Monday, October 20, 2014

Blackout MiniH Quad build log


It has been a long time since I have played with RC planes and decided that it was time to check out the drone game before it all gets banned, legislated against or relegated to the past by the fun police.

After looking at the options including just buying one off the shelf I decided it would be more fun to do the build more or less from scratch and learn how the insides work.


With a lot of sneaky work on Google, a few Gb in youTube videos and a flight of a DJI Phantom 2 I finally decided to go down the path of a mini quad.

The final selling point was that it would be good for first person view flight (FPV) and in the words of Justin Galbraith, would be like proximity flying in a wing suit without the risk of death.

You know you are getting old and semi responsible (read lazy) when you opt for a 220mm wide quad copter rather than allocating 10 years to skydiving and base jumping experience.

Anyhow, this is what I bought straight up to get this party started.

1 x Blackout MiniH quad frame (220mm)
1 x AfroFlight Naze32 Acro Flight Controller
4 x Afro ESC 20Amp speed controllers (SimonK Firmware)
4 x Cobra CM2208/20 2000kv Motors
12 x Gemfan 5030 Propellers - Green and Black, CW & CCW
4 x Turnigy nano-tech 1300mAh 3S 45~90C Lipo Packs
1 x FrSky D4R-II 4ch 2.4Ghz ACCST Receiver (w/telemetry)
1 x FrSky 2.4GHz TARANIS X9D Radio
5 x Male to Male servo leads
1 x Mini PC mount piezo buzzer (3 to 15v)
8 x M3 x 6 screws
12 x Rapstraps (4 would do but I wanted spares)


When buying the frame, I also bought a few spares for a crash kit including nylon screws and spacers. The extra props were also to make sure I had spares as all evidence suggested that crashes are common and props are the first to die. More on that later.

I also already had a good charger on hand for the LiPo batteries but have also added a cell balancer and parallel charging board so I can charge more than one battery at once and also ensure they remain healthy.

Links to bits:

Pretty much everything here can be found at various model shops but from Australia, this was the beptions on price I could find.

http://www.minihquad.com/

http://www.hobbyking.com/

http://boltrc.com/


Explaining what is what and why I bought what I bought

First up I have to thank Justin Galbraith for his input into this shopping list. He flys both a MiniH and a MiniX quad from Blackout so had a good insight into the set up that people are using and what works.

The list is also pretty close to the suggested equipment list on the Blackout website.

The frame:

The Blackout MiniH Quad is a 220mm H shaped quad copter, precision cut from carbon fiber sheet with a power distribution board and LEDs built in.

The majority of fasteners are M3 nylon screws so that in the event of a crash, cheap screws sheer off and protect the more expensive bits of the frame. In theory, in all but the most violent of crashes, a couple of props and screws later and you will be back flying.

I can already confirm that the design works as advertised.

The flight controller:

The Afroflight Naze32 Acro is the basic version of the Naze32 Funfly without the magnetometer (compass) and barometer. 
The acro version can control the quad (and other multirotor designs) without having the more fancy features like altitude hold and direction hold.

I understand it can be hooked up to a GPS but without the magnetometer and barometer it will struggle for useful accuracy.
The amazing thing here is that the whole Naze32 Acro package is only 36mm square and $27.00.

For that price you get the board with a bag of connectors that you need to solder on yourself so it is not the best place to start if you have not held a soldering iron before.

The speed controllers:

The speed controllers take inputs from the flight controller and tell the motors how fast to turn. As such there is one ESC per motor. 
The ESC is a reasonably complicated little computer with on board software (firmware) to allow it to do it's job.

As such when buying them, there are a number of ESCs that are already programmed for use in multirotors. If you get a standard ESC that would be used in an RC plane for example then you will have to learn about flashing firmware that will allow it to work properly with a mutlirotor.

The suggested ESCs for this quad are 12amp but I have gone for a larger 20amp ESC so that I can either move them to a larger quad down the track or if I upgrade the frame arms to the larger 6" arms I can go for bigger motors/props.

The Afro HV 20A multi rotor ESC is supplied with the SimonK firmware for multirotors and can handle up to an 8 Cell LiPo.

In hindsight, I probably should have just gone with 12amp ESCs as this quad will never have more than a 4 cell battery and I will probably just buy new gear for a new quad if I go that way down the track. It is all evolving so fast and is relatively cheap so who knows what will be available in a month or two.

The downside of the 20amp ESCs are their size and weight. On this tiny frame it is a bit of squeeze getting them all to fit and I have wasted about 60 grams :(

The Motors:

These were purchased direct from Blackout as most people did not have them in stock. The Cobra motors are well regarded for their performance and reliability and are half the price of the next best option.

They use a M3 mounting screw however the supplied screws are too short to use with the 3mm thick arms on the MiniH quad frame.

You will need to buy or acquire some M3 x 6mm screws so you can fit the motors.

The other quirk is that the arms have spacing for the M3 screws at 19mm pitch which will only allow two screws per motor. It seems to work fine. If you really want to use all four screws per motor then you will need to drill the extra two holes in the frame.

Finally, they come with nylock nuts for the prop shaft which is nice in a multirotor where the opposite rotation of two motors can cause a regular spinner to well, spin off!

Propellers:

The Gemfan 5030 props are matched well to the motors, are dirt cheap and as big as you can fit on this quad in the 5" short arm configuration. They come in packs of four with two clockwise and two counter clockwise blades.

Because I am starting flying visually, I have split the colours and put green on the front motors and black on the back to help with visibility and orientation.

I was warned that I would trash the props and I have now gone and bought a massive bag of 100 props to keep my flying adventurous and not be too worried about a prang taking me out of the air for a week while waiting for spares.

I can confirm that trees, doors, chairs, carpet, long grass and the Kavanagh Balloons factory building will all chew the props up really quick.

Batteries:

I knew very little about high performance LiPo batteries other than they are great for starting house fires if you are not careful when charging them.


Energy density in these things is impressive but it comes with the above risks. I would recommend doing a fair bit of reading on them if you are looking at playing with this stuff. I started here: http://www.rchelicopterfun.com/rc-lipo-batteries.html

I still have a lot to learn in this area so in the end I went for the Turnigy nano-tech 1300mAh 3S 45~90C Lipo Packs for no other reason that it was what was suggested by Justin. I could probably have gone for a lower discharge rating than the 45~90C but the higher the C rating (in this case 45 average/90 peak) the less chance of damaging your batteries by asking too much of them.

Next post...The radio gear and the build