Sunday, 30 September 2012

Multicopters - What to buy?

In this article I'm going to take a look at what's on the market at the moment and put together a list of components for 3 different budgets. A budget copter for someone just wanting to dip their toes into the world of multicopters, a mid-range copter for those that might also want to do a bit of aerial photography and also want a few extra features and a 'Blow the kids college fund' copter that uses the best of the best.

Only a few short years ago, if you wanted to build a multicopter it invariably meant getting your soldering iron out and doing it yourself and then spending an age sitting at a computer looking at code and trying to tweak it so that your beloved copter didn't suddenly become a flying lawnmower that takes out everything in it's path. Fast forward to today and you can buy Ready To Fly copters and there is a bewildering array of frames, controllers and motors to choose from, making it a bit of a minefield for anyone new to navigate.
Safety, Safety, Safety!!!

A quick note about safety. Multicopters are not toys and have the potential to cause serious harm. Make sure that you remove the propellers whenever you are working on the copter or changing settings with power on. Before you go for your first test, make sure that with the propellers removed, the motors appear to be operating in the correct sense. With the motors spinning, tilt the copter to one side and make sure that the down going motor speeds up and the up going motor slows down. Do this for every motor to make sure that it is setup correctly. Remember to do this with the propellers removed.

Budget Copter

For this copter it's all about keeping the costs down, but still having a capable machine that will fly well, so about $200 should easily get you in the air


As you'll probably end up crashing lots, you want a frame that can take some abuse and is easy to repair. For that reason I'm recommending the Q450 frame from Hobbyking. You can buy replacement parts from everywhere and it's only $11, so not a big investment and it's easy to mount all of your components on it. I recommend starting with a simple quadcopter and you can always upgrade to a hexacopter or octocopter later.

Hobbyking Q450 Frame

Control Board

Normally for a beginner copter I would recommend a very simple gyro only board, but in this case I'm going to suggest the KK2.0 from Hobbyking. This board has been designed to be beginner friendly, has the added bonus of accelerometers which allows autolevel and has multiple firmware pre-installed for just about any configuration of multicopter you can think of.

KK2.0 Control Board

I just found this great video on how to tune the KK2.0 Board: Link to youtube


For this build we just need some basic motors around 1000kv that are capable of swinging a 10" prop. There are loads of deals on packs of 4 motors on ebay. I like these ones because they're cheap and  come with prop adapters.

4x Pack 1000kv motors

Some other motors that I must mention are the X2212-980KV motors from SunnySky. These are really great quality motors and perfect for multicopters and I particularly like the propeller mount that comes with this one as it's great for multicopters.

SunnySky X2212


SimonK is the name we're looking for. That's the name of a man who developed some special firmware for ESCs specifically for multicopters, which gives them a faster response time and thus smoother control for your copter. You can buy standard ESCs and then cut them open and flash the firmware yourself or buy some that have already had it done, like these ones fom RCTimer. 20A is more than enough for this build, but buy the 30A or 40A if you think that you might want to upgrade Motors in the future.

SimonK Pre-flashed ESCs


For this build the maximum size prop that we want to use is 10" and there are loads of them on the market to choose from. These ones from Hobbyking are perfect for this build, but don't forget to balance them before using them. Don't forget to purchase a right hand and left hand rotation set and consider buying different colours for the front and back of your copter to help with orientation. To do this you would actually have to purchase 4 packs of props (left and right rotation in 2 colours), but you can never have too many props and you'll be glad for the spares when you have your first crash.

9*4.7 Slow Fly Prop
10*4.5 Slow Fly Prop for SunnySky


I've covered the main components in the build, but obviously you'll need a few extra bits to complete the build, such as battery, transmiter/receiver, heatshrink tubing, power distribution board, soldering iron, solder etc... Here's some links to some extras to help finish the build:

3s 2200mAh Lipo - Cheap, quality Lipo
Power distribution board - Inexpensive but effective or buy the integrated PCB Frame
Transmitter/Receiver - Lots of functions to play with
Heatshrink Tube - Buy lots of this in lots of different sizes and colours
Soldering Iron - Must have tool for every modeller


Obviously there is a myriad of other options out there and I couldn't even begin to list them all, but hopefully this will take some of the guesswork out of building your first quadcopter. Here's some links to alternative beginner setups that come complete with just about everything you need to get started, including a couple of RTF micro-copters.

RCTimer ARTF Quadcopter
Walkera Ladybird RTF
HobbyKng micro quad
Ebay kit - even includes Lipo and charger

Please leave a comment if you think I've missed something or want to recommend alternative items and I'll try and keep this page updated.

DT-3K Headtracker

Mini review of the DT-3K Hybrid Headtracker from Flytron.

If you want the full immersive experience of flying FPV then a headtracker adds that extra dimension which really gives you that feeling of flying from the pilots seat.

The DT-3K is available from Flytron for a very competitively priced $96 and support and customer service from Melih is first class. It is compatible with most brands of tansmitters, but check what sort of trainer connection you have on your transmitter and be sure to order the correct one. Note: This will not work with Spektrum or JR Transmitters that have the phono type jack for trainer connection.

This was, as far as I'm aware, the first hybrid head tracker to incorporate a magentometer into it in order to prevent drift. The first headtrackers that entered the market years ago relied on gyros only which have an inherent problem of drift and required a reset button to reset centre during flight, otherwise you would end up with your camera constantly looking out over a wing or down at the floor.

This headtracker gets around the problem of gyro drift by using what is essentially an electronic compass to keep the camera pointing only in the direction that your head is facing, with zero horizontal drift. The one problem with this is that you are now forced to always stand and face the same direction (either north or south) every time you fly. This is fine if you always fly from the same strip, but if you fly in different places at can become a pain.

The DT-3K can operate in 2 modes. In the first mode (ppm-inject) it allows you to add extra channels to your transmitter, effectively creating a channel 5 and channel 6 on a 4 channel radio or channel 7 and channel 8 on a 6 channel radio. this means that you can use it with even the most basic 4 channel radios that wouldn't normally have enough channels for headtracking.

In the second mode (ppm-create) it can replace any 2 consecutive channels in your radio. So, if you have a 6 channel radio and 6 channel receiver it can take over channel 5 & 6 and still leaving you the first 4 channels for basic aircraft control. I hope that explanation is clear, because I was certainly left scratching my head about which mode did what when I first read the manual.

Programming the DT-3K is relatively straightforward and if you follow the instructions then you can't go wrong. The only annoying part of the programming is that if you mess up or want to change something then you have to start from the beginning and remember all of the individual settings that you have already set. I reccommend writing down the settings as you go along so that you know which part to change if you need to make any changes.

One thing that caught me out the first time I used it was that having set it up at home, the pan seemed to be reversed when I got to the field. I was just about to dig the instructions out when I realised that all I needed to do was turn 180 degrees and then left became left and right became right again. Don't be caught out like I was, this is how it's supposed to work.

To get the headtracker to work, you need to hold the trainer switch on. Most trainer switches are spring loaded to off, so you either have to rig it to stay on using something like an elastic band or you can open up your transmitter and change the switch to a regular toggle switch.

One slightly annoying thing is where the cable exits from the unit, which makes it more difficult to mount to the top of your goggles or on your baseball cap. If the cable exited from the side it would make it easier to mount and you wouldn't have a cable sticking out of your forehead. I'm probably just being fussy though as I haven't heard anyone else complaining about it.

Overall this is a great unit and works flawlessly and was a real step forward in headtracking technology. This was released a few years ago and there are now other units using the same technology, but this was the first and still holds up well against the competition.

Pros: Price, Flytron service, flawless operation
Cons: Doesn't work with Spektrum/JR, slightly difficult to mount

Saturday, 29 September 2012

Lazy EZ* GoPro FPV

If like me you would rather be outside flying than inside building and tinkering with electronics, then this has to be one of the easiest FPV conversions that you can do.

What you will need for this conversion:
  • GoPro Camera
  • 2.4GHz 500mW video transmitter or similar - like this one
  • GoPro adapter cable available here
  • zip-tie
  • Velcro
The whole process takes about 2 mins from start to finish.

  1. Remove your EZ* cockpit canopy and cut a flat area the same width as your GoPro.
  2. Next cut a slot in the side of the canopy to slide the video transmitter in to.
  3. Next make 2 small holes, one at the front and one at the back of the flat are you cut in the first step.
  4. Now thread a zip-tie around the GoPro and through the 2 holes and the around the video transmitter and zip it up tight. Connect the power cable and GoPro adapter cable to the video transmitter.
  5. Attach a small piece of Velcro inside the canopy and use this for holding a small 2s 500mAh lipo for powering the video transmitter.

With a 3s 2200mAh lipo powering the EZ*, it balances very nicely on the CoG if you widen the rear of the battery bay so that you can push the lipo back about 2.5 inches further than normal.

This is by no means the best way to setup and FPV system and you can get much better range by using a better antenna and placing the video transmitter in a better position, but the big advantage with this is that you can just switch back to non-FPV by changing the canopy. Using completely stock antennae on the transmitter and receiver I have been out to over 1.5km with perfectly clear video. With this method, the nose of the EZ* will be in view, but I quite like flying like this as it gives me a bit of a reference point to have more of an idea of what the model is doing.

Important- Don't forget to use a couple of elastic bands to help secure the canopy on, because you don't want it falling off in flight.

Here's a little video to show what it looks like in flight. The flying starts at about 45 seconds and sorry about the music!

8" FPV Monitor 800*600

If you have seen my sneak peak look at my new ground station, you will have noticed that I have incorporated a small 8" monitor into it. I've wanted a small monitor for a while to help with lining up shots when doing aerial photography (AP) when flying semi-FPV, so flying visually and then just glancing down occasionally to check that my shot is lined up correctly. As my All in One ground station as AV out for my goggles, it will also serve has a backup screen in case I have a problem with my video glasses.

The usual place that I always go to first when looking for new equipment is ebay and there is a lot of choice when it comes to LCD screens, so it wasn't easy to decide on one. As it was going to go in my ground station, I wanted a screen only, without all the casing or speakers or any extras. I also wanted a screen with a good resolution, as many of the screens are 234x480, which I have found is a bit low. For outdoor use, you ideally want a screen with as high luminance as possible, but I found that with the anti-glare coating on this screen it still works fine outdoors even at only 200 cd/m2.

This is the screen I purchased from ebay seller njytouch and here is the link to it: 8" Monitor

The screen arrived very well packaged and shipping took around 2 weeks. At the time that I purchased it, I paid £34 including delivery, but I see that it has gone up a bit since then, but still represents good value for money. In the box you get the screen, control board, keypad board and various cables for composite, VGA and power, but no instructions.

Getting it to work is a simple matter of connecting the ribbon cable from the screen into the control board, connecting the screen power to the control board (more about this later) and then supplying 12v to the control board. The only slight problem with this screen is that the power cable from the screen isn't long enough to reach the control board if you want to mount the board on the back of the screen and not have it like in the picture above. This is easily solved as it just means extending 2 cables by about 6 inches.

Once the screen is setup to your liking using the keypad, you can disconnect it from the control board as it's not needed for normal operation as it automatically turns on and selects the last input when you supply power. My main reason for choosing this screen is that it has VGA-in as well, so that eventually I can install my Raspberry Pi into my ground station and have a computer in the field with me as well, so the 800*600 resolution will be ideal for that using a HDMI-VGA converter.

This screen does do the black screen of death, but the picture has to be really bad before that happens and it returns pretty quick when the signal improves. This does perhaps make it not ideal as a primary flight screen, but is perfectly fine for use as a backup monitor. The image quality is excellent and the colours are bright and vibrant and as I already said earlier, the anti-glare works quite well. Also, it's a 4:3 aspect ratio, so really good for use with CCTV type cameras for FPV.

Overall, I'm really pleased with this screen as it does exactly what I wanted it to do and apart from the minor issue of the power cable, I can't fault it.

Here's a little video to show how this monitor handles static and the recovery time from blue screen.

Friday, 28 September 2012

12v/5v CCTV Power Supply

I recently purchased one of these because I thought it would be handy to have when testing FPV equipment on the bench and it's turned out to be a really handy device.

I purchased it from ebay for the princely sum of £9.99 including delivery and it arrived in about 3 weeks from China. I opened it up to have a look at what's inside and there's a 5v regulator and a 12v regulator that should be good for about 2A each and what appears to be an 1800mAh 3s lipo battery. It also comes with a charger and a male to male barrel connector that fits most CCTV type equipment. It has a pretty low self discharge rate and even after a few weeks without use it still seems to be holding it's charge well.
This has turned out to be one of the best little gadgets that I've purchased in a while and is a really useful item to keep in the flight case. I've used it for testing a variety of FPV equipment including cameras and screens and also for emergency charging of mobile phones and other USB devices. If like me, you have one of those little keychain cams then you can use it for charging those and I also use it for keeping my video goggles topped up.
I really wouldn't be without it in my flight box now.
Pros: Price, Dual voltage output, size/weight
Cons: None that I can think of

AIO Ground Station - Update 16 Oct 2012

This is going to be my new All-In-One ground station for when I just want to get out and fly FPV with the minimum amount of time to set up. I'm using an 8" 800*600 TFT screen and the remains of a broken DX6i transmitter hooked up to a FrSky hack module. Inside is going to be a 5.8GHz receiver and eventually a DVR. The box is made from 1/8" high-density fiberboard that I have covered using carbon fibre effect vinyl. This is great because I don't own any power tools and I was able to cut it all using only a sharp craft knife.

DX6i with FrSky Hack Module
Connecting up the DX6i to the FrSky hack module is fairly straightforward, but it took a little while to work out how the 'Trainer Logic' circuit works in the DX6i. There are 4 cables going to the trainer port on the DX6i. The red and black are the power + and - and the yellow cable is PPM in. The fourth orange cable needs to be connected to the power cable in order to get the DX6i to accept the PPM input. When you connect power in this way, the power switch on the fron of the DX6i actually needs to stay in the off position and the on position becomes the off position. This is what I meant about trying to figure out how the 'Trainer Logic' works.

Connecting the Screen
Here is a picture showing the back of the screen with the control board all connected up. As I found out, it's really important to keep the back of the control board well insulated from the back of the screen and I did this using some thick double sided foam. I had to extend the power cables for the screen as they weren't quite long enough to be able to mount the control board otherwise. Having set up the screen using the keypad, I no longer need it, so the only 2 cables going to it are the power cable and composite input.

Next step is to connect up a 6v UBEC to power the DX6i and FrSky hack Module and then wire the switches up to power the screen and receiver. I eventually want to add a diversity receiver system, raspberry Pi and DVR so I have to try and think about it at this stage of the design so that I can try to avoid having loads of unused holes in the box when I add them.

Thursday, 27 September 2012

DIVIDesign Spider Quadcopter V4

I purchased this frame about 6 months ago from here as I've always liked the look of 'spider' copters and this was the first full carbon one that I had seen. As I was one of the first to purchase it, I managed to get it for under $100, but the current price has risen to $159 for the normal weight version that I have. I'm not sure there is any reason to buy the heavyweight version as the frame is very strong and stiff as it is.
The kit came delivered in a large padded envelope with all of the parts just floating around loose inside. I was a bit concerned that the parts would be damaged, but a quick inspection revealed that everything had arrived in one piece. The frame doesn't come with any instructions for assembly, so I was left to look at the pictures on the website. It's a very straightforward frame to put together and if you've built a quadcopter before then you won't have a problem putting this together.

There are a few things that really let down this kit, that if fixed, would make it a really top quality frame. The first thing is the ring mounts that have a threaded insert in them and some of them spin when you do them up, so you can't get the screws in tight enough and they vibrate out. Second is the motor mounts and the material that they're made of, which have to be reinforced with a fibreglass plate (supplied with the kit). The biggest disappointment however is the anti-vibration mount, which is absolutely useless at reducing vibrations to the camera.

To get round the problem of the anti-vibration mount, I discarded the rubber grommets and instead used a layer of neoprene foam between the camera mount and the frame and used bungee chord to cold the camera mount down. This method seems to work really well at reducing vibrations to the camera and I've now used it on a couple of builds with good success.

I won't bore you with details all of the equipment I used to get this in the air, but I will say that with 10" props mounted, they don't appear in frame when the GoPro is set to r3 720p mode. With a 3s 2200mAh lipo mounted on the battery mount at the back, the copter seems to be well balanced with the GoPro on the front.

When it comes to flying, it flies just like any other quadcopter that I've had in x-mode and doesn't display any odd flight characteristics. On my first flight I managed to crash into a tree and break one of the arms, but because it uses standard 12mm carbon tubes for the arms, it was soon replaced and back in the air.

Here's a picture of my finished copter before I discovered how bad the anti vibration mount was. I've since added a 200mW 5.8GHz transmitter which is powered from it's own 2s 500mAh lipo. I've mounted the video tx just behind the gopro, but am having interference issues when the motors are running, so will have to address this in the future.

Pros: Good design, rigid, lightweight
Cons: Poor anti-vibration mount, quality of some fittings, price

FMKIT RF Beacon - lost model finder

I've had a couple of these RF beacons for a while now and I made a little video showing some of the basic features of these beacons. Since I made the video there have been a few improvements to the design, but they basically retain the same features when used as a lost model finder.
The RF beacons are available here for $50 and are a great addition to any FPV aircraft and will massively improve your chances of finding a lost model. It can be set to come on after a set period of time, or it can use the microphone to detect when there is no noise and then turn on, that way if you fly with a Long Range UHF system you can be sure that it won't interfere with it. It can also be used as a data modem for sending GPS or other  telemetry, but I've never tested this function.

Review of 5.8GHz SP and CL antennae

I've just got hold of a pair of antennae made by Markus from RCGroups, so I thought I would put them to the test.

It cost me $55.50 for the pair of them including delivery, which I think is a fair price for some handmade and tuned antennae. If you want to get hold of a set for yourself then you have to send Markus a PM through RCGroups and he'll get back to you pretty quick. As they are all built to your specific requirements, there is a bit of a delay in getting them and it took about 3 weeks from ordering to arrival.

You can choose from a number of different options such as the type and style of connector (SMA/RP-SMA or straight/right angle connector) length of feed cable and even exact frequency that you want it tuned to. At 5.8GHz this is very important as the performance is significantly effected if they are not well tuned.

When I opened them, the first thing I noticed was how well built they looked and the quality of the soldering on them. I also noticed that they look a bit fragile and you can easily bend the lobes, which would affect performance, so you have to take a bit more care in handling them than you would with the standard antennae that come with most transmitter/receiver packages.

To test these antennae, I used a basic 200mW 5.8GHz transmitter with the RC305 receiver, which I purchased from Hobbyking.

First I did a test with the standard antennae to get something to compare them with. I set up my receiver connected to my dvr and left it on the kitchen table. I then hit record and went for a walk down my street. On reviewing the footage I could see that the signal started to break up when I was about 30m from my house and was unusable by the time I had walked 70m.

I then fitted the 3 lobe Clover leaf (CL) antenna to the transmitter and the 4 lobe skew planar (SP) antenna to the rx receiver and repeated the same test. This time I had much better results and had a rock solid image for at least 60m before I started to get the odd breakup in the picture. The video was still usable out to 120m, but by this time I had run out of space to walk and had some houses between me. Still, this quick test was enough to convince me that these are going to be great for FPV on my multicopter.

Pros:  Price, build quality, performance
Cons: Fragile


Hello and welcome to my all new blog where I will be reviewing all kinds of things related to RC models, but with a focus on multicopters and FPV.