First Parts

I was always fascinated from anything that flies! Ok, let me rephrase that a little bit to be more accurate! I was always fascinated from all the man made objects that are capable of flying! I am not saying that I am not appreciating the nature; just that I admire more the capabilities and speed that the human race is showing over this little period of time (compared to nature at least)!

And because I am going to be out of the subject soon I will get back on track now. I never owned a model airplane or helicopter or anything else during my childhood. At least nothing that can fly even 5cm from the ground for just 5 seconds. Yes, despite my passion… I never did! And then the years wend by and the flame somehow hided behind other stuffs. But it was always there!

One Sunday morning while I was watching a few YouTube videos about commercial “drones” I said: “F**k it! I will make my own!”
Yes! It was exactly like that! I am not kidding, I am not exadurating nor anything else.

I open multiple tabs on my browser for multiple days! Months to be honest! I subscribed to YouTube channels; download videos and manuals, read countless forum threads, hold notes about everything etc. Every day I became more and more oriented to the subject and somehow I was feeling like a pro even without a single hour of flight in my flight book (at least with multirotors).

I figure out that the tricopter form factor is the best for me. Not because it’s more easier to fly with (a slow speed foamy airplane is the best for that matter) but because it incudes what I need! I am living in a city and the free open spaces (without crowds) are sometimes a rare thing. Together with that the tricopter can hover (wow!) and it’s cheaper to make it compared to other multicopters.

I decided to use mainly the HobbyKing web store. It’s cheap; it has good positive feedbacks and includes warehouses both in China and in Europe/USA. Together with that, eBay and my local stores fulfilled my list of parts. I split the items I needed into multiple orders. With that way I can process them better without to over inform my brain. On top of that, multiple orders are somehow mirrored to multiple gift box unboxing’s! I put the first items on the web basket and hit the order button!

After a couple of weeks the first box was here! I was really excited about that, as this would be the beginning of my tricopter project! I cut the box with my old trusted knife and the story began! A few sheets of plastic bubble wrapping and a pillow filed with air from Asia were protecting the parts.

I removed everything and the first look of the components was in front of my eyes. I immediately figure out that the two black boxes were holding the brushless motors.

Those were consuming almost 40% of the box and my brain without even noticing it took the first one out!

Some strange (at least to me) Chinese letters or symbols on the side of the black box. I am guessing that it is translated to “Power” as it’s close together with the actual theoretical power of the motor (300W). But if I am mistaken, then I will be really happy if someone makes a translation to me on the comments bellow.

On top, the barcode and the name of the motor. It is the DT-750 from HexTronik. The “750” it basically means how many rotations per minute will have per every volt you put of its input. In the spec sheets this it defined as KV and is a unit that you have to pay attention when you are building a multicopter.

A lower KV motor can handle a bigger diameter propeller with greater pitch more easily compared to a higher KV motors, that are best suited for smaller props. And you want bigger props because of thrust! Have in mind that multicopters are flying more like helicopters and not like planes. In other words you need your multicopter to handle its weigh properly if you want to hover and fly stably/safely.

On the other hand, if you want a copter that can perform aerobatics and change it’s position fast, like a bee, then you have to choose small props with high KV brushless motors. This combination will output your control commands more rapidly to the environment.

And after this small brake filed with info about motors and aerodynamics I am continuing with the unboxing! The box lid of the DT-750 was holding on with a little bit of clear tape. I cut the one side and put the lid aside. You can clearly recognize the shape of the motor with the large bell and the ridiculously long shaft! Everything is protected with a zippie bag (or how else the name of this thing is).

From the side it looks even stranger! I have to cut this shaft in size but I still don’t know the actual length that I need. I can mount the prop without even cutting the shaft, but the size of it will be a messenger of bad news during a crash! Smaller thing hold their geometrical characteristics better in non-regular situations.

The second job I should do latter on is to solder some bullet connectors on the end of the three cables. The majority of those motors comes with those connectors pre soldered and ready for use but I am getting what I am paying here! Those are cheap motors… and they cut a little bit of money for here!

All the remaining parts were inside another bag. Pretty good packing method that should be followed by other companies as well!

The most pronounced item in here was the ESC. This stands for Electronic Speed Controller. I choose a Turnigy Puls 18. This can handle 18A continuously and something like 22A for peaks no longer than a few seconds.

It has two inputs. The first one is the power coming from the battery or any other source (input range 5.6V – 16.8V). The second is a three-pin cable (ground, power, signal -> black, red, white) that acts as the transition line that will carry the speed commands. Those commands are encoded into a pulse width modulation (PWM) stream.

The output is three wires. Those are outputting the same signal but they are activated in a predefined periods (in phase difference) in order to put the motor in movement. The direction of rotation is also defined from how those three cables are connected to the motor. For example if you swap two connections then the motor will spin in the different direction.

And those white plastics are front wheel steering arms. At least they are mend for this job. I am going to use them as the base for the tail yaw mechanism of my tricopter. An idea of David Windestål.

Following with the unboxing, the last two items are the XT60 connectors and the M4 locking nuts.

The XT60 connectors can handle easily multiple amps (a need feature for projects like this one). For example a rough calculation for my project, gives me 54A passing thru this connector at max power! They include a cutout for reverse polarity protection. The bag includes ten connectors or five pairs. For future use I am going to use the male part of this connector more often but for now this bag of five pairs in more than I need!

Finally, the M4 locknuts are for the three DT-750 motors. I am using lock style ones as they are going to be of the shaft, holding down the propeller. My first plan was to use one per motor (the propeller will sandwiched between the bell and the hex nut) but I think that I will stick with two (prop between two hex nuts).

And the above two photos are for anyone interested for a close up of the Turnigy ESC. It’s still on the protected antistatic bag. When you open it you are going to find an info paper like the one on the last photo. Is double printed and carries info about setting and operation of the ESC.

 

Next: KK2.1 Board

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