Category Archives: Quadcopters

Quadcopter 1 – Flying

Quadcopter 1 is built with the Naza M V2 flight controller from DJI. It is expensive but worth every penny for the novice pilot because it is very stable and very easy to fly. it will give you the satisfaction that you need so much and the confidence that you can do anything with it. My good friend Misha started flying with an Arducopter controller and quickly gave up.

Here is a recent video (published with permission of the participants) of me flying it in a small parking lot just a meter away from the excited crowd (children are the best crowd for this kind of stuff).

However, I must confess that I do this after relatively many hours of flying the Naza and, I’m not exaggerating, tens of broken propellors, two damaged engines and a fractured carbon fibre frame. DON’T DO YOUR FIRST FLIGHT IN A SMALL PARKING LOT.

My first flight was catastrophic. I bought only 8 propellors and I attached four of them to the engines in a random way. I remembered Misha laughing about people who buy ready made coppers like the Phantom, who don’t even know which way the propellors are attached, but I didn’t understand what he means and I didn’t know what to ask. So I attached the propellors, took it to a large parking lot at night, armed the controller, moved the throttle up and the quadcopter flopped on its head breaking two propellors. I replaced the propellors and tried again, same result with one broken propellor. I took it home and started reading the configuration instructions carefully I soon understood how to attach the propellors correctly (see the “Preparing to fly” post).

The next day I went to the parking lot again, this time with the propellors attached correctly. I armed the controller, moved the throttle up and the copter lifted off the ground, took a wide angle and crashed into a lighting pole. Two propellors broken again and I couldn’t continue flying. I went home and ordered a large number of propellors (I think 20) from a supplier in China but I couldn’t just sit and wait a month for them to arrive. So I went the next day and bought 2 propellors from an importer in a nearby city for six times the chinese price.

After a few more careful flights I could lift it off the ground an land. I decided that I must now start practicing on moving it sideways a bit. So I went to a large field, lifted off and it started flying away, assisted by the strong winds (I live in a mountain region, 800 meters above sea level with strong winds). I couldn’t understand how to make it return to me, so I panicked and switched to the RTH (return to home) mode. In this mode the Naza copter first climbs up to 20 meters and then heads “home”. I saw it climbing up then starting to fight the winds in order to return to the home position, suddenly something snapped and the copter fell from 20 meters to the ground not far away.

I ran to the crash spot and was amazed to see that 3 propellors were broken, one engine shaft was bent but the carbon fibre frame was intact apart from a very small dent. Now I really had to wait a month for new engines to arrive. When I inspected the copter I found the reason for the crash – the screws attaching one engine to the frame came loose, and the engine snapped off. This is something you don’t want to happen in mid-air, especially since I’m writing this post in an airplane on the way to the London Heathrow airport. Not a bright thought at all.

I now had some time to think and I understood that I must perform all the calibration steps and, most importantly, make sure that the propellors (and engines) are completely horizontal. If they aren’t then the copter will rotate or simply fly away. It is easy to detect which engine is not horizontal – it will be hotter than the other engines.

The next time I flew it, it lifted off cleanly, kept its position and height and responded to commands beautifully. Here is a video from that period.

After some more practice I became so confident that I let friends fly it with no training at all. I would give them the transmitter, stand behind them while holding their fingers, and show them the basic movements. They could fly it very nicely just like that without any practice. I stopped doing that after someone panicked and turned off the engines in mid-air and someone else borrowed it for a few days and returned it with 2 broken propellors.

Here is a video (published with permission) of some 2-legged friends and 4-legged friends flying my Quadcopter 1.

 

So, the main point is that anyone can fly a Naza and I strongly recommend paying more for a Naza at least for the first quadcopter.

An expensive evening

I’m a strong believer in putting my money where my mouth is and since I consider my Naza based quadcopter easy to fly I let my friends fly it. We meet almost every evening in our local dog park that doubles sometimes as a tennis court.

So this evening I let A. fly it for his third or fourth time and he did a great job. We even let E. fly it for the first time for a few minutes. By then the battery almost ran out, the red warning light was blinking, and we were going to land. Just at this moment Johny joined us and asked for a short ride. He flew it several times already so I said ok.

Johny lifted the quad into the air and flew it a few meters away. Suddenly, and I still don’t know the reason for it, the quad rolled at a steep angle and fell from about 3 meters right on the tennis net.

At first it seemed undamaged, but when I tried lifting off again it flew away to the right and I saw immediately that one engine shaft was bent.

A bent engine shaft

A bent engine shaft

This was the second accident this evening. Just before that I flew my quadcopter 2 which has a Hobbyking multicopter flight controller and I still struggle to learn to fly it.

In my last flight for today I lost control over it completely, it flew fast and downwards and hit a stone fence. One of its arms was broken.

Broken quadcopter arm

Broken quadcopter arm

So right after this sentence I will try to glue the broken arm and straighten the bent engine shaft. I believe none of these fixes will work  😦

Quadcopter 1: Assembly

Quadcopters are relatively easy to assemble but it took me the better part of a month to assemble Quadcopter 1 – my first quadcopter.

Figure 1 below shows the components of Quadcopter 1 and their connections to each other. In the following sections we explain how each sub-system is assembled.

Figure 1: Quadcopter 1 schematic diagram

Figure 1: Quadcopter 1 schematic diagram

The black lines in figure 1 show the power connections and the yellow lines show the control connections.

Figure 2 shows the assembled quadcopter.

quadcopter1-assembled

Figure 2: Quadcopter 1 – assembled

Frame assembly

The frame arrived as a set of flat carbon fibre pieces and a small bag of screws and spacers. I had to study carefully the photos of the assembled frame on eBay in order to understand how to assemble it. Here is one photo for example.

Figure 3: Zoom in on the top and front part of the frame

I used 2 mm and 2.5 mm hex screw drivers.

Figure 4: Hex screwdrivers

Battery and the power distribution board

I decided to connect the battery with cable ties to the bottom of the frame because I’m not planning to use quadcopter 1 for photography and I will not connect a camera at the bottom.

Figure 4: Battery connection

Figure 4: Battery connection

After some trial and error I decided to use a double-sided PCB for the power distribution board. I soldered two 1.5 mm cables to both sides of the PCB and the two other ends to a Deans plug.

Note that the the power cables must be thick enough to allow the high power consumption of the ESC. At first I soldered thin cables that overheated very quickly and started to melt the plastic cover of the Naza flight controller at the point where they touched it. I then replaced the thin cables with 1.5 mm cables.

Engines and the 4-in-1 ESC

I soldered gold plated plugs to the three leads from each engine. I also soldered an extension of 1.5 mm cable to each of the cables that came with the 4-in-1 ESC because the original cables were too short for my large frame. I covered all the solder points with heat shrink tubing.

I passed the cables from each engine through the hollow engine arms.

The 4-in-1 ESC fits nicely on the center of the frame under a small cover that is screwed to four spacers. Figure 5 shows the ESC assembly.

Figure 5: ESC assembly

Figure 5: ESC assembly

The ESC is held in place by velcro on it’s bottom and the cover piece with the text: “WTOTOY”

Naza components

The Naza system consists of the following components:

  • Flight controller
  • GPS
  • Power management unit (PMU) – distributes power to the components of the system.
  • LED module – indicates the system status and connects the controller to a PC for configuration.

I followed the assembly instructions in the Naza-M Quick start manual but I made a few changes in the location of the components as follows:

  • The flight controller is not exactly at the centre of gravity (CG) of the vehicle. It is located astern of the ship (on the back).
  • The GPS is also not at the center of gravity but on the bow (forward) of the airship. In the beginning I used the pole that came with the package and glued the GPS case (the white plastic protector around the GPS unit) to it right at the CG. However, after the first few crashes I realized it will be much safer if I attach it to the frame itself.

At first I connected the flight controller and the GPS with velcro strips but then I realised (I realised many things during the process  🙂 ) that the velcro allows the flight controller to move and shake a bit and this is certainly not good. Therefore I replaced the velcro with double sided glue strips similar to these – some were provided by DJI in the Naza package but I bought a few more myself.

50Pcs Double-Sided Adhesive 3M PE foam Sticker Size 25MMx40MM For RC Model Gyro

This glue is very strong after it bonds, but it is always possible to pry it off with a knife.

The receiver

I attached the Hitec Optima receiver with velcro strips to the back side of the frame near the flight controller. The choice of location was mainly because of the short servo cables that I had for connecting the Naza to the receiver. A side advantage is that it is also protected by the strong carbon fibre frame.

optima-receiver

Figure 6: The Optima receiver

Landing gear

The landing gear that came with the frame has very long plastic “legs”. It looked really good when it stood on these legs on my desk but they were too elastic, so often when the ship landed not completely softly it would bounce up and land on its back or side. This went on for quite a long time and through many crashes.

Luckily, if I may say so, I once completely lost control over the quadcopter and turned on the RTH (return to home) feature. When a Naza goes into RTH mode it first climbs to a height of 20 meters and then heads home. On that particular occasion the winds were very strong and the screws holding one of the engine to the frame became loose during all the crashes. So suddenly the engine broke loose and the ship crashed from 20 meters to the ground. Amazingly, all the carbon fiber parts were almost not damaged but one of the plastic legs broke. I didn’t have a replacement so I decided to cut the other three legs to the same length and suddenly I realised that this is perfect. The short legs are not elastic any more and when the craft lands it sets squarely on its legs and doesn’t bounce at all.

So I definitely recommend using a non-elastic landing gear. I am not planning to install a camera under the frame so I am not going to replace the legs that I have even though they are quite short.

Marking the “front”

In the basic flight mode the operator must be aware which side of the quadcopter is the front. Therefore I marked the front of the vehicle (the front legs and the front engine arms) with white tape as can be seen in the next photo.

Figure 7: Marking the front of the quadcopter

Figure 7: Marking the front of the quadcopter

Propellors

The propellors must be installed at the very last step of preparing the quad copters for its first flight. So I will describe the propellor installation in the next post on “Preparing to fly”.

Quadcopter 1: Parts

In this series of posts I will describe my first Quadcopter which I call: Quadcopter 1.

My friend Misha got me interested in quadcopter around May this year (2014). I started reading about this subject and made my first purchase on eBay on May 20. My first order was for this carbon fibre frame which cost me $73:

HJ-H4 Reptile 4 Axis Carbon Fiber Folding Frame Kit with Landing Gear

On the same day (or rather night) I ordered more stuff. First a 4-in-1 ESC from Emax. It was a package deal with 4 engines and all the accessories.

Emax XA2212 Brushless Motor 980KV x4 & 25A 4-in-1 ESC for Quadcopter Multicopter

At that time I didn’t know that sometimes engines are sold separately from the Bullet banana connectors (the gold plated connectors that connect the engines to the ESC) and the screws that attach the propellors to the engine. Luckily this package contained everything. Its price was: 53 Euro which was about $77.

I also bought the heart of the quadcopter – the flight controller. Misha said that since he has an APM I should order a Naza. It was a lucky choice because the Naza is so easy to fly and it motivates you to continue learning and experimenting.

DJI NAZA-M V2 WITH GPS AUTOPILOT +PMU + GPS PROTECTOR CASE Quadcopter Hexacopter

It was expensive – $315 + almost $20 in import taxes – but its worth every penny.

Two days later I ordered a 5000 mA battery for $37.90:

Freeship 11.1 V 30C 5000mAH 3S Lipo Li-Po Lipoly Battery for RC Trex Helicopter

and a LiPo charger. This one is a fake IMax B6 and it worked until last week – for about 5 months – which is not too bad. It seems that a fuse burned, so I believe that it will be easy to fix and I’ll describe the fix in a separate blog.

This is the charger  that I bought for $20:

New iMAX B6 LCD Screen Digital RC Lipo NiMh Battery Balance Charger D1

A quadcopter needs propellors, so being very naive I bought 2 pairs of 10×45 propellors and 2 pairs of 8×45 propellors – 4 propellors of each size.

DJI 8 x 4.5, 9 x 4.7, 10 x 4.5 carbon nylon propellers quadcopters cw ccw

Carbon reinforced Propellers cw & ccw 8×4.5 9×4.7 10×4.5 quadcopter UK Stock

Each pair cost me around $13.7 which was a very bad deal indeed. I ended up spending so much money on propellors until I found that I can buy 10 pairs of propellors for $26.

And finally I needed a transmitter (remote control) and I took Misha’s advice and chose the Hitec Aurora 9 with a 7 channel Optima receiver. The package cost me around $380.

AURORA 9 2.4GHz AFHSS COMBO 7CH RX NIMH (M2)

I bought the transmitter in the UK, the actual price was GBP 220, and brought it home with me. I was concerned that it will be held by customs if I’ll get it by the mail or DHL from china. I also preferred to have an original one.

And finally, I bought 8 pairs of Deans connectors for connecting the battery the the system. At the end I used only one but its always good to have more of these parts around. Their price was 4 GBP or $6.85.

Later, when building the quadcopter I realised that I need heat shrink tubing (I had no idea that it existed) so I borrowed some from a friend and ordered more from eBay for $3.5:

Heatshrink Tubing Red Black 6 Metre Pack Sleeving Kit

So here is a summary of the parts and costs for my first quadcopter. This is not the full price I paid in order to get it up in the air. This process took me about 3 months and I had to replace countless propellors and some engines as I’ll describe. This summary is how much it could cost me to build a similar high-end quadcopter today.

[table id=1 /]

The total (initial) cost of my quadcopter 1 was: $543.45 in addition to the $380 I spent on the transmitter.