On most flight controllers there are silk screen labels for the pins. This helps when you’re plugging in your connectors. Though you are free to solder only the pins you’ll need, it doesn’t take that much more time to solder the entire board. There are usually straight pins and right angle pins. Use the one that you like and that fit into your space. Straight pins tend to interfere with the lid going on your planes, so check for clearance. The right angle pins increase the footprint of your flight controller in your plane, also check for clearance. 

Direct solder

A number of old school quad pilots will tell you this is the only way to go. Less connections means less fail points. The idea behind this technique is to cover the pad (the hole) with solder and then tin your wires and solder them onto the pad.

Wire selection

The most common mistake people make is using wire that is too thick for the application. Typically soldering wire onto flight controllers means you’ll need wire between 22AWG to 30 AWG. You also really want to use silicone wire. I like the little seven color wire kits you can find online. I’d pick up 22AWG and 26AWG versions for now and perhaps 30 later on.

You’ll need to strip the wire, tin the wire, and then cut the part you stripped leaving just enough wire to cover the pad but not much more.


60/40 rosin core solder that is leaded tends to work best. I bought the cheap stuff out of China. It works, not that well however. It takes more heat to make the solder melt. The premium solder like Kester works better. It melts at lower temperatures. It’s around $25 a pound in the United States if not more. I’ve gone to buying up used inventory for around an 80% discount. Trust me, some of the stuff is 30 years old. But, it never really goes bad. You’ll need it in different thicknesses with the thinner solder (.5mm) good for soldering pins or wires on circuit boards.

There is a lot to solder, as in, you would be surprised to know about the breadth and variety of solders. Someone did a pretty good comparison online between solders. He examined around 30 different types of solder and found for the most part they all worked. Some better than others. But, that’s assuming a good iron, good tip and good technique.

I know this is a hobby where things start to add up fairly quickly. If I could talk you into buying a one pound roll of Kester or equivalent of half millimeter (.020 inch) solder and one around 1mm (.39) inches you’ll be pretty well set. The cheaper stuff from China doesn’t seem to melt well, which causes you to turn up the heat, and instead of melting better it runs away from the iron. When working on soldering pins I am between 300C to 320C.


Flux is your friend. Unlike solder, there really isn’t any bad flux per se. Some of it is harder to clean than others. They have 200 containers you can buy for a few dollars from China. It’s a paste, use toothpicks to apply it. There are better flux to buy, and they are usually cheap enough to experiment with. The rosin is often built into the solder, but it doesn’t matter, you’ll still want to apply a bit more.

Soldering Irons

When you bring up soldering irons you’ll get a lot of opinions where people will talk up their favorites. Some people buy an expensive Weller station and try to make it work with just that. Yes, they are nice, but the boards are getting so small that you cannot get by with just a Weller station alone. I believe in multiple irons/stations.

60 Watt iron

This is a brute force iron. The ones I like have no temperature control, and take around 5 minutes to get hot. I really only use them for soldering thick wires onto the PDB and melting foam. The tips clean up fairly easily. They aren’t that expensive which is good because you won’t use them that often for for long periods of time.

A Weller solder station

“I have been soldering for 30 years and I use a Weller…” is how the typical conversation goes. We’ll I’ve been cycling for 50 years and I don’t pretend to know the first thing about track cycling or downhill mountain biking on ski runs. Yes, Weller was king of the hill for many, many years. I know they last a very long time. And, if I were to need an station for soldering 10-18AWG wire over and over again, I would certainly select this. The stations are a bit price but hold up well. The issue with them is that they are often too large for the surface mount soldering that we do. But they are handy for other things, so though it may not be the first thing to buy, they are worth having. 

Microprocessor controller soldering stations.

T12 Tip Soldering stations

The soldering stations that use T12 tips are really fantastic. They plug in and come out of the iron very easily, and tend to be fairly cheap to buy by the tips. But even better when they are bundled. The microcontroller keeps track of the temperature and turn up the power when the tip gets cold and turns down the temperature when the tip is in the cradle for a minute or two. These things are fanatic for micro-soldering. Using this in conjunction with good solder really makes for a much easier time. You often want the thinnest tips you can find for the fine soldering jobs. 

TS100 Soldering irons 

have been popular in our hobby for the past couple of years. As you can see they come with the connector for an XT60 battery, thus allowing you to solder in the field. This is really the same concept, just smaller of the T112 station.


Instead of describing technique; its best that you observe it from others. I tend to like Lee from Painless 360’s videos and I know he would say that it was hard to film and solder at the same time. The problem was, his tip was too large for the Weller station. I’d watch a few videos and start listening to the common things that they express. I would look for common themes instead of trying to find a guru. https://www.youtube.com/results?search_query=flight+controller+soldering+tutorials. This is a skill, take your time, be patient. We’re not getting back to the flight controller for a few more weeks.

What to solder

This Matek F405-WING is the flight controller we suggested you buy. What you are looking at is everything you could possibly need connected to the flight controller. If you’re working on the S800 or another wing you only need 1 motor and 2 servos. The Motor would wire up to S1 or S2 which is on the top left. The Servos would hook up to S3 and S4 on the bottom right.

For this build, the only pins that I think you would want to solder on for certain are the servo pins S3-S8. The rest is up to you. If you would like to pin everything, feel free. The thing to keep in mind about the S800 is that we stick components in the bays on the wing. Thus, you’ll be running wires. Instead of using connectors you may want to solder the wires onto the board, if you feel your soldering skills can handle the task.

On the F405-WING in particular, the VTX and Camera wiring are reversed, it’s red, black, and white instead of black, red, and white. If you hook up your VTX or camera wrong, they will get instantly killed. This is why it’s important to always follow the color coding. This can be fixed by swapping the pins on the servo connector. Here’s a video how to do it.

You also may want to buy some of these, 40 pin DuPont cables, buy the Female/Female end only. You can cut them in half and solder your wire to them. This will be important if you’re using R9 or Crossfire. They are dirt cheap and one set will last you a very long time.

I also have a collection of these. Cut them in half and use 22 to 26AWG silicone wire to extend the wire so that you can place components onto your wing.

That’s it for now. As long as you’re buying a few extra things, make sure you pick up something called a smoke stopper. These come in a variety of styles. The idea is that one side plugs into your flight controller, and the other side plugs into your battery. If you have a short the flight controller won’t start. You can then find your problem and avoid blowing up your flight controller.

We won’t be getting back to the flight controller for a couple of weeks. Take your time, ask questions, get yourself ready to solder. If this is all new to you and a bit intimidating, just worry about soldering pins right now.

A word about INAV 3.0

We thought up Project Rosetta Stone S800 group build some months back. We wanted to help people who are sitting on the fence, thinking of building their first plane. The timeframe was specifically set so that people had more than enough time to order parts and have the plane finished with lots of summer months to enjoy the plane.

Right after we announce the S800 group build project; we got word that INAV 3.0 was going to come out and it would be simply amazing. Around the time you are finishing the build and getting ready for maiden, INAV 3.0 may be out as a release candidate. Usually we advise people to steer clear of release candidates, especially when they are new to INAV. INAV 3.0 is so very different from previous versions that it will make setting the plane up a lot easier.

There will be enough of us using the release candidates; so if problems come along, we’ll know about them fairly quickly. Usually within a few days of the release we’ll know if there is a show stopper. We’ll have more information when it becomes available.