Category Archives: RC Helicopter

Walkera QR W100 video streaming to PC

Walkera recently released a the new QR W100 FPV quadrocopter (see video for an review). What makes it stand out is that it uses WiFi for video transmission, making FPV very easy to set up, as you do not need a special FPV receiver.

When powered up the Quad will create a WiFi named WKxxxxxxxx, where xxxxxxxx is a random 8 digit number. Note that this is not a full fledged access-point – while multiple devices can connect to it, only the first one will get the video stream. So if you do not get any video, check your other devices.

Receiving with VLC

While in theory you could any WiFi capable device to receive the stream, Walkera unfortunately only has released an iOS app so far.
However as they are using a standard HTTP MJPEG for the video, one can use any video player, like VLC for receiving.

Connection settings for VLC

Connection settings for VLC

The address of the Quad is and the video is sent over port 7060, so the video URL is If you want to do FPV also make sure that you disable any buffering as it introduces latencies (1s by default in VLC)


You can also take pictures and record video with VLC – for this enable View -> Advanced Controls and the according buttons will appear in the UI

vlc recording

What is missing

Unfortunately VLC on android does not allow disabling network-caching or video recording, so you cant quite use the QR W100 with Android yet. Furthermore the iOS app also allows controlling the Quad over WiFi, which obviously requires more than a video player on the PC.

Flying RC helicopters in 3D

In case you are wondering what is so fascinating about flying RC helicopters – maybe you just got bored flying your own 4 channel helicopter – it is 3D flight. One might say that basically all helicopters are flying in 3D (up/ down, left/ right, forward/ backward), but 3D in this context means flying 3D pirouettes like loops and rolls which is not possible with an ordinary coaxial helicopter. See the following video to get an idea of what I am talking about

If you liked the video, but have no idea what collective pitch or 4 channels means, you might be interested in my introduction to RC helicopters.

In this post I want to discuss which machine one should get if one wants to progress from a simple 4 channel helicopter. Of course you might skip the 4 channel helicopters altogether and directly start with a 3D helicopter – but be prepared for a steep learning curve.

Choosing the right Helicopter

So one obvious choice is the SAB Goblin 700 from the video above, which is definitely capable. But there are a few hurdles with starting with that beast. First of all there is the price of about 1000€, then there is the size; the span of the rotor is about 150cm and it weights around 2kg. Thinking about physics and forces this means, that you can perfectly kill yourself using this thing (the guy in the link was only using a 450mm class helicopter), but also that on each crash something expensive will break (again due to the forces). Besides you will also need a small flight field to fly it.

I would rather suggest you to start with a micro sized collective pitch helicopter in the 100mm (rotor radius) class. They are basically capable of flying all the manoeuvres the big helicopters can, but as they are smaller and lighter, they do not break as much on crashes and do not hurt much in accidents. So what are the choices?

Nine Eagles Solo Pro 125

This is the helicopter I unfortunately started with. Priced around 125€ RTF it is probably the cheapest entry and also quite powerful in flight, but it is not really suited for beginners. As Nine Eagles use a cheap plastic, it breaks easily on crashes, which rules it out for indoor flight. However it might be acceptable if you only fly on grass. But based on my experiences I would not recommend it.

Walkera Genius CP v2

Somehow Walkera is not much present in europe. They have very nice build and technically advanced helicopters however. This one costs around 200€ RTF which is quite a number, but the package will get you one of the most durable helicopters out there. You have to try really hard to break it. Additionally you get 6 axis gyro/ accelerometer stabilisation and telemetry. While 6 axis stabilisation sounds better than the 3 axis stabilisation of the contenders on paper, it is not always an advantage. It literally nails the helicopter in the air – ignoring wind and performing some auto levelling. This is very good for beginners coming from a fixed-pitch helicopter, but gives you less control during 3D. Still the stabilisation helped me while learning flips and rolls, so I guess this makes it a good stepping-up helicopter. The telemetry is a less arguable feature; by sending voltage and temperature to the radio it you saves your battery and motor.
Probably the only bad thing about this helicopter is however that the landing skid is fused together with the main frame. The landing skid is the Achilles’ heel of this heli, meaning that it actually breaks sometimes. It is not that often, but when it does you have to disassemble the whole heli to replace it.

Blade mCP X v2

This probably the most prominent helicopter in this class. It will set you back around 200€ RTF and according to forums it has the best flybarless system. However it is said to be less durable than the Walkeras. I have no personal experience with this one, so I cant say much more here.

Walkera Mini CP / Super CP

These tow are really similar. Lets start with the Mini CP. It costs around 170€ RTF and features an improved construction and a stronger motor over the Genius CP v2. It uses the same durable materials, but has separate landing gear/ main frame, which makes it much easier and painless to repair. Furthermore the battery bay is larger, also fitting the walkera 350mAh batteries – whereas the Genius CP only fits the 240mAh batteries.
If the Mini CP would not lack the 6 axis stabilisation system, it would make the ideal beginners CP helicopter. As it is however, the Genius CP v2 is still a little bit easier to control (not much though).

The Super CP is a streamlined(i.e. cheaper) version of the Mini CP. It uses the weaker Genius CP v2 motor and has no temperature telemetry function. Furthermore Walkera moved the servo controllers onto the main board, which makes the servos cheaper in production (also the spare servos). All together makes it 150€ RTF. This makes it a pretty good package for beginners as saving 50€ for spare parts is worth more than the 6 axis stabilisation of the Genius.


While choosing the helicopter(-system) is the most important part, there are also some accessories you might want to consider:

Training Gear

If you are coming from a flybarred helicopter, you should consider getting yourself a training gear along the way, was flying a flybarless helicopter is quite different. While a flybar helicopter stabilises itself when you release cyclic control, a flybarless helicopter keeps flying in the current direction until you bring it back to hover manually. What seems just to be a small difference in theory is actually a quite big difference in practice, so prepare for crashes ;)


Unfortunately most super-glue does not hold the Walkera plastic. This is especially unfortunate if you have to disassemble the Genius CP just because the landing skid cracked. However the Pattex Plastix superglue does hold the plastic, so this a clear recommendation. (hint: Pattex is called Loctite in the US)

Swashplate leveling tool

While you can use the trim function on the remote to compensate an uneven swashplate on a flybarred helicopter(not that you should), you would most likely confuse the flybarless system when doing so on a flybarless helicopter. Therefore evening out the swashplate mechanically by adjusting the servo arms is a much better idea. A swashplate leveling tool comes in handy here. See this video, for instructions on how to use it.

Devention Theme for Deviation

In case you got confused by the title. This post is about a theme for the open source firmware Deviation to make it look like the original Walkera Devention Firmware.

Although the default theme of Deviation is more readable, you might have got used to the Devention icons, so this theme eases the transition.

Download Theme

Open issues:

  • the standard TX signal icons uses 8 bars, but the Devention one only displays 6. So you lose some information if you use the included “txpower.bmp”
  • The Devention icons are not quite as telling as the original ones, and Deviation unfortunately does not display any labels below the icons.

Note that this theme is based on the artwork included in the Walkera Devo 12S Firmware package. I assume the usage of this firmware is not restricted by Walkera copyright as not stated otherwise on their webpage. But obviously the CC-license of my website does not apply to this work.

Flying the Nine Eagles Solo Pro 125

If you are considering getting into 3D flybarless helicopters, one of your choices is Nine Eagles (NE) Solo Pro 125 (SP125) helicopter. As Nine Eagles is a quite prominent brand and the price of about 150€ RTF is affordable, this once is certainly worth considering. Unfortunately there is very little information on the Internet regarding reviews and flying experiences. So this is what the following text intends to change.

First of all lets see what an experience pilot can do with it

This is the official marketing video and obviously the pilots are very capable. But you get the idea what you could to with it – especially if you are used to flybar helicopters. But lets continue to the first-hand experiences I made.

Remote Control

The RTF package comes with the Nine Eagles J6Pro remote control. It is programmable and has model memory. This means you can also fly other Nine Eagles helicopters with it as long as they use the new protocol (J4Pro, J5Pro). At least the Solo Pro 270 works, but you have to figure out the settings yourself as they are nowhere documented.

Once you got the hang of the J6Pro, you can use it quite nicely – but again the documentation is quite bad and the usage principles are not clearly documented. Therefore I recommend watching this series of videos explaining how to change the most common settings

However the build quality of the remote is quite poor – the plastic feels cheap and I already had to repair one of the control sticks because of cracks in the plastic. You get what you pay is the rule.


The build quality of the helicopter is solid on the other hand – maybe too solid, as it breaks easily in crashes. More elastic parts could better withstand the crashes. Therefore you should directly order some spare parts – the following ones are quite handy from my experience

  • A metal swash-plate. This one costs about 20€ which is about double the price of the original plastic swash-plate by Nine Eagles. However with the plastic swash plate, each collision with something able to block the main rotor broke off one of these tiny balls on mine – the metal swash-plate on the other hand is more durable and in doubt something cheaper will break.
  • Several SP100 tail booms. This is probably the most fragile part of the SP125. Unfortunately you can can by the SP125 booms only in a package with the motor, which makes it unnecessarily expensive. The tail motor is able to survive most crashes. Luckily the SP100 tail boom also fits the SP125 and is just about 1/4 of the price.

Additionally the following parts are available which are really helpful when flying this helicopter

  • As you most likely have to change the swash plate at least once, a leveling tool is really handy – otherwise it is quite hard to get the swashplate straight on these tiny things.
  • The stronger 300mAh batteries are only 1.5g heavier than the stock ones, but give you more power and more flight time.

You can even upgrade to a better Radio using the Deviation Firmware. It allows using telemetry capable Devo Radios to controll J6Pro compatible helicopters. This way you can even get a nice touch-screen radio like the  Devention Devo 6S.


Once you got the metal swashplate, unfortunately the servos will be more likely to break. This is ok as they are a cheaper than the swashplate, but in the long run it is still expensive.

Fortunately when the servo stops working it is most likely that only one of the gears which are inside broke – so if you have several broken servos you can combine the spare gears to get one working servo.

The inside of the NE251328 servo. You can use this picture as a reference for assembly.

The inside of the NE251328 servo.

The image above shows the assembly of the gears inside the NE251328. You can use it as a reference how to re-assemble the servo from single gears.

Long term experience

After flying the little bird for about one month, I have spend 100€ in spare parts and many hours repairing it. As I replaced the swashplate with a metal one, the parts breaking most often were the tail broom, the landing skids and the servos. Furthermore one of the Control sticks of the J6Pro remote got loose and had to be repaired. Realising that I already spent about 250€ for the bird and as I wanted to upgrade the controller anyway, I took a leap and bought the Genius CP V2 with the Devo 6S controller.

While the controller is obviously a class on its own, also the Genius CP V2 is much more durable in comparison. Having already experienced similar crashes to the Solo Pro 125, there is nothing broken yet. Presumably the much more flexible landing skids and main rotor blades on the Genius CP do their job.

If you are a beginner, I would strongly recommend buying the Genius CP V2 over the Solo Pro 125 – the price difference is small and really justified. If you are an experience flyer and know what you are doing, the SP125 is probably still worth considering; the brusheless version of it, the solo pro 126 is quite a bit cheaper than the Blade mCP X BL.





Getting into RC Helicopters

Everything started when I got myself a coaxial RC helicopter for Christmas. I was playing with the idea for quite some time, and the moment seemed perfect to waste some money. Since then I have learned quite a lot about how helicopters work an by now I have moved on to a more capable helicopter. Unfortunately it is also more expensive to fly.. This post shall explain some general topics about RC helicopters which are useful if you are also considering getting a RC helicopter yourself. One can already get a small indoor RC helicopter for about 30€, but most likely you will get bored flying it after a few days. If you want to have something that lasts longer, there are some things you should consider, which we will discuss next.

 The remote Control

The idea to buy an helicopter first came up, when I saw an Infra Red (IR) controlled coaxial helicopter RC in a local coffee shop. It came with an traditional Remote Control (TX) as well as an IR module attachable to the headphone jack of my smart-phone. While the idea to control the helicopter with your phone sounds cool in the first place, it actually is not. If you ever tried to play a game with a digital-controller on the touch-screen, you will know what I mean. As there is no haptic feedback it is very difficult to give precise input without looking at the touchscreen all the time. So the smart-phone module is actually quite a useless gadget.

The other problem with that package is the Infra Red transmission technology – basically the same you have in your TV remote. Therefore it also suffers from the same shortcomings; if there is an object between you and the helicopter it is pure chance if it will receive a signal or not. Next the transmission is quite sensitive as there are many natural IR source around like the sunlight, heat or even light-bulbs. As one wants the transmission as reliable as possible, you should avoid IR remote controls.

An infra red controlled helicopter - dont get one of these.

An infra red controlled helicopter – dont get one of these.

An alternative transmission technology is radio in the 2.4Ghz spectrum, which is not only more reliable but also has a larger operation range. Fortunately 2.4Ghz radio controllers are not more expensive than the older IR controllers, so pay attention to get one of these. If you want to learn more on the used radio technology I recommend the Wikipedia article on Radio Gear.

How many channels do I need

Looking at the offered helicopters some are advertised as 3 channel or 4 channel. But how many channels do you need? First lets take a step back and explain what channel actually means in this context. Lets look at a simple remote controlled car for this. It can either go forward or backward and left or right. The important word here is “and”. As the car can go for instance forward and left, we need two independent communication channels: one for steering and one for acceleration.

Obviously a helicopter needs more channels; besides steering and accelerating forward and backward it can also lift or fall (throttle). So we need at least 3 channels to be able to do something with it. Now steering left and right can mean two things in the case of helicopters. Either you can rotate around the main rotor axis (yaw) or go straight left or right along the horizontal axis (cyclic bank). Therefore you need 4 channels to be control all possible movements of the helicopter.

Directions you can steer in a 4 channel helicopter

Directions you can steer in a 4 channel helicopter

But even though 4 channels are enough to control the movements, you actually need 5 channels to fly advanced manoeuvres like flying upside down or flying loops. You can think of the 5th channel as the gear stick in the car which changes the transmission. For helicopters the transmission roughly corresponds in the pitch of the rotor blades – and this is exactly what the 5th channel is for. But to fully understand why you need it, you have to understand how the physics of a helicopter work.

How real helicopters work

Instead of explaining all the theory by myself, I rather point you to Destins “Smarter Every Day” Series. They are really entertaining to watch and you get to know everything you need about RC helicopters physics – they are actually using a RC helicopter to explain the physics behind real ones.

You probably noticed that real helicopters are also quite fragile if not handled properly. That aside you should now also know that the 5 channel helicopters are called collective pitch and which manoeuvres you can do with them.

So what should you buy

After watching the 3D flight demos above, you probably want to go with a collective pitch helicopter straight ahead. But remember that it probably took the pilot years of practice and hundreds of € in spare parts to learn how to fly like that. There will be no “inverted flight” button on the remote control. Therefore you probably should start with a cheap 4 channel helicopter to see whether you enjoy flying enough to spend more time and money on it. The only thing you should observe with your first helicopter is that there should be spare parts available. Otherwise your first crash might cost you the whole 30€ of the helicopter instead of just 5€ for a spare rotor blade. This does not mean you neccesarily have to buy from a brand, which is more expensive. I ended up with a coaxial helicopter called “super uncommon 9998″, which could use the spare parts of the e-flite blade MCX system.

You should practice the basic manouvers with that cheap helicopter, as it will survive more crashes due to its slower flight speed. I recommend the rchelicopterfun youtube tutorial for an overfiew of exercices. You will need a collective pitch flybarless helicopter for the later ones, but you can do the first ones with a coaxial helicopter just as fine.

Once you are hooked up and decide to buy a more expensive collective pitch helicopter, you might be interested in my experiences with the Nine Eagles Solo Pro 125.This was just a small outline of the broad RC helicopter topic. If you want to know more I recommend you the excellent rchelicopterfun website.