Flying a Quadcopter with the Wii Remote and Arduino (2): More Materials

【Warning】
I strongly advise against flying this in any area where people or buildings are nearby.
The Wii Remote's sensors were not designed for RC use.
Loss of control, flyaways, and crashes are real risks.
Take full safety precautions before attempting anything like this.

Last time I covered the airframe components. Here's the rest of the materials list:

• Quadcopter airframe (frame / electronics / drive system)
• Propellers
• Battery
• Flight controller
• Receiver
• Transmitter
• Miscellaneous extras

Propellers

Hobby craft propellers from a hardware store won't work — they won't generate enough lift. Use multicopter-specific propellers.

For the HJ450 frame from last time, 7–10 inch props work. Larger generates more lift but risks hitting adjacent props; smaller feels more controllable.

A quadcopter has two motors spinning in reverse, so you need a pair of counter-rotating propellers.

Pick up plastic propellers from RC-E-Tech — get counter-rotating pairs in two colours, and buy extras.

Two colours because it's hard to tell front from back mid-flight; colour-coding the front and rear props solves that.

Carbon fibre propellers are now available on Amazon, but don't start with those.
A homemade copter is inherently unstable, and trying to fly one with a Wii Remote means it's going to run away and crash repeatedly at first.
Carbon fibre is extremely strong, so if it hits you it's serious — potentially blinding.
I got hit in the leg once and the bruise was spectacular.

Plastic props are still dangerous, but at least they break on impact — which is marginally better.
And carbon fibre is expensive, so it would be a costly mistake anyway.

Battery

Check on Amazon
You'll use a LiPo (Lithium Ion Polymer) battery. A typical spec is 11.1V, 3S, 30C, 2200mAh — which is probably gibberish the first time you read it.

"11.1V" is the voltage. The voltage determines the power circuitry, so don't substitute a different voltage.

"3S" is the cell count — three LiPo cells in one pack. Each cell is about 3.7V, so 3S = 11.1V.

"30C" is the burst rate — the maximum discharge capability. For a 2200mAh / 30C battery:
2200 mAh × 0.001 × 30C = 66A maximum discharge.
Higher means faster charging and handling higher current loads.

"2200mAh" is the capacity — enough to discharge at 2.2A for one hour.

Bigger seems better — but as I mentioned with props, you're going to crash a lot at first.
A damaged LiPo battery can catch fire or explode; once damaged, it has to be discarded.
Start cheap and low-capacity for practice.

Check on Amazon
Charging LiPo batteries requires a balance charger — a special charger that keeps all cells at equal voltage.

With a 3S pack, even if the total voltage is 11.1V, one cell might be at 2.0V while the other two are over 3.7V — which shortens the life of the higher-voltage cells.
The balance charger prevents this by equalising all cells during charge and also includes a conditioning discharge function.

Hyperion is the recommended brand but they're expensive — I use a cheap iMax unit.

Flight Controller

Check on Amazon
The brain of the quadcopter. Use a Multiwii SE V3.0.
I'm using V2.5, but V3.0 has horizontal-facing pins which should make assembly easier — or so I'd assume, having never used it.
Note: "SE" vs non-SE have different features; get the "SE" version.

The name has "Wii" in it, but it does NOT receive Wii Remote signals.
The name comes from its origin: someone smart hacked apart a Wii Remote, took the accelerometer, attached it to an Arduino, and built a flight controller from it. Hence "MultiWii." Incredible what people come up with.

Since it's Arduino-compatible, you flash the flight controller firmware via the Arduino IDE.
Details on that in a later part.

Check on Amazon
The FTDI USB-serial module I've mentioned before.
Needed to connect the Multiwii SE V2.5 to a PC.
The V3.0 apparently has a USB connector built in, so it may not be needed for that version.

Receiver

Finally — the Arduino UNO.
It receives the Wii Remote input via Bluetooth using a USB Host Shield and a Planex Bluetooth USB dongle, the same setup as the RC car build.
If you're using a SparkFun shield, a hardware mod is required — see the RC car post for details.

A normal RC build would use a commercial RC receiver here; since we want Wii Remote control, we're building a custom one with Arduino.

Bluetooth range is about 10 m — don't fly it out of range.

Check on Amazon (Arduino UNO) Check on Amazon (USB Host Shield) Check on Amazon (Bluetooth dongle)

Transmitter

A Wii Remote. Every household has a spare Wii Remote, right?
For reference, a proper RC transmitter runs ¥10,000 or more on its own.

Extras

Check on Amazon Of course you want aerial footage.
You'd love to mount a GoPro, but if you're going to do that, buy a proper DJI drone instead.

A regular compact camera is too heavy and destabilises the quad. It can work — I tried it — but it's marginal.

My recommendation: the Hoten X-Z-18. Terrible quality, but only 5g, and it records to micro SD.

The catch: it's designed for Walkera multirotors, has a proprietary connector that doesn't fit Arduino or Multiwii, and has no record button.
To trigger recording, you modify the cable to connect it, then send the correct pulse signal from Multiwii or Arduino.
I'll explain what signal to send in a future part.

Here's what it looks like. You'll get a sense of just how bad the quality is:



That's the full materials list.
Check on Amazon
To be honest, the parts alone cost more than buying several ready-made quads.
The path ahead is brutal.
Unless you're genuinely obsessed with building things, just give up now and buy something off the shelf.

More to come anyway.